Cells

Variation and Function of Cells

• Cell Theory states that:1. All living things are made of cells2. Cells are the basic unit of structure and functio n

in living things3. New cells are produced from existing cellsTwo major types of CellsProkaryotic cells are very small and have no membrane

bound organelles or a nucleus. All Bacteria are prokaryotes and have circular DNA.

Eukaryotic Cells are more organized and complex than prokaryotes, they have membrane bound organelles, linear chromosomes and tend to be very large in comparison. P169-173

Comparison: Prokaryotes and Eukaryotes• Prokaryotic cells are limited in their structure.

They have ribosomes, circular DNA, rely on the exterior membrane to complete any membrane related function and rely on diffusion for transport.

• Prokaryotic Kingdoms/Domains1. Eubacteria-are very diverse often have a cell

wall that contains peptidoglycan2. Archaebacteria- lack peptidoglycan in cell

walls, have different membrane lipids, and have some genes that are more similar to eukaryotes than eubacteria.

• Eukaryotes are complex in comparison to prokaryotes with several unique organelles that maximize their efficiency : they do or can

1. Grow much larger as they developed organization and distribution abilities2. Compartmentalize delicate and destructive processes within separate microenvironments.3. Specialize function of individual cells to work with other cells (multi-cellular)Plasma Membrane= the “skin” of a cell, it

protects, nourishes, and communicates with other cells. Organelle membranes do the same

Fig. 6-9a

ENDOPLASMIC RETICULUM (ER)

Smooth ERRough ERFlagellum

Centrosome

CYTOSKELETON:

Microfilaments

Intermediatefilaments

Microtubules

Microvilli

Peroxisome

MitochondrionLysosome

Golgiapparatus

Ribosomes

Plasma membrane

Nuclearenvelope

Nucleolus

Chromatin

NUCLEUS

Fig. 6-9b

NUCLEUS

Nuclear envelopeNucleolusChromatin

Rough endoplasmic reticulum

Smooth endoplasmic reticulum

Ribosomes

Central vacuole

Microfilaments

Intermediate filamentsMicrotubules

CYTO-SKELETON

Chloroplast

PlasmodesmataWall of adjacent cell

Cell wall

Plasma membrane

Peroxisome

Mitochondrion

Golgiapparatus

Fig. 6-30a

Collagen

Fibronectin

Plasma membrane

Proteoglycan complex

Integrins

CYTOPLASMMicro-filaments

EXTRACELLULAR FLUID

Fig. 6-7

TEM of a plasmamembrane

(a)

(b) Structure of the plasma membrane

Outside of cell

Inside ofcell 0.1 µm

Hydrophilicregion

Hydrophobicregion

Hydrophilicregion Phospholipid Proteins

Carbohydrate side chain

Fig. 7-6

RESULTS

Membrane proteins

Mouse cellHuman cell

Hybrid cell

Mixed proteinsafter 1 hour

Fig. 7-7

Fibers ofextracellularmatrix (ECM)

Glyco-protein

Microfilamentsof cytoskeleton

Cholesterol

Peripheralproteins

Integralprotein

CYTOPLASMIC SIDEOF MEMBRANE

GlycolipidEXTRACELLULARSIDE OFMEMBRANE

Carbohydrate

Fig. 6-30

EXTRACELLULAR FLUIDCollagen

Fibronectin

Plasmamembrane

Micro-filaments

CYTOPLASM

Integrins

Proteoglycancomplex

Polysaccharidemolecule

Carbo-hydrates

Coreprotein

Proteoglycanmolecule

Proteoglycan complex

Fig. 7-8

N-terminus

C-terminus

αααα HelixCYTOPLASMICSIDE

EXTRACELLULARSIDE

Fig. 7-15

EXTRACELLULAR FLUID

Channel protein

(a) A channel protein

Solute CYTOPLASM

Solute Carrier protein

(b) A carrier protein

2

EXTRACELLULAR

FLUID[Na+] high[K+] low

[Na+] low [K+] high

Na+

Na+

Na+

Na+

Na+

Na+

CYTOPLASM

ATP

ADPP

Na+

Na+

Na+

P

3

6 5 4

PP

1

Fig. 7-16-7

Fig. 7-19

Proton pump

–

–

–

–

–

–

+

+

+

+

+

+

ATP

H+

H+

H+

H+

H+

H+

H+

H+

Diffusionof H+

Sucrose-H +

cotransporter

Sucrose

Sucrose

Fig. 6-14a

Nucleus 1 µm

Lysosome

Lysosome

Digestive enzymes

Plasma membrane

Food vacuole

Digestion

(a) Phagocytosis

Fig. 6-14b

Vesicle containingtwo damaged organelles

Mitochondrion fragment

Peroxisome fragment

Peroxisome

Lysosome

DigestionMitochondrionVesicle

(b) Autophagy

1 µm

Fig. 7-13

Hypotonic solution

(a) Animalcell

(b) Plantcell

H2O

Lysed

H2O

Turgid (normal)

H2O

H2O

H2O

H2O

Normal

Isotonic solution

Flaccid

H2O

H2O

Shriveled

Plasmolyzed

Hypertonic solution

• All Eukaryotes have the following organelles and structures.

