Introducing Cells Cell Theory Microscopy Cell organelles Cell organelle function.

Introducing CellsIntroducing Cells

Cell TheoryCell Theory

MicroscopyMicroscopy

Cell organellesCell organelles

Cell organelle functionCell organelle function

The CellThe Cell

To understand life in a useful and To understand life in a useful and meaningful way, you have to understand meaningful way, you have to understand

the cell.the cell.

Seeing the big pictureSeeing the big picture

Chemistry (atoms and molecules)Chemistry (atoms and molecules)

Cells Cells

TissueTissue

OrganOrgan

OrganismOrganism

BiosphereBiosphere

The Cell TheoryThe Cell Theory

Although different living things may be as unlike as a violet and an Although different living things may be as unlike as a violet and an octopus, they are all built in essentially the same way. octopus, they are all built in essentially the same way.

The most basic similarity is that all The most basic similarity is that all living things are composed of living things are composed of one or more cellsone or more cells. This is known as the . This is known as the Cell TheoryCell Theory..

Prokayrotic bacteriaProkayrotic bacteria

Eukaryotic (true nucleus)Eukaryotic (true nucleus) animalanimal

plant plant fungusfungus

Cells are the building Cells are the building blocks of life.blocks of life.

The Cell TheoryThe Cell Theory

The Cell Theory can be summarized as:The Cell Theory can be summarized as:

A.A. All living organisms are made up of one or more All living organisms are made up of one or more cellscells

B.B. The cell is the basic unit of lifeThe cell is the basic unit of lifeC.C. All cells come from the division of pre-existing cellsAll cells come from the division of pre-existing cells

our knowledge of cells is built on work done with our knowledge of cells is built on work done with microscopesmicroscopes

cells come in many cells come in many shapesshapes and and sizessizes, although most , although most are are microscopicmicroscopic::

most cells are small, about 0.001 cm in length (1/100 of most cells are small, about 0.001 cm in length (1/100 of a mm, or 10 a mm, or 10 m).m).

Some cells are large. e.g. some giant algal cells may Some cells are large. e.g. some giant algal cells may be several centimeters long. A chicken's egg is a be several centimeters long. A chicken's egg is a single cell.single cell.

40,000 red blood cells40,000 red blood cells would fill the letter " would fill the letter "OO" on a " on a page of type. You produce about 2.5 million new red page of type. You produce about 2.5 million new red blood cells every second! Each square cm of your skin blood cells every second! Each square cm of your skin contains about contains about 150,000 skin cells150,000 skin cells..

Human beings are composed of about Human beings are composed of about 50 to 100 50 to 100 trillion cellstrillion cells..

cells cells carry on all the processes associated with lifecarry on all the processes associated with life, , such as such as reproducingreproducing and and interactinginteracting with the with the environment.environment.

microscopesmicroscopes

Sizes of cells, viruses, and other small things Sizes of cells, viruses, and other small things Biology Biology is a visually rich subject area. However, many of the is a visually rich subject area. However, many of the most interesting biological events and structures are most interesting biological events and structures are smaller than the unaided human eye can see. smaller than the unaided human eye can see.

In fact, human eyes have a resolution of about 100 µm. In fact, human eyes have a resolution of about 100 µm. On the chart below, notice that of all the structures listed, On the chart below, notice that of all the structures listed, only the plant cell is within our resolution--just barelyonly the plant cell is within our resolution--just barely

EUCARYOTIC CELL STRUCTUREEUCARYOTIC CELL STRUCTURE

At the most basic level, the cell's overall structure can be viewed as:At the most basic level, the cell's overall structure can be viewed as:

1.1. Cell MembraneCell Membrane2.2. NucleusNucleus3.3. OrganellesOrganelles4.4. CytoplasmCytoplasm

1.1. Cell MembraneCell Membrane: the thin layer which separates the cell : the thin layer which separates the cell contents from it's environment. contents from it's environment.

2.2. NucleusNucleus: specialized structure within the cell which : specialized structure within the cell which contains DNA and controls cell functioning and reproduction.contains DNA and controls cell functioning and reproduction.

3.3. OrganellesOrganelles: small bodies with specific structures and : small bodies with specific structures and functions within the cell.functions within the cell.

4.4. CytoplasmCytoplasm: the liquid substance between the nucleus : the liquid substance between the nucleus and the cell membrane, in which the organelles are located.and the cell membrane, in which the organelles are located.

