Topic 2: CellsTopic 2: Cells

2.1.1 Outline the cell theory.   2.1.1 Outline the cell theory.  

Discuss the theory that living Discuss the theory that living organisms are composed of cells.organisms are composed of cells.

The The Cell Theory states that: states that: – All organisms are composed of one or more All organisms are composed of one or more

cells. cells. – All cells arise from pre-existing cells. All cells arise from pre-existing cells. – All vital functions of an organism occur All vital functions of an organism occur

within cells. within cells. – Cells are the most basic unit of life. Cells are the most basic unit of life. – Cells contain hereditary information. Why?Cells contain hereditary information. Why?

2.1.2 Discuss the evidence for 2.1.2 Discuss the evidence for the cell theory. the cell theory. 

What is Evidence?What is Evidence? What is a theory?What is a theory? Evidence for Cell theory:Evidence for Cell theory:

– Living tissues= composed of cellsLiving tissues= composed of cells– Cells of an organism can sometimes survive on Cells of an organism can sometimes survive on

their own but smaller cell components can their own but smaller cell components can NOT. NOT.

– Classic experiments showed that spontaneous Classic experiments showed that spontaneous generation of life= impossible. generation of life= impossible.

The cell theory has amassed tremendous The cell theory has amassed tremendous credibility through the use of the microscope in the credibility through the use of the microscope in the following:following:

Robert Hooke- Robert Hooke- studied cork and found little tiny studied cork and found little tiny compartments that he called cellscompartments that he called cells

Antonie Van Leeuwenhoek- Antonie Van Leeuwenhoek- observed the first observed the first living cells, called them 'animalcules' meaning little living cells, called them 'animalcules' meaning little animalsanimals

Schleiden-Schleiden- stated that plants are made of stated that plants are made of 'independent, separate beings' called cells'independent, separate beings' called cells

Schwaan- Schwaan- made a similar statement to Schleiden made a similar statement to Schleiden about animalsabout animals

When scientists started to look at the structures of When scientists started to look at the structures of organisms under the microscope they discovered that all organisms under the microscope they discovered that all living organisms where made up of these small units which living organisms where made up of these small units which they proceeded to call cells. When these cells were taken they proceeded to call cells. When these cells were taken from tissues they were able to survive for some period of from tissues they were able to survive for some period of time. Nothing smaller than the cell was able to live time. Nothing smaller than the cell was able to live independently and so it was concluded that the cell was the independently and so it was concluded that the cell was the smallest unit of life. For some time, scientists thought that smallest unit of life. For some time, scientists thought that cells must arise from non-living material but it was cells must arise from non-living material but it was eventually proven that this was not the case, instead they eventually proven that this was not the case, instead they had to arise from pre-exsisting cells. An experiment to had to arise from pre-exsisting cells. An experiment to prove this can be done as follows: prove this can be done as follows:   

Take two containers and put food in both of theseTake two containers and put food in both of these Sterilize both of the containers so that all living organisms Sterilize both of the containers so that all living organisms

are killedare killed Leave one of the containers open and seal the other closed Leave one of the containers open and seal the other closed  What will happen is that in the open container mold will What will happen is that in the open container mold will

start to grow but in the container that was sealed no mold start to grow but in the container that was sealed no mold will be present. The reason for this is because in the open will be present. The reason for this is because in the open container, cells are able to enter the container from the container, cells are able to enter the container from the external environment and start to divide and grow. external environment and start to divide and grow. However, due to the seal on the other container no cells will However, due to the seal on the other container no cells will be able to enter and so no mold will develop, proving that be able to enter and so no mold will develop, proving that cells cannot arise from non-living material. cells cannot arise from non-living material. 

Exceptions to aspects of the Exceptions to aspects of the theory?theory?

Skeletal muscle – Skeletal muscle – multinucleate cytoplasm multinucleate cytoplasm

Some fungal Some fungal hyphae- - multinucleate cytoplasm. multinucleate cytoplasm.

Extracellular material Extracellular material (material outside the cell (material outside the cell membrane), such as teeth membrane), such as teeth and bone, forms a and bone, forms a significant part of the body. significant part of the body.

Some biologists consider Some biologists consider unicellular organisms to be unicellular organisms to be acellular. acellular.

Do you think these constitute Do you think these constitute exceptions to cell theory? exceptions to cell theory? Justify your answer. Justify your answer.

Note: this slide=not in new Note: this slide=not in new syllabus…syllabus…

2.1.3 State that unicellular organisms 2.1.3 State that unicellular organisms carry out all the functions of life.carry out all the functions of life.

Discussion: What are the necessary functions Discussion: What are the necessary functions of life?of life?

CC—Made of one or more than on cell—Made of one or more than on cell HH—Maintain Homeostasis —Maintain Homeostasis EE—Metabolize energy—Metabolize energy DD—Made of DNA—Made of DNA DD—Develop and Grow—Develop and Grow AA—Adapt —Adapt RR—Reproduce—Reproduce SS—Respond to stimuli—Respond to stimuli

2.1.42.1.4Compare the relative sizes of molecules, cell Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, membrane thickness, viruses, bacteria, organelles and cells, using appropriate SI units.organelles and cells, using appropriate SI units.

““Molly Membrane’s Virus Backed Off Most Cells”Molly Membrane’s Virus Backed Off Most Cells”

Molecules (1 nm) (Smallest) Molecules (1 nm) (Smallest) Cell membrane thickness (10 nm) Cell membrane thickness (10 nm) Viruses (100 nm) Viruses (100 nm) Bacteria (1 µm) Bacteria (1 µm) Organelles (<10 µm) Organelles (<10 µm) Most cells (<100 µm) (Largest) Most cells (<100 µm) (Largest)

Interactive Interactive http://www.cellsalive.com/howbig.htm

2.1.52.1.5Calculate linear Calculate linear magnification of magnification of drawings.drawings.– Drawings should Drawings should

show cells and cell show cells and cell ultrastructure. ultrastructure. Include: Include:

– A A scale barscale bar: |------| = 1 : |------| = 1 µm µm

– MagnificationMagnification: ×250 : ×250 To calculate To calculate

magnificationmagnification: : – Magnification = Magnification =

Measured Size of Measured Size of Diagram ÷ Actual Size Diagram ÷ Actual Size of Objectof Object

2.1.62.1.6Explain the importance of Explain the importance of

the surface area to the surface area to volume ratio as a volume ratio as a factor limiting cell size.factor limiting cell size.– The rate of The rate of

exchange of exchange of materials materials (nutrients/waste) (nutrients/waste) and energy (heat) is and energy (heat) is a function of its a function of its surface area. (Why?)surface area. (Why?)

