Cellular Architecture

Or the typical/nontypical cell

Figure 4-1Page 68

I. Limits to cell size

A. Surface to volume ratio

1. function of membrane

2. relationship of surface area to volume

3. consequences of growing too large

Figure 4-2Page

68

2 mm

2 mm

1 mm

1 mm

I. Limits to cell size

B. Control issues1. Informational flow

2. Transcription

3. Diffusion

4. Translation

5. Cell gets too large, lag time in the control of activities

6. Analogy

II. Few Generalizations

• A. Procaryotic vs. eukaryotic

• B. Typical cell– 1. animal– 2. plant– 3. discuss the

similarities first

III. Organelles of synthesis

• A. Introduction– 1. Going to act as an assembly line– 2. Nucleus– 3. Endoplasmic reticulm– 4. ribosome– 5. Golgi apparatus

III. Organelles of synthesis

B. Nucleus-headquarters

1. chromatin

2. chromosomes

3. nucleolus

4. double membrane with pores

Nuclear Pores From Surface of Nuclear Membrane

Artist conception of nuclear pores

III. Organelles of synthesis

• C. Endoplasmic Reticulum• 1. definition• 2. nickname• 3. types of

– Rough– Smooth

Rough and smooth endoplasmic reticulum

Endoplasmic reticulum continuous with pores

III. Organelles of synthesis

• D. Ribosomes-protein synthesis• 1. found free in cytoplasm-endogenous use• 2. attached to E.R.-proteins for export• 3. responsible for translation of mRNA into protein

Ribosomes translate mRNA

III. Organelles of synthesis

• D. Golgi Body or Golgi Apparatus

• 1. nick name of bottling center• 2. modifies product• 3. concentrates product• 4. packages product into

vesicles• 5. exports via exocytosis

III. Organelles of synthesis

• E. Cell membrane with exocytosis

IV. Organelles of homeostasis

• A. Mitochondria• Nickname• Structure• Endosymbiosis• More active tissue• Both animal and plant

B. Chloroplasts

• Nickname• Structure• Endosymbiosis

Mitochondria and chloroplasts are tied tightly together

Figure 4-7(2)

Page 72

Vacuole

Cell wall

Plasma membrane

Granum Stroma

Chloroplast Rough and smooth endoplasmic reticulum (ER)

Nucleus

Nuclearenvelope

Nucleolus

Nuclearpores

Chromatin

Smooth ER

Rough ER

Ribosomes

C. Lysosome

• Nickname• Structure• Functions

D. Peroxisomes

• Similar in appearance to lysosomes• Contain enzymes important in lipid breakdown• Detoxification centers• Possess enzyme catalase important in the

breakdown of hydrogen peroxide

E. Cytoskeleton

Composed of microtubules and microfilaments

1. Microtubules

• “Skeleton” of the cell• Produce the structural

framework for cilia and flagella

1. microtubules

• Act as a railway along which organelles travel

• Microtubules may walk past one another

• Motor molecules may transport organelles from one area of the cytoplasm to another

2. microfilaments

• “muscles” of the cell• Same proteins that are found in our muscles

Microfilaments (cont)

• produce swaying of microvilli

• Movements of cytoplasmic streaming

Relationship of the cytoskeleton to the cell membrane and extracellular fibers

F. Cell wall of plant cells

• Primary cell wall• Secondary cell wall• Middle lamellae pectin• Importance of plasmodesmata

Plantcell walls

Plasmodesmata

Plasmodesmata

G. Centrioles

H. Central vacuole

I. Cilia and flagella

• Microtubules• 9 +2• Triplets in basal

body• Form from

centrioles?