Nucleus• Nuclear envelope- a membrane that contains the DNA

and the proteins necessary to organize and maintain the DNA

• Chromatin-DNA and Protein that is found unwound in a cell between divisions.

• Chromosomes-condensed form of chromatin these are linear and found during mitosis.

• Nucleolus- area of the nucleus thought to be used to assemble ribosomes.

Cytosol• Ribosomes- RNA and protein complex that work

together to read mRNA and build a protein from its code.

Fig. 6-10

NucleolusNucleus

Rough ER

Nuclear lamina (TEM)

Close-up of nuclear envelope

1 µm

1 µm

0.25 µm

Ribosome

Pore complex

Nuclear pore

Outer membraneInner membraneNuclear envelope:

Chromatin

Surface ofnuclear envelope

Pore complexes (TEM)

• Organelles are membrane bound, specially designed and tasked parts of cells

• Endoplasmic Reticulum- network of membrane found in the cell along side the nucleus, makes lipid and protein components of the membrane and materials for export from the cell.

• Rough ER looks grainy because it has ribosomes embedded in its membrane. Produces membrane bound proteins and proteins for export.

• Smooth ER is the side of the ER away from the nucleus this is the ER responsible for lipid synthesis and detoxification often refines or modifies products from rough ER

Fig. 6-12

Smooth ER

Rough ER Nuclear envelope

Transitional ER

Rough ERSmooth ERTransport vesicle

RibosomesCisternaeER lumen

200 nm

• Golgi Apparatus- Acts as a processing center for products from the ER. May modify some chemicals, while just sorting and packaging others for storage or release.

• Lysosomes are membrane bags of hydrolytic enzymes. Lysosomes keep these dangerous chemicals separate from the rest of the cell’s chemicals and concentrated. They bind with food vacuoles to start the digestions of materials that have been consumed.

• Vacuoles-mean membrane bag and is used to refer to contractile vacuoles that pump out extra water, food vacuoles, and central vacuoles.

Fig. 6-13

cis face(“receiving” side of Golgi apparatus) Cisternae

trans face(“shipping” side of Golgi apparatus)

TEM of Golgi apparatus

0.1 µm

• Mitochondria-the “power house” of the cell. This is the organelle that takes glucose or other chemical energy sources and converts them into ATP. Mitochondria have their own circular DNA, a lot of membrane folds, and their own ribosomes.

• Chloroplasts are the organelles that house chlorophyll allowing them to capture sunlight and convert the energy it carries into the chemical energy (glucose). These also have their own circular DNA, large amounts of internal membrane, and their own ribosomes.

Fig. 6-17

Free ribosomesin the mitochondrial matrix

Intermembrane spaceOuter membrane

Inner membraneCristae

Matrix

0.1 µm

Fig. 9-19

Glucose

Glycolysis

Pyruvate

CYTOSOL

No O2 present:Fermentation

O2 present:Aerobic cellular

respiration

MITOCHONDRION

Acetyl CoAEthanolor

lactateCitricacidcycle

Fig. 9-2

Lightenergy

ECOSYSTEM

Photosynthesisin chloroplasts

CO2 + H2O

Cellular respirationin mitochondria

Organicmolecules + O2

ATP powers most cellular work

Heatenergy

ATP

Fig. 10-3b

1 µm

Thylakoidspace

Chloroplast

GranumIntermembranespace

Innermembrane

Outermembrane

Stroma

Thylakoid

Fig. 10-7

Reflectedlight

Absorbedlight

Light

Chloroplast

Transmittedlight

Granum

• Structure unique to Plants• Cell Wall- in plants these are made up of

Cellulose and lignin creating a rigid outer shell that is made stronger when the plant has a hypotonic environment

• Plastids- several different membrane sacs that hold various pigments, metabolites, etc.

• Chloroplast- the light converting plastid (membrane sac) it absorbs light energy and converts it to chemical energy.

• Central Vacuole- a huge vacuole found in the center of the cell that tends to hold water and keeps the organelles nearer the edge of the cell

Fig. 6-9b

NUCLEUS

Nuclear envelopeNucleolusChromatin

Rough endoplasmic reticulum

Smooth endoplasmic reticulum

Ribosomes

Central vacuole

Microfilaments

Intermediate filamentsMicrotubules

CYTO-SKELETON

Chloroplast

PlasmodesmataWall of adjacent cell

Cell wall

Plasma membrane

Peroxisome

Mitochondrion

Golgiapparatus

• Cytoskeleton is the structural framework found inside of cells.

• Microfilaments are the smallest form of cytoskeleton fibers and are made of actin These resist tension very well. These are the fibers that are pulled on in muscles to create a contraction.

• Microtubules are the largest form of cytoskeleton fibers made of tubulin and they resist compression very well. These provide support to a cell against being crushed and act as a rail along which vacuoles and lysosomes can be transported. They are also the basis for the movement of cilia and flagella

Fig. 6-20

Microtubule

Microfilaments0.25 µm

Table 6-1b

Actin subunit

10 µm

7 nm

Table 6-1a

10 µm

Column of tubulin dimers

Tubulin dimerαααα ββββ

25 nm

Fig. 6-21

VesicleATP

Receptor for motor protein

Microtubuleof cytoskeleton

Motor protein (ATP powered)

(a)

Microtubule Vesicles

(b)

0.25 µm