– As cell size As cell size increases, the increases, the surface area to surface area to volume ratio volume ratio decreases decreases

This can make This can make the exchange the exchange rate inadequate rate inadequate for large cellsfor large cells

– Cell size, therefore, Cell size, therefore, remains smallremains small

2.1.7 State that multicellular organisms show 2.1.7 State that multicellular organisms show

emergent properties.emergent properties.   Multicellular organisms show emergent Multicellular organisms show emergent

properties. For example: cells form tissues, properties. For example: cells form tissues, tissues form organs, organs form organ systems tissues form organs, organs form organ systems and organ systems form multicellular organisms. and organ systems form multicellular organisms. The idea is that the whole is greater than the The idea is that the whole is greater than the composition of its parts. For example your lungs composition of its parts. For example your lungs are made of many cells. However, the cells by are made of many cells. However, the cells by themselves aren’t much use. It is the many cells themselves aren’t much use. It is the many cells working as a unit that allow the lungs to perform working as a unit that allow the lungs to perform their function.their function.

Define Define tissuetissue, , organorgan and and organ systemorgan system..

TissueTissue: An integrated : An integrated group of cells that share group of cells that share stucture and are adapted stucture and are adapted to perform a similar to perform a similar function. function.

OrganOrgan: A combination of : A combination of two or more tissues which two or more tissues which function as an integrated function as an integrated unit, performing one or unit, performing one or more specific functions. more specific functions.

Organ systemOrgan system: A group of : A group of organs that specialize in a organs that specialize in a certain function together. certain function together.

2.1.82.1.8ExplainExplain that cells in that cells in multicellular multicellular organisms organisms differentiate to differentiate to carry out carry out specialized specialized functions by functions by expressing some of expressing some of their genes but not their genes but not others.others.– Differentiation: :

becoming specialized becoming specialized in structure and in structure and function. function.

– Supporting examples?Supporting examples?– Multicellular organisms Multicellular organisms

show show emergent emergent properties (What??)properties (What??)

See Previous See Previous slide…slide…

Video: http://www.pbs.org/wgbh/nova/sciencenow/archive/title-m-z.html

2.1.9 State that stem cells retain the capacity to divide and 2.1.9 State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways. have the ability to differentiate along different pathways. 

Stem cells Stem cells – Retain the capacity to divideRetain the capacity to divide– Have the ability to differentiate Have the ability to differentiate

along different pathways.along different pathways. Therapeutic Use:Therapeutic Use:

– Many possibilitiesMany possibilities Repair of damaged tissue Repair of damaged tissue

– Actual usesActual uses Restore neural insulation tissue Restore neural insulation tissue

in rats.in rats. Use of umbilical cord blood stem Use of umbilical cord blood stem

cells for leukemia patients. cells for leukemia patients. – Sources and ethical issues:Sources and ethical issues:

EmbryonicEmbryonic placenta/umbilical cordplacenta/umbilical cord Many other tissues have stem Many other tissues have stem

cellscells Pluripotent vs. Pluripotent vs.

totipotent/omnipotenttotipotent/omnipotent

Video: http://www.pbs.org/wgbh/nova/sciencenow/archive/title-m-z.html

2.1.10 Outline one therapeutic use of stem cells.2.1.10 Outline one therapeutic use of stem cells.   Bone marrow transplants are one of the many therapeutic uses of stem cells. Stem Bone marrow transplants are one of the many therapeutic uses of stem cells. Stem

cells found in the bone marrow give rise to the red blood cells, white blood cells and cells found in the bone marrow give rise to the red blood cells, white blood cells and platelets in the body. These stem cells can be used in bone marrow transplants to platelets in the body. These stem cells can be used in bone marrow transplants to treat people who have certain types of cancer. treat people who have certain types of cancer. 

When a patient has cancer and is given high doses of chemotherapy, the When a patient has cancer and is given high doses of chemotherapy, the chemotherapy kills the cancer cells but also the normal cells in the bone marrow. chemotherapy kills the cancer cells but also the normal cells in the bone marrow. This means that the patient cannot produce blood cells. So before the patient is This means that the patient cannot produce blood cells. So before the patient is treated with chemotherapy, he or she can undergo a bone marrow harvest in which treated with chemotherapy, he or she can undergo a bone marrow harvest in which stem cells are removed from the bone marrow by using a needle which is inserted stem cells are removed from the bone marrow by using a needle which is inserted into the pelvis (hip bone). Alternatively, if stem cells cannot be used from the into the pelvis (hip bone). Alternatively, if stem cells cannot be used from the patient then they can be harvested from a matching donor. After the chemotherapy patient then they can be harvested from a matching donor. After the chemotherapy treatment the patient will have a bone marrow transplant in which the stem cells treatment the patient will have a bone marrow transplant in which the stem cells are transplanted back into the patient through a drip, usually via a vein in the chest are transplanted back into the patient through a drip, usually via a vein in the chest or the arm. These transplanted stem cells will then find their way back to the bone or the arm. These transplanted stem cells will then find their way back to the bone marrow and start to produce healthy blood cells in the patient. Therefore the marrow and start to produce healthy blood cells in the patient. Therefore the therapeutic use of stem cells in bone marrow transplants is very important as it therapeutic use of stem cells in bone marrow transplants is very important as it allows some patients with cancer to undergo high chemotherapy treatment. allows some patients with cancer to undergo high chemotherapy treatment. Without this therapeutic use of stem cells, patients would only be able to take low Without this therapeutic use of stem cells, patients would only be able to take low

doses of chemotherapy which could lower their chances of curing the diseasedoses of chemotherapy which could lower their chances of curing the disease..

