Cellular Biochemistry

Question 1

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

Answer 1

Cyclins

Question 2

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

Answer 2

Cyclin-CDK complexes

Question 3

p53 induces what gene that then inhibits CDKs

Answer 3

p21

Question 4

Effects of p21 inhibition of CDKs (2)

Answer 4

1) hypophosphorylation (activation) of Rb

2) inhibition of G1-S progression.

Question 5

(Cell Type) Remain in G0, regenerate from stem cells

Answer 5

Permanent cells

Question 6

(Cell Type) Enter G1 form G0 when stimulated

Answer 6

Stable (quiescent) cells

Question 7

(Cell Type) Never go to G0, divide rapidly with a short G1. Most affected by chemotherapy.

Answer 7

Labile cells

Question 8

The peroxisome is involved in four major processes

Answer 8

1) beta oxidation of very-long-chain fatty acids (VLCFA)
2) alpha oxidation
3) Catabolism of branched-chain fatty acids, amino acids, and ethanol
4) Synthesis of cholsterol, bile acids, and plasmalogens

Question 9

Autosomal recessive disorder of peroxisome biogenesis due to mutated PEX genes. Hypotonia, seizures, hepatomegaly, early death.

Answer 9

Zellweger syndrome

Question 10

Autosomal recessive disorder of alpha-oxidation. Phytanic acid not metabolized to pristanic acid. Scaly skin, ataxia, cataracts/night blindness, shortening of 4th toe, epiphyseal dysplasia. Treatment: diet, plasmapheresis.

Answer 10

Refsum disease

Question 11

X-linked recessive disorder of beta-oxidation due to mutation in ABCD1 gene. VLCFA in adrenal glands, white (leuko) matter of brain, testes. Progressive disease that can lead to adrenal gland crisis, coma, and death.

Answer 11

Adrenoleukodystrophy

Question 12

Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins. Defects in this system have been implicated in some cases of Parkinson disease.

Answer 12

Proteasome

Question 13

A network of protein fibers within the cytoplasm that supports cell structure, cell and organelle movement, and cell division

Answer 13

Cytoskeletal elements

Question 14

Inhibits Na+-K+ ATPase pump by binding to the K+ site

Answer 14

Ouabain

Question 15

Directly inhibits the Na+-K+ ATPase, which then indirectly inhibits Na+/Ca2+ exchange. Increase in calcium leads to increase in cardiac contractility

Answer 15

Cardiac Glycosides (ex: Digoxin and digitoxin)

Question 16

Most abundant protein in the human body. Organizes and strengthens the extracellular matrix

Answer 16

Collagen

Question 17

(Collagen type) Most common variety. Featured in the bone, skin, tendons, dentin, fascia, cornea, and late wound repair.

Answer 17

Collagen Type I

Question 18

(Collagen type) Featured in cartilage, vitreous body (part of eye), and nucleus pulposus (some jelly like shit in the vertebrae)

Answer 18

Collagen Type II

Question 19

(Collagen type) Featured in reticulin fibers, skin, blood vessels, uterus, fetal tissue, granulation tissue

Answer 19

Collagen Type III

Question 20

(Collagen type) Featured in the basement membrane (basal lamina) and lens of the eye

Answer 20

Collage Type IV

Question 21

Six (generalized) steps of collagen synthesis

Answer 21

1) synthesis of collagen alpha chains (Gly-X-Y)
2) Hydroxylation of specific proline and lysine residues (requires Vit C)
3) Glycosylation of pro-alpha-chain hydroxylysine residues and formation of procollagen via hydrogen and disulfide bonds
4) exocytosis of procollagen into extracellular space
5) Proteolytic processing. Cleavage of disulfide-rich terminal regions of procollagen
6) Cross-linking

Question 22

Genetic bone disorder also referred to as brittle bone disease. Most common form is autosomal dominant with decreased production of Type I collagen. Frequent fractures, blue sclerae (white of the eye), tooth abnormalities and hearing loss.

Answer 22

Osteogenesis Imperfecta

Question 23

Faulty collagen synthesis causing hyperextensible skin, hypermobile joints, and tendency to bleed/bruise.

Answer 23

Ethlers-Danlos Syndrome

Question 24

X-linked recessive connective tissue disease caused by impaired copper absorption and transport due to defective Menkes. Leads to decreased activity of lysyl oxidase and then defective collage. Brittle kinky hair, growth retardation, and hypotonia.

Answer 24

Menkes disease

Question 25

Stretchy protein within skin, lungs, large arteries, elastic ligaments, and vocal cords.

Answer 25

Elastin

Question 26

Elastase is normally inhibited by what from breaking down elastin?

Answer 26

alpha 1 antitrypsin

Question 27

Autosomal dominant connective tissue disorder affecting seleton, heart, and eyes. Mutated gene results in defective fibrillin, a glycoprotein that forms a sheath around elastin. Findings: tall with long extremities, pectus carinatum ( rare chest wall deformity), hypermobile joints, long tapering fingers and toes, etc.. etc..

Answer 27

Marfan syndrome