Beginner's Guide to Genetics

Genes

• Genes are the units of heredity.
• They make up the chromosomes.

Chromosomes

• Chromosomes are threadlike structures.
• Chromosomes are composed of DNA molecules that contain the genes.

Heredity

• Heredity is the passing of traits from parents to offspring.

Traits

• Traits are inherited characteristics.

Alleles

• Alleles are different forms of a gene.

Homologous Chromosomes

• Homologous chromosomes share the same gene sequence and structure.

Phenotype

• Phenotype refers to an organism's physical appearance or visible traits, such as red, tall, or round characteristics.

Genotype

• Genotype is the genetic makeup of an organism, such as RR, Rr, or rr.

Dominant Allele

• A dominant allele's trait always manifests in an organism when present.

Recessive Allele

• A recessive allele is masked when a dominant allele is present.

Homozygous

• Homozygous refers to an organism with two identical alleles for a trait, also known as a purebred (e.g., BB or bb).

Heterozygous

• Heterozygous refers to an organism with two different alleles for a trait, also known as a hybrid (e.g., Bb).

Punnett Squares

• Punnett Squares are charts showing all possible allele combinations in a genetic cross.

"BB" Genotype

• Represents Homozygous Dominant.

"Bb" Genotype

• Represents Heterozygous.

"bb" Genotype

• Represents Homozygous Recessive.

Acquired Traits

• Acquired traits are characteristics or behaviors that are not genetic or inherited.

Inherited Traits

• Inherited traits are passed from parents to their offspring.

Sexual Reproduction

• Sexual reproduction involves two parents combining genetic material.
• Results in offspring that differ from both parents, inheriting 50% of genetic material from each.

Asexual Reproduction

• Asexual reproduction involves one parent.
• Offspring are identical to the parent, inheriting 100% of genetic material from that single parent.

Body Cell

• A body cell has two sets of chromosomes, which are arranged in pairs.

Sex Cell

• Sex cells are gametes produced by meiosis.
• They contain half the number of chromosomes found in body cells.

Mutation

• Mutation is a change in a DNA sequence that affects genetic information.
• Mutations can have no effect, a small effect, or a major effect on an organism's traits.
• Mutations might change a trait or how the trait is expressed.