Lecture 3 - Basic concepts pt2

Question 1

What is an allele?

Answer 1

The DNA sequence(s) 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

Question 4

What is a heterozygote?

Answer 4

Two different alleles at the same locus

Question 5

What is a hemizygous/hemizygote?

Answer 5

• One allele presents, while another allele is missing
• Hemizygous genotype is 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 (Law of Segregation)

Question 7

What is a single nucleotide polymorphism (SNP)?

Answer 7

• A single nucleotide is changed to another
• The most common DNA sequence variation account for >90% of all genetic variations
• Most pgx polymorphisms are SNPs

Question 8

How often do SNPs happen?

Answer 8

1 SNP/about 300-750bp in genome

Question 9

Explain SNP in the coding region (cSNP)

Answer 9

Question 10

What is a copy number variation (CNV)?

Answer 10

• A DNA region has 0-n copies in a population
• Structural variation
• 1 kb-several Mb
• Making each chromosomes longer or shorter?

Question 11

What is insertion/deletion (indel)?

Answer 11

• Nucleotide(s) present or absent from a locus: 0 or 1 copy
• Can be 1 to N nucleotides
• Single nucleotide indel is a specific form of SNP
• Indel, other than 3 nucleotides, often causes frameshift

Question 12

Explain the differences between CNV, gene expression, missense, and nonsense related changes.

Answer 12

Question 13

Explain gene nomenclature.

Answer 13

Question 14

Explain CYP2C19 allele nomenclature.

Answer 14