chromosome abnormalities, mutations and analysis

Question 1

types of chromosome abnormalities

Answer 1

• numerical
• structural
• mutational

Question 2

aneuploidy

Answer 2

the presence of an abnormal number of chromosomes in a cell

Question 3

trisomy

Answer 3

disorder characterised by the presence of the three homologous chromosomes instead of two

Question 4

down syndrome cause

Answer 4

3 copies of chomosome 21 (trisomy 21)

Question 5

down syndrome characteristics

Answer 5

characteristic facial features (flattened, upward slanting eyes)
IQ less than 50

Question 6

patau syndrome cause

Answer 6

3 copies of chromosome 13 (trisomy 13)

Question 7

Patau syndrome characteristics

Answer 7

multiple dysmorphic features (eg. cleft lip and palate)

very few survive beyond first year

Question 8

Edwards syndrome cause

Answer 8

3 copies of chromosome 18 (trisomy 18)

Question 9

edwards syndrome characteristics

Answer 9

severe developmental problems such as small head, heart, kidney and breathing problems.
Many don’t live past first birthday.

Question 10

turner syndrome cause

Answer 10

one X chromosome

Question 11

turner syndrome characteristics

Answer 11

females of short stature and infertile, neck webbing and widely spaced nipples.

Question 12

flinefelter syndrome cause

Answer 12

sex chromosomes XXY

Question 13

klinefelter syndrome characteristics

Answer 13

tall statue and long limbs.
male but infertile, small testes and half exibit gynaecomastia
mild learning difficulties.

Question 14

balanced chromosome rearrangements

Answer 14

structural chromosome abnormalities that don’t lead to the loss of genetic information

Question 15

unbalanced chromosome rearrangements

Answer 15

structural chromosome abnormalities that lead to the loss of genetic information

Question 16

acrocentric chromosome

Answer 16

chromosome in which the centromere is located near to the end of the chromosome

Question 17

metacentric chromosomes

Answer 17

chromosomes with their centromere in the middle of the chromosome

Question 18

balanced translocation

Answer 18

a section of a chromosome breaks off from two non-homologous chromosome and they are swapped.

Question 19

unbalanced translocation

Answer 19

occurs when one parent has normal chromosomes and one has chromosomes that have undergone a balanced translocation. This causes the loss of genetic information.

Question 20

deletion

Answer 20

chromosome breaks in two place and the section in between is removed. Then the two sections join back together

Question 21

inversion

Answer 21

the chromosome breaks in two places then the section cut out inverts and is reinserted into chromosome

Question 22

pericentric inversion

Answer 22

inversion that occurs with centromere in the inverted section

Question 23

paracentric inversion

Answer 23

inversion that occurs when the section of the chromosome that inverts does not contain the centromere

Question 24

germline mutation

Answer 24

A gene change in a body’s reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body of the offspring

Question 25

somatic mutation

Answer 25

An alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children

Question 26

polymorphism

Answer 26

natural variation in the genome of organisms of the same species

Question 27

types of mutation

Answer 27

Silent
Missense
Nonsense
Frameshift – deletion / insertion

Question 28

sillent mutation

Answer 28

point mutation in which the substitution of a base pair has no effect on the amino acid the codon it is part of codes for

Question 29

missense mutation

Answer 29

point mutation in which the substitution of a base pair causes the coding of a different amino acid in a protein

Question 30

nonsense

Answer 30

point mutation in which the substitution of a base pair causes the the formation of as stop codon in the wrong place, this causes the protein chin produced to be truncated.

Question 31

frameshift mutations

Answer 31

deletion and insertion.
the insertion or deletion of a base pair causes every codon after the point mutation to be incorrect and so every subsequent amino acid has the possibility to be incorrect in the polypeptide produced

Question 32

methods for detecting mutations

Answer 32

• Polymerase chain reaction (PCR)
• Gel electrophoresis
• Restriction fragment length polymorphism (RFLP) analysis
• Amplification refractory mutation system (ARMS)
• DNA sequencing

Question 33

why is it necessary to detect mutations

Answer 33

to determine mutations are pathogenic, due to polymorphism or have no known significance.

Question 34

amplification refractory mutation system (ARMS)

Answer 34

form of PCR used to derermine mutations form the wildtype.

Question 35

how ARMS works

Answer 35

a normal and mutant primer can by used in PCR, if amplification occurs with the normal primer then that sequence of dna is not mutated. If amplification occurs with the mutant primer it is.

Question 36

how RFLP works

Answer 36

restriction endonucleases cut DNA strands at specific sequences. This can be used to determine if certain mutated sequences occur in a DNA strand by electrophoresing the strands produced and comparing lengths.

Question 37

DNA sequencing, Sanger method

Answer 37

chain termination method. termination dideoxynucleotides are used.