CellsObjectives:•List scientists who contributed to the cell theory •List the components of the cell theory •Compare prokaryote and eukaryote cells •Label a plant and an animal cell •Know the functions of cell organelles

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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION

Nonliving Levels:

ATOM (element)

MOLECULE (compounds like

carbohydrates & proteins)

ORGANELLES (nucleus, ER, Golgi …)

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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION

Living Levels:

CELL (makes up ALL organisms)

TISSUE (cells working together

ORGAN (heart, brain, stomach …)

ORGAN SYSTEMS (respiratory, circulatory …)

ORGANISM (living individual)

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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION

Living Levels continued:

POPULATION (one species in an area)

COMMUNITY (several populations in an area

ECOSYSTEM (forest, prairie …)

BIOME (Tundra, Tropical Rain forest…)

BIOSPHERE (all living and nonliving things on Earth)

Early Contributions

Robert Hooke - First person to see cells and give them their name, he was looking at cork and noted that he saw "a great many boxes” that looked like the cells that monks lived in. (1665)

Anton van Leeuwenhoek - Observed first living cells in pond water and scrapings from his teeth, which he called "animalcules" (1673)

Early Contributionso Theodore Schwann - zoologist who observed tissues

of animals and concluded they had cells. Also the cofounder of the Cell Theory (1839)

o Mattias Schleiden - botanist, observed tissues of plants and said they contained cells. Also the cofounder of the Cell Theory ( 1845)

o Rudolf Virchow – observed under the microscope, cells dividing and concluded that cells come from pre-existing cells and that all living things are made of cells (1850 )

The Cell Theory

1. Every living organism is made of one or more cells.

2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions.

3. All cells arise from pre-existing cells. * Why is the Cell

Theory called a Theory and not a Fact?

Cell Features

ALL cells have these parts

Ribosomes- make protein for use by the organism

Cytoplasm- fluid material within cell

DNA- genetic material

Cytoskeleton- internal framework of cell

Cell Membrane- outer boundary, some things can cross the cell membrane

Comprehension Checkpoint

Answer true or false

1. Robert Hooke was the first person to see cells.

2. Bacteria cells have a cell membrane.

3. The Cell Theory was developed by a single scientist.

4. Plant cells have cytoplasm

5. Cells taken from fungi do not have DNA.

6. Cells can only come from pre-existing cells.

7. It only took five years to develop the Cell Theory.

Prokaryote Cells The first cells to inhabit the earth Simple cells Only example: Bacteria These cells do NOT have a nucleus, their DNA is circular and

floats in the cytoplasm Nucleoid region (center) contains the DNA Surrounded by cell membrane & cell wall

(peptidoglycan) Contain ribosomes in their cytoplasm to make proteins

Some bacteria have a tail-like structure called a flagella, that helps it to move

A capsule surrounds some bacteria and helps them avoid the body’s immune system

pilliDNA

Ribosomes

Cell membraneCell wall

Bacterial Images

Bacteria that causes Anthrax

Eukaryotic Cells True Cells

Complex

Cells found in plants, animals, protists and fungi

The cell is composed of 4 main parts:

1. Cell membrane

2. Cytoplasm (cytosol and organelles, except nucleus)

3. Nucleus- “control center” of cell, houses DNA

4. Membrane Bound Organelles- small structures that carry out specific functions (“little organs”). Shape determines function.

Other VocabProtoplasm (nucleus and cytoplasm)

Cytosol (fluid part of cytoplasm)

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Two Main Types of Eukaryotic Cells

Plant Cell

Animal Cell

Cheek Cells Seen Through Microscope

Nucleus Controls the normal activities of the

cell

Usually found at center of cell and the largest organelle in animal cells

Has a nuclear membrane/envelope & nuclear pores 

Contains cell’s DNA in one of 2 forms

chromatin - DNA bound to proteins and spread out (non-dividing cell)

chromosomes - condensed structures DNA wrapped around proteins, seen in dividing cell

 Also contains an organelle called nucleolus - which makes the cell’s ribosomes (disappears when cells divide)

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•Jelly-like substance enclosed by cell membrane

•Provides a medium for chemical reactions to take place

• Contains organelles to carry out specific jobs

CytoplasmCytoplasmcytoplasm

Cell Organelles

Mitochondria – this is the cell’s energy center. It turns food into a chemical energy called ATP during Cellular Respiration

More active cells like muscle cells have MORE mitochondria

The mitochondria is sometimes called the “powerhouse” of the cell

Has its own DNA

Interior called Matrix

Outer Membrane

Folded Inner Membrane called Cristae to increase surface area for chemical reactions

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Interesting Fact ---Interesting Fact ---

Mitochondria Come from cytoplasm in the EGG cell during fertilization

Therefore …

You inherit your mitochondria from your mother!

Cell Organelles

Golgi Apparatus – receive proteins from ER to modify/processes, package and secrete proteins. It is comparable to a factory or a post office.

*A vesicle forms with Golgi to transport substances outside cell.  