When a patient has cancer and is given high doses of chemotherapy, When a patient has cancer and is given high doses of chemotherapy, the chemotherapy kills the cancer cells but also the normal cells in the the chemotherapy kills the cancer cells but also the normal cells in the bone marrow. This means that the patient cannot produce blood cells. bone marrow. This means that the patient cannot produce blood cells. So before the patient is treated with chemotherapy, he or she can So before the patient is treated with chemotherapy, he or she can undergo a bone marrow harvest in which stem cells are removed from undergo a bone marrow harvest in which stem cells are removed from the bone marrow by using a needle which is inserted into the pelvis the bone marrow by using a needle which is inserted into the pelvis (hip bone). Alternatively, if stem cells cannot be used from the patient (hip bone). Alternatively, if stem cells cannot be used from the patient then they can be harvested from a matching donor. After the then they can be harvested from a matching donor. After the chemotherapy treatment the patient will have a bone marrow chemotherapy treatment the patient will have a bone marrow transplant in which the stem cells are transplanted back into the transplant in which the stem cells are transplanted back into the patient through a drip, usually via a vein in the chest or the arm. These patient through a drip, usually via a vein in the chest or the arm. These transplanted stem cells will then find their way back to the bone transplanted stem cells will then find their way back to the bone marrow and start to produce healthy blood cells in the patient. marrow and start to produce healthy blood cells in the patient. Therefore the therapeutic use of stem cells in bone marrow transplants Therefore the therapeutic use of stem cells in bone marrow transplants is very important as it allows some patients with cancer to undergo is very important as it allows some patients with cancer to undergo high chemotherapy treatment. Without this therapeutic use of stem high chemotherapy treatment. Without this therapeutic use of stem cells, patients would only be able to take low doses of chemotherapy cells, patients would only be able to take low doses of chemotherapy which could lower their chances of curing the disease.which could lower their chances of curing the disease.

2.1.10 - Outline one use of therapeutic stem cells .2.1.10 - Outline one use of therapeutic stem cells .  

1.Non-Hodgkins Lymphoma is a cancerous disease of 1.Non-Hodgkins Lymphoma is a cancerous disease of the lymphatic system: the lymphatic system:

   Outline of the disease: Outline of the disease: 1. patient requires heavy does of radiation and or 1. patient requires heavy does of radiation and or

chemotherapy. This will destroy health blood tissue as chemotherapy. This will destroy health blood tissue as well as the diseased tissue. well as the diseased tissue.

2. Blood is filtered for the presence of peripheral 2. Blood is filtered for the presence of peripheral ((blood-forming) blood-forming) stem cells. Cells in the general stem cells. Cells in the general circulation that can still differentiate into different circulation that can still differentiate into different types of blood cell otherwise known as stem cells. types of blood cell otherwise known as stem cells.

3. Bone marrow can be removed before treatment.3. Bone marrow can be removed before treatment. 4. Chemotherapy supplies toxic drugs to kill the 4. Chemotherapy supplies toxic drugs to kill the

cancerous cells.cancerous cells. 5. Radiation can be used to kill the cancerous cells. In 5. Radiation can be used to kill the cancerous cells. In

time however the cancerous cells adapt to this time however the cancerous cells adapt to this treatment so that radiation and chemotherapy are treatment so that radiation and chemotherapy are often used together.often used together.

6. Post radiation/ chemotherapy means that the 6. Post radiation/ chemotherapy means that the patients health blood tissues is also destroyed by the patients health blood tissues is also destroyed by the treatment.treatment.

7. Health stem cells or marrow cells can be 7. Health stem cells or marrow cells can be transplanted back to produce blood cells again transplanted back to produce blood cells again

Bone marrow transplants Bone marrow transplants only work because what only work because what you are actually you are actually transplanting is the transplanting is the hematopoietic (blood cells hematopoietic (blood cells that give rise to all the that give rise to all the other blood cells) stem other blood cells) stem cells in the marrow. cells in the marrow.

peripheral blood stem cells-- peripheral blood stem cells-- method of replacing blood-method of replacing blood-forming stem cells destroyed, for forming stem cells destroyed, for example, by cancer treatment. example, by cancer treatment. Immature blood cells Immature blood cells hematopoietic (blood cells that hematopoietic (blood cells that give rise to all the other blood give rise to all the other blood cells) stem cells in the circulating cells) stem cells in the circulating blood that are similar to those in blood that are similar to those in the bone marrow are collected by the bone marrow are collected by apheresis from a potential donor.apheresis from a potential donor.

Cord blood stem cells, can be Cord blood stem cells, can be used in lieu of bone marrow, used in lieu of bone marrow, making being a donor FAR easier making being a donor FAR easier today than in decades past.today than in decades past.

2.2.1 Draw and Label a diagram of the Ultrastructure of 2.2.1 Draw and Label a diagram of the Ultrastructure of Eschrichia coli (E. coli) Eschrichia coli (E. coli) as an example of a Prokaryote as an example of a Prokaryote

Draw a generalized Draw a generalized prokaryotic cell as seen in prokaryotic cell as seen in electron micrographselectron micrographs

The diagram should include:The diagram should include:– the cell wall, the cell wall, – plasma membrane,plasma membrane,– cytoplasm,cytoplasm,– PiliPili– FlagellaFlagella– RibosomesRibosomes– nucleoid ( region nucleoid ( region

containing naked DNA). containing naked DNA).

2.2.2 Anotate the diagram from 2.2.1 with the function of each named structure

Cell Wall: Maintains the cell's shape and give protection.

Plasma Membrane: Regulates the Plasma Membrane: Regulates the flow of materials (nutrients, waste, flow of materials (nutrients, waste, oxygen, etc.) into and out of the oxygen, etc.) into and out of the cell. cell.

