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VS 307 > Test 6 > Flashcards

Test 6 Flashcards

1
Q

What trait is a result of quantitative genetics?

A

skin color

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2
Q

What is the Infinitesimal model of genetics?

A

lots of small genes, each with roughly equal effect

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3
Q

Why does the environment need to be standardized when studying genetic effects?

A

Genes interact with the environment; indeed, the environment is part of the phenotype

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4
Q

What was one of the impact’s when RA Fisher’s Infinitesimal theory was applied?

A

Dairy producers saw a logrithmic increase in milk production per cow

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5
Q

What is the difference between the population average and the variation in the population for a trait?

A

The variation is the range around the average

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6
Q

Which of the following has a heritability of 0.0?

A

Number of legs

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7
Q

Which of the following has a heritability of 0?

A

clipped mane of horse

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8
Q

Which of the following is genetic and has a heritability of 0?

A

number of legs

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9
Q

Which of the following traits is mostly the result of additive genetics?

A

Height

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10
Q

Why do heritability studies focus on additive modes of inheritance rather than recessive/dominant and epistasis?

A

Dominant/recessive genetics and epistasis requires a specific set of genes be inherited together and that is less predictive than genes with additive modes of inheritance

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11
Q

What is the difference between heritability and estimated breeding value (EBV)?

A

Heritability is characteristic of the trait and estimated breeding value is characteristic of the individual

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12
Q

Will heritability of a trait be the same in different breeds?

A

No

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13
Q

Heritability is standard characteristic of the trait in all members of a species.

A

False

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14
Q

Why might heritability for a trait decrease over time?

A

Improvement of the breed through selection and Discovery that offspring are performing more poorly than predicted

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15
Q

What is the period when the Thoroughbred horse is considered to have been founded?

A

1600s-1700s

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16
Q

What aspect of genetics does the sire-line track?

A

Y chromosome

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17
Q

What aspect of genetics does the dam-line track?

A

Mitochondria

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18
Q

Approximately what percent of Thoroughbred horses trace their male line back to the Darley Arabian?

A

95%

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19
Q

Approximately what percent of the genes in Thoroughbred horses are descended from the Darley Arabian

A

6.5%

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20
Q

Which is an accurate description of the modern Thoroughbred breed?

A

Hybrid of native English horses and horses imported from the Mediterranean region

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21
Q

What was Cunningham’s Paradox?

A

Thoroughbred horses have had limited improvement in race times but the population has lots of variation measured for racing performance.

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22
Q

Heritability of race time in Thoroughbred horses is difficult to measure because of which of the following?

A

There is no single trait we can identify as racing. Horses race different distances, at different ages on different surfaces

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23
Q

Which of the following two traits resulted in discovery of the best heritability scores for racing?

A

Log of Money earned and handicapping

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24
Q

What was the result of GWAS studies for racing performance in Thoroughbred horses?

A

Lots of areas of interest were identified, but different ones in different studies

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25
Q

Evidence was found for MSTN, PDK4 and COX4I2 having an impact on racing performance. Why were those particularly significant?

A

The evidence was confirmed by cross checking the effects in multiple tests for each one of them, sometimes confirming statistical effect by testing a second population.

26
Q

Bruce Lowe numbers measure….

A

Prominent dams in a pedigree

27
Q

Dosage measures….

A

Deep pedigree of sires

28
Q

Nicking measures…

A

Values of mating

29
Q

Why do heritability values vary between studies?

A

Different distances measured
Different populations
Different measures of performance

30
Q

Why might the slope of race-time improvement have declined for Thoroughbred horses?

A

Top horses reaching a physical limit for performance

31
Q

Handicapping is…

A

A subjective evaluation of quality
Weight added to a saddle to slow a horse down
Time Form and Beyer’s Numbers

32
Q

What does hemizygous mean?

A

A normally diploid individual has only one copy of a gene; genes on X in males; genes on X for XO females

33
Q

The X chromosome does not have any genes.

A

False

34
Q

What is the likely origin of DNA found in mitochondria?

A

Bacteria that colonized primordial cells

35
Q

What is a function of mitochondria in the cell?

A

Gernerate energy in the form of ATP

36
Q

Why do we refer to the inheritance of mitochondrial DNA as having “Tail-Female” inheritance?

A

Mitocondria are almost always inherited from the egg.

37
Q

What is associated with the number of mitochondria in a cell?

A

Cells with high metabolic activity have more mitochondria than cells with low activity

38
Q

When a research result is statistically significant, what does that mean?

A

The result is repeatable

39
Q

Which of the following is true about the mitochondria genome?

A

It is small, having only 16,500 bp compared to 2.5 billion bp on chromosomes

40
Q

What is true about the genes for function of mitochondria?

A

Most of the genes for mitochondria function are actually on chromosomes

41
Q

Why do we think that mitochondria are descended from primordial prokaryotes (bacteria)?

A

Their DNA sequence is more similar to that of prokaryotes than than of autosomes.
Mitochondria have codons like bacteria and not like vertebrate codons
The mitochondria genome is circular like bacteria

42
Q

What is the name of the theory that prokaryotes were the origin of mitocondria?

A

Endosymbiotic theory

43
Q

Why is the mitochondrial DNA a good tool for a molecular clock?

A

Mitochondia DNA polymerase is error prone

44
Q

What conclusions followed the comparison of mitochondria haplotypes of horses from around the world?

A

Many mares were part of the foundation of domestic horses

45
Q

The X and Y chromosome have very clear differences. Why do the X and Y chromosome pair during meiosis?

A

They share a small set of genes in the pseudo autosomal region

46
Q

Why do we think the Y chromosome evolved from the X chromosome?

A

When the PAR is longer in some species, the genes found are X chromsosome genes

47
Q

Why do we think a large number of stallions contributed to the foundation of the domestic horse?

A

We see a large number of Y chromosome haplotypes in ancient DNA

48
Q

Why do we think that most modern horse breeds have a single Y chromosome haplotype?

A

Breeders choose stallions from the Mediterranean region between 700 and 1200 years ago

49
Q

Where is the microbiome found?

A

Throughout the body

50
Q

What is the difference between pathogenic bacteria and commensal bacteria?

A

Commensal bacteria do not cause disease while pathogenic bacteria do.

51
Q

There is more variation between individuals in their microbiome than in their genome.

A

True

52
Q

What is the ratio of microbiome cells to the genome cells? (Roughly)

A

3:1; micorbiome cells outnumber animal cells

53
Q

What is the mass (weight) of the microbiome?

A

About 6 pounds, according to the video. By comparison, the human brain weighs only 3 pounds.

54
Q

The microbiome contributes gene functions and substances not found or produced by the horse or human genome.

A

True

55
Q

What was the limit on discovery for early investigations (up to 1970) of the microbiome?

A

Ability to grow the microbes in the laboratory

56
Q

How did DNA sequencing make it possible to advance microbiome studies?

A

DNA sequences were found that were for microbes we had not been able to culture

57
Q

What was the initial basis for identifying microbes as belonging to species never seem before? Or identifying which species they did belong to?

A

Sequence of 61s Ribosomal DNA sequence

58
Q

What influences the type of microbe found in a location?

A

vaginal vs cesarean birth
diet
Age
Genome

59
Q

What are biofilms?

A

A community of microbes that interact in a commensal fashion

60
Q

What is the most common site for study of the microbiome?

A

fecal material

VS 307 (5 decks)

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