Genetics

Question 1

The total set of chromosomes in a cell constitute a…?

Answer 1

Genome

Question 2

Genomes in which chromosomes occur in pairs = ?

Answer 2

Diploid

Question 3

What is meiosis?

Answer 3

The process of gamete formation

- gametes each contain one member of each pair of chromosomes = haploid

Question 4

What the 4 different DNA nucleotides and the base pairs?

Answer 4

Cytosine and Guanine

Adenine and Thymine

Question 5

What is a gene?

Answer 5

A segment of DNA coding for a particular polypeptide

Question 6

What are the sections that are expressed and which sections are not expressed?

Answer 6

Exons are expressed

Introns are not expressed

Question 7

What are the 3 types of point mutation?

Answer 7

Nonsense = functional triplet into a stop codon
Mis-sense = amino-acid substitution 
Silent = doesn't change the code

Question 8

Why are mutations not always a negative thing?

Answer 8

Increase diversity
Can become desirable
Natural selection

Question 9

The location of a gene on a chromosome is called…?

Answer 9

Locus

Question 10

What is an allele?

Answer 10

Different forms of a segment of DNA

Question 11

Give a definition of genotype and phenotype

Answer 11

Genotype = the particular combination of genes or alleles an animal inherits
Phenotype = what we observe or measure

Question 12

Compare the number of alleles, possible genotypes and phenotypes in dominance vs co-dominance

Answer 12

Dominance = 2 alleles, 3 genotypes, 2 phenotypes
Co-dominance = 2 alleles, 3 genotypes, 3 phenotypes

Question 13

What is epistasis?

Answer 13

The presence of an allele at one locus masks the effect of an allele at another locus

Question 14

What is the name given to when one of the X chromosomes becomes inactive in each cell of all female embryos at an early stage of development

Answer 14

Random inactivation

Question 15

What is the difference between a sex linked gene and a sex limited gene?

Answer 15

Sex-linked = genes located on sex chromosomes
Sex-limited = autosomal genes, trait they affect is only shown by one sex

Question 16

Give some examples of single genes in animal breeding

Answer 16

Coat colour
Polledness
Milk protein types
Scrapie susceptibility in sheep 
Several genetic disorders

Question 17

What is an SNP?

Answer 17

Single nucleotide polymorphism - source of genetic variation
- alleles that differ by a single base substitution