Genetics

Question 1

In what direction is DNA replicated?

Answer 1

5’ to 3’

Question 2

What does the 5’ indicate?

Answer 2

the carbon number that the bond is attached to

Question 3

Which DNA bonds are strongest?

Answer 3

C-G

Question 4

What is the most common DNA mutation?

Answer 4

C-T

Question 5

How is DNA kept?

Answer 5

tightly wound round proteins such as histones and condensed in the nucleus

Question 6

how many bases are there in the human genome?

Answer 6

3 billion

Question 7

How many genes are there in the human genome?

Answer 7

30,000

Question 8

What are the 5 phases to the cell cycle?

Answer 8

G0 - resting phase
S - synthesis for replication
G2 - checkpoint for mitosis
Mitosis
G1 - final check point for new cell

Question 9

What are the implications of DNA damage and repair mechanisms?

Answer 9

DNA repair mechanisms can be damaged thus preventing them from occurring

Question 10

what is mitosis?

Answer 10

the splitting of one cell into almost identical daughter cells which are diploid

Question 11

What is meiosis?

Answer 11

the splitting of a parent cell into 4 haploid cells and contains two episodes of cell division.
crossing over and DNA recombination occurs
DNA errors more likely to occur

Question 12

what does splicing involve?

Answer 12

the removal of introns

Question 13

How is splicing initiated?

Answer 13

through gene sequence motifs that indicate a need for splicing or insertions

Question 14

What is the process of protein production?

Answer 14

DNA - premRNA (spliced) - mRNA - protein

Question 15

What can cause variations in the human genome?

Answer 15

changes in promoter sequence
changes in exon sequence
SNP
Larger deletions or duplications

Question 16

What is a polymorphism?

Answer 16

a variation that has a population frequency of >1% and does not cause disease - may still pre-dispose to a disease

Question 17

What is a mutation?

Answer 17

a gene that causes a genetic disorder

Question 18

What is FGFR3?

Answer 18

an achondraplasia mutation that causes a form of dwarfism - one or two mutations cause it

Question 19

Why is FGFR3 achondraplasia relatively common?

Answer 19

because spermatids that have this mutation have a selective advantage over normal spermatids

Question 20

What are the short arm and long arms of chromosomes also referred to as?

Answer 20

short (p)

long (q)

Question 21

What are acrocentric chromosomes?

Answer 21

chromosomes where the short arm does not exist but is not typically required i.e. 21

Question 22

what is a balanced chromosome rearrangement?

Answer 22

when all chromosome material is present

Question 23

What is an unbalanced chromosome rearrangement?

Answer 23

where extra or missing chromosome material is present i.e. 1 or 3 copies

Question 24

what is aneuploidy?

Answer 24

having a whole extra or missing chromosome

Question 25

What is translocation?

Answer 25

rearrangement of chromosomes

Question 26

what are microdeletions?

Answer 26

deletions that cant be seen in a microscope - need to be 5m bp to be seen

Question 27

What is the likely cause of Downs Syndrome?

Answer 27

extra 21 sneaking into the egg

Question 28

what are the likely changes from maternal and paternal transmission?

Answer 28

maternal is more likely to be chromosomal | paternal is more likely to be gene changes

Question 29

what is a robertsonian translocation?

Answer 29

where two acrocentric chromosomes are passed on through translocation i.e. mother has one normal 21 and a 21 attached to 14 therefore child gets normal from mother and father and extra from mum

Question 30

What occurs with trisomy 18?

Answer 30

Edward Syndrome

Question 31

What is the notation for Turners syndrom?

Answer 31

45X

Question 32

What is the notation for Triple X?

Answer 32

47 XXX

Question 33

What is the notation for Klinefelter syndrome?

Answer 33

47 XXY

Question 34

why is having one X ok?

Answer 34

because one X is only ever active in cells

Question 35

Why are bigger translocations better?

Answer 35

Child will either have normal or balanced chromosomes - although potential risk for reproduction

Question 36

What does the FISH technique allow?

Answer 36

the staining of protein or gene in a cell to see if production is normal, heightened or lessened i.e. HER2 gene

Question 37

What is somatic mosaicism?

Answer 37

where all cells suffer mutations but those mutations are variable throughout the body

Question 38

What is next generation sequencing?

Answer 38

DNA with exons cut out and compared to a reference frame

Question 39

What is an SNP?

Answer 39

a genetic variation that is prevalent in the population and not, in itself, disease causing