Genetics: Heredity, Traits, and Reproduction

• Genetics studies how traits pass from parents to offspring across generations.
• Heredity refers to traits passing from parent to offspring.
• Traits are distinguishing characteristics common to all members of a species.
• Variations are different forms of the same trait.

Gametes & Asexual Reproduction

• Gametes are male or female reproductive cells.
• Four basic types of asexual reproduction: propagation, spore formation, budding, and fission.
• Genes are small DNA segments carrying hereditary information.
• Chromosomes consist of long strands of genetic material containing genes.

Alleles, Genotypes & Phenotypes

• An allele is a different form of a single gene.
• Genotype refers to an organism's combination of dominant or recessive alleles for a trait.
• Phenotype refers to the observable trait (physical).
• Heterozygous means having different alleles from each parent.
• Homozygous means having the same alleles from each parent.
• A hybrid is offspring from cross-fertilization.
• Self-fertilization occurs when male and female gametes from the same plant reproduce.
• Dominance describes the relationship where one version of a gene (or allele) determines a trait.
• A dominant allele masks the effect of the recessive allele.
• Recessive describes a trait that is only expressed when an individual inherits two copies of the same recessive allele for a gene (one from each parent).
• Incomplete dominance occurs when a blend of parents' traits occurs because the traits have equal dominance.
• Punnett Squares are diagrams to visually represent the possible genotypes of offspring from a cross between two parents.

Genetic Code

• The genetic code provides instructions that translate genetic information.
• Mutagens are physical or chemical agents that cause mutations.
• Mutation is a change in the sequence of one or more nucleotides in a DNA molecule.
• mRNA copies the DNA code, detaches, and carries the message to the ribosomes.
• tRNA receives the coded message and gathers materials.

Mitosis and Meiosis

• Mitosis allows a body cell to reproduce by dividing into two identical daughter cells and is vital for growth and repair.
• Meiosis is a type of cell division (reproduction) that creates reproductive cells, or gametes.
• Somatic cells are body cells, each containing the full number of chromosomes.
• Cytokinesis is the final stage of cell division, with 2 identical daughter cells formed.

Genome

• A Genome is the total genetic material of an organism
• Codominant alleles are alleles expressed jointly.
• Neither is recessive nor dominant: seen commonly in blood type, where A and B are equal, creating a new blood type: AB.
• Sex-linked traits are traits carried on the X chromosome; gender is determined by the father.

Genetic Engineering

• Genetic engineering is the process to transfer genes (or parts of DNA) from one organism to another.
• Inbreeding is the mating of closely related organisms.
• Selective breeding intentionally crosses plants or animals with desired traits to produce offspring with those traits.
• Cloning creates identical cells with identical DNA and the clone has genetically identical cells to the "parent" cell with recombinant DNA.
• A genetically modified organism is a living thing whose DNA has been altered by the addition or deletion of genes.

Human Genome Project

• The Human Genome Project involved scientists in 6 countries who worked together to identify and map the 21,000 genes in the human body.
• The intended goal was to cure and prevent many diseases.
• The findings included the human genome is made up of 3 billion base pairs.
• Humans are 99.9% similar, it shared DNA.
• Humans have 20,000 - 25,000 genes.