Classical Genetics Flashcards

Questions and Answers

Who is the father of modern genetics?

Gregor Mendel

What should you know about page 119 regarding the basics of probability math?

know

Law of Dominance basically means that ____ alleles will always be masked by _ alleles (except for heterozygous).

recessive; dominant

Law of Segregation occurs during ___ Phase (meiosis).

Anaphase Signup and view all the answers

Law of Independent Assortment occurs during ___ Phase (meiosis).

Metaphase Signup and view all the answers

The law of segregation basically states that the homologs ____ during metaphase (meiosis).

separate Signup and view all the answers

What does Mendel's law of segregation state about homologous chromosomes?

separate; 1; gamete; 2; separate; meiosis Signup and view all the answers

What does the law of independent assortment state?

independently; random Signup and view all the answers

If the phenotype ratio of the offspring is 3 to 1, then both of the parents are ____ of the trait.

heterozygous Signup and view all the answers

If the phenotype ratio of the offspring is 1 to 1, then one of the parents is __ recessive and the other is _.

homozygous; heterozygous Signup and view all the answers

The law of independent assortment applies when a cross is carried out between 2 individuals that are ____ for 2 traits on separate chromosomes.

heterozygous Signup and view all the answers

What determines how alleles are inherited in the law of Independent Assortment?

arranged; 1 Signup and view all the answers

When would you use a dihybrid cross? - when you need to cross individuals that are hybrid for ___ different traits.

2 Signup and view all the answers

What is the phenotype ratio for a dihybrid cross?

9:3:3:1 Signup and view all the answers

In incomplete dominance, a red flower + a white flower = __ flower.

pink Signup and view all the answers

In codominance, a white cow + a red cow = ___ cow.

roan Signup and view all the answers

What is an example of codominance in humans?

blood types Signup and view all the answers

Multiple alleles is where there are more than allelic forms of a _.

2; gene Signup and view all the answers

How many different blood groups are there in humans?

4 Signup and view all the answers

What are the alleles that determine blood types?

3; A; B; O Signup and view all the answers

What are traits controlled by two or more genes called?

polygenic Signup and view all the answers

What are genes located on either sex chromosome called?

sex linked genes Signup and view all the answers

Why are males more vulnerable to diseases?

because males (XY) only need to get one x allele whereas females (XX) need to get 2 Signup and view all the answers

Females must inherit _ copies of sex-linked genes but males only need to inherit .

2; 1 Signup and view all the answers

If a female inherits 1 copy of the sex-linked genes, she will be called a _. If she inherits 2, then she will express the _.

carrier; phenotype Signup and view all the answers

In sex-linked inheritance, who passes the trait to his daughters only?

father Signup and view all the answers

Where does mitochondria come from?

mother Signup and view all the answers

What are common examples of recessive sex-linked traits?

color blindness; hemophilia Signup and view all the answers

What is hemophilia?

A hereditary disease where blood does not coagulate to stop bleeding Signup and view all the answers

What is true about all daughters of affected fathers?

carriers Signup and view all the answers

Can sons inherit a sex-linked trait from the father?

False Signup and view all the answers

What percentage chance does a son have of inheriting a sex-linked trait from a carrier mother?

50 Signup and view all the answers

There is a carrier state for X-linked traits in males.

False Signup and view all the answers

Can the environment alter the expression of genes?

True Signup and view all the answers

Study Notes

Classical Genetics Overview

Gregor Mendel is recognized as the father of modern genetics.
Probability math fundamentals are crucial for understanding genetic inheritance.

Key Genetic Laws

Law of Dominance: Recessive alleles are masked by dominant alleles, except in heterozygous situations.
Law of Segregation: Homologous chromosomes separate during Anaphase of meiosis, ensuring only one chromosome from each pair is present in each gamete.
Law of Independent Assortment: Genes independently separate during metaphase of meiosis, resulting in random combinations of traits.

Phenotype Ratios

A 3:1 phenotype ratio in offspring indicates that both parents are heterozygous for the trait.
A 1:1 phenotype ratio suggests one parent is homozygous recessive and the other is heterozygous.

Genetic Crosses and Ratios

Dihybrid crosses involve individuals that are hybrid for two different traits.
The phenotype ratio for a dihybrid cross is 9:3:3:1.

Inheritance Patterns

Incomplete dominance: Example where a red flower crossed with a white flower produces a pink flower.
Codominance: Example is a white cow crossed with a red cow resulting in a roan cow; also applies to human blood types.
Multiple alleles refer to more than two allelic forms for a gene, like blood type (A, B, AB, O).
In humans, four different blood groups are dictated by three alleles: A, B, and O.

Genetic Traits and Sex Linkage

Polygenic traits are controlled by two or more genes.
Sex-linked genes are located on sex chromosomes, and males are more vulnerable to related diseases due to inheriting only one X chromosome.
Females need two copies of a sex-linked gene to express the trait, while males only need one.
Fathers transmit sex-linked traits to their daughters but not their sons, since sons inherit the Y chromosome.

Mitochondrial Inheritance

Mitochondria are inherited maternally.

Common Sex-linked Disorders

Color blindness and hemophilia are examples of recessive sex-linked disorders.
Hemophilia is a hereditary condition that impairs blood coagulation, leading to excessive bleeding.
All daughters of affected fathers will be carriers of the trait, while sons cannot inherit the trait from their fathers. The chance of a son inheriting a trait from a carrier mother is 50%.

Miscellaneous

There is no carrier state for X-linked traits in males; they either express the trait or they do not.
Environmental factors can potentially alter gene expression, demonstrating the interaction between genetics and surroundings.

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Test your knowledge of classical genetics with these flashcards. Cover key concepts such as Gregor Mendel, laws of dominance and segregation, and probabilities in genetics. Ideal for students looking to reinforce their understanding of foundational genetics principles.