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Genetics PCB 3063 > Chapter 3 - Basic Heredity > Flashcards

Chapter 3 - Basic Heredity Flashcards

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1
Q

The first genetic model organism was? Who used them, and why?

A

Pea plants. Mendel used them because they were easy to grow in his university’s greenhouse, they had rapid generation time, and numerous progeny.

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2
Q

T or F: Mendel used the scientific method when carrying out his studies.

A

True

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3
Q

Mendel focused on ___ traits because they had only _____ clearly discernible forms: flower ______ (axial or terminal), pod ____, pod ____ (inflated or constricted), stem _____, seed _____, seed ____, and seed coat _____.

A

7; 2; position, color, shape, length, color, shape, color.

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4
Q

In Mendelian genetics, a gene is an ________ factor that determines a ______.

A

inheritable; characteristic

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5
Q

_____ are different versions of a gene.

A

Alleles

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6
Q

Mendel’s studies involved ____ alleles of each gene that encoded for a trait of interest.

A

2

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7
Q

A locus is a specific place on a chromosome where a(n) gene/allele resides.

A

Gene

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8
Q

The set of all alleles is known as the organism’s _____.

A

genotype

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9
Q

Identical alleles are ______; different alleles are _______.

A

homozygous; heterozygous.

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10
Q

What defines the potential (or range of the) phenotype?

A

genotype

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11
Q

Mendel _____ the genotype from the phenotype - this is known as forward ______.

A

inferred; genetics

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12
Q

Phenotype is delimited by the _____, but progeny do not ______ the phenotype.

A

genotype; inherit

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13
Q

What is meant when Mendel began his experiments with “true breeding parents”?

A

They were homozygous for the characteristic of interest.

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14
Q

What is meant by a monohybrid cross in Mendel’s pea plants? Dihybrid?

A

Monohybrid = cross homozygous plants that differ in a SINGLE TRAIT.

Dihybrid = cross homozygous plants that differ in TWO TRAITS.

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15
Q

Anthers vs. stigma in pea plant flowers?

A

Anthers are the male sex organ (pollen is the gamete); stigma is the female sex organ.

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16
Q

F in F1 stands for _____ and means relating to, or befitting a son or daughter.

A

Filial

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17
Q

Mendel found that all F1 progeny from monohybrid crosses had the phenotype of only one parent, what are the implications?

A

The trait demonstrated in the F1 phenotype is dominant.

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18
Q

When Mendel self-fertilized F1 (from monohybrid crosses), what phenotype did he see? What was the ratio/proportions of the different phenotypes?

A

He saw the phenotype of both P generations in a ratio of 3:1 - that is, the phenotypes were 3/4 seen in F1 (one of the two P), and 1/4 of the other P generation not seen in F1.

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19
Q

When Mendel saw the phenotype of both parent plants in the F2 generation, he was able to conclude that the traits don’t _______, and the traits are not ______. In other words, there are ______ genetic factors (aka ______) that determine a specific phenotype.

A

blend; lost. Two; alleles

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20
Q

When Mendel saw the phenotype of both parent plants in the F2 generation, he was able to conclude that fertilization brings one _____ from each parent together to form the _____ of the offspring.

A

allele; genotype

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21
Q

When Mendel saw the phenotype of both parent plants in the F2 generation, he was able to conclude that the trait that was unchanged in the F1 generation was ______, whereas the trait that disappears in the F1 generation is ______.

A

Dominant; recessive

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22
Q

Mendel’s First Law, the Principle of _________, states:
Diploid organisms have two ____ of each _____.
One ______ segregates to each gamete.
_____ segregate into gametes in _____ proportions.

A

Segregation.
alleles, gene.
allele
alleles, equal.

23
Q

Mendel was able to confirm the concept of dominance by selfing F2 progeny, many of which were round, and a few that were wrinkled. What did he see in the F3?

A

F2 wrinkled seeds (the recessive trait) only produced wrinkled seeds. F2 round seeds (dominant) produced (mostly) round as well as (some) wrinkled (3:1).

24
Q

The relationship between genes and chromosomes was established about ____ years after Mendel’s studies when Walter Sutton developed the Chromosome Theory of _____ by studying meiosis in ______.

A

40; Heredity; grasshoppers.

25
Q

Walter Sutton demonstrated that homologous pairs of chromosomes contain one ____ and one ____ chromosome, and that only one of the chromosomes from each pair (per parent) _______ into a ________.

A

maternal and paternal; segregates; gamete

26
Q

Walter Sutton concluded that the segregation of homologous chromosomes in gametes must be the basis of Mendel’s Principles of _______.

A

Heredity

27
Q

If there is crossing over during meiosis, will there be a difference in the phenotypic ratio when examining only one allele?

A

No - genetically the chromosomes will be different from the P generation, but the phenotypic ratios will be the same with or without crossing over.

28
Q

A ____ _____ is a simple method to predict the outcome of a monohybrid cross.

A

Punnett square

29
Q

T or F: the following is a Mendelian cross: Tt x tt

A

False - Tt is not a “true breeding parent”.

30
Q

A _____ is a method where an F1 is crossed to one of the parental genotypes to affirm dominance; whereas a _______ is a cross between a homozygous recessive and an organism with an unknown genotype.

