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Chapter 2 Flashcards

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1
Q

What principle of gene inheritance did Mendel discover?

A

Mendel’s principle of equal segregation

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2
Q

How are individual genes identified using progeny ratios?

A

By analyzing phenotypic ratios from controlled matings

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3
Q

What is the chromosomal basis of Mendel’s principle?

A

Gene pairs reside on homologous chromosomes that segregate during meiosis

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4
Q

What is the significance of controlled matings in studying single-gene inheritance?

A

They allow the analysis of mutant and wildtype organisms

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5
Q

What is a trait?

A

A distinguishing quality, for example, seed color

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6
Q

Define phenotype.

A

An organism’s observable characteristics or traits

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7
Q

What are pure lines?

A

When a cross of two individuals results in all progeny having the same phenotype

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8
Q

What was the result of Mendel’s cross of pure yellow seeds and pure green seeds?

A

All seeds in the F1 generation were yellow

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9
Q

What phenotypic ratio results from selfing the F1 generation?

A

3:1 ratio

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10
Q

What is Mendel’s Law of Equal Segregation?

A

During meiosis, allele pairs separate equally into eggs and sperm

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11
Q

What is a gamete?

A

The haploid sperm and egg cells

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12
Q

Define zygote.

A

A fertilized egg (diploid)

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13
Q

What is a homozygote?

A

An organism with two of the same allele for a gene

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14
Q

What is a heterozygote?

A

An organism with two different alleles for a gene

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15
Q

What are the genotypic ratios for single-gene inheritance?

A

1:2:1 for F2 generation, 1:1 for test cross

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16
Q

What occurs during meiosis?

A

Production of gametes through two cell divisions, resulting in four haploid cells

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17
Q

What is the role of restriction enzymes in tracking inheritance?

A

They cut DNA at specific base sequences to create RFLPs

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18
Q

What is an RFLP?

A

Restriction Fragment Length Polymorphism, a molecular marker for tracking inheritance

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19
Q

What is phenylketonuria (PKU)?

A

A genetic disorder caused by defective alleles of the PAH gene

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20
Q

What is a null allele?

A

A mutant allele that has no function

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21
Q

What is a leaky allele?

A

A mutant allele that has some, but not all of the wild-type function

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22
Q

What is a silent (neutral) allele?

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A

A mutant allele that has no measurable effect on function

23
Q

Fill in the blank: The Y allele is ______ and the y allele is ______.

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A

dominant; recessive

24
Q

True or False: Gametes contain two members of the gene pair.

25
What is a null allele?
A mutant allele that has no function ## Footnote Null alleles can result from mutations that disrupt the gene's ability to produce a functional product.
26
Define a leaky allele.
A mutant allele that has some, but not all of the wild-type function ## Footnote Leaky alleles may produce partially functional proteins, leading to milder phenotypes.
27
What is a silent (neutral) allele?
A mutant allele that has no measurable effect on function ## Footnote Silent alleles do not alter the phenotype even if they change the genotype.
28
What does it mean for a gene to be haplosufficient?
One functioning copy is enough to produce a wild-type phenotype ## Footnote In this case, a mutant allele would be recessive.
29
What does it mean for a gene to be haploinsufficient?
One functioning copy is NOT enough to produce a wild-type phenotype ## Footnote Here, the wild type allele can be considered recessive.
30
What condition is caused by haploinsufficiency for the CBFA gene?
Cleidocranial dysostosis ## Footnote This condition is characterized by skeletal abnormalities and underdeveloped bones and joints.
31
What are the common phenotypic segregation ratios based on Mendelian genetics?
1:1 and 3:1 ## Footnote These ratios arise from the equal segregation of alleles during gamete formation.
32
In a cross of red and white flowers, what was the F2 ratio observed?
378 red and 122 white flowers, ratio = 3:1 ## Footnote This suggests that the white flower color is a recessive trait.
33
What does a ~1:1 ratio in progeny suggest about a mutation?
It suggests a dominant mutation in a single gene ## Footnote This ratio indicates that the trait is likely controlled by a single gene with a dominant allele.
34
What is a test cross used for?
To determine the genotype for an individual with a dominant phenotype ## Footnote A test cross involves crossing the individual with a homozygous recessive.
35
What is the principle of forward genetics?
Proceeding from a mutant phenotype to identify a gene ## Footnote This approach helps in understanding genetic causes of observed mutations.
36
What is the difference between homogametic and heterogametic sex?
Homogametic sex has sex chromosomes of one type, while heterogametic sex has different sex chromosomes ## Footnote In humans, females are homogametic (XX) and males are heterogametic (XY).
37
What is sex linkage?
Inheritance pattern for genes that lie within distinct regions of the X or Y chromosome ## Footnote Sex-linked traits often show different patterns of inheritance in males and females.
38
What are the tendencies to look for in autosomal recessive disorders?
Appears in progeny of unaffected parents, affects both males and females ## Footnote Examples include Cystic Fibrosis and Polycystic Kidney Disease.
39
What are the characteristics of X-linked recessive disorders?
More males than females affected, daughters of affected males are carriers ## Footnote Examples include color blindness and hemophilia.
40
What is the inheritance pattern of X-linked dominant disorders?
Affected males pass condition to all daughters, not sons ## Footnote Affected females have a 50% chance of passing the condition to children.
41
What is the significance of the SRY gene?
Initiates male development ## Footnote It is located on the Y chromosome and is crucial for male sex determination.
42
What does pedigree analysis involve?
Searching medical records for informative matings to infer a trait's inheritance pattern ## Footnote Pedigrees are interpreted according to Mendel's law of equal segregation.
43
What is the product rule in pedigree analysis?
The probability of two independent events occurring simultaneously is the product of the individual probabilities ## Footnote This rule is useful for calculating the likelihood of genetic disorders in offspring.
44
What is a polymorphism?
Coexistence of two or more common phenotypes ## Footnote Examples include variations in eye color and blood type.
45
What rule states the probability of two independent events occurring simultaneously?
The product rule ## Footnote The product rule states that the probability of two independent events occurring simultaneously is the product of the individual probabilities.
46
What is the expected genotype ratio when both parents are heterozygous?
1: T/T, 2: T/t, 1: t/t ## Footnote This ratio reflects the Mendelian inheritance patterns for a monohybrid cross.
47
What is the chance of being heterozygous for a specific trait?
2/3 ## Footnote This probability is derived from the ratios of possible genotypes.
48
What is the probability of a child being t/t if both parents are heterozygous?
¼ ## Footnote This calculation is based on the expected ratios of offspring from heterozygous parents.
49
How is the probability of an individual being heterozygous calculated?
Using the product rule ## Footnote The calculation involves multiplying the chance of one parent being heterozygous by the chance of the other parent being heterozygous.
50
What is the formula to calculate the probability of being t/t?
P (t/t) = 1/3 x 1/3 x ¼ = 1/36 ## Footnote This formula takes into account the probabilities of each parent contributing to the t/t genotype.
51
True or False: Individuals in pedigree analysis are assumed to be homozygous normal when the disease is rare.
True ## Footnote This assumption is based on the low prevalence of the disease, leading to a higher likelihood of normal genotypes.
52
Fill in the blank: The chance of a parent being heterozygous is ______.
2/3
53
What is the probability of the child being T/t if one parent is heterozygous and the other is homozygous normal?
1/3 ## Footnote This probability reflects the contribution of the heterozygous parent to the child's genotype.

genetics (12 decks)

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