Genetics: Independent Assortment and Inheritance

These flashcards cover key concepts from the lecture on genetics, focusing on independent assortment, the principles of inheritance, and the various patterns of genetic dominance.

Principal of Independent Assortment

Alleles of different genes do not stay together when gametes form.

Independent alleles

Can pass any combination of alleles to offspring.

Dependent alleles

Violates independent assortment; variations of a gene that are not inherited independently.

Chromosome alignment

Random alignment of chromosomes during gamete formation allows for independent assortment.

Hypothesis of independent assortment

Alleles for different traits segregate independently during gamete formation.

Mendelian genetics

The study of the inheritance of traits based on Mendel's laws.

Principal of Dominance

Heterozygotes will express only the dominant trait.

Principal of Segregation

Copies of a gene separate into different cells during meiosis.

Autosomal gene

A gene located on any chromosome other than the sex chromosomes.

Incomplete dominance

A pattern of inheritance where heterozygotes express a blend of two homozygous phenotypes.

Gene dosing effect

The effect of different quantities of genes producing varying phenotypes.

Codominance

Heterozygotes express both phenotypes of homozygous individuals.

Example of Codominance

Human blood type AB expresses both A and B antigens.

Principal of independence

Genes affecting different traits are passed down independently of each other.

Mitosis

Cell division that results in two identical daughter cells.

Gamete formation

The process by which gametes are produced during meiosis.

Heterozygous

Having two different alleles for a specific gene (e.g., Bb).

Homozygous

Having two identical alleles for a specific gene (e.g., RR or rr).

Genetic variation

Differences in DNA sequences among individuals.

Linked genes

Genes that are located close to each other on the same chromosome and tend to be inherited together.

Segregation

The separation of alleles during gamete formation.

Phenotype

The observable characteristics or traits of an organism.

Genotype

The genetic makeup of an organism, typically represented by alleles.

Meiosis

The process of cell division that produces gametes with half the number of chromosomes.

Functional proteins

Proteins that perform a specified function in a biological context.

Alleles

Different forms of a gene that can exist at a specific locus.

Antigens

Substances that trigger an immune response, can be present on red blood cells.

Dominant allele

An allele that masks the effect of a recessive allele when present.

Recessive allele

An allele that does not mask the effect of a dominant allele.

Principal of Dominance

Heterozygotes will express only the dominant trait. This means that if an individual possesses one dominant allele and one recessive allele for a gene, only the phenotype associated with the dominant allele will be observable.

Principal of Segregation

During gamete formation (meiosis), the two copies of a gene (alleles) separate from each other so that each gamete receives only one copy. This process, often referred to as segregation, ensures that offspring inherit one allele from each parent.

Principal of Independent Assortment

Alleles of different genes do not stay together when gametes form; instead, they segregate independently of each other. This principle (also known as the hypothesis of independent assortment or principal of independence) is possible due to the random alignment of chromosomes during gamete formation, allowing for any combination of alleles to be passed to offspring.

Alleles: Dominant and Recessive

Alleles are different forms of a gene that can exist at a specific locus.

• Dominant allele: An allele that masks the effect of a recessive allele when present in a heterozygous individual.
• Recessive allele: An allele that does not mask the effect of a dominant allele and only expresses its phenotype when two copies are present (homozygous recessive).

Independent vs. Dependent Alleles & Linked Genes

• Independent alleles: Refer to variations of a gene that are inherited independently, meaning they can pass any combination of alleles to offspring, consistent with the Principal of Independent Assortment.
• Dependent alleles: Variations of a gene that are not inherited independently, often because they are part of Linked genes.
• Linked genes: Genes that are located close to each other on the same chromosome and tend to be inherited together, violating the principle of independent assortment.

Mendelian Genetics

The study of the inheritance of traits based on Mendel's laws, which include the principles of dominance, segregation, and independent assortment.

Autosomal Gene

A gene located on any chromosome other than the sex chromosomes (X or Y).

Incomplete Dominance

A pattern of inheritance where heterozygotes express a blend or intermediate phenotype between the two homozygous phenotypes. This often demonstrates a gene dosing effect, where different quantities of genes producing varying phenotypes are observed.

Codominance

A pattern of inheritance where heterozygotes express both phenotypes of homozygous individuals simultaneously and distinctly, without blending.

• Example of Codominance: Human blood type AB, where both A and B antigens are expressed on the red blood cells. Antigens are substances that trigger an immune response and can be present on red blood cells.

Heterozygous and Homozygous

• Heterozygous: Having two different alleles for a specific gene (e.g., Bb).
• Homozygous: Having two identical alleles for a specific gene (e.g., RR or rr).

Genotype and Phenotype

• Genotype: The genetic makeup of an organism, typically represented by the specific combination of alleles (e.g., BB, Bb, bb).
• Phenotype: The observable characteristics or traits of an organism, which result from the interaction of its genotype and the environment.

Genetic Variation

Differences in DNA sequences among individuals within a population, which contribute to the diversity of traits.

Cell Division for Reproduction: Meiosis and Gamete Formation

• Meiosis: The process of cell division that produces gametes (sex cells) with half the number of chromosomes (haploid).
• Gamete formation: The specific process by which these reproductive cells (sperm and egg) are produced during meiosis.

Mitosis

Cell division that results in two genetically identical daughter cells, maintaining the same number of chromosomes as the parent cell.

Functional Proteins

Proteins