Biochemistry First Aid- Cellular

Question 1

what molecules regulate the cell cycle at checkpoints

Answer 1

cyclins, cyclin-dependent kinases (CDK’s) and tumor suppressors

Question 2

what do cyclins do to CDK’s

Answer 2

activate them

Question 3

what factors normally inhibit G1-to-S progression

Answer 3

p53 and hypophosphorylated Rb

Question 4

name a disease associated with mutated p53 that predisposes to cancer

Answer 4

Li-Fraumeni (autosomal dominant)

Question 5

name the phases of the cell cycle in order beginning with mitosis and ending right before the subsequent mitosis

Answer 5

mitosis, G1 and/or (G0), S, G2, subsequent mitosis

Question 6

what is interphase

Answer 6

G1, S, G2

Question 7

what stage of the cell cycle do permanent cells remain in

Answer 7

G0

Question 8

what kinds of cells are permanent cells

Answer 8

neurons, skeletal cardiac myocytes, RBC’s

Question 9

when stable cells are stimulated what do they do with respect to the cell cycle

Answer 9

stimulated quiescent (stable) cells move from G0 back into G1

Question 10

what kinds of cells are stable (quiescent) cells

Answer 10

hepatocytes, lymphocytes

Question 11

what kind of unique cell cycle activity do labile cells demonstrate and what are they affected by that no other cell types are affected by

Answer 11

do not enter G0, but rather continue from mitosis to G1 and continue dividing; most affected by chemotherapy

Question 12

what kinds of cells in the body are labile cells

Answer 12

gastrointestinal epithelium, skin, hair follicles, germ cells and bone marrow

Question 13

what are Nissl bodies

Answer 13

RER in neurons

Question 14

which cells have a lot of smooth endoplasmic reticulum

Answer 14

hepatocytes and steroid hormone producing cells of the adrenal cortex and gonads

Question 15

what does the golgi apparatus do to aspargine?

serine and threonine?

Answer 15

modifies N-oligossacharides on aspargine

adds O-oligosaccharides to serine and threonine

Question 16

what kind of sugar is added to proteins so that they can be trafficked to lysosomes

Answer 16

mannose-6-P

Question 17

what is I-cell disease

Answer 17

inclusion cell disease: an inherited lysosomal storage disease caused by deficiency of phosphotransferase which normally adds mannose-6P to proteins so that they can be trafficked to lysosome; instead the proteins are secreted by the cell

Question 18

what clinical symptoms do patients with I-cell disease have

Answer 18

coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes, often fatal in childhood

Question 19

what is the role of signal recognition particle (SRP)

Answer 19

to traffic proteins from the ribosome to the RER in order to prevent them from accumulating in the cytoplasm

Question 20

name three vesicular trafficking proteins

Answer 20

COPI (Golgi to Golgi and Golgi back to ER), COPII (Golgi to Golgi and ER to Golgi), and Clathrin (Golgi to lysosomes, plasma membrane to endosomes (endocytosis))

Question 21

what do peroxisomes catabolize

Answer 21

long-chain fatty acids, branched-chain fatty acids, amino acids

Question 22

what is a proteasome and what condition has it been implicated in

Answer 22

protein complex that degrades damaged or ubiquitin-tagged proteins
defects in ubiquitin-proteasome system is implicated in Parkinson’s

Question 23

what are the two dimers of the microtuble

Answer 23

alpha-tubulin and beta-tubulin

Question 24

what is bound to each dimer of microtubules

Answer 24

2 GTP

Question 25

what role do microtubules play in the body

Answer 25

comprise mitotic spindles, cilia, flagella and allow for transport of neurons

Question 26

what are the two molecular motor proteins that move along microtubules and what direction do they move

Answer 26

kinesin moves in the forward direction (- to +) | dynein moves in the backward direction (+ to -)