Mesosome: A tightly folded region Mesosome: A tightly folded region of cell membrane. (has attached of cell membrane. (has attached proteins for proteins for respiration/photosynthesis)respiration/photosynthesis)

Cytoplasm: Holds and suspends the Cytoplasm: Holds and suspends the cell's ribosomes and enzymes. cell's ribosomes and enzymes. Region where glycolysis occurs. Region where glycolysis occurs.

Ribosome: Protein synthesis. Ribosome: Protein synthesis. NucleoidNucleoid region: Contains the cell's region: Contains the cell's

genetic material (naked DNA) genetic material (naked DNA) Slime capsule:Slime capsule: Used as energy Used as energy

storagestorage Flagella: Flagella: MobilityMobility Pili: Pili: Interacting with other cellsInteracting with other cells Plasmid: Plasmid: Extra DNA which helps Extra DNA which helps

with adaptations to the with adaptations to the environmentenvironment

2.2.3 Identify the structures from 2.2.1 in 2.2.3 Identify the structures from 2.2.1 in electron micrographs of electron micrographs of E.ColiE.Coli

2.2.4 State that prokaryote cells 2.2.4 State that prokaryote cells divide by Binary Fissiondivide by Binary Fission

Prokaryotic cells Prokaryotic cells divide by binary divide by binary fissionfission– AsexualAsexual– splits directly into splits directly into

two equal-sized two equal-sized offspring, each with offspring, each with a copy of the a copy of the parent's genetic parent's genetic material. material.

FYI for future referenceFYI for future reference State that prokaryotes State that prokaryotes

show a wide range of show a wide range of metabolic activity metabolic activity including fermentation, including fermentation, photosynthesis and photosynthesis and nitrogen fixation.nitrogen fixation.

EX.EX. Cyanobacteria (Cyanobacteria (blue-green blue-green

algaealgae)--photosynthesis. )--photosynthesis. Bacteria can convert organic Bacteria can convert organic

substances into other organic substances into other organic substances. (i.e., glucose to substances. (i.e., glucose to lactic acid during lactic acid during anaerobic respiration) )

Nitrogen fixation– convert NNitrogen fixation– convert N2 2 in in air to ammonia. air to ammonia.

Cyanobacteria

BacteriaBacteria

Video: http://www.pbs.org/wgbh/nova/sciencenow/3401/04.html

Harvard AnimationHarvard Animation

Why are cells cool?Why are cells cool? http://multimedia.mcb.harvard.edu/

Eukaryotic CellsEukaryotic Cells2.3.1Draw a 2.3.1Draw a

diagram to show diagram to show the ultrastructure the ultrastructure of a generalized of a generalized animal cell (liver animal cell (liver cell) as seen in cell) as seen in electron electron micrographs.micrographs.

Should includeShould include free ribosomesfree ribosomes roughrough smooth ERsmooth ERLysosomeLysosomeGolgi apparatus Golgi apparatus mitochondriamitochondria

nucleusnucleus. .

An Animal CellAn Animal Cell

Define Define organelleorganelle.. An An organelle is a discrete is a discrete

structure within a cell, and has structure within a cell, and has a specific function. a specific function.

2.3.2 Annotate the diagram 2.3.2 Annotate the diagram from 2.3.1 with the funciton of from 2.3.1 with the funciton of each named structureeach named structure– mitochondrion– golgi bodygolgi body– endoplasmic reticulumendoplasmic reticulum– vacuolevacuole– lysosomelysosome– ribosome In contrast to the ribosome In contrast to the

other organelles, they are other organelles, they are not surrounded by a not surrounded by a membrane.membrane.

– centriole (Unique to animal centriole (Unique to animal cells)cells)

– chloroplastchloroplast

ORGANELLE MAIN FUNCTIONS DIMENSIONS

Nucleus Cell division, protein synthesis

10 µm diameter

Mitochondrion Respiration pathways

1.0 to 12.5 µm

Chloroplast Photosynthetic pathways

5 to 10 µm diameter

Lysosome Digestion, recycling & isolation

0.5 to 3.0 µm diameter

Golgi apparatus Secretion, reprocessing, lysosome synthesis

Cisternae: 0.5µm thick, l-3µm diameter

Endoplasmic Reticulum (ER)

Support, Golgi apparatus synthesis.

26 to 56 nm thick

Ribosome Protein synthesis

20 nm diameter

EUKARYOTE CELL ULTRASTRUCTURE

Summary of the major cell organelles:Practice: What are the respective magnifications of the cell as a whole and of each of its organelles in the following cell picture?

State one function of each of State one function of each of these organelles: ribosomes, these organelles: ribosomes, rough endoplasmic reticulum, rough endoplasmic reticulum, lysosome, Golgi apparatus, lysosome, Golgi apparatus, mitochondrion and nucleus.mitochondrion and nucleus.

Ribosomes: protein synthesis Ribosomes: protein synthesis Rough endoplasmic reticulum Rough endoplasmic reticulum

(rER): Packages proteins(rER): Packages proteins Lysosome: digests old cell parts, Lysosome: digests old cell parts,

macromolecules (food) and macromolecules (food) and engulfed viruses/bacteriaengulfed viruses/bacteria

Golgi apparatus: Modifies, stores : Modifies, stores and routes products of the and routes products of the endoplasmic reticulum. endoplasmic reticulum.

Mitochondrion: cellular respiration. Mitochondrion: cellular respiration. Nucleus: contains genetic material Nucleus: contains genetic material

–transcription occurs here. –transcription occurs here.

Ribosomes: Ribosomes: Found either floating free in the cytoplasm or attached Found either floating free in the cytoplasm or attached to the surface of the rough endoplasmic reticulum and in to the surface of the rough endoplasmic reticulum and in mitochondria and chloroplast. Ribosomes are the site of protein mitochondria and chloroplast. Ribosomes are the site of protein synthesis as they translate messenger RNA to produce proteins.synthesis as they translate messenger RNA to produce proteins.

