Genetics: Heredity and Variation

• Genetics is the study of heredity and variation in organisms

Haploid

• A cell or organism with only one set of chromosomes is haploid
• Gamete cells are haploid
• Haploid cells contain half the number of chromosomes as a body cell

Diploid

• A cell or organism with two sets of chromosomes is diploid
• Body cells are diploid, possessing twice the haploid number of chromosomes

Inheritance

• Inheritance is the process where genetic material passes from parents to offspring

Dominant

• A dominant allele is always expressed in an organism's phenotype

Recessive

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

Heterozygous

• A heterozygous organism has two different alleles for a particular trait

Homozygous

• A homozygous organism has two identical alleles for a particular trait

Trait

• A trait is a distinguishing quality or characteristic that can be inherited

Allele

• An allele is an alternative form of a gene

Gene

• A gene is a segment of DNA on a chromosome that codes for a specific trait

Gregor Mendel

• Gregor Mendel is known as the father of genetics

Genotype

• Genotype refers to an organism's genetic makeup or allele combinations, representing the actual letter combinations

Phenotype

• Phenotype is an organism's physical appearance or visible traits

Punnett Square

• A Punnett square is a diagram used to predict the genotype and phenotype combinations in a genetic cross

X-Linked Trait

• An X-linked trait is determined by a gene carried on the X chromosome

Incomplete Dominance

• Incomplete dominance occurs when one allele is not completely dominant over another

Codominance

• Codominance is when both alleles for a gene are fully expressed

Pedigree

• A pedigree is a diagram that shows the occurrence of a genetic trait across multiple generations of a family

Karyotype

• A karyotype is a display of chromosome pairs of a cell, arranged by size and shape

Chromosome

• A chromosome is a threadlike structure of DNA and protein containing genetic information

Asexual Reproduction

• Asexual reproduction involves a single parent and produces offspring identical to that parent

Carrier

• A carrier is an individual with one recessive allele for a trait, but who does not express the trait

Inherited

• Inherited characteristics are passed from parent to offspring

Mutation

• A mutation is a change in a gene or chromosome

Offspring

• Offspring are the product of reproduction, a new organism produced by one or more parents

Sperm

• Sperm is the male sex cell

Egg

• An egg is the female sex cell

Fertilization

• Fertilization is the process in sexual reproduction where male and female reproductive cells join to form a new cell