Cell (Outline)

- Components of a functional cell- Major Events in the History of Earth: abiotic and biotic phases;

anaerobic and aerobic atmosphere- Prokaryotic cells impact on the biosphere- Origin of Eukaryotic cells- Emergent properties of eukaryotic cells: animal and plant cells- Role of cellular membranes: external and internal- Cytoskeleton: structure and functions- Flow of genetic information: DNA to protein- The endo-membrane system- Other organelles: Fatty acid metabolism and Energy Processing- Cell surface and extracellular matrix

Components of a functional cell

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

& particulates• DNA-information• Ribosomes-protein synthesis

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

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Prokaryotic Cell Structure

Eukaryotic Cell Structure

Differ in - size - complexity- internal membrane, creating

organelles

(Sub-cellular compartments where different cell functions of eukaryotic cells are carried out)

Comparing Prokaryotic and Eukaryotic Cells

Evolution of Eukaryotic cells

“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

Ancestral eukaryotic cells two or more prokaryotic cells in a state of endo-symbiosis:• animal cell- 2 different prokaryotes• plant cell- 3 different prokaryotes

• Overview of Eukaryotic Cell structureshttps://www.youtube.com/watch?v=URUJD5NEXC8 (7:21 minutes)

• Organelles of the Cell (updated)https://www.youtube.com/watch?v=RKmaq7jPnYM (~ 30 minutes)

Emergent Properties of Eukaryotic cells

Functions– Structural support, movement, and

communication– Manufacturing of molecules– Breakdown of molecules– Energy processing

Eukaryotic cells structures and organelles specialize for functions

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Role of Cell membranes in Compartmentalization of cellular

functions

https://www.khanacademy.org/science/biology

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 biochemical

functions

The cytoskeleton is a network of protein fibersthat 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

Components of the cytoskeleton pull past each other

Vesicles or organelles carried to various destinations along “monorails’ of microtubules

Role of Microtubules

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– Home of most genetic material (DNA)– Double membrane with pores, nuclear

envelope – Site of transcription of RNA – Nucleolus is the place where ribosomes are

made• Ribosomes

– Site of protein synthesis

Nucleus Ribosomes

The Endomembrane SystemSub-cellular components

Nuclear envelopeEndoplasmic reticulum Golgi apparatus VesiclesLysosomes Vacuoles Plasma membrane

Function- Sites of certain metabolic functions in the cell (Synthesis, modification, & breakdown of macromolecules)- Regulation of protein traffic within the cell http://vcell.ndsu.edu/animations/proteintrafficking/movie-flash.htm

Two connected regions of ER that differ in structure and function.– Smooth ER

(No ribosomes)– Rough ER

(bound ribosomes) are attached to the outside

Smooth ERContains enzymes for – synthesis of lipids, phospholipid, steroids– Metabolism of carbohydrates– Detoxification of poison– Storage of Ca+2 for in muscle cells (necessary

for contraction)

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

transport by vesicles, destined for secretion

- Membrane-embedded and secretory proteins

- Site of protein glycosylation (glycoproteins)

The Golgi Apparatus• Finishing, sorting, and shipping cell products• Transport vesicles from the ER travel to the Golgi

apparatus for modification of their contents• Extensive in cells specialized for secretion.

Lysosomes• Garbage collector for recycling and breakdown

within the cells. Membrane-bounded sacs of hydrolytic enzymes that digests macromolecules: proteins, fats, polysaccharides, and nucleic acids.

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

Vacuoles

• Larger versions of vesicles• Many functions in cell maintenance

– Food vacuoles– Contractile vacuoles, found in freshwater

protists, pump excess water out of the cell.– Central vacuoles- mature plant cells storage

of some pigments.

Other Membranous Organelles not part of the endomembrane system

• Peroxisomes– generate and degrade H2O2 in performing various

metabolic functions– Fatty Acid metabolism

• Mitochondria and chloroplasts- sites of energy transformation from one form to another and of recycling of matter- Mitochondria (respiration) are present in animal &

plant cells- Chloroplasts (photosynthesis) only in plant cells

Peroxisomes

• A single membrane• Abundant in liver and

kidney- breakdown of fatty acids for transport to mitochondria for fuel - detoxify alcohol and other harmful compounds.- Conversion of fatty acids in seeds to sugars.

Mitochondria and Chloroplasts

• Contain their own ribosomes and cytosol• Have double membranes.• Contain small quantities of DNA that direct the

synthesis of the polypeptides produced by these internal ribosomes.

• Grow and reproduce as semi-autonomous organelles

• Not part of the endomembrane system• Mobile and move around the cell along tracks in

the cytoskeleton

• Matrix-contains DNA and ribosomes

• Cristae-contains enzymes for ATP generation during cellular respiration

MitochondriaVideo (4)

Chloroplasts• Present in plants and eukaryotic algae are the • Sites of photosynthesis-production of sugar from

CO2 and water(high levels of the green pigment chlorophyll)

Review of Functional Compartments of Eukaryotic cells

• Structural support, movement, and communication: cytoskeleton, plasma membrane, and cell wall

• Manufacturing: nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus

• Breakdown of molecules: lysosomes, vacuoles, and peroxisomes

• Energy processing: chloroplasts & mitochondria

• Cell wall in plant cells

• The extracellular matrix (ECM) in animal cells

• Extracellular components and connections between cells help coordinate cellular activities

Cell Surfaces

Polysaccharidemolecule

Carbo-hydrates

Proteoglycanmolecule

Coreprotein

A proteoglycan complex

Functions of the ECM include– Support– Adhesion– Movement– Regulation

EXTRACELLULAR FLUID

Microfilaments

Collagen fiberConnectingglycoprotein

Integrin

Plasmamembrane

Glycoproteincomplex with longpolysaccharide

CYTOPLASM

Intercellular junctions

• Plants-Plasmodesmata

• Animals-Tight junctionsDesmosomesGap junctions

Cells talk!