Exam #2 - Section 7 Patterns of Inheritence

What are alleles?

Different versions of a gene that occupy the same locus on homologous chromosomes.

How are alleles related to mutations?

Mutations create new alleles, which can lead to variation in traits.

How can different alleles impact protein function and traits?

Some alter the structure or function of a protein, leading to changes in phenotype.

What are Mendel’s Principles of Genetics?

The Principle of Segregation and the Principle of Independent Assortment.

What does Mendel’s Principle of Segregation state?

Each individual has two alleles for each gene, and these alleles separate during gamete formation so each gamete receives one allele.

What does Mendel’s Principle of Independent Assortment state?

Alleles for different traits are distributed to gametes independently of each other.

How do Mendel’s Principles relate to meiosis?

Segregation occurs when homologous chromosomes separate in meiosis I; independent assortment occurs when chromosomes align randomly.

What experiments did Mendel conduct?

He crossed pea plants with contrasting traits and analyzed patterns in offspring over multiple generations.

What did Mendel’s experiments reveal?

Traits are inherited as discrete units (genes) rather than blending together.

What is a dominant allele?

An allele that is expressed even if only one copy is present (masks the recessive allele).

What is a recessive allele?

An allele expressed only when both copies are present.

What does homozygous mean?

Having two identical alleles for a trait (AA or aa).

What does heterozygous mean?

Having two different alleles for a trait (Aa).

What is genotype?

The genetic makeup of an organism for a particular trait.

What is phenotype?

The observable physical or biochemical characteristics of an organism.

How can Punnett squares be used?

To predict the genotypes and phenotypes of offspring from parental crosses.

What is a monohybrid cross?

A cross that examines the inheritance of one trait.

How do you interpret Punnett squares for multiple traits?

Use a dihybrid cross to predict combinations of alleles for two genes using independent assortment.

What is incomplete dominance?

A pattern where the heterozygous phenotype is intermediate between the two homozygous phenotypes (e.g., red + white = pink).

What is codominance?

A pattern where both alleles are fully expressed in the phenotype (e.g., AB blood type).

What are multiple alleles?

When more than two possible alleles exist for a gene (e.g., ABO blood group).

What are polygenic traits?

Traits influenced by multiple genes (e.g., skin color, height).

How can environmental factors influence traits?

Conditions like temperature, diet, or sunlight can affect gene expression and phenotype.

What is gene linkage?

The tendency of genes located close together on the same chromosome to be inherited together.

What is nondisjunction?

An error in meiosis when chromosomes fail to separate properly, leading to abnormal chromosome numbers in gametes.

How does nondisjunction affect offspring?

It can cause conditions such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X).

How can Punnett squares be used for non-Mendelian genetics?

To predict incomplete dominance, codominance, and X-linked inheritance patterns in offspring.

What are X-linked traits?

Traits controlled by genes on the X chromosome, often showing different patterns in males and females.