Rough endoplasmic reticulum: Rough endoplasmic reticulum: Can modify proteins to alter their Can modify proteins to alter their function and/or destination. Synthesizes proteins to be excreted function and/or destination. Synthesizes proteins to be excreted from the cell.from the cell.

Lysosome: Lysosome: Contains many digestive enzymes to hydrolyze Contains many digestive enzymes to hydrolyze macromolecules such as proteins and lipids into their monomers.macromolecules such as proteins and lipids into their monomers.

Golgi apparatus: Golgi apparatus: Receives proteins from the rough endoplasmic Receives proteins from the rough endoplasmic reticulum and may further modify them. It also packages proteins reticulum and may further modify them. It also packages proteins before the protein is sent to it’s final destination which may be before the protein is sent to it’s final destination which may be intracellular or extracellular.intracellular or extracellular.

Mitochondrion: Mitochondrion: Is responsible for aerobic respiration. Converts Is responsible for aerobic respiration. Converts chemical energy into ATP using oxygen.chemical energy into ATP using oxygen.

Nucleus: Nucleus: Contains the chromosomes and therefore the hereditary Contains the chromosomes and therefore the hereditary material. It is responsible for controlling the cell. Transcription material. It is responsible for controlling the cell. Transcription occurs here. occurs here.

2.3.3 Identify structures from 2.3.1 in 2.3.3 Identify structures from 2.3.1 in electron micrographs of liver cellselectron micrographs of liver cells

1. Nucleus1. Nucleus2. Mitochondria2. Mitochondria3. Cell border3. Cell border4. Nucleoli4. Nucleoli5. Red blood cell 5. Red blood cell

Another exampleAnother example

Prokaryotic cells vs. Eukaryotic cells Prokaryotic cells vs. Eukaryotic cells Contain naked DNA vs. DNA associated with protein Contain naked DNA vs. DNA associated with protein

DNA in cytoplasm vs. DNA enclosed in a nuclear envelope DNA in cytoplasm vs. DNA enclosed in a nuclear envelope No membrane-enclosed organelles vs. membrane-enclosed No membrane-enclosed organelles vs. membrane-enclosed

organelles (e.g., mitochondria, chloroplasts) organelles (e.g., mitochondria, chloroplasts) 70S vs. 80S ribosomes70S vs. 80S ribosomes

No mitochondria vs. MitochondriaNo mitochondria vs. Mitochondria Circular DNA vs. Linear DNACircular DNA vs. Linear DNA

Flagella lack internal microtubules vs. Flagella have Flagella lack internal microtubules vs. Flagella have microtubules. microtubules.

No mitosis/Meiosis (Reproduce via Binary fission vs. No mitosis/Meiosis (Reproduce via Binary fission vs. Mitosis/Meiosis Mitosis/Meiosis

2.3.5 State three differences between 2.3.5 State three differences between plant and animal cells.plant and animal cells.

Only plant cells have:Only plant cells have: Cell walls Cell walls ChloroplastsChloroplasts Large central vacuoles and tonoplast Large central vacuoles and tonoplast Plasmodesmata (microscopic channels Plasmodesmata (microscopic channels

which traverse the cell walls of plan cells which traverse the cell walls of plan cells and some algal cells, enabling transport and some algal cells, enabling transport and communication between them and communication between them

Starch granules for storage of Starch granules for storage of carbohydrates carbohydrates

Only animal cells have:Only animal cells have: Centrioles Centrioles Lysosomes—careful, I have read where some Lysosomes—careful, I have read where some plants have lysosomes. plants have lysosomes. Glycogen for storage of carbohydrateGlycogen for storage of carbohydrate

Also: Plant cells usually have much less Also: Plant cells usually have much less cholesterol in their plasma membranes.cholesterol in their plasma membranes.Remember--Remember--Cholesterol is required to build and maintain membranes; it modulates membrane fluidity

Said a little differentlySaid a little differently Animal cells only have a Animal cells only have a plasma membrane and no cell plasma membrane and no cell

wallwall. Whereas plant cells have a . Whereas plant cells have a plasma membrane and a plasma membrane and a cell wallcell wall. Animal cells do not have chloroplasts whereas . Animal cells do not have chloroplasts whereas plant cells do for the process of photosynthesis.plant cells do for the process of photosynthesis.

Animal cells store Animal cells store glycogenglycogen as their carbohydrate resource as their carbohydrate resource whereas plants store whereas plants store starchstarch..

Animal cells do not usually contain any vacuoles and if Animal cells do not usually contain any vacuoles and if present they are small or temporary. On the other hand present they are small or temporary. On the other hand plants have a large vacuole that is always present.plants have a large vacuole that is always present.

Animal cells can change shape due to the lack of a cell wall Animal cells can change shape due to the lack of a cell wall and are usually rounded whereas plant cells have a fixed and are usually rounded whereas plant cells have a fixed shape kept by the presence of the cell wall.shape kept by the presence of the cell wall.

2.3.6 Outline two roles of 2.3.6 Outline two roles of extracellular components extracellular components

Animal cellsAnimal cells– Extracellular matrix (secreted Extracellular matrix (secreted

glycoproteins)glycoproteins)SupportSupportAdhesion Adhesion MovementMovement

2.3.6 Outline two roles of extracellular 2.3.6 Outline two roles of extracellular components components Plant cell wallPlant cell wall

– Main component= celluloseMain component= cellulose Cellulose molecules are arranged in bundlesCellulose molecules are arranged in bundles give the cell wall great tensile strength and allow give the cell wall great tensile strength and allow

high pressures to develop inside the cell. high pressures to develop inside the cell. Functions= structure, support, protection. Functions= structure, support, protection.

……State the composition and function of the plant cell wall. (Just State the composition and function of the plant cell wall. (Just an FYI—not an IB component)an FYI—not an IB component)

Three layers: Three layers: – middle lamella (between adjacent cells– attachment) middle lamella (between adjacent cells– attachment) – primary cell wall primary cell wall – secondary cell wall (stronger– has lignin for strength)secondary cell wall (stronger– has lignin for strength)

Functions= structure, support, protection.Functions= structure, support, protection.

