Chromosome Abnormalities, Mutations & Analysis

Question 1

Types of Chromosome Abnormalities

Answer 1

Numerical
Structural
Mutational

Question 2

Numerical

Answer 2

Trisomy

Monosomy

Question 3

Trisomy

Answer 3

Patau
Edwards
Down
Klinfelter

Question 4

Patau

Answer 4

47 XX +13

Question 5

Edwards

Answer 5

47 XY +18

Question 6

Down

Answer 6

47 XX +21

Question 7

Klinefelter

Answer 7

47 XXY

Question 8

Monosomy

Answer 8

Turner

Question 9

Turner

Answer 9

45 X

Question 10

Origins of chromosome abnormalities

Answer 10

Non-disjunction at meiosis I

Non-disjunction at meiosis II

Question 11

Non-disjunction at meiosis I

Answer 11

2 gametes with disomy

Question 12

Non-disjunction at meiosis II

Answer 12

2 normal gametes and one with disomy

Question 13

Why are origins of non-disjunction maternal?

Answer 13

Females developing ova as developing babies and when they are born they have all their eggs
Arrested at meiosis I
Longer period of arrest = abnormalities

Question 14

Characteristic of Trisomy 21 (5)

Answer 14

Downs
Distinct facial features
Low IQ
Increases in advanced maternal age
Unbalanced Robertsonian translocation

Question 15

Characteristic of Trisomy 13 (5)

Answer 15

Patau syndrome
Mental retardation
Dysmorphic features
Maternal origin- non-disjunction
Unbalanced Robertsonian

Question 16

Characteristic of Trisomy 18 (4)

Answer 16

Edwards syndrome
Severe developmental problems
Most patients die within first year
Non-disjunction (maternal)

Question 17

Characteristic of Aneuploidy (Monosomy) Syndrome

Answer 17

Turner syndrome

appear females- short stature and infertile

Question 18

Characteristic of 47 XXY

Answer 18

Klinefelter syndrome
Tall stature, long limbs
Male but infertile, small testes
Gynaecomastia
Mild learning difficulties

Question 19

Structural

Answer 19

Balanced or unbalanced rearrangements
Translocations
Deletions
Insertions
Inversions

Question 20

Outcomes of Balanced Translocation

Answer 20

Normal
Balanced
Partial trisomy + partial monosomy

Question 21

Reciprocal Translocation

Answer 21

Involving breaks in 2 chromosomes with formation of two new derivative chromosomes

Question 22

Robertsonian Translocation

Answer 22

Fusion of two acrocentric chromosomes

Loss of short arms

Question 23

Outcomes of Robertsonian Translocation

Answer 23

Trisomony (chromosome)

Monosomy (chromsome)

Question 24

Deletions

Answer 24

Interstitial

Terminal

Question 25

Inversions

Answer 25

Paracentric | Pericentric

Question 26

Pericentric

Answer 26

Piece involves Centromere

Question 27

Genetic

Answer 27

Germ line or Somatic | Non-coding or Coding

Question 28

Coding

Answer 28

Silent- codon change, aa stays the same Missense- amm changes Nonsense- stop codon Franeshift

Question 29

Point Mutations

Answer 29

Transition | Transversion

Question 30

Transitions

Answer 30

Purine to Purine | Pyrimidine to Pyrimidine

Question 31

Transversions

Answer 31

Purine to Pyrimidine | Pyrimidine to Purine

Question 32

Cys64Arg

Answer 32

• At position 64, mutation from Cys to Arg

Question 33

M252X

Answer 33

• Mutation at position 252 to stop codon

Question 34

1294del40

Answer 34

Deletion of 40 nucleotides at position 1294

Question 35

1298A>G

Answer 35

Position 1298 mutation of A >G

Question 36

662-42C>T

Answer 36

Introns use position of exons Position 662 -42 has mutation of C > T

Question 37

IVS2+12insG

Answer 37

Position IVS2 + 12 nucleotides has insertion of G

Question 38

Detecting Mutations

Answer 38

PCR Gel electrophiresis Restriction fragment length polymorphism analysis (RFLP) Amplification refractory mutation system (ARMS) DNA sequence

Question 39

PCR

Answer 39

Oligonucleotide primers Denature Anneal primers and nucleotide Extend with DNA polymerase

Question 40

Gel Electrophoresis

Answer 40

Separate DNA fragments by size Across electric field DNA is negatively charged

Question 41

RFLP

Answer 41

Enzymes from bacterial cells Recognise specific DNA sequences (4-8bp) Cut DNA Requires gel electrophoresis or southern blot

Question 42

ARMS

Answer 42

Normal primer matches= amplification of wild type Mutant primer = no amplification Mutant primer attaches= amplification of mutant alleles Normal primer= no amplification Electrophoresis required

Question 43

DNA Sequence

Answer 43

Uses dideoxynucleotides ddATP, ddCTP, ddGTP, ddTTP Gold standard for mutation detection Uses gel electrophoresis