Genetics Flashcards

1
Q

Define genetics

A

Study of heredity

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2
Q

When and who started modern genetics? (Quantitative genetic testing)

A

Gregor Mendel 1800s

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3
Q

Define phenotype

A

Physical appearance of animal
Physical expression of genes

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4
Q

Define genotype

A

Genetic makeup

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5
Q

Define genome

A

Entire genetic material of an animal

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6
Q

Define genes

A

Functional units of inheritance

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7
Q

Polymer of DNA and its 3 parts

A

Nucleotide
1. 5 carbon sugar (ribose vs. deoxyribose)
2. Phosphate
3. Nitrogenous base

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8
Q

5 main nitrogenous bases

A

Pyrimidines: cytosine and thymine (uracil)
Purines: Adenine and Guanine

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9
Q

Significance of base pairing

A

Easy to exactly replicate (duplicate) accurately

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10
Q

Define mutation

A

When replication is not exact due to chemical change in DNA
(This word is overused)

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11
Q

Define migration

A

Bringing new genotypes through breeding stock into a population

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12
Q

Define selection

A

Using some animals more than others as parents
Natural: by nature
Artificial: by management

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13
Q

What are the products of genes?

A

Protein molecules via synthesis of amino acids

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14
Q

Triplet codes vs. codon

A

Triplet code: DNA
Codon: RNA
- 64 possibilities for 20-21 amino acids

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15
Q

Define autosomes

A

Chromosomes in somatic cells

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16
Q

How many chromosome pairs do humans, horses, cattle, wheat, and fruit flies have?

A

Humans- 23
Horses- 32
Cattle- 30
Wheat- 21
Fruit fly- 4

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17
Q

Define transcription

A

Synthesis of mRNA strand by “copying” a DNA segment

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18
Q

Define translation

A

Production of amino acids from RNA codon sequences

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19
Q

Protein synthesis pathway

A

DNA (transcription in nucleus) mRNA (translation in ribosomes) proteins folding

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20
Q

3 types of RNA

A

Messenger (mRNA)- contains information to directs protein synthesis
Ribosomal (rRNA)- structure and function of ribosomes
Transfer (tRNA)- identifies codons in mRNA and brings correct amino acid

21
Q

Define locus

A

Location of a particular gene on a chromosome (address)

22
Q

Define homologous chromosomes

A

Same loci and structure

23
Q

Define alleles

A

Different forms of the same gene

24
Q

Define homozygous

A

Genes are alike for a particular trait (same alleles)

25
Q

Define heterozygous

A

Genes are not alike for a particular trait (different alleles)

26
Q

Define dominant

A

An allele that overpowers and prevents the expression of another allele

27
Q

Define recessive

A

An allele that is expressed only when animal is homozygous for non-dominant allele

28
Q

Where does random (independent) assortment occur?

A

Meiosis

29
Q

3 gene actions

A

Qualitative inheritance (simple traits)
Sex-linked inheritance
Quantitative inheritance (polygenic traits)

30
Q

Describe qualitative inheritance

A

Controlled by a single gene
Phenotype is discontinuous
(Ex. Cow coat color)

31
Q

Define codominance

A

When two alleles are both expressed in heterozygote
Ex. Checkered chickens

32
Q

Define incomplete dominance

A

Get 3 distinct phenotypes instead of 2
Hetero is dilute or medium
(Ex. Pink flower)

33
Q

Sex-linked inheritance in mammals vs. birds/ reptiles

A

Mammal
F- XX
M- XY

Reptiles/ Birds
F- ZW
M- ZZ

Genes uncontested on sex chromosome is expressed no matter what.

34
Q

Describe quantitative inheritance

A

Many genes involved (additive effects)
Phenotypes described by measurements
Continuous distribution of phenotypes

35
Q

Define heterosis

A

Other names: overdominance + hybrid vigor
Heterozygote shows better results than either homozygote
Often in crossbreeding

36
Q

Most common equation in genetics

A

Phenotype= genotype + environment
(Means we must standardize environment for studies)

37
Q

Formula for genetic progress

A

Genetic gain/year= (heritability x selection differential (intensity))/generation interval in years

38
Q

What is heritability?

A

(h^2)
Percent of trait dictated by genetics
Estimates variation in phenotypes
Ranges from 0-1
.4-.5 for weight
.1 for health, fitness, reproduction

39
Q

How to calculate selection differential?

A

Compare average of selected male/female with population average and divide by two.
Then Add to pop. Avg.

40
Q

What is the generation interval?

A

The average age of parents when offspring born.

41
Q

Evidence of genetic change

A

Meat to bone ratio in turkey
Lean pigs

42
Q

3 selection methods

A

Tandem- one trait at a time
Independent culling levels- minimal acceptable levels assigned to traits
Selection index- traits evaluated and expressed as a single score (can include economics and correlation)

43
Q

Define registered

A

Recorded in some breed association and meets criteria outlined by org.

44
Q

Define “grade”

A

Not registers
Could be about same genetically as registered

45
Q

3 effects of inbreeding

A

Increases homozygosity
Decrease reproductive performance and growth
More susceptible to stress and disease

46
Q

Define line breeding

A

Milder form of inbreeding
Emphasizes one outstanding ancestor

47
Q

3 types of outbreeding

A

Species cross: ex. Mule or beefalo
Crossbreeding: same species by different breed (max. Heterosis and breed complementation)
Outcrossing: mating unrelated animals within a breed

48
Q

How fast can inbreeding effects be eliminated?

A

In one generation

49
Q

Positive vs. negative correlations

A

Positive= both increase together
Negative= one goes up and the other decreases
Close to 1 or -1 is stronger