Genetics

Question 1

How is activated and repressed expression of DNA?

Answer 1

Histone methylation —– repress DNA expression

Histone acethylation —– relaxes DNA coiling – activate DNA expression

Question 2

which modification in mRNA is mediated by the sequence AATAAA? and where is made?

Answer 2

Polyadenylation signal—— 3’ extreme

Question 3

Difference between variable expressivity and incomplete penetrance

Answer 3

• variable expressivity: mutant genotype and variables fenotypes
• incomplete penetrance: mutante genotype NO mutant phenotype

Question 4

Correlates:

1. T (9,22)
2. T(15,17)
3. T (14,18)
4. T (8,14)
5. T (11, 14)

Answer 4

1. BCR/ABL Chronic myelogenous leukemia
2. Acute myelogenous leukemia, retinoid receptor alpha
3. Follicular lymphoma (bcl-2)
4. Burkitt lymphoma, c-myc
5. mantle cell lymphma (cyclin D)

Question 5

Kosak consensus sequence

Answer 5

is like shine dalgarno sequence (E. coli)
gccRccAUGG
R is adenine and guanine: positioned 3 bases upstream of AUG: plays a role in initiation of translation process

Question 6

RAS genes

Answer 6

code for a family of G - protein signal transduction in Ras- MAPK pathway
RAS proteins exist in two states:
- Inactive GDP bound state
- Active GTP bound state
RAS become activated when a growth factor ligand binds toa receptor tyrosine kinase

RAS mutations: colon cancer and pancreatic malignancies

Question 7

Heteroplasmy

Answer 7

presence of both normal and mutated mitochondrial DNA —- resulting in variable expression in mitochondrial inherited diseases

Question 8

Linkage desequilibrium

Answer 8

measured in population
when their respective alleles are inherited together (in the same gamete) less or more that is expected corresponding with frequencies.
Is the result of physical proximity of genes in chromosomes

Question 9

Frameshift mutation

Answer 9

deletion or insertion of a # of bases thatis nor divisible by 3

Question 10

Loss of heterogenicity

Answer 10

1 hereditary gene mutation (1st hit)to malignant transformation
Additional somatic mutation (loss ofheterogenicity) 2nd hit to malignant transformation

Question 11

Variable expresivity vs genetic heterogeneity

Answer 11

VE: The same mutations different clinic manifestations
GE: same phenotype, different genotypes

Question 12

Polymerase chain reaction

Answer 12

healing: denatures DNA fragments
Cooling: allowing premade DNA primers anneal to specific sequences on the single strands.
Rewarmed: DNA polymerase synthesized a new complementary DNA strand. 5´ - 3´

Question 13

Hand foot genital syndrome

Answer 13

dominantly inherited condition: malformation of distal limbs, hypoplastic firts digits and mullerian fusion abnormalities (uterus didelphys).
- HOXA13 mutation

Question 14

Some beta thalassemia mutation

Answer 14

splice site: retaines intron in mRNA

Question 15

Heterochromatin and euchromatin

Answer 15

• *condensed- methylated DNA or deacethylated - compact body at the peripheryof nucleus (barr body). low level of transctiptional activity
• • Euchormatin: acetylated - high level of transcriptional activity

Question 16

Chromosomal translocations

Answer 16

abnormality caused by rearrangement of parts between non homologous chromosomes.
** would be carries of balance translocation wherethe parent is asymptomatic but conceived fetuses that are not viable