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3.7 Inheritance Flashcards

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1
Q

What is a genotype?

A

The genetic constitution of an organism (the alleles it has for a gene)

Genotype refers to the specific alleles present in an organism’s DNA.

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2
Q

What is a phenotype?

A

The expression of the genes and its interaction with the environment

Phenotype includes physical traits and characteristics influenced by both genetic and environmental factors.

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3
Q

Define homozygous.

A

A pair of homologous chromosomes carrying the same alleles for a single gene

Homozygous individuals have two identical alleles for a given trait.

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4
Q

Define heterozygous.

A

A pair of homologous chromosomes carrying two different alleles for a single gene

Heterozygous individuals have two different alleles for a particular trait.

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5
Q

What is a recessive allele?

A

An allele that is only expressed if there are no dominant alleles present

Recessive alleles require two copies to be expressed in the phenotype.

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6
Q

What is a dominant allele?

A

An allele that will always be expressed in the phenotype

Dominant alleles can mask the presence of recessive alleles.

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7
Q

Define codominant.

A

Both alleles are equally dominant and are both expressed in the phenotype

In codominance, the traits of both alleles are visible in the organism.

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8
Q

What are multiple alleles?

A

More than two alleles for a single gene

Multiple alleles allow for a greater variety of phenotypes.

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9
Q

What is sex-linkage?

A

A gene whose locus is on the X chromosome

Sex-linked traits often show different patterns of inheritance in males and females.

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10
Q

Define autosomal linkage.

A

Genes that are located on the same chromosome (not the sex-chromosomes)

Autosomal linkage can affect the inheritance patterns of traits.

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11
Q

What is epistasis?

A

When one gene modifies or masks the expression of a different gene at a different locus

Epistasis can complicate the expected ratios in genetic crosses.

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12
Q

What is a monohybrid inheritance?

A

Genetic inheritance cross of a characteristic determined by one gene

Monohybrid crosses typically examine the inheritance of a single trait.

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13
Q

What is a dihybrid inheritance?

A

Genetic inheritance cross for a characteristic determined by two genes

Dihybrid crosses involve tracking two traits simultaneously.

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14
Q

What is the coding system for monohybrid inheritance?

A

Single letter, capital or lower case

This coding system allows for easy representation of alleles.

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15
Q

Fill in the blank: In codominant inheritance, alleles are represented as _______.

A

Geneallele

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16
Q

What is the coding system for sex-linkage?

A

Chromosomeallele

This coding indicates the chromosome on which the allele is located.

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17
Q

What is the genetic diagram coding for multiple alleles?

A

Geneallele

This system is used to show the various alleles present for a single gene.

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18
Q

What type of inheritance only involves one gene?

A

Monohybrid inheritance

This type of inheritance deals with a single gene and its alleles.

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19
Q

What is cystic fibrosis caused by?

A

A recessive allele of one gene

Cystic fibrosis is a genetic disorder resulting from the recessive allele.

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20
Q

If two carriers reproduce, what is the probability they will have a child with cystic fibrosis?

A

25%

The probability is calculated using the genotypes of the parents.

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21
Q

What is the probability that two carriers will have a girl with cystic fibrosis?

A

12.5%

This is derived from the 25% chance of having a child with cystic fibrosis multiplied by the 50% chance of it being a girl.

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22
Q

What is the first piece of information needed to gain full marks in genetic crosses?

A

The parents’ genotypes

This is essential for understanding the inheritance pattern.

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23
Q

What is the second piece of information needed in genetic crosses?

A

The gametes

Gametes are the sex cells that carry alleles to offspring.

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24
Q

What is the third piece of information needed in genetic crosses?

A

The offspring genotype

This indicates the genetic makeup of the offspring.

