Cell Structure and Function (Outline)• Abiotic and biotic phases of the earth; aerobic and anaerobic

atmospheric conditions on earth. • Components of a functional cell;• Prokaryotic and eukaryotic cells. List their similarities and differences.• The “Endo-symbiotic Theory”• Structure and function of membranes• structure and function of all eukaryotic cellular organelles:

o Cytoskeletono Nucleuso Ribosomeso The endo-membraneo The mitochondrion and theo The peroxisome

Major Events in the History of EarthCenozoic

Humans

Land plants

Animals

Multicellulareukaryotes

Single-celledeukaryotes

Origin of solarsystem andEarth

1

2

4

3

Proterozoiceon

Archaeaneon

Atmospheric oxygen

Prokaryotes

Major Events in the History of EarthCenozoic

Humans

Land plants

Animals

Multicellulareukaryotes

Single-celledeukaryotes

Origin of solarsystem andEarth

1

2

4

3

Proterozoiceon

Archaeaneon

Atmospheric oxygen

Prokaryotes

Anaerobic

Aerobic

A cell is a living unit greater than the sum of its parts

Components of a functional cell

• Boundary-membrane• Cytoplasm: Cytosol (soluble components) &

particulates• DNA-information• Ribosomes-protein synthesis

Nucleoid

Ribosomes

Plasma membrane

Cell wall

Capsule

Flagella

Bacterialchromosome

Pili

Prokaryotic Cell Structure

Eukaryotic Cell Structure

Evolution of larger Eukaryotic cells was accompanied by ability of

cells to increase their surface area/volume ratio

The Endo-symbiotic Theory

Cenozoic

Humans

Land plants

Animals

Multicellulareukaryotes

Single-celledeukaryotes

Origin of solarsystem andEarth

1

2

4

3

Proterozoiceon

Archaeaneon

Atmospheric oxygen

Prokaryotes

The Endo-symbiotic Theory:

Origin of Eukaryotes

Engulfing ofphotosyntheticprokaryote

Chloroplast

Mitochondrion

Somecells

Host cell

Mitochondrion

Host cellEngulfing of aerobicprokaryote

• The ancestral eukaryotic animal cell evolved from 2 different prokaryotes present in a state of endosymbiosis

• The ancestral eukaryotic plant cell evolved from 3 different prokaryotes present in a state of endosymbiosis

• Evidence supporting the endosymbiotic theory:– mitochondria and chloroplasts have circular

DNA and ribosomes– Endosymbiosis is seen among some existing

prokaryotic cells today

Differ in - size - complexity- presence of internal membrane

creating organelles(Sub-cellular compartments where

different cell functions of eukaryotic cells are carried out)

Comparing Prokaryotic and Eukaryotic Cells

Similarities Prokaryotes Eukaryotes

Plasma membrane

Cytosol

Chromosomes made of DNA

Ribosomes for protein synthesis

Differences Prokaryotes Eukaryotes

Chromosomes

Nuclear membrane

Membrane-bounded organelles

Prokaryotic & Eukaryotic Animal and Plant cells

• http://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/cell_structure.htm

• http://www.wisc-online.com/objects/index.asp?objID=AP11604

Smooth endoplasmicreticulum

Roughendoplasmicreticulum

CYTOSKELETON:

NUCLEUS:Nuclear envelopeChromosomesNucleolus

Ribosomes

Golgiapparatus

Plasma membrane

Mitochondrion

Peroxisome

Centriole

Lysosome

MicrotubuleIntermediatefilamentMicrofilament

Smooth endoplasmicreticulum

Rough endoplasmicreticulum

CYTOSKELETON:

NUCLEUS:Nuclear envelope

ChromosomeNucleolus

Ribosomes

Golgiapparatus

Plasma membrane

Mitochondrion

Peroxisome

Cell wall

Central vacuoleMicrotubule

Intermediatefilament

Microfilament

Cell wall ofadjacent cell

Chloroplast

Plasmodesmata

Role Cell membranes Compartmentalization of

cellular functions

A. Plasma membrane- Boundary of the cell- Surrounds the cytoplasm- Selective barrier- Allows passage of oxygen, nutrients, and wastes.

B. Internal membranes of eukaryotes

Partitioning the cell into compartments

- Local environments that facilitate specific metabolic functions

Hydrophilic heads

Hydrophobic tails

Proteins

Hydrophobic region ofprotein

Inside cell Hydrophilic region ofprotein

A network of protein fibers that functions in cell structural support and motility

Cytoskeleton

Microfilament

Actin subunit

7 nm

Intermediate filament

Fibrous subunits

10 nm

Microtubule

Tubulin subunit

25 nm

Nucleus

Nucleus

Roles of the Cytoskeleton:

1. structural or mechanical support to the cell2. cell motility and organelle motion3. regulation of structural organization and

activities of the cell

Vesicles or organelles carried to various destinations along “monorails’ provided by the cytoskeleton.

