Genetics 1

Question 1

Mitochondrial DNA codes for?

Answer 1

tRNA

Oxidative phosphorylation

Question 2

Next generation sequencing detects?

Answer 2

Nucleotide variations

Question 3

Most common pathogenic variant?

Answer 3

Missense mutations ( misspell) - Defects build-up in ER

Question 4

In Silico tools used for detecting missense variant?

Answer 4

Grantham constraint and SIFT (shit) and had CADD (heart attack)

Grantham - amino acid properties
Constraint - conserved gene
SIFT - protein function change
CADD - Harmful effects of SNV

Question 5

Treatment for missense mutation?

Answer 5

Chemical chaperone (Tegretol, Metformin) = push correct amino acid into place

Question 6

Treatment for nonsense mutation?

Answer 6

MRNA destroyed by decay protein

so give decay protein inhibitor - cycloheximide

Question 7

function of topoisomerase enzyme?

Answer 7

unwind DNA histone

Question 8

what does introns give rise to?

Answer 8

Non-translation RNA ( tRNA, sRNA, mRNA)

Question 9

Imprinting of allele occurs via?

Answer 9

methylation of gene promoters

Question 10

Aneuploidy ( abnormal chromosomes sets) caused by?

Answer 10

Chromosome non-disjunction

Question 11

what RNA involved in protein synthesis? ( translation)

Answer 11

tRNA and rRNA

Question 12

Regulatory sequences;
Promoter region found where?

Enhancer/silencer region found where?

Answer 12

Promoter - upstream, contain TATA box

Enhancer/Silencer region - anywhere

Question 13

What are responsible for evolutionary changes?

Answer 13

Variants - alterations to DNA sequences

Question 14

Dominant and recessive inheritance refers to?

Homozygousity/heterozygousity refers to?

Answer 14

Dominant/recessive = phenotypic trait

Homozygous/heterozygous = genotype

Question 15

Commonest cause of primary hypogonadism?

Answer 15

Klinefelter syndrome

Question 16

Most common mode of inheritance?

Answer 16

autosomal dominant

Question 17

Mosaicism means

Chimerism means?

Answer 17

Mosaicism = 2 or more cell lineage with different genotypes from single zygote ( post-zygote mutation + non-disjunction)

Chimerism = 2 or more cell lineage with different genotypes from different zygotes

Question 18

Amniocentesis do when?

CVS do when?

Non-invasive prenatal testing do when?
-special about it?

Answer 18

Amniocentesis = 15th week of pregnancy

CVS = 10th week of pregnancy

NPT = 10th weeks onwards - fragments of DNA extracted from maternal blood
-determine sex of foetus, aneuploidy, deletion syndromes

Question 19

Mitochondrial inheritance - from mother only - why?

Answer 19

Mitochondrial DNA in sperm is in the tail - doesn’t enter egg

No introns!

Question 20

3 components in gene regulation?

Answer 20

ncRNA (non-coding RNA)
DNA methylation ( CpG promoter region)
-!methylate silences the gene!-
Histone modification - affects chromatin

Question 21

SNP - single nucleotide polymorphisms - what and where it is located and function?

Answer 21

Non-coding regions - variation nucleotide at specific locus
Determines;
-susceptibility to disease
-response to drugs
-genetic linkage markers

Question 22

What is CRISPR and CAS9

Answer 22

CRISPR - regions of DNA genome that stores genetic information from infecting viruses/bacteria

CAS9 - endonuclease ( scissors) - guided by gRNA to the snip/cut out specific DNA sequence

Question 23

what does FISH detects?

satellite probing cities

Answer 23

Presence/absence of DNA sequences on chromosome
Localisation locus-specific DNA target
Balanced rearrangements

Question 24

SNP microarray use to detect what?

google street view

Answer 24

Copy number variations - CNV
Allelic imbalance ( detect 2 copies of allele of same or different )
Uniparental disomy
Chimerism
Long continuous stretches of homozygosity (LCSH)

Question 25

LCSH ( occurs in consaguinity) usually unmask what?

Answer 25

Recessive disease

Question 26

Sanger sequencing detects what?

Answer 26

Single gene mutation!

Question 27

Southern blot vs western blot?

Answer 27

Southern blot - For DNA
DNA fragments chopped up by restriction endonuclease enzyme
Labelled DNA probe added to hybridize area of interest

Western blot - For proteins ( remember HIV proteins)
cells lysed and protein removed
Antibodies to target proteins

Question 28

MLPA use to detect what?

Answer 28

Microdeletions/duplications that is too small for FISH and Microarray to detect
+
Locus specific

Can detect methylation ( imprinting disorder) in methylation sensitive MLPA

Question 29

Next generation sequencing detects what?
-Whole genome/exome sequencing

Targeted gene panel testing for what?

Answer 29

NGS : Genetic heterogeneity

Targeted gene panels : multiple groups of genes causing a particular systemic disease
eg. group of genes causing cardiomyopathy

Question 30

X-linked Recessive Father - key features?

X-linked Dominant Father - key features?

Answer 30

Sons NOT affected
Daughters obligate carriers! - no recombination

Sons NOT affected
Daughters affected!!

Question 31

what is recurrent mutations?

Answer 31

Specific similar mutations but in different people due to independent event ( not having similar genetic background)