Genetics Chapter Quiz: Inheritance Patterns

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Questions and Answers

What is a characteristic of mitochondrial inheritance?

It can only affect males.

Mitochondria are equally contributed by both parents.

It can appear in every generation. (correct)

It is passed through the paternal line.

Who receives all their mitochondria from the mother?

Only females.

Both male and female offspring. (correct)

Only males.

Only affected individuals.

Which type of inheritance is characterized by genes present in both sexes but expressed in only one?

Codominance.

Autosomal dominant.

Sex-influenced traits. (correct)

Incomplete dominance.

Which trait is an example of a sex-limited inheritance?

Beard in males. Signup and view all the answers

How does sex-linked dominant inheritance typically present among offspring?

Both affected males and females can appear in the same generation. Signup and view all the answers

What does the term 'sex-influenced traits' imply?

The expression varies between sexes. Signup and view all the answers

Which statement about sex-linked recessive inheritance is true?

Affected males appear in every generation. Signup and view all the answers

In a Punnett square, what does a dominant allele combination usually indicate?

The organism will display the dominant trait. Signup and view all the answers

What is the genotype of a female who carries a Sex-linked Dominant trait but does not express it?

XA Xa Signup and view all the answers

Which statement about Sex-linked traits is true?

A male cannot be a carrier of a Sex-linked Recessive trait. Signup and view all the answers

What is the condition for two unaffected parents in a pedigree to produce affected offspring?

Both parents must be carriers. Signup and view all the answers

What depicts the pattern of inheritance in a family for a specific trait?

Pedigree Signup and view all the answers

In a Punnett Square involving a cross between two heterozygous parents with one affected trait, what proportion of offspring would likely be affected?

50% Signup and view all the answers

How would a pedigree diagram symbol for a female carrier of a trait appear?

Half-filled circle Signup and view all the answers

Which of the following represents the only way for a male to express a Sex-linked Recessive trait?

Xa Y Signup and view all the answers

What is the expected outcome in a Punnett Square crossing AA with Aa?

Three-quarters are affected Signup and view all the answers

What is a key characteristic of traits that follow autosomal recessive inheritance?

Two unaffected parents can produce an affected child if they are both carriers. Signup and view all the answers

In the case of sex-linked recessive traits, what must be true for a daughter to express the trait?

Her father must also have the trait and her mother must be affected or a carrier. Signup and view all the answers

Which of the following is NOT an example of an autosomal dominant disorder?

Sickle Cell Anemia Signup and view all the answers

What would be the expected outcome of a Punnett square involving two heterozygous parents (Aa x Aa) for an autosomal recessive trait?

25% offspring affected Signup and view all the answers

How does the presence of close relatives reproducing affect the likelihood of affected children in autosomal recessive traits?

It greatly increases the likelihood of affected offspring. Signup and view all the answers

Which of the following disorders is a result of autosomal recessive inheritance?

Albinism Signup and view all the answers

What is a common misconception about carriers of autosomal recessive traits?

They always express the trait. Signup and view all the answers

What can be inferred about the offspring of two affected parents with an autosomal recessive trait?

All offspring will express the trait. Signup and view all the answers

Study Notes

Introduction to Inheritance Patterns

Inheritance can arise from autosomal chromosomes, sex chromosomes, or mitochondrial DNA.

Types of Inheritance

Mendelian Patterns

Autosomal Dominant: Each affected offspring has an affected parent, appearing in every generation. A dominant allele in an organism results in the dominant trait.
Autosomal Recessive: Both parents of an affected person are carriers, and this type isn't typically seen in every generation.
Sex-linked Dominant: Females are more frequently affected, especially when fathers are affected. This is heavily reliant on the X chromosome, where the X chromosome acts as a recessive allele.
Sex-linked Recessive: Males are more frequently affected, and affected males often appear in each generation.

Non-Mendelian Patterns

Mitochondrial: This affects both males and females, inheriting through the maternal line. Offspring receive all mitochondria from the mother via the egg.
Complex and Multifactorial Inheritance: This classification encompasses complex interactions not readily categorized by Mendelian or simple inheritance.

Autosomal Dominant Traits

Affected offspring have an affected parent and the trait appears in every generation.
One or both dominant alleles result in the dominant trait.