Question 27

name 5 drugs that act on microtubules

Answer 27

``` mebendazole griseofulvin colchicine (gout treatment) vincristine/vinblastine (cancer treatment) paclitaxel (cancer treatment) ```

Question 28

what is Kartagener syndrome (primary ciliary dyskinesia)

Answer 28

defect in dynein that causes immotile cilia ==> immotile sperm and dysfunctional fallopian tube cilia leads to infertility and ectopic pregnancy risk in women can also cause bronchiectasis, recurrent sinusitis and situs inverses

Question 29

what is the arrangement of microtubules in cilia

Answer 29

9 + 2

Question 30

what does axonemal dynein do

Answer 30

bend the cilia

Question 31

_______ are polymers and _______ are dimers (myosin vs. actin)

Answer 31

actin are polymers and myosin are dimers

Question 32

name some intermediate filaments (they provide structure

Answer 32

vimentin, desmin, cytokeratin, lamin, glial fibrillary acid proteins, neurofilaments

Question 33

name some common components of a plasma membrane and what particular molecules is specific to fungal membranes

Answer 33

cholesterol, phospholipids, sphingolipids, glycolipids and proteins (ergosterol in fungi)

Question 34

what intermediate filament can you use to stain for connective tissue

Answer 34

vimentin

Question 35

what intermediate filament can you use to stain for muscle

Answer 35

desmin

Question 36

what intermediate filament can you use to stain for epithelial cells

Answer 36

cytokeratin

Question 37

what intermediate filament can you use to stain for neuroglia

Answer 37

GFAP

Question 38

what intermediate filament can you use to stain for neurons

Answer 38

neurofilaments

Question 39

for every ATP consumed by the NaK pump how many Na and K go in/out

Answer 39

3 Na out, 2 K in

Question 40

which drug inhibits the K binding site of the NaK pump

Answer 40

ouabain

Question 41

what cardiac drugs works by inhibiting the NaK pump

Answer 41

cardiac glycosides: digoxin and digitoxin

Question 42

which bone disease involves low production of type I collagen

Answer 42

osteogenesis imperfecta type I

Question 43

what tissues of the body are made from type I collagen

Answer 43

bone, tendons, skin, dentin, fascia, cornea and late wound repair

Question 44

what type of tissue is made from type II collagen

Answer 44

cartilage ("car-two-lage"

Question 45

what type of tissue is made from type III collagen

Answer 45

reticulin: comprises skin, blood vessels, uterine tissue, fetal tissue and granulation tissue

Question 46

what disease results from deficient type III cartilage

Answer 46

Ehler's-Danlos

Question 47

what is made from type IV collagen

Answer 47

basement membrane, basal lamina, lens

Question 48

what disease results from defective type IV collagen

Answer 48

``` Alport syndrome (nephritis caused by thinning and splitting of GBM, also associated with lens defects and hearing deficits) Goodpasture's (autoantibodies target the defective collagen) ```

Question 49

30% of collagen consists of what amino acid

Answer 49

glycine

Question 50

vitamin C is important for what part of collagen synthesis

Answer 50

hydroxylation; specific proline and lysine residues are hydroxylated

Question 51

name the six stages of collagen synthesis

Answer 51

1. synthesis (in RER) 2. hydroxylation (in RER) 3. glyosylation (in RER) 4. exocytosis 5. proteolytic processessing (procollagen cleaved to make tropocollagen) 6. cross-linking (covalent lysine-hydroxylysine cross-linkage are formed to connect tropocollagen molecules to make collagen fibrils)

Question 52

besides multiple fractures and blue sclera what other symptoms do patients with osteogenesis imperfecta have

Answer 52

hearing loss (abnormal ossicles) and dental imperfections (deficient dentin)

Question 53

what conditions may Ehler's Danlos syndrome be associated with

Answer 53

berry aneurysms, joint dislocation, aortic aneurysms and organ rupture

Question 54

name three different types of Ehler's Danlos syndrome

Answer 54

``` hypermobility type (most common): flexible joints classic type: type V collagen mutation vascular type: deficient type III collagen ```

Question 55

what is Menkes disease

Answer 55

connective tissue disease caused by impaired copper absportion and transport --> low lysyl oxidase activity leads to brittle, kinked hair, growth retardation and hypotonia

Question 56

what molecule inhibits break down of elastin by elastase

Answer 56

alpha1-antitrypsin

Question 57

defect in what protein causes Marfan syndrome

Answer 57

fibrillin (a glycoprotein that forms a sheath around elastin)

Question 58

emphysema can be caused by deficiency of what molecule involved in elastin regulation

Answer 58

alpha1-antitrypsin deficiency ==> excess elastase activity leads to low elastin

Question 59

what are the 3 major steps of PCR

Answer 59

1. denaturation 2. anealling 3. elongation