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Flashcards in biochem: cellular Deck (38):
1

CDKs

constitutive and inactive

2

cyclins

regulatory proteins that control cell cycle events; phase specific; activate CDKs

3

cyclin-CDK complexes

phosphorylate other proteins to coordinate cell cycle progression; must be activvated and inactivated at appropriate times for cell cycle to progress

4

tumor suppressors

p53 and hypophosphorylated Rb normally inhibit G1-to-S progression; mutations in these genes result in unrestrained cell division (e.g. li-fraumeni syndrome)

5

phases of cell cycle

G0G1->S->G2->M->G1

6

permanent cells

remain in G0, regenerate from stem cells. e.g. neuron,s skeletal and cardiac muscle, RBCs

7

stable (quiescent) cells

enter G1 from G0 when stimulated. e.g. hepatocytes, lymphocytes

8

labile cells

never go to G0, divide rapidly with a short G1. most affected by chemotherapy. e.g. bone marrow, gut epithelium, skin, hair follicles, germ cells

9

rough ER

site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide additions to proteins.

10

Nissl bodies

= RER in neurons. synthesize peptide neurotransmitters for secretion

11

free ribosomes

= unattached to any membrane; site of synthesis of cytosolic and organellar proteins

12

goblet cells and plasma cells are rich in:

RER. they're secreting mucus/antibodies! so lots of export

13

smooth ER

site of steroid synthesis and detoxification of drugs and poisons. lacks surface ribosomes

14

hepatocytes, adrenal cortex, and gonads are rich in:

SER! they have to detoxify stuff/make steroids

15

golgi

= distribution center for proteins and lipids from ER to vesicles and plasma membrane. also modifies N-oligosaccharides on arparagine and adds O-oligosaccharides on serine and threonine. Adds mannose-6-phosphate to proteins for trafficking to lysosomes

16

endosomes

= sorting centers for material from outside the cell or from the golgi, sending it to lysosomes for destruction or back to the membrane/golgi for further use

17

I-cell dz

= inherited lysosomal storage disorder. defect in N-acetylglucosaminyl-1-phosphotransferase -> failure of the golgi to phosphorylate mannose residues, so proteins are secreted extracellularly rather than delivered to lysosomes. -> coarse facial features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes. often fatal in childhood.

18

signal recognition particle (SRP)

abundant, cytosolic ribonucleoprotein that traffics proteins from the ribosome to the RER. absent or dysfunctional SRP -> protein accumulation in cytosol

19

vesicular trafficking proteins

COPI: golgi->cis-golgi -> ER, retrograde. COPII: ER -> cis-golgi, anterograde. clathrin: trans-golgi -> lysosomes; plasma membraine -> endosomes (receptor-mediated endocytosis)

20

peroxisome

membrane-enclosed organelle involved in catabolism of very-long-chain fatty acids, branched-chain fatty acids, and AAs

21

proteasome

barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins. defects in the ubiquitin-proteasome system have been implicated in some cases of PD

22

microfilaments

usually fxn for muscle contraction, cytokinesis. e.g. actin

23

intermediate filaments

maintain cell structure. e.g. vimentin, desmin, cytokeratin, lamins, GFAP, neurofilaments

24

microtubules

usually fxn for movement, cell division. e.g. cilia, flagella, mitotic spindle, axonal trafficking, centrioles. made of alpha and beta tubulin dimers. grows slowly, collapses quickly.

25

drugs that act on microtubules

Microtubules Get Constructed Very Poorly: mebendazole (antihelminthic), Griseofulvin (antifungal), colchicine (antigout), vincristine/vinblastine (anticancer), paclitaxel (anticancer)

26

molecular motor proteins

transport cellular cargo toward opposite ends of microtubule tracks. dynein = retrograde (+ -> -), kinesin = anterograde (- -> +)

27

kartagener syndrome

= primary ciliary dyskinesia. immotile cilia due to dynein arm defect. causes infertility, bronchiectasis, recurrent sinusitis, and situs inversus

28

ouabain

inhibits Na-K-ATPase by binding to K site

29

cardiac glycosides

= digoxin. directly inhibit Na-K-ATPase, indirectly inhibiting Na/Ca exchange -> increased [Ca] -> inc. cardiac contractility

30

collagen type mnemonic

Be (So Totally) Cool, Read Books: I: bone, skin, tendon; II: cartwolage; III: reticulin (in skin, blood vessels, uterus, fetal tissue, granulation tissue); IV: basement membrane, basal lamina (type IV, under the floor)

31

type I collagen defect

OI type I. problem forming triple helix during glycosylation step

32

type IV collagen defect

alport syndrome, targeted by Abs in goodpasture syndrome

33

steps of collagen synthesis

inside fibroblasts: 1. synthesis (RER). 2. hydroxylation (RER). 3. glycosylation (RER). 4. exosytosis. outside fibroblasts: 5. proteolytic processing. 6. cross-linking

34

scurvy

caused by vit. C deficiency: hydroxylation of collagen requires it

35

ehlers-danlos syndrome

faulty collagen, classically type V but can be type III in vascular type. causes hyperextensible skin, easy bruising, and hypermobile joints. variable genetics

36

menke's dz

x-linked recessive dz caused by impaired copper absorption and transport -> dec. activity of lysyl oxidase (part of collagen/elastin synthesis) (Cu = cofactor), -> brittle kinky hair, growth retardation, and hypotonia

37

marfan syndrome

caused by defect in fibrillin = glycoprotein that forms a sheath around elastin

38

alpha-1-antitrypsin

inhibits elastase. deficiency can cause emphysema because elastase breaks down elastin in the lungs.