Fiser Chapter 1. CELL BIOLOGY

Question 1

cell membrane composition

Answer 1

lipid bilayer with protein channels, enzymes, and receptors

Question 2

What increases membrane fluidity?

Answer 2

Cholesterol

Question 3

Membrane potentional

Answer 3

Cells are negative inside compared to outside due to Na/K ATPase (3 Na out, 2 K in)

Na gradient is used for co-transport of glucose, proteins, and molecules

Question 4

Desmosomes/hemidesmosomes

Answer 4

Adhesion molecules (cell-cell and cell-extracellular matrix, respectively) which anchor cells

Question 5

Tight junctions versus Gap junctions

Answer 5

Tight junctions: cell-cell occluding junctions; form an impermeable barrier (eg epithelium)

Gap junctions: allow communication between cells (connexin subunits)

Question 6

G proteins

Answer 6

Intramembrane proteins; transduce signal from receptor to response enzyme

Question 7

Ligan-triggered protein kinase

Answer 7

Receptor and response enzyme are a single trans-membrane protene (insulin, epidermal growth factor). Binding actiates the kinase domain, which phosphorylates substrate proteins.

Question 8

Examples of glycolipids and glycoproteins on cell membrane

Answer 8

ABO bloody-type antigens: glycolipids

HLA-type antigens: glycoproteins (Gp)

Question 9

Osmotic equilibrium

Answer 9

Water moves from area of low solute concentration to an area of high solute concentration and approach osmotic equilibrium

Question 10

Cell cycle sequence

Answer 10

G1, S (proteine synthesis, chromosomal duplication), G2, M (mitosis, nucleus divides)

Can also go to G0 (quiescent) from G1

Question 11

What detemines cell cycle length?

Answer 11

G1: growth factors affect cell here too

Question 12

Mitosis

Answer 12

PMAT

Prophase (centromere attachment, spinder formation, nucleus disappears)

Metaphase: chromosome alignment

Anaphase: chromosomes pulled apart

Telophase: separate nucleus reforms around each set of chromosomes

Question 13

Steroid and tyroid hormones

Answer 13

Both transcription factors (bind DNA and help transcription of genes), but steroid binds receptor in CYTOPLASMand then enters nucleus, while thyroid hormone binds receptor in nucleus

Question 14

Purines and pyrimidines

Answer 14

Purines: adenine and guanine

Pyrimidines: cytosine, uracil (RNA), thymidine (DNA), “pyramids cut”

AU or AT is with 2 hydrogen bonds; GC is with 3 hydrogen bonds

Question 15

Glycolysis overall does what?

Answer 15

Turns a glucose molecule into 2 ATP and 2 pyruvate

Question 16

Krebs cycle overall does what?

Answer 16

Located on inner matrix of mitochondria, it takes the 2 pyruvate molecules created in glycolysis, to create NADH and FADH2. These then enter the ETC to create ATP. Overall 1 glucose creates 36 ATP

Question 17

How much ATP does each glucose molecule create during aerobic metabolism?

Answer 17

Glycolysis then krebs cycle then ETC:

36 ATP

Question 18

Gluconeogenesis overall

Answer 18

Lactic acid (from cori cycle) and amino acids are converted to glucose

Fat and lipids NOT available for gluconeogenesis because acetyle CoA (breakdown of fat metabolism) cannot be converted back to pyruvate

Question 19

Cori cycle overall

Answer 19

Liver turns muscle lactate into new glucose; pyruvate plays a key role