genetic variation in disease

Question 1

Allelle

Answer 1

alternative forms of gene/locus/variant

Question 2

Homozygous

Answer 2

two copies of same allele at same locus (genotype AA or BB)

Question 3

Heterozygous

Answer 3

different alleles at same locus (genotype AB or BA)

Question 4

Autosomes

Answer 4

anything but sex chromosomes

Question 5

how many base parts is a codon made of

Answer 5

3

Question 6

what sequence of bases encodes for methionine and starts the translation of all proteins

Answer 6

AUG

Question 7

how many codons encode for the 20 amino acids ( redundant code)

Answer 7

61

Question 8

how many codons stop translation of proteins

Answer 8

3
UGA
UAA
UAG

Question 9

3 types of DNA variation

Answer 9

single base substitutions ( SNPs - single nucleotide polymorphisms)
deletions
insertions

Question 10

what is a synonymous/silent variation

Answer 10

No change to the amino acid sequence
No change in function
Doesn’t not cause disease

Question 11

what is a non-synonymous mutation

Answer 11

Changes amino acid sequence of protein
Can changes structure of the protein
Can change function of the protein
Can cause disease and normal variation

Question 12

silent mutation

Answer 12

mutation does not alter the polypeptide product of the gene
often single pair substitution a the third position of a codon
triplet codes for same aa
no alteration in properties of the resulting proteins
could be outside of the coding region - in an intronic region

Question 13

where is the most common place for a silent mutation

Answer 13

third position of a codon

Question 14

nonsense mutation

Answer 14

stop codon formation terminating translation

express truncated protein

Question 15

nonsense mediated decay is a form of what

Answer 15

RNA surveillance that is believed to have evolved to protect the body from the possible consequences of truncated proteins interfering with normal function.

Question 16

mRNA is degraded by what

Answer 16

nonsense-mediated decay so NO protein is made.

Question 17

missense mutation

Answer 17

codes for different aa

can be chemically dissimilar and similar

Question 18

2 types of missense mutation

Answer 18

non-conservative substitution

conservative substituions

Question 19

non-conservative substitution

Answer 19

Gross reduction, or even a complete loss, of biological activity.
Qualitative changes in the function of a protein may also occur
Ie the protein retains its normal biological activity but maybe less stable for example

Question 20

conservative substitution

Answer 20

Some single base-pair substitutions result in the replacement of a different amino acid that is chemically similar,
No or very little difference in functional effect.

Question 21

frameshift mutation

Answer 21

inseriton or deletion of nucleotides - if not a multiple of 3 ( non frameshift) will always disrupt the reading frame - usually premature stop leading to truncated protein

Question 22

variant

Answer 22

Variant can be used to describe an alteration that may be benign, pathogenic, or of unknown significance. The term variant is increasingly being used in place of the term mutation.

Question 23

mutation

Answer 23

Mutation – rare variant in DNA sequence – disease causing

Question 24

polymorphism

Answer 24

Polymorphism - common variant in DNA seqeunce – benign (does not cause disease) present in >1% of the population

Question 25

cDNA sequence

Answer 25

Complementary DNA
(No introns, only coding sequence, derived from mRNA sequence, same as coding strand of DNA without introns)