L3 Basic Concepts II

Question 1

What is an allele?

Answer 1

The DNA sequences at a locus of one of the two homologous chromosome

Question 2

What is a genotype?

Answer 2

The combination of alleles at the same locus of the homologous chromosomes in a genome/cell

Question 3

What is a homozygote?

Answer 3

When an individual has a pair of identical alleles at the locus, the genotype is homozygous

Question 4

What is a heterozygote?

Answer 4

When there are two different alleles at the same locus, the genotype is heterozygous

Question 5

What is hemizygous/hemizygote?

Answer 5

One allele present while another allele is missing

also heterozygous

Question 6

What is Mendel’s Law?

Answer 6

Each of the parents passes a randomly selected allele (one of the two homologous chromosomes) to the offspring

Question 7

What is the most common DNA sequence variation?

Answer 7

Single nucleotide polymorphisms

a single nucleotide is changed to another

Question 8

What is a cSNP?

Answer 8

SNP in the coding region

Question 9

What is a non-synonymous SNP?

missense SNP, nonsense SNP

Answer 9

changing amino acid in the protein

Question 10

What is a missense SNP?

Answer 10

amino acid substitution that could either lead to a gain or loss of function for the protein depending on what amino acid it changes to

Question 11

What is a nonsense SNP?

Answer 11

amino acid changes to stop codon (normally lead to loss of function)

Question 12

What is a synonymous SNP?

silent SNP

Answer 12

Does not change amino acids, usually does not change gene/protein function.

Question 13

What is copy number variation (CNV)?

Answer 13

A DNA region has 0-n copies in a population

Question 14

What is an Indel (insertion/deletion)?

Answer 14

Nucleotide(s) added or removed from a locus

Question 15

Unless the indel is of 3 nucleotides, what will happen?

Answer 15

• Frameshift
• frameshift of the open reading frame leads to truncated protein for degradation (loss of function)

Question 16

When “c.” is in front of the nomenclature, which sequence are you looking at?

Answer 16

coding DNA sequence

Question 17

When “p.” is in front of the nomenclature, which sequence are you looking at?

Answer 17

protein position

Question 18

What does *1A indicate?

Answer 18

No change

Question 19

What does *2D indicate?

Answer 19

splicing defect (loss of function)

Question 20

What does *3A indicate?

Answer 20

nonsense (Stop codon) (loss of function)

Question 21

What does *17 indicate?

Answer 21

missense (point mutation) `