Lecture 2 Outline (Ch. 6)

I. Prokaryotes vs Eukaryotes

II. Organelles Overview

III. Endomembrane System

IV. Energy Organelles

VI. Cytoskeleton

VII. Extracellular Structures

VIII. Summary

Prokaryotes vs. Eukaryotes

Prokaryotes:

- Archaea and Bacteria

nucleoid (DNA)

ribosomes

plasma membrane

cell wall

capsule

pili

flagella

1-10μm

Eukaryotes:

- Protists, Fungi, Plants, Animals

- Several organelles

- Larger

Prokaryotes vs. Eukaryotes

10-100μm

333 μm

Eukaryotic Organelles

Eukaryotic Organelles Nucleus – genetic material

• chromosomes (DNA + proteins)• nuclear envelope

-double bilayer

• nuclear pores• nuclear matrix

Nucleolus makes rRNA

Chromosomes/DNA

Eukaryotic Organelles Nucleus – genetic material

Ribosomes – protein synthesis

• Made in nucleolus

• Bound or free • Two subunits

• Made of RNA & proteins

• Free – make cytoplasmic proteins

Bound Ribosomes Build Membrane & Exported Proteins

Ribosomes – protein synthesis

Ribosomes – protein synthesis

Eukaryotic Endomembrane System

Endomembrane System – shipping and transport in cells

Lipid SynthesisDetoxify Drugs

Membrane FactoryAdds Carbohydrates to

Glycoproteins

Endomembrane System

1. Endoplasmic reticulum (e.r.)

• Two types – rough & smooth

Endomembrane System

”bleb” off in vesicles

• Extensive membrane

• Continuous with nuclear envelope

• Inside is the lumen

2. Golgi apparatus• Shipping and receiving

• Flattened sacs

• Vesiscles – transport around cell

• Protein modification & direction

Endomembrane System

3. Lysosomes

• Cellular digestion

• Not in plants

• Bleb off Golgi or cell membrane

• Acidic inside – break down (a) food particles or (b) old cell parts - both by HYDROLYSIS

Endomembrane System

“phagocytosis” “autophagy”

Plant cell

4. Vacuoles • Storage/maintenance compartments

• Food vacuole

• Water vacuole

-contractile vacuole

• Disposal for by-products

• Central vacuoleAnimal cell

Endomembrane System

5. Plasma membrane

• Lipid bilayer – selective barrier

• Membrane-associated proteins – depend on cell type

Endomembrane System

• Present in ALL CELLS

MitochondriaHarvest Chemical Energy

ribosomes and own DNA

ribosomesand own DNA!

ChloroplastLight to Chemical

Energy

Question: Why do mitochondria and chloroplasts have their own DNA and ribosomes?

Cytoskeleton - Eukaryotes

Thick!

Thin!Intermediate filaments – Intermediate!

• Radiate from center

• Internal transport, motility, cell division

Cytoskeleton - Microtubules

• Inside flagella

• Inside cilia • Make centrioles

• Localized at membrane

• Cell movement

Cytoskeleton - Actin filaments

• Muscle fiber contraction

• Pseudopodia

• Cytoplasmic streaming (plants)

• Throughout cell to support shape

• make up nuclear lamina, and mesh outside nucleus

Example: keratins

Cytoskeleton - Intermediate filaments

• fibers linked into sheets, then ropes

Extracellular Spaces – Cell wall

• In plants

- made of cellulose

• Thick

• cells connected through cell wall

• plasma membrane

• cell wall

• cell wall

• Animal cells - glycoproteins Ex. collagen

• ECM – cell communication, movement

Extracellular Spaces – Extracellular Matrix (ECM)

• Animal cells - three types

1. tight junctions (no-leak)

2. desmosomes (flexible)

3. gap junctions (communication)

Extracellular Spaces – Junctions

Organelle Function Part of Endomembrane

System?

In Bacteria? Plants? Animals?

Nucleus Store genetic info no P, A

Ribosomes

Rough e.r.

Smooth e.r.

Golgi

Plasma Membrane

Lysosomes

Vacuoles

Cytoskeleton

Cell Wall

ECM