Unit 10_Meiosis and Genetics Fundamentals

Vocabulary flashcards covering the biological processes of meiosis, Mendelian inheritance laws, Non-Mendelian patterns, and human genetic traits as described in the lecture notes.

Meiosis

A type of cell division that creates gametes (sex cells) which contain half ($1n$) the number of chromosomes that the parent cell had.

Gamete

Sex cells, such as egg and sperm, produced at the end of meiosis.

Haploid ($1n$)

Cells containing a half set of chromosomes ($n=23$ in humans), such as sperm, eggs, or pollen.

Diploid ($2n$)

Cells containing a full set of chromosomes ($2n=46$ in humans), representing the starting state of cells before meiosis.

Genetic Variation

The result of each daughter cell in meiosis being genetically different from the others.

Crossing Over

A process during meiosis where chromosomes pair up and exchange segments of their genetic material, leading to genetic variation.

Zygote

The cell formed when a sperm and egg unite during fertilization.

Identical Twins

Individuals formed from one egg and one sperm that split into separate clumps before the cells differentiate, resulting in the same genetic makeup.

Fraternal Twins

Non-identical siblings born at the same time, formed from two separate eggs and two separate sperm.

Genetics

The study of heredity.

Heredity

The passing on of characteristics (traits) from parents to offspring through sexual reproduction.

Trait

A particular characteristic that can vary from one individual to another, such as hair color or eye color.

Genes

Sections of a chromosome that determine the trait that will be inherited.

Alleles

Different forms of one gene, such as brown, red, or blond hair color.

Dominant gene

A gene that is always expressed if the allele is present; represented by a capital letter (e.g., $B$).

Recessive gene

A gene that is only expressed if two alleles are present for that trait; represented by a lowercase letter (e.g., $b$).

Homozygous

An organism that has two identical alleles for a trait, such as $BB$ (dominant) or $bb$ (recessive).

Heterozygous

An organism that has two different alleles for a trait, such as $Bb$.

Genotype

The genetic makeup or combination of two alleles (e.g., $BB$, $Bb$, or $bb$).

Phenotype

The physical expression or characteristics of a trait, representing what is seen (e.g., brown eyes).

Gregor Mendel

An Austrian monk known as the Father of Genetics who studied inheritance through common pea plants.

Law of Segregation

Principle stating that during meiosis, the pairs of genes separate so that each gamete receives only one gene for each trait.

Law/Principal of Dominance

Principle stating that some alleles are dominant and others are recessive; recessive traits only show up if the dominant allele is not present.

Punnett Square

A diagram used to predict the probability of genotypes and phenotypes in the offspring of a particular cross.

Law of Independent Assortment

Principle stating that segregating pairs of alleles for different traits assort independently of each other during gamete formation.

Incomplete Dominance

A Non-Mendelian inheritance pattern where no traits are dominant, creating a blending effect when both alleles are present (e.g., pink flowers from red and white parents).

Co-Dominance

A Non-Mendelian inheritance pattern where two or more dominant alleles exist, and both traits are displayed at the same time when present (e.g., speckled black and white chickens).

Multiple Alleles

A condition where there are more than two types of alleles possible for a trait, such as human blood types ($A$, $B$, and $O$).

Universal Donor

Blood type $O$ Negative ($O-$), which can be received by all other blood types.

Autosomes

The first 22 pairs of chromosomes in humans that are the same for both males and females.

Sex Chromosomes

The 23rd pair of chromosomes ($XX$ for female and $XY$ for male) that determine the gender of an individual.

Carrier

A female who inherits one recessive and one dominant trait for a sex-linked condition; she carries the gene but does not express the trait.

Hemophilia

A sex-linked trait caused by a recessive allele on the $X$ chromosome that results in problems with blood clotting.

Pedigree

A diagram used to show phenotypically affected and unaffected individuals across generations, using squares for males and circles for females.