The Flow of Genetic Information:The “Central Dogma” of Molecular Biology

The sequence of bases in DNA determines the sequence of amino acids in proteins

- DNA codes for the production of messenger RNA. - Messenger RNA codes for the production of protein. - Proteins do not code for the production of protein, RNA or DNA

Cell organelles and structures involved with the flow of genetic information

• Nucleus• Ribosomes

• Home of most genetic material (DNA)• Site of transcription of:

- messenger RNA (mRNA)- ribosomal RNA (rRNA) (nucleolus)

Nucleus

Two membranes ofnuclear envelope Nucleus

NucleolusChromatin

Pore

Endoplasmicreticulum Ribosomes

Ribosomes• Made of rRNA and protein.• Sites of protein synthesis• Free and bound ribosomes (to endoplasmic

reticulum)

Cytoplasm

Endoplasmic reticulum (ER)Free ribosomesBound ribosomes

RibosomesER

SmallsubunitDiagram of

a ribosomeTEM showing ERand ribosomes

Largesubunit

The Endomembrane System

Sub-cellular components Nuclear envelopeEndoplasmic reticulum Golgi apparatus VesiclesLysosomes Vacuoles Plasma membrane

Function- Regulation of protein traffic within the cell- Sites of synthesis, breakdown, & modification of

macromolecules

– Smooth ER (No ribosomes.

– Rough ER (bound ribosomes) are attached to the outside

The endoplasmic reticulum (ER)

Smooth ER

Nuclearenvelope

RibosomesRough ER

Smooth ERContains enzymes for functions that include– synthesis of lipids, phospholipid, steroids

Rough ER (membrane factory)- Produces proteins and membranes for transport

by vesicles

Transport vesiclebuds off

Secretoryproteininside trans-port vesicle

GlycoproteinPolypeptide

Ribosome

Sugarchain

Rough ER

1

2

3

4

The Golgi Apparatus• Finishing, sorting, and shipping cell products

Golgi apparatusGolgi apparatus

“Receiving” side ofGolgi apparatus

Transportvesiclefrom ER

New vesicleforming

“Shipping” sideof Golgi apparatus

Transportvesicle fromthe Golgi

Lysosomes• Membrane-bounded sacs of hydrolytic enzymes

that digestive enzymes

http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter5/animations.html#

Lysosome

Vesicle containingdamaged mitochondrion

Digestion

Nucleus

VacuoleLysosome Plasma membrane

Smooth ER

Nuclearmembrane

Golgiapparatus

Rough ER

Transportvesicle

Transportvesicle

Vacuoles

• Larger versions of vesicles• Many functions in cell maintenance

– Food vacuoles, fuse with lysosomes– Contractile vacuoles, pump excess water out– Central vacuoles in plant cells

Nucleus

Chloroplast

Centralvacuole

Nucleus

Contractilevacuoles

Other Membranous Organelles not part of the endomembrane system

• Energy transformers of cellsMitochondria- sites of cellular respiration (animals & plants)Chloroplasts- sites of photosynthesis (plants only)

• Peroxisomes- Generate and Degrade H2O2-

Mitochondria and Chloroplasts

• Contain their own ribosomes and cytosol• Contain small quantities of DNA that direct

the synthesis of the polypeptides produced by these internal ribosomes.

• Grow and reproduce as semi-autonomous organelles

MitochondriaVideo (4)

ChloroplastVideo (4)

Peroxisomes

• A single membrane• Abundant in liver and

kidney- breakdown of fatty acids- detoxify alcohol

EXTRACELLULAR FLUID

Microfilaments

Collagen fiber

Connectingglycoprotein

Integrin

Plasmamembrane

Glycoproteincomplex with longpolysaccharide

CYTOPLASM

Cell Surfaces

The extracellular matrix (ECM) proteins and polysaccharides, in animal cells

Vacuole

Wallsof twoadjacentplant cells

Cytoplasm

Primary cell wall

Plasma membrane

Plasmodesmata

Secondary cell wall

Plant cells have a cell wall and Plasmodesmata as an intercellular junction

Intercellular animal junctions

Animals-Tight junctionsDesmosomesGap junctions

Tight junctions

Anchoring junction

Gap junctions

Plasma membranesof adjacent cells

Extracellular matrix