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GolgiGolgi

copyright cmassengale

Cell Organelles

Lysosome – Contains digestive enzymes, breaks down food, bacteria and worn out cell parts

Programmed for cell death (autolysis), "suicide sac”

Lyse (break open) and release digestive enzymes to break down and recycle cell parts

Cell Organelles

Endoplasmic Reticulum (ER) – Connects to nuclear envelope and cell membrane

Functions in Synthesis of cell products and Transport, "intracellular highway".

-Rough ER contains many ribosomes & is involved in protein synthesis

 -Smooth ER (ribosomes not found on surface) Makes membrane lipids

(steroids) Regulates calcium (muscle

cells) Destroys toxic substances

(Liver)

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Cell OrganellesCell Organelles

Ribosomes are made of proteins and rRNA where protein synthesis occurs by joining amino acids together

Can be attached to Rough ER or be Free (unattached) in the cytoplasm

Cell Organelles

Cytoskeleton – Helps cell maintain support & shape; movement microtubules-hollow structures; also

-help build cilia  flagella microfilaments-threadlike

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Cell OrganellesCell Organelles Centrioles are found only in animal cells

Paired structures near nucleus

Made of bundle of microtubules

Appear during cell division forming mitotic spindle

Help to pull chromosome pairs apart to opposite ends of the cell

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CentriolesCentrioles & the Mitotic & the Mitotic SpindleSpindle

Made of MICROTUBULES (Tubulin)

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Cell OrganellesCell Organelles

Cilia are shorter and more numerous on cells

Flagella are longer and fewer (usually 1-3) on cells

Function in moving cells, in moving fluids, or in small particles across the cell surface

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Cell Movement with Cell Movement with Cilia Cilia & Flagella& Flagella

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Cilia Cilia Moving Away Dust Particles Moving Away Dust Particles from the Lungsfrom the Lungs

Respiratory SystemRespiratory System

Cell Membrane

Selectively permeable ; it regulates what comes into the cell and what leaves the cell

It is composed of a double layer of phospholipids with proteins embedded throughout

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Cell or Plasma MembraneCell or Plasma Membrane

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Composed of double layer of phospholipids and proteins

Surrounds outside of ALL cellsControls what enters or leaves the cellLiving layer

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PhospholipidsPhospholipidsHeads contain glycerol &

phosphate and are hydrophilic (attract water)

Tails are made of fatty acids and are hydrophobic (repel water)

Make up a bilayer where tails point inward toward each other

Can move laterally to allow small molecules (O2, CO2, & H2O to enter)

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The Cell Membrane is FluidThe Cell Membrane is Fluid

Molecules in cell membranes are constantly moving and changing

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Cell Membrane ProteinsCell Membrane Proteins

Proteins help move large molecules or aid in cell recognition

Peripheral proteins are attached on the surface (inner or outer)

Integral proteins are embedded completely through the membrane

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Recognize “self”

GLYCOPROTEINSGLYCOPROTEINS

Glycoproteins have carbohydrate tails to act as markers for cell recognition

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•Lies immediately against the cell wall in plant cells

•Pushes out against the cell wall to maintain cell shape

Cell Membrane in PlantsCell Membrane in PlantsCell membrane

Plant Cells

Have additional structures

CELL WALL – surrounds membrane & provides additional support

CHLOROPLASTS – contain green pigment, function in photosynthesis

CENTRAL VACUOLE – large water container in center of cell

LACK Centrioles

Plant Cell

Can you identify all the parts?

Anacharis Cells Viewed With a Microscope

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o Cell Wall- Nonliving layer found in plants, fungi, & bacteria

o Made of cellulose in plants, peptidoglycan in bacteria and chitin in Fungi

o Supports and protects cell

o Found outside of the cell membrane

Cell wall

Cell OrganellesCell Organelles

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ChloroplastsChloroplasts

Found only in producers (organisms containing chlorophyll)

Use energy from sunlight to make own food (glucose)

Energy from sun stored in the Chemical Bonds of Sugars

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Chloroplasts

Surrounded by DOUBLE membrane

Outer membrane smoothInner membrane modified

into sacs called Thylakoids

Thylakoids in stacks called Grana & interconnected

Stroma– gel like material surrounding thylakoids

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Chloroplasts

Contains its own DNA

Contains enzymes & pigments for Photosynthesis

Never in animal or bacterial cells

Photosynthesis – food making process

Cell Organelles

Vacuole – storage area for sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes, plant cells usually have a large central vacuole

Small or absent in animal cells

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Contractile Contractile VacuoleVacuoleFound in unicellular

protists like paramecia

Regulate water intake by pumping out excess (homeostasis)

Keeps the cell from lysing (bursting)

Contractile vacuole animation

Organelles with DNA In 1970, American biologist, Lynn Margulis, provided

evidence that some organelles within cells were at one time free living cells themselves

Supporting evidence- Mitochondria and chloroplasts have their own DNA (separate from the nucleus)

This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells.

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Multicellular Organisms

Cells in multicellular organisms often specialize (take on different shapes & functions)

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Cell Specialization

Cells in a multi-cellular organism become specialized by turning different genes on and off

This is known as DIFFERENTIATION

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Specialized Animal Cells

Muscle cells Red blood cells

Cheek cells