Concepts in Genetics

Question 1

Mitosis

Answer 1

Asexual reproduction of somatic cells
Continuous
2n (2 daughter cells)
Mutations during this process are non-inheritable

Question 2

Meiosis

Answer 2

Asexual reproduction of gametes for sexual reproduction
Occurs during embryonic stage and puberty
1n (female) or 4n (male)
Recombination occurs
Mutations are heritable

Question 3

No effect mutations in DNA

Answer 3

DNA is mutated but phenotype/disease is not affected

Question 4

Missense mutations in DNA

Answer 4

Mutation altering DNA structure, and thus function

Question 5

Frame-Shift mutations in DNA

Answer 5

Extensive missense mutations or immediate nonsense (e.g. insertion of a stop codon)

Question 6

Insertion or Deletion mutations in DNA

Answer 6

Can be a point mutation or frame-shift mutation in DNA
Tandem repeats
Single-nucleotide polymorphism (SNP)

Question 7

Define veterinary genetics

Answer 7

The study of inherited diseases that occur in animals

Question 8

Genotype

Answer 8

The genetic makeup of an organism, determined by the specific set of alleles it possesses

Question 9

Alleles

Answer 9

Variable copies of the same gene

Question 10

Phenotype

Answer 10

The obesrvable traits or characteristics of an organism

Question 11

Mode of inheritance

Answer 11

How the disease or trait is transmitted across generations

Question 12

Autosomal dominant

Answer 12

Affected individuals have an affected parent
No skipping generations
No sex bias

Question 13

Semi-Dominant/Co-Dominant/Additive Inheritance

Answer 13

One copy (heterozygous) is sufficient to express the phenotype, but two copies (homozygous) will express the phenotype more severely

Question 14

Autosomal Recessive Inheritance

Answer 14

Homozygous will express the phenotype, but heterozygous will not
May skip generations
No sex ratio bias

Question 15

X-Linked Mode of Inheritance

Answer 15

Gene is located on the X chromosome
Sex-linked, so carrier females will pass on to males who will express the phenotype

Question 16

Loss-of-function mutations

Answer 16

Phenotype is a partial or complete loss of protein function
Common for recessive mutations

Question 17

Gain of function mutations

Answer 17

Phenotype has new or enhanced protein activity
Commonly dominant mutations

Question 18

Risk/Susceptibility locus

Answer 18

Increases the risk of disease, but not all animals will get the disease if they have the variant and not all instances of disease are caused by the variant
Commonly the trait is polygenic

Question 19

Incomplete penetrance

Answer 19

The animal has enough copies of the gene to be affected but does not express an affected phenotype
The animal is still a carrier of the trait
Can be determined retrospectively by pedigree analysis

Question 20

Expressivity

Answer 20

Individuals with the same genotype are phenotypically different along a spectrum

Question 21

Dominant Epistasis

Answer 21

One dominant allele at one gene masks both dominant and recessive alleles at another gene

Question 22

Epistasis

Answer 22

Individuals with the same genotype are phenotypically different

Question 23

X-Inactivation

Answer 23

One X in each cells gets inactivated by a methylation process
Random process
Occurs early in embryonic development

Question 24

Environmental influence on disease presentation

Answer 24

Environmental factors can affect phenotype if animal is genetically predisposed

Question 25

Signalment

Answer 25

Basic patient information (name, age, sex, breed)

Question 26

Broad uses for PCR-based DNA tests

Answer 26

Determine an animal’s specific genotype
Test for DNA of pathogens in patient samples

Question 27

Sample sites for PCR testing

Answer 27

Cheek swab
Serum
Fecal matter
Urine
Cerebrospinal fluid

Question 28

Limitations of PCR

Answer 28

Assays test for a specific mutation within a sample, not all possible mutations
Assays cannot detect mutations in all other genes

Question 29

Genetic mutation test

Answer 29

Tests for mutations of a specific gene
Ideal test for heritable disease testing

Question 30

Genetic marker test

Answer 30

Looks for a marker that is associated with a specific phenotype, but cannot detect the mutation itself
Not ideal due to greater error rate

Question 31

Uses for DNA testing for an animal

Answer 31

Detect carriers of autosomal recessive genes
Detect late-stage disease
Detect disease with a complex mode of inheritance
Determine relative risk
Susceptibility tests for risk alleles
Determine allele frequency within a population