Intro and qualitative genetics

Question 1

What is a genome?

Answer 1

Total set of chromosomes in a cell

Question 2

What are diploid chromosomes?

Answer 2

Genomes in which chromosomes are in pairs

Question 3

What are homologues?

Answer 3

Two members of a homologous pair (in diploid chromosomes)

Question 4

DNA is double stranded. What are the 4 nucleotides and which are purines and pyrimidines?

Answer 4

Adenine (purine)
Guanine (purine)
Cytosine (pyrimidine)
Thymine (pyrimidine)

Question 5

What is a gene?

Answer 5

Segment of DNA coding for a polypeptide

Question 6

mRNA does not have what feature?

Answer 6

Introns

Question 7

What are introns and axons?

Answer 7

Exons = coding regions
Introns = non-coding regions

Question 8

What are mutations?

Answer 8

Alteration of nucleotide sequence

Mistake in DNA replication

Question 9

What are examples of a point mutation?

Answer 9

Substitution of one nucleotide for another
Addition
Deletion

Question 10

Mutations can be non-sense, missense or silent. What do these mean?

Answer 10

Non-sense= change of functional codon to stop/terminating codon 
Missense = single nucleotide change causes codon to code for a different AA
Silent = no change to amino acid sequence

Question 11

What is a loci?

Answer 11

Location of a gene on a chromosome

Question 12

What is an allele? What is homozygous/heterozygous?

Answer 12

Different forms of the same gene
2 of the same alleles = homozygous
2 different alleles = hetereozygous

Question 13

What is a genotype?

Answer 13

Particular combination of genes/alleles that an animal inherits

Question 14

What is a phenotype?

Answer 14

What characteristic is measured/observed

Question 15

What is codominance/additive gene action? How many possible genotypes/phenotypes can codominance lead to?

Answer 15

No allele is dominant to the other

3

Question 16

What is the First law of Mendelian’s inheritance?

Answer 16

Two alleles separate from each other in the formation of gametes

Question 17

What is the Second law of Mendelian’s inheritance?

Answer 17

Genes for different traits assort independently of one another in the formation of gametes

Question 18

What is epistasis? Give an example

Answer 18

The presence of an allele at one locus masks the effect of an allele at a different locus
Labrador colours: yellow, chocolate, black

Question 19

What is inactivation? Give an example

Answer 19

One of the X chromosomes becomes inactive in each cell of female embryos during development
Tortoise shell cats = female

Question 20

What are sex-linked genes?

Answer 20

Genes located on sex chromosomes

Question 21

What are sex limited genes? Give an example

Answer 21

Autosomal genes affect a trait that is only shown by one sex (e.g. milk production)

Question 22

What are autosomal genes?

Answer 22

Non-sex genes

Question 23

What are sex-influenced genes? Give an example

Answer 23

The same genotype can lead to a different phenotype depending on the sex
E.g. horns in some breeds

Question 24

What are single nucleotide polymorphisms?

Answer 24

Alleles that differ by a base substitution

Source of genetic variation