Lecture 2 Outline (Ch. 6)

I. Cell Background

II. Organelles

A. Nucleus, ribosomes

B. Endomembrane System

C. Energy Organelles

i. Mitochondria

ii. Chloroplasts

III. Cytoskeleton

IV. Extracellular Spaces

V. Lecture Concepts

How are cells studied?

Laser scanning microscopyFluorescence

Bright field

Scanning electron microscopy (SEM)

Transmission electron microscopy (TEM)

Microscopy

Stained or unstainedContrast

Prokaryotes vs. Eukaryotes

Prokaryotes:

- Archae 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)

• nucleolus -ribosome RNA made

• nuclear envelope-double bilayer

• nuclear pores• nuclear matrix

Ribosomes – protein synthesis

• Made in nucleolus

• Bound or free

• Two subunits

• Made of RNA & proteins

1. Endoplasmic reticulum (e.r.)

• Two types – rough, smooth

Rough e.r. – proteins for membrane or secretion

Smooth e.r. – detoxification, lipid and carbohydrate synthesis

Endomembrane System

– ”bleb” off in vesicles

• Extensive membrane

• Continuous with nuclear envelope

• Inside - 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 – food particles (a) or old cell parts (b)

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 bacteria, animals, and plants

Endomembrane System

Energy production

1.Mitochondria • energy from nutrients ATP

• Two membranes, each bilayer -inner -outer

• Intermembrane space

• Matrix

• Folds – cristae

• Own DNA!

• Own ribosomes!

2. Chloroplasts • Light to chemical energy

• Only in plants

• Outer and inner membranes - bilayer

• Internal membranes – thylakoids, stacks called grana

• Spaces – intermembrane, stroma, thylakoid

• Own DNA

• Own ribosomes

Energy production

Organelle summary

In plant cells only:

ChloroplastsCentral vacuole

In animal cells only:

Lysosomes(Flagella)

Self-Check

Organelle Name

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 MembraneLysosomes

Vacuoles

Mitochondria

Chloroplasts

Cytoskeleton

• Shape/support

• Cell movement

• Internal transport

• Cell division

Unique to eukaryotic cells - essential to cell survival/function

Cytoskeleton overview

Three types of cytoskeletal elements:

Cytoskeleton Components

• Actin filaments (microfilaments)

• Microtubules • Intermediate filaments

• Localized at membrane

• Cell movement

Actin filaments

• Muscle fiber contraction

• Pseudopodia• Cytoplasmic streaming (plants)

• Radiate from center

• Internal transport, motile structures

Microtubules

• Inside flagella

• Inside cilia • Make centrioles

• Dispersed throughout cell

• Animal cells

Intermediate filaments

keratin

lamins

• Strength/support

Extracellular Spaces – Cell wall

• In plants

- made of cellulose

• Thick

• cells connected

Why?• plasma membrane

• secondary wall

• primary wall

• Animal cells - glycoproteins Ex. collagen

• ECM – cell communication, movement

Extracellular Spaces – Extracellular Matrix

• Animal cells - three types

1. tight junctions (seal cells)

2. desmosomes (anchoring)

3. gap junctions (communicating)

Extracellular Spaces – Junctions

Lecture 2 concepts

- List at least 3 types of microscopy and pros & cons for each

- Explain differences between prokaryotic and eukaryotic cells

- *For each organelle mentioned, list the name, function and whether it is present in bacteria, plant, & animal cells*

- Name the three fibers of the cytoskeleton and describe the function for each one

- Discuss the cell wall in plants, include purpose and material

- Explain the extracellular matrix of cells, include purpose and material/composition

- Describe how plant and animal cells are connected

- Write out a list of new terminology and provide descriptions