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25
What is the fourth piece of information needed in genetic crosses?
The offspring phenotypes ## Footnote This describes the observable traits of the offspring.
26
What is the fifth piece of information needed in genetic crosses?
The probability of the offspring having the condition/feature ## Footnote This is critical for predicting genetic outcomes.
27
What is an example of codominance in genetics?
Cows can be red, white, or roan in colour ## Footnote In this case, both red and white are dominant alleles.
28
What is a common example used to assess multiple alleles and codominance?
Human blood groups ## Footnote Human blood groups demonstrate multiple alleles and codominance through various blood types.
29
List the blood groups and their corresponding phenotypes.
* Blood group A: Blood group A * Blood group B: Blood group B * Blood group AB: Blood group AB * Blood group O: Blood group O ## Footnote These blood groups are determined by the presence of specific antigens.
30
What antibodies are present in blood group AB?
None ## Footnote Blood group AB does not produce antibodies against A or B antigens.
31
Fill in the blank: Blood group O has _______ antibodies.
Anti-A and Anti-B ## Footnote Blood group O produces antibodies against both A and B antigens.
32
What causes colour blindness?
Recessive allele found only on the X chromosome ## Footnote Colour blindness is inherited through a specific allele located on the X chromosome.
33
What is epistasis?
When one gene influences (affects or masks) the expression of another gene ## Footnote Examples include coat colour in mice, coat colour in Labradors, and fruit colour of vegetables.
34
What does Gene 1 control in Labrador coat colour?
Whether pigment will be expressed ## Footnote Allele E is dominant and codes for pigment production, while allele e is recessive and codes for no pigment production.
35
What does Gene 2 control in Labrador coat colour?
Which pigment is expressed ## Footnote Allele B is dominant and codes for black fur, while allele b is recessive and codes for brown fur.
36
What is epistasis?
The interaction of genes in controlling a phenotype, such as fruit colour in squash. ## Footnote In this case, one gene can mask the expression of another gene.
37
What is dihybrid inheritance?
The inheritance of two genes predicted together. ## Footnote This concept is linked to Mendel's work on pea plants.
38
What are the two characteristics Mendel observed in pea plants?
* Shape (round or wrinkled) * Colour (green or yellow) ## Footnote These characteristics are coded by different genes.
39
What does gene 1 in pea plants code for?
Shape of the pea ## Footnote It has two alleles: round (R) is dominant and wrinkled (r) is recessive.
40
What does gene 2 in pea plants code for?
Colour of the pea ## Footnote It has two alleles: yellow (Y) is dominant and green (y) is recessive.
41
In the context of pea plants, which allele is dominant for colour?
Yellow (Y) ## Footnote The yellow colour masks the green colour.
42
What does autosomal linkage mean?
Alleles for each gene linked on the same chromosome will be inherited together ## Footnote This affects the predicted phenotypes of the gametes.
43
What phenotypic ratio results from the linked alleles in the dihybrid cross example?
3 yellow and round : 1 green and wrinkled ## Footnote This ratio is derived from the linked inheritance of alleles.
44
In a Punnett square, what does each cell represent?
Possible genotype combinations of offspring ## Footnote Each cell is filled based on the gametes contributed by the parents.
45
True or False: In a dihybrid cross, crossing two heterozygous parents always results in the same phenotypic ratio regardless of genetic linkage.
False ## Footnote Genetic linkage can alter the expected phenotypic ratio.
46
What results from crossing over in meiosis?
New combinations of alleles in the gametes ## Footnote This leads to different predicted gametes than those in a Punnett square.
47
What does the chi-squared statistic help determine?
If the expected ratio significantly differs from the observed ratio ## Footnote This statistical test is commonly used in genetics to analyze inheritance patterns.
48
Why are yellow and round and green and wrinkled phenotypes more common?
They result from gametes RY + RY or ry + ry fusing ## Footnote These combinations are not formed by crossing over, making them more frequent.
49
What is the significance of crossing over during meiosis?
It creates new combinations of alleles, leading to genetic diversity ## Footnote However, crossing over is relatively rare, resulting in fewer gametes like Ry or rY.
50
True or False: Crossing over occurs frequently and leads to numerous genotypes.
False ## Footnote Crossing over is a rare event, which limits the variety of genotypes formed.
