Ch. 2b Cellular Division

Question 1

Meosis

Answer 1

in germ cells (sexual); yield cells that have n (haploid), fertilization (2n) zygote
Interphase: crossing over, genetically recombined gametes/cells
Meosis 1: 4 phases= 2 cells
Meosis 2: 4 phases= 4 cells
genetically different

Question 2

Mitosis

Answer 2

in soma cells; have 2n (diploid) chromosomes (n+n)
has 4 phases: interphase, chromosomes duplicate
identical

Question 3

Cell Death (messy vs tidy)

Answer 3

is of two types:

a) necrosis: cell swells, chromosome disintegrate, invade neighbours, inflammation
b) apoptosis: cell shrinks, parts picked up or by immune cells, little globules, disintegrate/new cells (no pain)
eg. webbed fingers/toes in fetus, disappear during development
eg. intestinal epithelium renewed every 3-4 days
eg. gene p53, triggers apoptosis; malfunction= breast and lung cancer

Question 4

Metabolism

Answer 4

sum of all reactions:
a) catabolism: breaks down complex molecules, generates fresh energy eg. glucose
b) anabolism: uses energy
ATP:
- readily available, break up which produces energy
- metabolic “money”

Question 5

ATP Production: Glycolysis

Answer 5

chemical process involving 10 steps that break down glucose into two Pyruvic Acid molecules; used 2 ATP and produced 4 ATP molecules= net of 2 ATP

Question 6

Citric Acid Cycle or Kreb’s Cycle

Answer 6

produced 2 ATP

Question 7

Electron Transport Chain

Answer 7

-34 ATP

-

Question 8

Aerobic Metabolism

Answer 8

• always in the presence of oxygen
• produce 36 ATP
• net yield is 4 ATP 10 NDAH 2 FADH2

Question 9

Anaerobic Metabolism

Answer 9

• minus oxygen
• used to explain exercise; no more than 1 minute
• goes only up to glycolysis; net yield is 2 ATP
• lactic acid (burn)

Question 10

Plasma Membrane Structure

Answer 10

1. abundant molecules are phospholipids
   - phospholipid bilayer; polar heads (glycerol, phosphate, R) and nonpolar tails (fatty acids)
   - form basic structure
2. has small amount of carbohydrates:
   - “self” identity markers, surface markings in forming tissues
3. cholesterol:
   - insert into lipid layer
   - prevent fatty acid tails from crystallizing and destroying membrane
   - provide stability over a wide range of temperature
4. Proteins: channels, carriers, receptors, enzymes, CAM (cell adhesion molecules), docking markers, glycoproteins
   - integral (transmembrane)
   - peripheral: do not span membrane

Question 11

Biological Glue: ECM

Answer 11

• mostly insoluble proteins:
• collagen (strength), elastin (recoil), fibronectin (hold cells together)
• secreted by the tissue, composition will vary
• mechanical properties will vary

Question 12

Biological Glue: CAMs

Answer 12

• help to form tissues

- integrins, cadherins

Question 13

Biological Glue: Specialized Junctions

Answer 13

Desmosomes: “spot rivets”, stretch to help in tissue growth, “anchoring junctions”, eg. skin, heart muscle tissue, uterus
Tight Junctions: prevent leaks between cells, claudins and occludins eg. kidney, intestinal, blood brain barrier
Gap Junctions: “communicating” most abundant, connexons,
eg. cardiac, smooth muscle, ovaries, thyroid, liver, pancreas

Question 14

Channels

Answer 14

• span the membrane to form water-filled pathways across lipid bilayer
• selectively attract or repel particular ions

Question 15

Carrier Molecules

Answer 15

• spans the membrane

- uniport, symport, antiport

Question 16

Docking-Marker Acceptors

Answer 16

• inner membrane surface

- proteins bind in a lock-and-key fashion with the docking markers of secretory vesicles

Question 17

Membrane-Bound Enzymes

Answer 17

surface-located proteins, control specific chemical reactions at either the inner or outer cell surface

Question 18

Receptor Sites

Answer 18

• recognize and bind with specific molecules in the cell’s environment
• chemical messengers in the blood can influence only the specific cells that have receptors for a given messenger
• on outer-surface

Question 19

Cell Adhesion Molecules

Answer 19

• protude from outer membrane surface and form loops or hooks that the cells use to grip each other and to grasp the connective tissue fibers that interlace between cells
• ex. cadherins and integrins

Question 20

Osmosis

Answer 20

net diffusion of water down its concentration gradient

• isotonic: equalibrium
• hypotonic
• hypertonic

Question 21

Diffusion

Answer 21

• Fick’s Law of Diffusion:
• greater difference in concentration the faster the rate of diffusion, higher permeability the more rapidly substance can diffuse, higher surface area the greater the rate of diffusion
• heavier the molecular weight, slower the net diffusion
• greater the distance, slower the diffusion
• equilibrium

Question 22

Facilitated Diffusion

Answer 22

• uses a carrier
• high to low concentrations
• glucose (GLUT)
• equilibrium

Question 23

Primary Active Transport

Answer 23

• low to high concentrations
• slips ATP molecule
• disequilibrium
• antiport carrier: sodium-potassium pump

Question 24

Secondary Active Transport

Answer 24

• symport (sGLUT)
• 1:1
• found in kidney and intestine cells

Question 25

Pinocytosis

Answer 25

- "cell drinking" - membrane dips inward with ECF, seals at surface of the pouch trapping contents in small, intrecellular endocytotic vesicle - dyamin, protein pinches off vesicle and forms ring that wraps around pouch

Question 26

Receptor- Mediated Endocytosis

Answer 26

- import large molecules needed from environment - binding of a specific molecule to a surface membrane receptor site, causes plasma membrane to sink in then seal at surface - insulin, vitamins, and iron - viruses and bacteria

Question 27

Exocytosis

Answer 27

- membraned enclosed vesicle fuses with the plasma membrane, then opens up and releases its contents to the exterior - ER and Golgi complex - docking marker (protein marker) - recognition marker, sorting signal (packaged in vesicle) - coat proteins (form a dome-shaped bud around cargo) - V-SNAREs link in lock and key with t-SNARE (docking markers)