MembranesMembranes 2.4.1 Draw a diagram of the fluid mosaic model.2.4.1 Draw a diagram of the fluid mosaic model. http://www.youtube.com/watch?v=Qqsf_UJcfBchttp://www.youtube.com/watch?v=Qqsf_UJcfBc Diagram should showDiagram should show

– the phospholipid bilayer, the phospholipid bilayer, – cholesterol, cholesterol, – glycoproteins,glycoproteins,– Integral proteinsIntegral proteins– peripheral proteins. peripheral proteins. – Be sure you use the term “phospholipid bi-layer, NOT cell membraneBe sure you use the term “phospholipid bi-layer, NOT cell membrane

2.4.2 Explain how the hydrophobic and hydrophilic 2.4.2 Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the properties of phospholipids help to maintain the

structure of cell membranes.structure of cell membranes.HydrophilicHydrophilic

-”water loving”-”water loving”-phosphate heads-phosphate headsHydrophobicHydrophobic-”water-fearing”-”water-fearing”-fatty acid tails-fatty acid tails

Phospholipid molecules make up the cell membrane and are hydrophilic (attracted to water) as well as hydrophobic (not attracted to water but are attracted to other hydrophobic tails). They have a hydrophilic phosphate head and two hydrophobic hydrocarbon tails. Cell membranes are made up of a double layer of these phospholipid molecules. This is because in water the hydrophilic heads will face the water while the hydrophobic tails will be in the center because they face away from the water. The phospholipid bilayer makes the membrane very stable but also allows flexibility. The phospholipid in the membrane are in a fluid state which allows the cell to change it’s shape easily.

Functions of membrane proteinsFunctions of membrane proteins

Hormone binding sites. Hormone binding sites. Enzymes Enzymes Cell adhesionCell adhesion

– Attachment to the cytoskeleton and Attachment to the cytoskeleton and extracellular matrixextracellular matrix

Cell communication Cell communication – Signal transduction Signal transduction – Cell-cell recognitionCell-cell recognition

Channels for passive transport Channels for passive transport Pumps for active transport. Pumps for active transport. Electron carriers Electron carriers

Define diffusion Define diffusion

Diffusion: the Diffusion: the passive passive movement of movement of particles from a particles from a region of higher region of higher concentration to concentration to a region of lower a region of lower concentration, concentration, as a result of the as a result of the random motion random motion of particles. of particles. Animation

http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion2.gif

Define OsmosisDefine OsmosisOsmosis: the passive movement of Osmosis: the passive movement of

water molecules, across a water molecules, across a selectively permeable membrane, selectively permeable membrane,

from a region of lower solute from a region of lower solute concentration to a region of higher concentration to a region of higher

solute concentration. (i.e. the solute concentration. (i.e. the diffusion of water)diffusion of water)

Remember: Lowers solute Remember: Lowers solute concentration = higher water concentration = higher water

concentration!!!concentration!!!Hypertonic (hyperosmotic)Hypertonic (hyperosmotic)Hypotonic (hypoosmotic)Hypotonic (hypoosmotic)

Isotonic (isoosmotic)Isotonic (isoosmotic)http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm effect of osmosis on cell animation

2.4.5 Explain passive transport across membranes in 2.4.5 Explain passive transport across membranes in terms of diffusion.terms of diffusion.

Simple diffusion Simple diffusion facilitated diffusion. facilitated diffusion.

– No ATP usedNo ATP used– Channel proteins (integral membrane Channel proteins (integral membrane

proteins) proteins) – Down concentration/electrochemical Down concentration/electrochemical

gradientgradient– SpecificSpecific

ex. Ion Channels in neuronsex. Ion Channels in neurons

2.4.6 Explain the role of protein pumps and 2.4.6 Explain the role of protein pumps and ATP in active transport across membranes.ATP in active transport across membranes.

Active transport is the Active transport is the movement of substances movement of substances across membranes using across membranes using energy from ATP. energy from ATP. – moves substances against a moves substances against a

concentration gradient.concentration gradient.

Carrier proteins– protein Carrier proteins– protein pumpspumps

Active transport animations:http://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/09endoexo/index.shtml

Types of transport Types of transport

2.4.62.4.6 Active transport involves the movement of substances Active transport involves the movement of substances

through the membrane using energy from ATP. through the membrane using energy from ATP. The advantage of active transport is that substances can be The advantage of active transport is that substances can be

moved against the concentration gradient, meaning from a moved against the concentration gradient, meaning from a region of low concentration to a region of high region of low concentration to a region of high concentration. concentration.

This is possible because the cell membrane has protein This is possible because the cell membrane has protein pumps embedded it which are used in active transport to pumps embedded it which are used in active transport to move substances across by using ATP. move substances across by using ATP.

Each protein pump only transports certain substances so Each protein pump only transports certain substances so the cell can control what comes in and what goes out.the cell can control what comes in and what goes out.

2.4.72.4.7 Explain how vesicles are used to transport materials within a Explain how vesicles are used to transport materials within a cell between the rough endoplasmic reticulum, Golgi apparatus, cell between the rough endoplasmic reticulum, Golgi apparatus,

and plasma membrane.and plasma membrane. Proteins synthesized by ribosomesProteins synthesized by ribosomes enter the rough endoplasmic enter the rough endoplasmic

reticulum to be modifiedreticulum to be modified Vesicles bud from rER and carry Vesicles bud from rER and carry

the proteins to the Golgi the proteins to the Golgi apparatus. apparatus.

Golgi apparatus modifies the Golgi apparatus modifies the proteins. proteins.

Vesicles bud off from the Golgi Vesicles bud off from the Golgi apparatus and carry the modified apparatus and carry the modified proteins to the plasma membraneproteins to the plasma membrane– This is a process called This is a process called

exocytosis. exocytosis. Endocytosis is a similar process Endocytosis is a similar process

which involves the pulling of the which involves the pulling of the plasma membrane inwards so that plasma membrane inwards so that the pinching off of a vesicle from the pinching off of a vesicle from the plasma membrane occurs and the plasma membrane occurs and then this vesicle can carry its then this vesicle can carry its content anywhere in the cell.content anywhere in the cell.

