cellular biochem

Question 1

cyclin-CDKs in G1

Answer 1

cyclin D-CDK4- phosphorylates Rb

cyclin E-CDK2- progression to S

Question 2

cyclin-CDKs in G2

Answer 2

cyclin A-CDK2- prophase of mitosis

cyclin B-CDK1- activated by cdc25- initiates mitosis with breakdown of nuclear envelope

Question 3

control G1-S progression

Answer 3

p53- controls activation of p21

Rb- binds E2F (tf)

Question 4

tubulin structure

Answer 4

polymerized dimers of a/B tublulin with 2 GTP bound

Question 5

2 molecular motor proteins

Answer 5

kinesin- anterograde

dyenin- retrograde

Question 6

drugs that act on microtubules (5)

Answer 6

mebendazole
friseofulvin
vincristine/vinblastine
paclitaxel
colchicine

Question 7

cilia structure

Answer 7

9+2 arrangement of microtubules

dyenin arms

Question 8

what allows for coordinated movement of cilia on separate cells?

Answer 8

gap junctions

Question 9

effect of increased cholesterol on cell membrane

Answer 9

decreased fluidity

increased melting point

Question 10

vimentin

Answer 10

connective tissue (sarcoma)

Question 11

desmin

Answer 11

muscle (rhabdomyosarcoma)

Question 12

cytokeratin

Answer 12

epithelial cells (carcinoma)

Question 13

GFAP

Answer 13

glial cells (glioma)

Question 14

neruofilaents/peripherin

Answer 14

neurons

Question 15

nuclear localization signal

Answer 15

4-8 amino acids rich in lysine, arginine, proline; recognized by nuclear pores, granted access to nucleus

Question 16

inhibits Na/K ATPase by binding to K site

Answer 16

oubain

Question 17

type I collagen (3)

Answer 17

strong

bone, skin, tendon

Question 18

type II collagen (3)

Answer 18

slippery

cartilage, nucelus pulposis, vitreous body

Question 19

type III collagen (6)

Answer 19

bloody

reticulin, blood vessels, granulation tissue, fetal tissue, uterus, keloids

Question 20

type IV collagen

Answer 20

basement membrane

Question 21

nuclear lamins

Answer 21

part of the nuclear envelope

Question 22

defects in nucelar lamins (2)

Answer 22

progeria, muscular dystrophy

Question 23

first step after activation of a tyrosine kinase receptor

Answer 23

autophosphorylation

Question 24

use single-pass tyrosine kinase receptors

Answer 24

PDGF, growth factors

Question 25

use extracellular tyrosine kinase receptors (2)

Answer 25

insulin

IGF-1

Question 26

6 steps in collagen synthesis

Answer 26

1- synthesis of pre-procollagen in RER
2- hydroxylation of lysine, proline
3- glycosylation of hydroxylysine
4- exocytosis of procollagen
5- cleavage of N terminus to make tropocollagen
6- cross-linking to make collagen fibrils

Question 27

required for hydroxylation, deficit

Answer 27

vit c

scurvy

Question 28

required for cross linking, defect (2)

Answer 28

Cu, lysyl oxidase
cu deficit- menke’s disease
lysyl oxidase defect- ehlers-danlos

Question 29

classical EDS

Answer 29

collagen types I, V

hyperextensible joints, skin

Question 30

vascular EDS

Answer 30

collagen type III

bv rupture, hemorrhage, berry aneurysm

Question 31

type VI EDS (defect, enzyme, cofactor)

Answer 31

kyphoscoliosis variant
defect of lysyl hydroxylase
cofactor- vitamin C

Question 32

elastin =

Answer 32

tropoelastin + fibrillin scaffolding