Class 3 - Cell Form & Function

Question 1

Size range of human cells

What limits their size?

Answer 1

Most human cells are 10 to 15 micrometer BUT egg cells are 100 micrometer in diameter and nerve cells can be over 1 m long

If cell gets too large if will rupture; for given increase in diameter, volume increases more than surface area.

Question 2

Structure of plasma membrane

Answer 2

98% lipids
75% phospholipids (bilayer)
20% cholesterol (stiffens, holds still)
5% glycolipids (glycocalyx)

2% proteins (50% weight)
Transmembrane protein (pass thru)
Peripheral protein (on one face)

Question 3

Second messenger system and importance to human physiology

Answer 3

Where one messenger (epinephrine) reaches receptor, which releases G protein, which binds to enzyme (adenylate cyclase), which creates second messenger (cAMP), which activates kinase

60% of drugs work thru G protein and second messengers

Question 4

Glycocalyx composition and functions (7)

Answer 4

Carbohydrate attachments to glycoproteins/glycolipids on outside of plasma membrane

1. Protection
2. Immunity to infection
3. Defense against cancer
4. Transplant compatability
5. Cell adhesion
6. Fertilization
7. Embryonic development

Question 5

Structure and function of microvilli, cilia, flagella, and pseudopods

Answer 5

Microvilli - Extensions of membrane which increase surface area. Most used for absorption.

Cilia - Short processes. All cells have nonmotile “antenna” primary cilium. Motile ones use power and recovery stroke to move mucus atop saline layer

Flagellum - Long, undulating process

Pseudopod - changing extensions of cell used for locomotion or capturing particles

Question 6

Cell shapes: Thin, flat, scaly

Answer 6

Squamous

Question 7

Cell shapes: squarish-looking

Answer 7

Cuboidal

Question 8

Cell shapes: Taller than wide/rectangular

Answer 8

Columnar

Question 9

Cell shapes: irregular angular shape, multiple sides

Answer 9

Polygonal

Question 10

Cell shapes: Starlike shape

Answer 10

Stellate

Question 11

Cell shapes: Round to oval (2)

Answer 11

Spheroid to ovoid

Question 12

Cell shapes: disc-shaped

Answer 12

Discoidal

Question 13

Cell shapes: thick in middle, tapered toward end

Answer 13

Fusiform

Question 14

Cell shapes: Threadlike

Answer 14

Fibrous

Question 15

Changes in microscopy and view of cell structure + 3 types

Answer 15

Improvements allowed ultrastructure to be visualized

1. Light microscope (LM) - revealed basic components
2. Transmission electron microscope (TEM) - improved resolution (detail)
3. Scanning electron microscope (SEM) - produces dramatic 3D images with high magnification and resolution for surface features

Question 16

4 components of cell theory

Answer 16

1. All organisms composed of cells/cell products
2. Cell is simplest structural and functional unit of life
3. An organism’s structure and functions are due to activities of cells
4. Cells come only from preexisting cells

Question 17

Functions of membrane proteins (6)

Answer 17

1. Receptors - bind signals, trigger changes
2. Enzymes - catalyze reactions (digestion, production of 2nd messengers).
3. Channels - Allow hydrophilic solute/water thru membrane
4. Carriers - Bind solutes and transfer across (pumps: consume ATP)
5. Cell-identity markers - Glycoproteins
6. Cell-adhesion molecules (CAMs) mechanically link cell to another

Question 18

Types of channel proteins (4)

Answer 18

1. Leak - Always open
2. Ligand-gated - Respond to chemical messengers
3. Voltage-gated - Respond to charge changes
4. Mechanically gated - Respond to physical stress on cell

Question 19

Cystic fibrosis

Answer 19

Cells fail to install chloride pumps in plasma membrane so no saline layer on cell surface for cilia to push mucus on