mutations and genetic analysis

Question 1

what are the 3 types of chromosomal abnormalities?

Answer 1

numerical, structural and mutational abnormalities

Question 2

what makes up around 50 percent of chromosomal abnormalities?

Answer 2

first trimester miscarriages

Question 3

what is the aetiology of patau syndrome?

Answer 3

trisomy 13

Question 4

what is the aetiology of edwards syndrome?

Answer 4

trisomy 18

Question 5

what is the aetiology of downs syndrome?

Answer 5

trisomy 21

Question 6

what is the aetiology of klinefelter syndrome?

Answer 6

Y chromosome along with 2 X chromosomes

Question 7

what is the aetiology of turner syndrome?

Answer 7

monosomy - only a single x chromosome

Question 8

what is non-disjunction?

Answer 8

failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Question 9

what are some symptoms of turner syndrome?

Answer 9

females are short of stature and infertile
neck webbing
widely spaced nipples

Question 10

what are some symptoms of klinefelter syndrome?

Answer 10

tall stature, long limbs
infertile males with small testes
gynaecomastia in around 50%
mild learning difficulties

Question 11

what are some examples of structural abnormalities in DNA?

Answer 11

balanced or unbalanced rearrangements
translocations
deletions
insertions
inversions

Question 12

what are the two types of translocations?

Answer 12

reciprocal - involves breaks in two chromosomes with the formation of two new derivative chromosomes
robertsonian - fusion of two acrocentric chromosomes

Question 13

what are some outcomes of unbalance translocation?

Answer 13

partial trisomy

partial monosomy

Question 14

what is lost in robertsonian translocation?

Answer 14

the two short arms of the acrocentric chromosome, however, no genetic information is lost

Question 15

what are the 2 classifications of genetic mutation?

Answer 15

non-coding

coding

Question 16

what types of coding mutations are there?

Answer 16

silent
missense
nonsense
frameshift

Question 17

what causes frameshift mutations?

Answer 17

insertion and deletion

Question 18

what are the types of point mutation?

Answer 18

transitions and transversions

Question 19

what classifies a point mutation as a transition?

Answer 19

purine > purine or pyrimidine > pyrimidine

Question 20

what classifies a point mutation as a transversion?

Answer 20

purine to pyrimidine or pyrimidine to purine

Question 21

what are some methods used to detect mutations?

Answer 21

PCR
gel electrophoresis
restriction fragment length polymorphism (RFLP) analysis
amplification refractory mutation system (ARMS)
DNA sequencing

Question 22

what are the 3 steps of PCR and what temperatures do they take place at?

Answer 22

denature - 93-95 celsius
anneal- 50-70 celsius
extend - 70-75 celsius

Question 23

what are the steps in gel electrophoresis?

Answer 23

separate DNA fragments by size
apply an electric field (DNA is negatively charged)
separation occurs through an agarose gel matrix
fragments of DNA are then visualized

Question 24

what are some advantages of gel electrophoresis?

Answer 24

speed
ease of use
sensitive
robust

Question 25

what are some applications of PCR?

Answer 25

DNA cloning
DNA sequencing
gene identification
forensic medicine
detection of mutations

Question 26

what are some advantages of ARMS?

Answer 26

cheap

labelling not required

Question 27

what are some disadvantages of ARMS?

Answer 27

need sequence information
limited amplification size
limited amounts of product
infidelity of DNA replication
electrophoresis required
primer design critical

Question 28

what are restriction endonucleases?

Answer 28

enzymes from bacterial cells
protective mechanism
degrade DNA of invading viruses
recognise specific DNA sequences
always cut the DNA at same site

Question 29

what are some advantages of RFLP?

Answer 29

simple
cheap
non radioactive

Question 30

what are some disadvantages of RFLP?

Answer 30

requires gel electrophoresis

not always feasible

Question 31

what are some advantages of gene sequencing?

Answer 31

best option for detection of mutation
automated
can sequence a huge length of base pairs

Question 32

what are some limitations of gene sequencing?

Answer 32

expensive equipment

poor quality sequence read.