2

3

3

1

3

3

3

4

Eukaryotic CellsEukaryotic Cells

liver cellliver cell

Now Let’s Have a Now Let’s Have a DETAILEDDETAILED look at CELL ORGANELLES look at CELL ORGANELLES

The Cell Membrane and the “Fluid The Cell Membrane and the “Fluid Mosaic” ModelMosaic” Model

the the cell membranecell membrane functions in functions in transporttransport of materials of materials in and out of cellin and out of cell, , recognitionrecognition, , communicationcommunication, and , and homeostasishomeostasis..

The Fluid MosaicThe Fluid Mosaic Model:Model:

Cells are surrounded Cells are surrounded by a thin membrane of by a thin membrane of

lipidlipid and and proteinprotein..

Please Label this Diagram

Please Label this Diagram

• scientists today agree upon The Fluid Mosaic Model of membrane structure. The cell membrane is a remarkable structure that has properties of a solid and a liquid.

• It forms a "fluid sea" in which proteins and other molecules like other lipids or carbohydrates are suspended (like icebergs) or anchored at various points on its surface.

• the “sea” or “fluid” parts composed of side by side phospholipids arranged in a bilayer (called a lipid bilayer).

• The solid part (the “mosaic”) is the variety of proteins etc. embedded in the bilayer.

each phospholipid has a …

1. hydrophobic tail and a

2. hydrophylic head.

• the membrane has consistency of light machine oil.

• the membrane is SELECTIVELY PERMEABLE (will let some substances in but not others of the same size).

Cell Cell MembraneMembrane

NucleusNucleus

NucleusNucleus

The nucleus is a The nucleus is a large, centrally located organellelarge, centrally located organelle surrounded by surrounded by nuclear envelopenuclear envelope. .

The nuclear envelope is a The nuclear envelope is a double membranedouble membrane (2 (2 phospholipid bilayers) that has phospholipid bilayers) that has pores.pores.

Nuclear poresNuclear pores allow proteins into the nucleus and allow proteins into the nucleus and ribosomal subunits out. ribosomal subunits out.

The envelope is very The envelope is very porousporous and is a and is a continuation of continuation of the membranesthe membranes of the of the endoplasmic reticulumendoplasmic reticulum..

•Double-membraneDouble-membrane (envelope) (envelope)•Numerous pores Numerous pores •RNA and other chemicals to RNA and other chemicals to pass to cytoplasm, but notpass to cytoplasm, but notDNADNA

Structure of the Structure of the nuclear envelope nuclear envelope and nuclear pores. and nuclear pores.

NucleusNucleus

The NucleusThe Nucleuscontrol centercontrol center or " or "brainbrain" of cell. The " of cell. The site where genetic information is stored site where genetic information is stored in chromosomes.in chromosomes.

Although each cell gets a copy of every gene, Although each cell gets a copy of every gene, only certain ones are turned on in a particular only certain ones are turned on in a particular cell.cell.

The DNA is contained by a number of The DNA is contained by a number of chromosomeschromosomes, which consist of long strands , which consist of long strands of DNA tightly wound into of DNA tightly wound into coilscoils with with proteinsproteins called called histoneshistones. The combination of DNA and . The combination of DNA and histone proteins is known as histone proteins is known as CHROMATINCHROMATIN..

Genes contain DNA which works with RNA to Genes contain DNA which works with RNA to bring about the synthesis of proteinsbring about the synthesis of proteins

The nucleus, therefore, determines the The nucleus, therefore, determines the metabolismmetabolism, , growthgrowth, , differentiationdifferentiation, , structurestructure, and , and reproductionreproduction of cell. of cell.

The The nucleolusnucleolus( 1-2 darker bodies)( 1-2 darker bodies), is the site , is the site of rRNA synthesis (protein to from ribosomes).of rRNA synthesis (protein to from ribosomes).

NuThe Nucleus

RibosomesRibosomes

SiteSite for for PROTEIN SYNTHESIS !!PROTEIN SYNTHESIS !!

Ribosomes Ribosomes consist of consist of rRNArRNA and and proteinsproteins

each ribosome is made of 2 each ribosome is made of 2 non-identical subunits (small and non-identical subunits (small and large)large)

rRNA is produced in the nucleolus and joined with proteins -- then rRNA is produced in the nucleolus and joined with proteins -- then migrate through the nuclear pore to the cytoplasm for final assemblymigrate through the nuclear pore to the cytoplasm for final assembly

ribosomes attach themselves to the endoplasmic reticulumribosomes attach themselves to the endoplasmic reticulum

ribosome

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

the ER is a system of the ER is a system of MEMBRANOUS TUBULAR MEMBRANOUS TUBULAR CANALSCANALS that begins just outside the nucleus and that begins just outside the nucleus and branches throughout the cytoplasm.branches throughout the cytoplasm.