Describe how the fluidity of the membrane allows it to Describe how the fluidity of the membrane allows it to change shape, break and reform during exocytosis.change shape, break and reform during exocytosis.

In exocytosis vesicles fuse with the plasma membrane. In exocytosis vesicles fuse with the plasma membrane. The contents of the vesicles are then expelled. The The contents of the vesicles are then expelled. The membrane flattens out again. membrane flattens out again.

animations:http://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/09endoexo/index.shtml

Describe how the fluidity of the membrane Describe how the fluidity of the membrane allows it to change shape, break and reform allows it to change shape, break and reform during endocytosis during endocytosis

In endocytosis part of In endocytosis part of the plasma membrane the plasma membrane is pulled inwards. is pulled inwards. A droplet of fluid A droplet of fluid becomes enclosed becomes enclosed when a vesicle is when a vesicle is pinched off. pinched off. Vesicle can then Vesicle can then move through the move through the cytoplasm carrying its cytoplasm carrying its contents. contents.

Cell DivisionCell Division State that the cell-State that the cell-

division cycle involves division cycle involves interphase, mitosis, and interphase, mitosis, and cytokinesis.cytokinesis.

New cells are produced by New cells are produced by the division of existing cell, the division of existing cell, remember the cell theory. remember the cell theory.

Interphase: DNA replication Interphase: DNA replication and transcription occurs. and transcription occurs. Also, normal cell life.Also, normal cell life.

Mitosis: Cell begins to divide. Mitosis: Cell begins to divide. Cytokinesis: The cell finishes Cytokinesis: The cell finishes

dividing and the cytoplasm dividing and the cytoplasm splits between them. splits between them.

MitosisMitosis

2.5.1Outline the stages in the 2.5.1Outline the stages in the cell cyclecell cycle

Must includeMust include– Interphase (G1, S, G2)Interphase (G1, S, G2)– MitosisMitosis– CytokinesisCytokinesis

2.5.12.5.1

The first stage of cell division is interphase which The first stage of cell division is interphase which is divided into 3 phases; G1, S and G2. The cell is divided into 3 phases; G1, S and G2. The cell cycle starts with G1 (Gap phase 1) during which cycle starts with G1 (Gap phase 1) during which the cell grows larger. This is followed by phase S the cell grows larger. This is followed by phase S (synthesis) during which the genome is (synthesis) during which the genome is replicated. Finally, G2 (gap phase 2) is the second replicated. Finally, G2 (gap phase 2) is the second growth phase which separates the newly growth phase which separates the newly replicated genome and marks the end of replicated genome and marks the end of interphase. interphase. 

2.5.12.5.1

The fourth stage is mitosis which is divided into The fourth stage is mitosis which is divided into prophase, metaphase, anaphase and telophase. prophase, metaphase, anaphase and telophase. During mitosis the spindle fibers attach to the During mitosis the spindle fibers attach to the chromosomes and pull sister chromatids apart. chromosomes and pull sister chromatids apart. This stage separates the two daughter genomes.This stage separates the two daughter genomes.

Finally, cytokinesis is the last stage during which Finally, cytokinesis is the last stage during which the cytoplasm divides to create two daughter the cytoplasm divides to create two daughter cells. In animal cells the cell is pinched in two cells. In animal cells the cell is pinched in two while plant cells form a plate between the while plant cells form a plate between the dividing cells.dividing cells.

2.5.2 State that tumours (cancers) are the 2.5.2 State that tumours (cancers) are the result of uncontrolled cell division and result of uncontrolled cell division and

that these can occur in any organ or that these can occur in any organ or tissue. tissue. 

Tumors are formed when cell division Tumors are formed when cell division

goes wrong and is no longer goes wrong and is no longer controlled. This can happen in any controlled. This can happen in any organ or tissue.organ or tissue.

2.5.3 State that interphase is an active 2.5.3 State that interphase is an active period in the life of a cell when many period in the life of a cell when many metabolic reactions occur, including metabolic reactions occur, including

protein synthesis, DNA replication and protein synthesis, DNA replication and an increase in the number of an increase in the number of

mitochondria and/or chloroplasts. mitochondria and/or chloroplasts. 

Interphase continued…Interphase continued…

Phases of InterphasePhases of Interphase– GG11 = growth of cell, protein synthesis = growth of cell, protein synthesis

– S = replication of DNAS = replication of DNA

– GG22 = growth of cell, increase in = growth of cell, increase in organelles, preparation for cell division. organelles, preparation for cell division.

2.5.4 Describe the events that occur in the four 2.5.4 Describe the events that occur in the four phases of mitosis…phases of mitosis…

ProphaseProphase the mitotic spindle (made the mitotic spindle (made

from microtubules) starts from microtubules) starts growing (going from pole to growing (going from pole to pole).pole).

Chromatin coils up to form Chromatin coils up to form distinct chromosomes. distinct chromosomes. (Each chromosome (Each chromosome contains two identical contains two identical sister chromatids, attached sister chromatids, attached to each other at the to each other at the centromere region.) centromere region.)

The nuclear envelope starts The nuclear envelope starts breaks down. breaks down.

……Describe the events that occur in the Describe the events that occur in the four phases of mitosis…four phases of mitosis…

each chromosome each chromosome attaches to two spindle attaches to two spindle microtubules (one going microtubules (one going to each pole) at the to each pole) at the centromere.centromere.

line up at the equatorline up at the equator mitotic spindle is fully mitotic spindle is fully

developeddeveloped some microtubules are some microtubules are

attached to attached to chromosomes and reach chromosomes and reach to the equator; others go to the equator; others go from pole to pole. from pole to pole.

……Describe the events that occur in the Describe the events that occur in the four phases of mitosis…four phases of mitosis…

AnaphaseAnaphase– the spindle the spindle

microtubules microtubules pull the sister pull the sister chromatids to chromatids to opposite poles opposite poles

– each sister each sister chromatid chromatid becomes one becomes one new new chromosomechromosome of the daughter of the daughter cell. cell.