A

backcross; testcross

31
Q

Backcrosses can be performed to show that tall (T) plants are ______ to short (t) plants

A

Dominant

32
Q

When determining probability for _______ events, the keyword “and” indicates using the _______ rule (e.g. rolling one 4 “and” one 5).

A

independent; multiplication

33
Q

When determining probability for _______ _____ events, the key words “either” AND “or” indicates using the _______ rule (e.g. rolling “either” a 3 “or” a 4).

A

mutually exclusive; addition

34
Q

A _______ reveals the genotype of an organism by crossing it to a homozygous recessive phenotype - if progeny demonstrate only the dominant characteristic, than the unknown is ______ for the allele; if the progeny demonstrate a 3:1 ratio of the unknown phenotype to the homozygous recessive, the unknown is ______ for the allele.

A

testcross; homozygous; heterozygous

35
Q

Testcrosses always include a ______ ______ to cross with the unknown.

A

homozygous recessive

36
Q

T_ x tt is an example of a ________; Tt x tt (or TT) is an example of a ________.

A

testcross; backcross

37
Q

In genetic nomenclature:
Genes are usually depicted by 1 - 3 letters in _____.
Lowercase letters indicate _____, uppercase (the whole thing or just the first letter) indicates ____.
____ or ____ are sometimes used if there are 3 or more alleles.

A

italics.
recessive; dominant
Superscript or subscript

38
Q

The most commonly found allele is referred to as the _____ ______ and indicated with a superscript ____ symbol.

A

wild type; plus (+)

39
Q

Gene names are often based on the ____ version of the phenotype.

A

mutant

40
Q

When Mendel performed dihybrid crosses (dominant yellow/round x recessive green/wrinkled), he found that his F1 generation had the phenotype of the _____ traits; and when he self-fertilized the F1 generation, his F2 generations displayed _____ discrete phenotypes which had _____ possible genotypes. What were the phenotypes, and in what proportion?

A

dominant; four; sixteen

Yellow/round, green/round, yellow/wrinkled, and green/wrinkled in a 9:3:3:1 ratio.

41
Q

The ratio of the phenotypes seen in Mendel’s dihybrid cross results from ______ _____ of the genes; this ratio is possible only when the traits are located on _____ chromosomes.

A

independent assortment; different

42
Q

T or F: genes that are widely separated on the “SAME” chromosome appear to sort independently due to random distribution.

A

False: genes on the “same” chromosome will appear to sort independently only when there is crossing over (AKA genetic recombination).

43
Q

In dependent assortment observed by Mendel is due to the behavior of the chromosomes during ______.

A

Meiosis.

44
Q

When genes for two traits segregate independently, the multi-hybrid crosses can be treated as multiple _________ crosses by considering each trait ______ and using the ______ rule.

A

monohybrid crosses; individually; multiplication

45
Q

The ___-____ test is a statistical test to determine the probability that the difference between observed results and expected results can be explained purely by _____.

A

chi-square; chance

46
Q

T or F: DNA synthesis in eukaryotic cells occurs during interphase (between G1 and G2).

A

True

47
Q

T or F: If both parents show the dominant phenotype, then 100% of the offspring will be homozygous for the dominant allele.

A

False - the genotype of the P’s is needed to determine ratios.

48
Q

Mendel determined that for a given character, such as pea seed shape, an individual has 2 factors, and that these can exist in 2 forms (R or r). Today we would describe R and r as being different _____ of the seed shape _____.

A

alleles; gene

49
Q

Which of the following statements is false?
A. Genotype is inherited.
B. Phenotype is only determined by genotype.
C. Genotype can be directly determined with current technology.
D. Phenotype is a quantifiable (measurable) or otherwise observable characteristic.
E. Select this answer if none of the statements A-D are false.

A

B. Phenotype is only determined by genotype.

Genotype determines limits, but environmental factors play a role.

50
Q

Hemophilia is associated with a sex-linked recessive genetic mutation. Assume that a man with hemophilia marries a woman who does not suffer from the disease, but her father had hemophilia. What % of the daughters will have hemophilia?

A

Bb x bb = 1/2 bb, 1/2 Bb - 50%

51
Q

How many Barr Bodies are present in a cell from a male who is XXXY?

A

2

52
Q

A human with an XXY sex chromosome karyotype appears female. Somatic cells contain 1 Barr Body. What might explain why this person does not look to be male?
A. This person suffers from Turner syndrome.
B. This person suffers from Klinefelter syndrome.
C. This person has a mutated SRY gene.
D. This person has an extra copy of the SRY gene.
E. The XXY determination was an error because it is impossible for a human XXY individual to be female.

A

C. This person has a mutated SRY gene.

53
Q 
What kind of dominance does the following example demonstrate? Individuals with the genotype HH have healthy levels of cholesterol, those with Hh have higher levels of cholesterol, and those with hh have dangerous levels that often lead to heart attacks during childhood.
A. complete dominance
B. incomplete dominance
C. codominance
D. recessive
E. none of the above
A

B. incomplete dominance

Phenotype of the heterozygote is within the range, yet is still distinguishable from the homozygous dominant or homozygous recessive

Genetics PCB 3063 (27 decks)

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