Autosomal Recessive Traits

Both parents of an affected person are carriers.
Not typically seen in every generation.

Sex-Linked Dominant Traits

Females are more frequently affected, especially when the father is affected.
Both males and females can be affected in the same generation.
This depends heavily on the X chromosome and the X chromosome acts as a recessive allele. XX makes a female and XY makes a male.

Sex-Linked Recessive Traits

Males are often affected more frequently.
Affected Males often appear in each generation.

Mitochondrial Inheritance

Can affect both males and females.
Inherited through the maternal line, Embryos receive all mitochondria from the mother.
Can appear in every generation.

Sex-Limited Traits

Genes are present in both sexes but are normally expressed in only one.
Hormonal determinants influence expression in a specific sex.
Traits can appear in one but not all members of that sex. The trait's genes can be carried by the opposite sex without being expressed due to anatomical or physiological differences.

Sex-Limited Inheritance Examples

Red-Green Colorblindness
Hemophilia
Hairy ears (Y Chromosome)
Beard in males (hormonal development)

Sex-Influenced Traits

Genetically controlled traits that appear in both sexes but expressed differently (influenced by sex)
These are autosomal traits influenced by the sex.
The trait acts dominantly in one sex and recessively in the other.

Sex-Influenced Trait Examples

Pattern baldness (males)
Index finger length

Incomplete Dominance

Neither allele is dominant over the other.
Offspring show an intermediate phenotype of the two homozygous parents. This is a heterozygous phenotype.
Example: A pink flower from a red and a white flower.

Law of Incomplete Dominance

Principle where a cross between homozygous dominant and recessive alleles results in a heterozygous dominant and recessive trait progeny.
Both alleles exert an effect and produce an intermediate phenotype.

Co-Dominance

Both alleles in a heterozygous organism contribute to the phenotype.
Both alleles are independently and equally expressed.
Example: A red bull breeding with a white cow creates a roan-colored cow (a mix of red and white).

Law of Co-Dominance

Principle where cross between homozygous dominant genes result in a progeny/offspring featuring a heterozygous gene mix determining phenotypes where both dominant and recessive traits mix.

Autosomal Traits

Genes located on autosomes.
Autosomal traits and disorders are controlled by chromosomes.
Types include Autosomal Dominant and Autosomal Recessive.

Autosomal Dominant Trait Genotypes

AA and Aa result in the affected trait (Heterozygotes are affected).
aa results in no expression of the trait.

Autosomal Recessive Trait Genotypes

aa results in expressing the trait.
AA or Aa results in a lack of expression (either homozygous dominant or heterozygous). AA or Aa are carriers.

Sex-Linked Dominant Trait Genotypes

Heterozygous or homozygous dominant genotype will express trait.
Genotypes without the dominant trait. Male- X^AY, Female- X^AX^A or X^AX^a

Sex-Linked Recessive Trait Genotypes

X^aX^a for trait expression in females.
X^aY for trait expression in males.
Females X^AX^A or X^AX^a; Males- X^AY will not express the trait.

Pedigrees

Visual representation of inheritance patterns in a family.
Symbols represent males, females, affected individuals, unaffected individuals, and carriers.
Rules exist for constructing pedigrees linking parents to offspring and arranging vertically.

Punnett Squares

Diagrams used to predict the outcome of a cross or breeding experiment.
Used to determine probability of offspring genotypes.
Example: Predicts normal and hemophilia trait expressions based on genotypes and ratios.

Examples of Autosomal Dominant Disorders

Dwarfism
Polydactyly and syndactyly
Hypertension
Hereditary Edema

Examples of Autosomal Recessive Disorders

Congenital Deafness
Diabetes Mellitus
Sickle Cell Anemia
Albinism
Phenylketonuria (PKU)
Galactosemia
Cystic Fibrosis
Tay Sachs Disease

Examples of X-Linked Recessive Disorders

Red/Green Colorblindness
Hemophilia
Deafness
Night blindness
Duchenne Muscular Dystrophy

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Description

Test your knowledge on various patterns of inheritance in genetics. This quiz covers mitochondrial inheritance, sex-linked traits, and the implications of dominant and recessive alleles. Explore essential concepts essential for understanding genetic principles and their applications.