Molecular Genetics 🧬

Question 1

Medullary Thyroid Ca
Originating cells and genes?
Clinical vignette?

Answer 1

Calcitonin - c-cells of parafoliicular thyroid cell
Hypercalcemia
Ret genes
MEN2A/B

Question 2

Breast Ca genes ?

Answer 2

1. BRCA1/2 - TSG : ass with Ovarian Ca

2.HER2 (ERBB2)- aggressive / treat with EGFR inhibitor mAb

Usually : treat with hormone inhibitor( Anti estrogen ) - Tamoxifen , if no HER2 mutation

Question 3

Roles of i-KB during infection and how it regulates immune response ?

Answer 3

IkB binds to NF kB as inactive (dormant ) state in cytoplasm of immune cell
Become activated due to external factors (when viral/bac protein binds with TLR on CM)
Active TFkB produces :
Cytokines
Acute Phase Reactant

Question 4

Molecular basis of HPV oncogenesis

Answer 4

HPV produce viral onco protein(E6/E7)
E6 binds to TP53 and E7 to Rb
E6+p53 - loss of tumor suppression
E7 +Rb - cell cycle activation and proliferation through E2F

Question 5

Genes coding TKR (tyrosine kinase receptor )

Answer 5

EGFR / ERBB1- lung adenocarcinoma
HER2/ERBB2- Breast

Question 6

Role of PD1L-PD1in tumor microenvironment

Answer 6

Immune evasion
T cell exhaustion
Cytokines - IL2 down regulations
Decrease T cell perform release
Increase ROS
Up regulate inmmunoinhibitory cytokines(IL10/TGF-b)

Question 7

What does Western blot test used for

Answer 7

Identify protein (viral/bac/etc) via electrophoresis to separate proteins and add intended protein antibody to confirm the protein types or pathogen

Question 8

What does northern boot test ?

Answer 8

mRNA sequences

Question 9

What does Western Blot Test for ?

Answer 9

DNA migration pattern / DNA fragments from sequence

Question 10

Frame shift mutation
Diseases

Answer 10

Change DNA SIZE
Substitution or substraction of NTs
CF
Tay Zach
Dunchenne muscular

Question 11

Hexoaminadazse A mutation

Answer 11

Frameshift mut
Tay Sach

Question 12

Slipped strand mispairing problem occurs in

Answer 12

Occurs in Repeated NT sequences (A-A)
Can lead to frameshift

Question 13

Stop codon

Answer 13

UAA
UAG
UGG

Question 14

Sickle cell mutation type

Answer 14

Missense
Glu-Val

Question 15

Trinucleotides repeat d/o

Answer 15

Example : CAGx (n)
Huntington (AD)
Fragile X
Freidrich Ataxia
Myotonic dystrophy

Question 16

Micro satellite instability

Answer 16

Repeated sequence (CACACACA)
Short segment of DNA
Mix match repair&raquo_space; instability of these microsetallite
Can be due to DNA slippage

Question 17

Purine

Answer 17

Adenosine
Guanine

Question 18

Pyrimidine

Answer 18

T- thymine
Cytosine

Question 19

Type of DNA damage

Answer 19

Depurination - loss of purine
Deamination ( cytidine)DNA left with uracil
Rings - Oxidation /methylation /hydrolysis

Question 20

Base excision repair step

Answer 20

Glycosylase
AP endonuclease -5’ (break OH bond )
AP lyase- 3’ ( break OH and open up sugar ring)
SsDNA with missing NT
DNA Polymerase (add new NT)
Ligase

AP= apurinic or pyramidic

Question 21

NT excision repair
“Bulky damage “
Seen where ?

Answer 21

UV damage
XP
Often form Pyrimidine dimers

Question 22

Condition occurs with impaired Non -homologous end joining (NHEJ) ?
DNA repair enzymes problem

Answer 22

Fanconi anemia (inherited aplastic anemia )

Question 23

Ataxia telangiectasia
Mutation
Problems

Answer 23

NHEJ impaired
Double strand breakage
Normal until first year
Wheelchair by 10 Yr
Recurrent (immune cell dna are impaired ) Resp /sinus infection

Question 24

MiRNA function

Answer 24

Block MRNA translation into protein

Question 25

Sn RNA

Answer 25

Splicing of mRNA

Question 26

Hn RNA

Answer 26

Becomes mRNA