Genetics

Question 1

What constitutes the backbone of the DNA molecule?

Answer 1

deoxyribose and phosphate backbone

Question 2

What type of bond joins bases?

Answer 2

hydrogen

Question 3

What other name is the long arm of the chromosome called?

Answer 3

q arm

Question 4

What is the short arm of the chromsome known as?

Answer 4

p arm

Question 5

Waht is the function of the formation of chiasma bewteen homologous chromsomes during meisosis I?

Answer 5

genetic recombination

Question 6

What is mosaicism?

Answer 6

2 or more populations of cells with different genetic constitutions within the same individual

Question 7

What is germline mosaicism?

Answer 7

proportion of gametes in an individual have the same mutation

Question 8

What is the usual cause of aneuploidy?

Answer 8

non-disjunction during meiosis

Question 9

What happens in a Robertsonian translocation?

Answer 9

long arms of two acrocentric chromsomes join with loss of the short arms

Question 10

What is found in the short arms of acrocentric chromosomes, and why does their loss in Robertsonian translocations not cause a clinical phenotype?

Answer 10

highly repetitive DNA sequences and ribosomal RAN genes

Question 11

What is the translocation resulting in the philidelphia chromosome?

Answer 11

(9;22)

Question 12

When is deletion of a segment of chromosome likely to visible microscopically?

Answer 12

greater than 5 megabases

Question 13

Waht is needed for the use of FISH?

Answer 13

detects loss or gain of a specific small chromosomal region- need to know the region to be analysed

Question 14

What is the function of microarray CGH?

Answer 14

allows analysis of the entire genome for small losses or gains

Question 15

What does the HER2 gene encode?

Answer 15

epidermal growth factor receptors

Question 16

What is a mendelian mutation?

Answer 16

mutation in a single gene

Question 17

What is the likely cause if a patient has an AD disease that their parents don’t have?

Answer 17

germline mosaicism

Question 18

Why may females who carry an x-linked recessive disorder display signs and sypmtoms of the disease?

Answer 18

random x-inactiviation

Question 19

Why would a female with an X-linked recessive disorder have a disease of the same severity as a male?

Answer 19

skewed X-inactivation e.g non-random inactivation or have Turner’s

Question 20

How are mitochondria inherited?

Answer 20

exclusively maternal

Question 21

What would be a mutation affecting all mitochondria in a cell?

Answer 21

homoplasmic

Question 22

what is the name for a mitochondrial mutation affecting a proportion of hte mitochondria in a cell?

Answer 22

heteroplasmic

Question 23

What are imprinted genes?

Answer 23

genes that are differentially expressed depending who whether they are maternally or paternally inherited

Question 24

What happens in Angelman’s syndrome?

Answer 24

child hasn’t inherited a functioning copy of the UBE3A gene on chromosome 15- needs to be maternally inherited to be active

Question 25

What would cause Angelman's syndrome if there wasn't a mutation in the UBE3A gene in the mother?

Answer 25

unusual transmission of genes- paternal uniparental disomy (inherited both chromosome 15 from father)

Question 26

What are the types of regulatory elements foudn upstream from genes?

Answer 26

enhancers and silencers

Question 27

What binds to the promotor in transcription?

Answer 27

transcription factor

Question 28

What are the differences between DNA and RNA?

Answer 28

RNA sugar phosphate backbone has ribose and uracil is substituted for thymine

Question 29

What is involed in splicing?

Answer 29

removal of intron

Question 30

Why do autosomal dominant loss of function mutations cause disease if one allele still works ?

Answer 30

haploinsufficiency or loss of function of second copy during somatic cell division

Question 31

What is haplosufficincy?

Answer 31

level of protein is important so loss of single copy reduces amount of protein produced sufficiently to cause a disease phenotype

Question 32

What is a dominant negative mutation?

Answer 32

mutation leads to creation of an abnormal protein that has an effect on the function of the normal version of the protein that is produced

Question 33

What is the function of immunohistochemsitry?

Answer 33

identifies protein expression in a cell

Question 34

Waht is a single nucleotide polymorphism ?

Answer 34

polymorphism involving a single change of base sequence

Question 35

What is a cop number variation?

Answer 35

polymorphism involving deletion or suplication of larger regions of hte genome

Question 36

What type of study is used to identify SNPs assocaited with disease?

Answer 36

association study

Question 37

Waht is mutation seen with ichthyosis vulgaris?

Answer 37

homozygous for mutation in the filaggrin gene

Question 38

What is the function of filaggrin?

Answer 38

during formation fo the cornified layer it is cleaved into multiple peptides that cause keratin filmanets to aggregate

Question 39

What is meant by codon usage shows redundancy?

Answer 39

the change in bases doesn't change the amino acid

Question 40

Why does next generation sequencing have an advantgae over sanger sequencing?

Answer 40

allows sequencing of a larger number of genes

Question 41

Why is array comparative genomic hybridisation better than karyotyping as a first test for chromsome analysis?

Answer 41

higher resolution

Question 42

Can post-translational modification correct a wrong protein sequence?

Answer 42

No

Question 43

What is the difference in accuracy between sanger sequencing or NGS?

Answer 43

NGS is slightly less accurate than sanger sequencing

Question 44

What is the function of aCGH?

Answer 44

quantifies amount of DNA