Week 4a - Cells

• Prokaryotic vs Eukaryotic Cells• Membrane Structure• Endomembrane System

– Nucleus– ER– Golgi– Lysosome and Vacuoles

• Mitochondria and Chloroplast• Cytoskeleton

Scale of Tissue, Cells, Organelles, Atoms

Molecular Biology of the Cell, 4th Ed.

Traits Common to all cells

• Plasma membrane encloses cell– Cytoplasm: the compartment within the

plasma membrane• Four major classes of Biomolecules• DNA as genetic material with same

genetic code• Ribosomes synthesize proteins • Energy and Nutrients from environment

Prokaryotic Vs Eukaryotic Cells

Prokaryotes• No Nucleus• Lacks membrane bound organelles• Typically 1-10μM• Circular DNA Genome

Eukaryotes• Membrane Bond Nucleus• Numerous Membrane Bond Organelles• Typically 10-100 μM• Linear DNA chromosomes

Both possess plasma membranes, ribosomes, all four classes of macromolecules, have DNA as genetic material and use the same genetic code.

Prokaryotes

1. Small 2. Plasma Membrane3. Cytoplasm4. Ribosomes5. Nucleoid Region6. Many have

1. Cell Wall2. Flagella

Eukaryotic Cells

Fluid Mosaic Model of Membranes

(a) Phospholipid bilayer of membrane

(b) Fluid mosaic model of membrane

Outside of cell Outside of cell

Hydrophilichead

Hydrophobictail

Hydrophilicregion of

protein

Hydrophilichead

Hydrophobictail

Hydrophobicregions of

protein

Phospholipidbilayer

Phospholipid

Proteins

Cytoplasm (inside of cell)

Cytoplasm (inside of cell)

Endomembrane System

Nucleus

Figure 4.12-3

Synthesis ofmRNA in thenucleus

Nucleus

DNA

mRNA

Cytoplasm

mRNAMovement ofmRNA intocytoplasm vianuclear pore

Ribosome

Protein

Synthesis ofprotein in thecytoplasm

1

2

3

Ribosomes

Endoplasmic Reticulum (ER)

Golgi

Lysosome

Vacuoles

Mitochondria and Chloroplast(Not part of Endomembrane System)

Endosymbiotic Theory

Photosyntheticeukaryotic cell

Photosyntheticprokaryote

Aerobicheterotrophicprokaryote

Endosymbiosis

Mitochondrion

Chloroplast

Figure 4.21

(a) Microtubules in the cytoskeleton

(b) Microtubulesand movementL

M

LM

Cytoskeleton

Flagellum and Cilia

Animal vs. Plant

Animal Cells• Lysosome• Centriole

Plant Cells• Chloroplast• Central Vacuole• Cell Wall

Both have Nucleus, Ribosomes, ER, Golgi, Mitochondria, Cytoskeleton,