Part of the ER is studded with ribosomes and called Part of the ER is studded with ribosomes and called

ROUGHROUGH Endoplasmic Reticulum Endoplasmic Reticulum

The areas without ribosomes is called The areas without ribosomes is called SMOOTH SMOOTH Endoplasmic ReticulumEndoplasmic Reticulum. .

RoughE.R.

Smooth E.R.


Both rough and smooth ER are involved in synthesis Both rough and smooth ER are involved in synthesis and modification of macromolecules. and modification of macromolecules.

Rough ERRough ER is the site where PROTEIN SYNTHESIS is the site where PROTEIN SYNTHESIS occurs on the attached ribosomes.occurs on the attached ribosomes.

Smooth ER producesSmooth ER produces different molecules depending different molecules depending on the type of cell. on the type of cell.

RoughE.R.

Smooth E.R.

Smooth Endoplasmic ReticulumSmooth Endoplasmic ReticulumFunction 1: Synthesis of lipids:Function 1: Synthesis of lipids:

Ex. Smooth ER is abundant in testes and adrenal cortex , both Ex. Smooth ER is abundant in testes and adrenal cortex , both of which produce of which produce steroid hormonessteroid hormones (e.g. testosterone) (e.g. testosterone)

Sometimes referred to as the cell’s Sometimes referred to as the cell’s membrane factorymembrane factory b/c it is b/c it is where where phospholipidsphospholipids are synthesized. are synthesized.

Function 2: Detoxification of Drugs:Function 2: Detoxification of Drugs:

Ex. In liver cells the smooth ER is capable of releasing Ex. In liver cells the smooth ER is capable of releasing enzymes that can detoxify substance such as alcohol. enzymes that can detoxify substance such as alcohol.

It does this through attached peroxisomes that contain It does this through attached peroxisomes that contain detoxification enzymes).detoxification enzymes).


Most of the macromolecules (proteins, lipids, etc) leaving the Most of the macromolecules (proteins, lipids, etc) leaving the endoplasmic reticulum are still endoplasmic reticulum are still not maturenot mature. .

They must undergo They must undergo further processingfurther processing in another organelle, in another organelle, the the Golgi apparatusGolgi apparatus, before they are ready to perform their , before they are ready to perform their functions within or outside the cell. (fig. 3.6 p. 55)functions within or outside the cell. (fig. 3.6 p. 55)

RoughE.R.

Smooth E.R.

Golgi ApparatusGolgi Apparatus

The Golgi Apparatus (“X” in diagram),The Golgi Apparatus (“X” in diagram),

are are stacksstacks of of flattenedflattened, , hollowhollow cavitiescavities

enclosed by membranes, which are enclosed by membranes, which are

often often continuouscontinuous with the membranes with the membranes

of the endoplasmic reticulumof the endoplasmic reticulum..

located near to the nucleus and ER.located near to the nucleus and ER.

Looks like a Looks like a flattened stackflattened stack of hollow tubes. of hollow tubes.

Golgi ApparatusGolgi ApparatusThus, the Golgi apparatus functions in protein …Thus, the Golgi apparatus functions in protein …

1. Modification1. Modification (i.e. addition of a carbohydrate or phosphate group) (i.e. addition of a carbohydrate or phosphate group)

2. Packaging 2. Packaging (often in secretory vesicles that move to plasma (often in secretory vesicles that move to plasma membrane)membrane)

3. Secretion3. Secretion (of substances to cytoplasm or export from the cell) (of substances to cytoplasm or export from the cell)

it receives newly manufactured protein (from the ER) on it's inner surface. it receives newly manufactured protein (from the ER) on it's inner surface.

Within the Golgi apparatus, the proteins are Within the Golgi apparatus, the proteins are sorted outsorted out, , labeledlabeled, and , and packaged into vesiclespackaged into vesicles that " that "pinch offpinch off" the outer surface into vesicles. " the outer surface into vesicles.

