Biochem: cellular

Question 1

Where do Rb and p53 regulate the cell cycle?

Answer 1

G1/S phase checkpoint

therefore, mutations lead to unrestrained cell division

Question 2

What cell types are permanent? What does permanent mean?

Answer 2

remain in G0, regenerate from stem cells

neurones, skeletal and cardiac muscle, RBCs

Question 3

What cell types are stable? What does stable mean?

Answer 3

hepatocytes, lymphocytes

enter G1 from G0 when stimulated

Question 4

What cell types are labile? What does labile mean?

Answer 4

never go to G0, divide rapidly with a short G1

bone marrow, gut epithelium, skin, hair follicles, germ cells

Question 5

What takes place in the RER?

Answer 5

synthesis of secretroy proteins

N-linked oligosaccharide addition to many proteins

Question 6

What does the SER do?

Answer 6

synthesize steroids
detoxify drugs and poisons
(prominant in hepatocytes and steroid hormone producing cells of the adrenal cortex)

Question 7

What does golgi apparatus do?

Answer 7

distribution center for proteins and lipids from the ER to the vesicles and plasma membrain
modified N oligosaccharides on asparagine
adds O oligosaccharides on serine nad threonine
adds mannose 6 phosphate to proeteins for trafficking to lysosomes
glycosylates core proteins to form proglycans
adds sulfate groups to sugar and tyrosine

Question 8

What is I cell disease caused by?

Answer 8

failure of addition of mannose 6 phosphate to lysosome proteins (enzymes sent to outside of cell instead of lysosome)

Question 9

What are the sx of I cell disease?

Answer 9

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

Question 10

Which protein traffics from golgi to golgi (retro) or golgi to ER?

Answer 10

COPI

Question 11

Which protein traffics from golgi to golgi (antero) or ER to golgi?

Answer 11

COPII

Question 12

What does clathrin do?

Answer 12

traffics from trans golgi to lysosomes or from plasma membrane to endosomes

Question 13

What do peroxisomes do?

Answer 13

catabolize very long fatty acids and amino acids

Question 14

What are the 3 methods of proteolysis?

Answer 14

1. lysosomal degradation
2. proteasomal degradation
3. Ca 2+ dependent enzymes

Question 15

What does the proteasome do?

Answer 15

degrade damaged or unnecessary proteins tagged for destruction with ubiquitin

Question 16

What does dynein do?

Answer 16

retrograde microtubule transport (+ —> - )

Question 17

Waht does kinesin do?

Answer 17

anterograde microtubule transport ( - —> + )

Question 18

What drugs act on microtubules?

Answer 18

mebendazole/thiabendazole
griseofulvin
vincristine/vinblastine
paclitaxel
colchicine

Question 19

What casues chediak higashi syndrome?

Answer 19

mutation in lysosomal trafficking regulator gene LYST, whose product is required for microtubule dependent sorting of endosomal proteins into late multivesicular endosomes

Question 20

What are the sx of Chediak higashi syndrome?

Answer 20

recurrent pyogenic infections, partial albinism, peripheral neuropathy
(lysosomes of phagocytes are neffective and there is abnormal storage of melanin)

Question 21

Where is a 9 + 2 arrangement of microtubules found?

Answer 21

cilia

Question 22

What coordinates cilia movement?

Answer 22

gap junctions between cells

Question 23

What causes Kartagener’s syndrome? Sx?

Answer 23

immotile cilia due to a dynein arm defect

infertility (M & F) , bronchiectasis, recurrent sinusitis, assoc w/situs inversus

Question 24

What cell type is vimentin found in? what type of ccancer does it denote?

Answer 24

connective tissue

sarcoma

Question 25

What cell type is desmin found in? What type of cancer does it denote?

Answer 25

desmin | myosarcoma

Question 26

What cell type is cytokeratin found in? What type of cancer does it denote?

Answer 26

epithelial cells | carcinoma

Question 27

What cell type is GFAP found in? What type of cancer does it denote?

Answer 27

neuroglia | astrocytomas/glioblastoma

Question 28

What cell type is neurofilaments found in? What type of cancer does it denote?

Answer 28

neurons neuroblastoma, etc any primitive neuroectoderm tumor

Question 29

What drugs inhibit the sodium potassium pump?

Answer 29

digoxin & ouabain

Question 30

Where is type I collagen found?

Answer 30

bone, skin, tendon, late wound repair

Question 31

When is defective type I collagen found?

Answer 31

in osteogenesis imperfecta

Question 32

Where is type II collagen found?

Answer 32

cartilage, vitreous body, nucleus pulposis

Question 33

Wher is type III collagen found?

Answer 33

reticulin-skin, blood vessels, uterus, fetal tissue, granulation tissue

Question 34

When is defectivetype III collagen found?

Answer 34

Ehlers-Danlos

Question 35

Where is type IV collagen found?

Answer 35

Basement membrane/basal lamina

Question 36

When is defective type IV collagen found?

Answer 36

Alport s/o

Question 37

What steps of collagen synthesis occur inside the fibroblast?

Answer 37

synthesis (RER) hydroxylation (ER) Glycosylation (ER) {osteogenesis imperfecta (problems forming triple helix)} Exocytosis

Question 38

What steps of collagen synthesis occur outside the fibroblast?

Answer 38

``` Proteolytic processing (cleavae of terminal regions of procollagen [procollagen ---> tropocollagen]) Cross Linking to make collagen fibrils {ehlers danlos} ```

Question 39

How is osteogenesis imperfecta inherited?

Answer 39

AD (most common) | AR (OI II, perinathal lethal type)

Question 40

What are sx of OI?

Answer 40

blue sclera mutliple fractures hearing loss dental imperfections (lack of dentin)

Question 41

What are the sx of Ehlers danlos?

Answer 41

2 types 1. hyperextensible skin, hypermobile joints 2. tendency to bleed (vascular ED) may be associaed with join dislocation, berry aneurysms and organ rupture

Question 42

What causes a keloid?

Answer 42

too much collagen in the scar, inject with glucocorticoid to try and help

Question 43

What are the sx of alport s/o? Inheritance?

Answer 43

XR progressive hereditary nephritis and deafness may get occular disturbances "can't see, can't ee, can't hear high C"

Question 44

What breaks down elastin? What inhibits elastin breakdown?

Answer 44

elastase | a1 antitrypsin

Question 45

Where is elastin commonly found?

Answer 45

skin, lungs, large arteries, ligaments, vocal cords, ligamenta flava

Question 46

What AAs is elastin rich in?

Answer 46

proline & glycine (non hydroxylated)

Question 47

What serves as scaffolding for elastin? When is it defective?

Answer 47

fibrillin | Marfan's

Question 48

When a patient has panacinar emphysema, young onset, with liver disease, what is likely deficient?

Answer 48

a1 Antitrypsin

Question 49

What causes wrinkles?

Answer 49

reduced collagen and elastin production