51
What is a population in the context of species?
A group of the same species in the same habitat at the same time ## Footnote This definition helps in understanding the concept of gene pools and allele frequencies.
52
Define gene pool.
All the alleles for all the genes for a population at one time ## Footnote The gene pool is essential for studying genetic variation within a population.
53
What does allele frequency represent?
The proportion of each allele within the gene pool ## Footnote Understanding allele frequency is crucial for population genetics.
54
What is the Hardy-Weinberg principle?
A mathematical model used to predict allele frequencies within a population ## Footnote It assumes no change in allele frequency between generations.
55
What assumptions does the Hardy-Weinberg principle make?
No deaths, births, or migration ## Footnote These assumptions mean that the model may not always be accurate in real-world scenarios.
56
What is the Hardy-Weinberg equation?
p² + 2pq + q² = 1 ## Footnote This equation is used to calculate different allele frequencies in a population.
57
What does p represent in the Hardy-Weinberg equations?
The frequency of the dominant allele ## Footnote This is a key variable in predicting allele frequencies.
58
What does q represent in the Hardy-Weinberg equations?
The frequency of the recessive allele ## Footnote Understanding q is essential for calculating the frequencies of genotypes.
59
What does p² represent in the Hardy-Weinberg equations?
The frequency of the homozygous dominant genotype ## Footnote This helps in understanding how many individuals are homozygous dominant in a population.
60
What does 2pq represent in the Hardy-Weinberg equations?
The frequency of the heterozygous genotype ## Footnote This is significant for understanding carrier frequencies in populations.
61
What does q² represent in the Hardy-Weinberg equations?
The frequency of the homozygous recessive genotype ## Footnote This is important for identifying the prevalence of recessive traits.
62
Fill in the blank: Cystic fibrosis is caused by a _______.
recessive allele ## Footnote This is a key concept in genetic disorders and inheritance patterns.
63
If 0.02% of the UK population suffers from cystic fibrosis, what is q²?
0.0002 ## Footnote This value is crucial for calculating carrier frequency.
64
How do you find q from q²?
q = √(0.0002) ## Footnote This step is necessary to calculate the frequency of the recessive allele.
65
What is the value of p if p + q = 1 and q = 0.014?
p = 0.986 ## Footnote This calculation is essential for determining allele frequencies.
66
What is needed to predict the results of genetic crosses in monohybrid inheritance?
Definitions and ability to predict results ## Footnote This includes concepts such as dihybrid inheritance, multiple alleles, codominance, sex-linkage, epistasis, and autosomal linkage.
67
What is dihybrid inheritance?
Inheritance of two genes at the same time ## Footnote In a cross between two heterozygous parents, the expected phenotype ratio is 9:3:3:1.
68
What is autosomal linkage?
When two genes are located on the same chromosome (not a sex chromosome) ## Footnote This affects inheritance patterns.
69
What does crossing over in meiosis create?
New combinations of alleles in gametes ## Footnote If the expected ratio is not observed, it may be due to crossing over.
70
Why is crossing over considered rare?
You will observe fewer individuals expressing these alleles ## Footnote This leads to deviations from expected genetic ratios.
71
What is the Hardy-Weinberg principle?
A mathematical model to predict allele frequencies within a population ## Footnote It assumes no change in allele frequency between generations (no deaths, births, or migration).
72
What are the limitations of the Hardy-Weinberg principle?
Not accurate if there are changes in allele frequency ## Footnote Changes can occur due to factors like deaths, births, or migration.
73
What genetic diseases are linked to inheritance?
Cystic fibrosis, colour-blindness, thalassemia ## Footnote These are examples of conditions that can be studied in relation to genetic inheritance.
74
How does inheritance relate to the structure and function of DNA?
Inheritance links to DNA's role in genetic information transfer ## Footnote Understanding DNA structure helps explain inheritance patterns.
75
What types of natural selection are linked to inheritance?
Stabilising, directional, and disruptive selection ## Footnote These types of selection illustrate how traits are favored in populations over time.
76
What does predicting inheritance outcomes link to?
The chi-squared statistic ## Footnote This statistical method helps determine the significance of deviations from expected genetic ratios.

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