These vesicles can then be transported to where they are needed within These vesicles can then be transported to where they are needed within the cell, or can move to the cell membrane for export to the outside of the the cell, or can move to the cell membrane for export to the outside of the cell by cell by exocytosis exocytosis (i.e hormone secretion)(i.e hormone secretion)

See figure 3.6 in textSee figure 3.6 in text

Vacuoles and Vesicles: Vacuoles and Vesicles: Storage & TransportStorage & Transport

a a VACUOLE is a large membrane-enclosed sacVACUOLE is a large membrane-enclosed saca VESICLE is a small membrane-enclosed saca VESICLE is a small membrane-enclosed sac

vacuoles and vesicles are formed by: vacuoles and vesicles are formed by:

1) pinching off from the Golgi apparatus or ER1) pinching off from the Golgi apparatus or ER2) Endocytosis (pinching in of cell membrane to import)2) Endocytosis (pinching in of cell membrane to import)

are used for are used for transporttransport and and storagestorage of materials of materials lysosomes are examples of a vesiclelysosomes are examples of a vesicle peroxisomes are an example of a vacuoleperoxisomes are an example of a vacuole

LysosomesLysosomes

Lysosomes: Cellular “Stomachs”Lysosomes: Cellular “Stomachs”

specialized vesiclesspecialized vesicles which are formed by the Golgi which are formed by the Golgi apparatus.apparatus.

contain powerfulcontain powerful hydrolytic enzymes hydrolytic enzymes functions in :functions in :

1)1) cellular cellular digestiondigestion 2)2) autodigestionautodigestion or disposal of damaged cell components or disposal of damaged cell components

like mitochondria. (e.g. in development of embryo-like mitochondria. (e.g. in development of embryo-fingers)fingers)

3)3) breakdown of a whole cellbreakdown of a whole cell (by releasing their (by releasing their contents into the cell cytoplasm). For this reason, they contents into the cell cytoplasm). For this reason, they are sometimes called “are sometimes called “suicide sacssuicide sacs.”.”

LysosomesLysosomes

Lysosomes are known to contain over Lysosomes are known to contain over 40 different 40 different enzymesenzymes that can that can digest almost anythingdigest almost anything in the cell, in the cell,

including including proteinsproteins, , RNARNA, , DNADNA, and , and carbohydratescarbohydrates..

Lysosomes help Lysosomes help destroy invading destroy invading bacteriabacteria..

PeroxisomesPeroxisomes

PEROXISOMESPEROXISOMES are also single-membrane are also single-membrane organelles (Vacuoles).organelles (Vacuoles).

contain enzymes which are able to react contain enzymes which are able to react with toxic substances and break them with toxic substances and break them down. Detoxifydown. Detoxify

i.e. alcohol in liver cellsi.e. alcohol in liver cells

MitochondriaMitochondria

The Cell’s PowerhouseThe Cell’s Powerhouse

generates energy (ATP) for the cell by ‘burning’ generates energy (ATP) for the cell by ‘burning’ sugar (glucose).sugar (glucose).

Mitochondria are the Mitochondria are the largest organelleslargest organelles in an animal in an animal cell, after the nucleus (about the size of bacteria).cell, after the nucleus (about the size of bacteria).

Are sausage-shaped or filamentous structures Are sausage-shaped or filamentous structures

surrounded by a surrounded by a double-layered membranedouble-layered membrane..

a.________________

b.________________


The mitochondrion has The mitochondrion has two two membranesmembranes: an outer and an inner. : an outer and an inner.

The The innerinner is convoluted into shelf-like is convoluted into shelf-like folds called folds called cristaecristae..

The enzymes responsible for cellular The enzymes responsible for cellular respiration are arranged, in assembly-respiration are arranged, in assembly-line fashion, on the line fashion, on the cristaecristae. .

a.________________

b.________________


Function = Function = AEROBIC ENERGY METABOLISMAEROBIC ENERGY METABOLISM (AKA (AKA CELLULAR RESPIRATIONCELLULAR RESPIRATION). Converts ). Converts glucoseglucose and and fatty acidsfatty acids to to ATP ENERGY!ATP ENERGY!

The overall formula for cellular respiration is:The overall formula for cellular respiration is:

Carbohydrate + OCarbohydrate + O2 2 CO CO2 2 + H + H22O + O + ENERGYENERGY

In the end, In the end, 3838 molecules of ATP molecules of ATP (adenosine (adenosine triphosphate) are formed for every molecule of triphosphate) are formed for every molecule of glucoseglucose that is used up in respiration.that is used up in respiration.

a.________________

b.________________cristaecristaematrixmatrix

Introducing Cells Cell Theory Microscopy Cell organelles Cell organelle function.

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