Genetics

Question 1

How are the strands of DNA lined up?

Answer 1

Anti-parallel

Question 2

In what direction is DNA transcribed and read?

Answer 2

5’ to 3’

Question 3

Which base pair bond is strongest and why?

Answer 3

C to G because it has 3 bonds, whereas A to T has 2

Question 4

During which stages of the cell cycle is a cell able to carry out its normal function?

Answer 4

G0 and Synthesis

Question 5

What two things do all DNA sequences have?

Answer 5

Promotor and stop sequence

Question 6

What is the majority of a gene sequence made up of?

Answer 6

Exons and Introns

Question 7

What are exons?

Answer 7

Coding parts of DNA

Question 8

What are introns?

Answer 8

Non-coding parts of DNA

Question 9

What are the three stages of turning a genome into a protein and what happens at each?

Answer 9

Transcription - genome is copied
Splicing - transcribed strand is tidied up - leaving only exons
Translation - made into a protein

Question 10

What 4 factors determine the amount of protein produced by transcription, splicing and translation?

Answer 10

The rate of transcription
Rate of splicing to mRNA
Half-life of mRNA
Rate of processing of polypeptide

Question 11

What is a polymorphism?

Answer 11

A variation in the human genome that does not cause a disease in its own right, but may however predispose to a common disease

Question 12

What is a mutation?

Answer 12

A gene change that causes a genetic disorder

Question 13

What factor increases the number of inherited mutations?

Answer 13

Paternal Age

Question 14

Why are all the inherited mutations very spread apart?

Answer 14

Due to crossing over at chiasmata during meiosis

Question 15

What is the normal karyotype for a healthy female?

Answer 15

46 XX

Question 16

What are the three features by chromosomes can be recognised?

Answer 16

Its banding pattern with specific stains
Length
Position of centromere

Question 17

What are acrocentric chromosomes?

Answer 17

The short arm of the chromosome does not matter, and is instead replaced with a ‘satellite’

Question 18

What does the satellite of a chromosome contain?

Answer 18

Ribsomal genes and tRNA

Question 19

What is balanced chromosomal rearrangement?

Answer 19

When all the chromosomal material is still present, so the karyotype will still be 46XX

Question 20

What is unbalanced chromosomal rearrangement?

Answer 20

When there is extra or missing chromosomal material, so the patient’s karyotype will change.

Question 21

What is the common example of chromosomal rearrangement?

Answer 21

1 or 3 copies of a chromosome

Question 22

What is aneuploidy?

Answer 22

The term used to describe a whole extra or missing chromosome

Question 23

What is translocation?

Answer 23

The rearrangement of chromosomes

Question 24

What are microdeletions?

Answer 24

Any changes to the chromosome that are too small to see down the microscope

Question 25

What is the smallest number of bases that can be viewed under a microscope?

Answer 25

5 million bases

Question 26

What is the chromosomal term for down syndrome?

Answer 26

Trisomy 21

Question 27

What is the chromosomal description for downs syndrome?

Answer 27

47 XX + 21

Question 28

Why is it sometimes difficult to see any extra chromosome in the karyotype?

Answer 28

It can be stuck on top of another chromosome

Question 29

What is a Robertsonian Translocation?

Answer 29

The pairing of two acrocentric chromosomes

Question 30

What condition has the karyotype 47 XY +18

Answer 30

Edward syndrome

Question 31

What is the prognosis of Edwards syndrome?

Answer 31

Child dies within days of birth

Question 32

What is the condition that has the karyotype 45X?

Answer 32

Turner Syndrome

Question 33

What is the condition that has the karyotype 47 XXY?

Answer 33

Klinefelter Syndrome

Question 34

What conditions are associated with Klinefelter syndrome?

Answer 34

Both male and female charateristics

Question 35

Why is X chromosome aneuploidy better tolerated than any other aneuploidy?

Answer 35

Due to X inactivation

Question 36

What is reciprocal translocation?

Answer 36

Where the ends of chromosomes swap

Question 37

What is the consequence of reciprocal translocation?

Answer 37

Miscarriage or severe disability

Question 38

What can FISH be used for?

Answer 38

Looking at genes on a chromosome

Question 39

What test is genome wide?

Answer 39

Array Comparative Genomic Hybridisation (aCGH)

Question 40

What test can be used to look at specific loci or chromosomes?

Answer 40

Quantitative PCR

Question 41

What kind of things can Array CGH find?

Answer 41

Polymorphisms

Question 42

What kind of things can microarray CGH find?

Answer 42

Missing or duplicated pieces of chromosome (i.e. any microdeletions)

Question 43

What is Mosaicism?

Answer 43

The presence of two or more populations of cells with different genotypes in a individual who developed from a single fertilised egg