Telophase Telophase – each sister chromatid reaches its pole (becoming a each sister chromatid reaches its pole (becoming a

chromosome). chromosome). – nuclear envelope starts to reform. Spindle microtubles nuclear envelope starts to reform. Spindle microtubles

deteriorate.deteriorate.

Cytokinesis (division of the cytoplasm) takes place. Cytokinesis (division of the cytoplasm) takes place.

Summary of Summary of MitosisMitosis

Summary of mitosis continuedSummary of mitosis continued

2.5.5 2.5.5 Explain how mitosis produces two genetically Explain how mitosis produces two genetically identical nuclei. (an IB standard)identical nuclei. (an IB standard)

Mitosis is divided into four stages; prophase, metaphase, anaphase Mitosis is divided into four stages; prophase, metaphase, anaphase

and telophase. During prophase, the chromosomes become visible and telophase. During prophase, the chromosomes become visible under a light microscope as they super coil and therefore they get under a light microscope as they super coil and therefore they get shorter and more bulky. The nuclear envelope disintegrates and shorter and more bulky. The nuclear envelope disintegrates and the spindle microtubules grow and extend from each pole to the the spindle microtubules grow and extend from each pole to the equator. At metaphase the chromatids move to the equator. The equator. At metaphase the chromatids move to the equator. The sister chromatids are two DNA molecules formed by DNA sister chromatids are two DNA molecules formed by DNA replication and are therefore identical. These sister chromatids are replication and are therefore identical. These sister chromatids are then separated in anaphase as the spindle microtubules attaches then separated in anaphase as the spindle microtubules attaches to centromere and pulls the sister chromatids to opposite poles. to centromere and pulls the sister chromatids to opposite poles. As the sister chromatids separate they are called chromosomes. As the sister chromatids separate they are called chromosomes. This means that each pole has the same chromosomes (same This means that each pole has the same chromosomes (same genetic material). Finally the microtubules break down, the genetic material). Finally the microtubules break down, the chromosomes uncoil and the nuclear membrane reforms. The cell chromosomes uncoil and the nuclear membrane reforms. The cell then divides into two daughter cells with genetically identical then divides into two daughter cells with genetically identical nuclei.nuclei.

2.5.6 State that 2.5.6 State that grgrowth, owth, eembryonic mbryonic development, development, ttissue issue rrepair, and epair, and aasexual sexual rreproduction involve mitosis.eproduction involve mitosis.

GreGreater ater TrTracy acy ArArea ea

Outline the differences in Outline the differences in mitosis and cytokinesis mitosis and cytokinesis between animal and plant between animal and plant

cells.cells. (l(limit this to the lack of the imit this to the lack of the centrioles in plant cells and the centrioles in plant cells and the formation of the cell wall.)formation of the cell wall.)

Animals: Animals: – CentriolesCentrioles– No cell wallNo cell wall

Plants:Plants:– No No centriolescentrioles– Cell wall (cell plate) is Cell wall (cell plate) is

formed between cells as formed between cells as vesicles transport cell wall vesicles transport cell wall materials to middle. materials to middle.

State that tumors are the State that tumors are the result of uncontrolled cell result of uncontrolled cell division and that these division and that these can occur in any organ.can occur in any organ.

Cancer cells do not respond Cancer cells do not respond to cell cycle regulationto cell cycle regulation

Transformation– results from Transformation– results from successive mutationssuccessive mutations– mutagensmutagens

Tumor: benign (don’t Tumor: benign (don’t spread) or malignant (do spread) or malignant (do spread)spread)– ClonalClonal

Metastasis – spreading of Metastasis – spreading of cancer cells to other areascancer cells to other areas

http://www.pbs.org/wgbh/nova/cancer/ (Cancer Warrior– http://www.pbs.org/wgbh/nova/cancer/ (Cancer Warrior– angiogenesis resources)angiogenesis resources)

http://www.pbs.org/wgbh/nova/cancer/http://www.pbs.org/wgbh/nova/cancer/

program.htmlprogram.html (Video: Cancer Warrior-- angiogenesis)(Video: Cancer Warrior-- angiogenesis) http://www.pbs.org/wgbh/nova/cancer/grows.html http://www.pbs.org/wgbh/nova/cancer/grows.html

End of IB stuffEnd of IB stuff

State that a virus is State that a virus is a non-cellular a non-cellular structure structure consisting of DNA consisting of DNA or RNA surrounded or RNA surrounded by a protein coat.by a protein coat.

Characteristics of Characteristics of VirusesViruses – not considered livingnot considered living– no metabolism.no metabolism.– Unable to reproduce Unable to reproduce

without a hostwithout a host– Others? Others?

Explain three Explain three advantages of advantages of using light using light microscopes.microscopes.– color instead of color instead of

monochrome (black monochrome (black and white) images. and white) images.

– large field of view. large field of view. – Facilitate preparation Facilitate preparation

of sample material. of sample material. – Allow for the Allow for the

examination of living examination of living material and the material and the observation of observation of movement. movement.

– Relatively Relatively inexpensive inexpensive

Outline the advantages of using Outline the advantages of using electron microscopes.electron microscopes.

1) higher 1) higher resolutionresolution and and magnificationmagnification than light microscopes. than light microscopes. – ResolutionResolution refers to the ability to distinguish two objects refers to the ability to distinguish two objects

as seperate entities. as seperate entities. – MagnificationMagnification refers to the ability to increase the size of refers to the ability to increase the size of

a viewed object. a viewed object. 2) May provide a three dimensional view. 2) May provide a three dimensional view. Scanning Electron MicroscopesScanning Electron Microscopes (SEM) provide images of the (SEM) provide images of the

specimen's surface specimen's surface Transmission Electron MicroscopesTransmission Electron Microscopes (TEM) provide images of (TEM) provide images of

a sample's interior. The resolution of an SEM is a sample's interior. The resolution of an SEM is approximately half that of a TEM. approximately half that of a TEM.

TEM SEM