Student Presentations

Question 1

diagnostic test for Down syndrome

Answer 1

karyotyping or interphase FISH

Question 2

abnormal cellular process for Down syndrome

Answer 2

trisomy 21 - failure of chromosomes to separate during cell division (non-dysjunction)

Question 3

what is insulin, where is it produced, and how is it released in the body?

Answer 3

• hormone made by beta cells of pancreas

- released into blood when blood glucose increases

Question 4

what induces glycogen synthesis and degradation?

Answer 4

synthesis - insulin

degradation - glucagon

Question 5

where is glucagon made?

Answer 5

made by alpha cells of pancreas

Question 6

what is MLPA?

Answer 6

multiplex ligation dependent probe amplification - used for diagnosis of Duchenne muscular dystrophy

Question 7

Duchenne’s MD inheritance

Answer 7

x-linked

Question 8

dystrophin - cell function and molecules it connects?

Answer 8

binds actin and skeletal muscle

Question 9

non structural roles of dystrophin in muscle

Answer 9

low dystrophin can allow excess Ca2+ into sarcolemma -> allows water to enter mitochondria -> lysis
-mitochondria defect causes increase in stress induced calcium levels and ROS

Question 10

what causes hereditary spherocytosis?

Answer 10

normal shape of RBCs disrupted due to defects in genes of ankyrin and spectrin

Question 11

integral membrane proteins of RBC plasma membrane and function of each

Answer 11

glycophorin - hydrophilic (sialic acid)

Band 3 - anion exchanger: Cl- for HCO3-

Question 12

protein disrupted in X-ALD

Answer 12

ALD = peroxisomal membrane transport protein (ATP-binding cassette protein class D = ABCD protein) 
ABCD specific for LCFA synthase

Question 13

location of disrupted protein in X-ALD and how it gets there

Answer 13

peroxisome - C-terminal sequence= SKL binds PTS1R

PTS1R:SKL complex binds Pex14p (receptor on peroxisomal membrane) that transports protein into peroxisome

Question 14

cellular activity of disrupted protein in X-ALD

Answer 14

transport fatty acid into peroxisome

Question 15

two diseases that are caused by triplet repeat expansion

Answer 15

1. Huntington disease (CAG repeat > 40 repeats)

2. Fragile X syndrome (CGG repeats)

Question 16

two lab methods that can be used to genetically diagnose triplet repeats expansion

Answer 16

1. PCR

2. southern blot

Question 17

biochemical defect in I-cell disease and result of this defect

Answer 17

GlcNAc phosphotransferase defect
-fails to transfer phosphate to mannose residues -> can’t go to golgi -> are secreted due to “default” pathway -> accumulate as inclusions

Question 18

M6P modification - pre or post translational?

Answer 18

post translational

Question 19

where does M6P modification happen?

Answer 19

cis-golgi network

Question 20

what enzymes are involved in M6P modification?

Answer 20

GlcNAc phosphotransferase

GlcNAc phosphodiesterase

Question 21

mechanism of M6P modification

Answer 21

• in rER, Man8(GlcNAc)2 is made and sent to cis-golgi
• in cis golgi, GlcNAc phosphotransferase adds phosphate to C6 of mannose
• GlcNAc phosphodiesterase removes the GlcNAc part = M6P

Question 22

fibroblasts from I-cell disease: what can they uptake and why?

Answer 22

lysosomes can uptake enzymes made extracellularly b/c plasma membrane has M6P receptors (via receptor mediated endocytosis)

Question 23

fibroblasts from I-cell disease: therapeutic strategies and limitations?

Answer 23

strategy - replace defective enzyme with normal one

• *phosphotransferase insertion into cis golgi
• • treatment w/ lysosomal enzymes

limitations: enzymes would have to be put in all cells, continuous injections, and lysosomal enzymes would need to be stabilized until they were put into the lysosome (so you don’t get digested)