Genetics: Key Concepts in DNA, Meiosis, and Inheritance

Gene

A segment of DNA on a chromosome that codes for a specific trait or protein

Allele

Different forms of a gene (B b)

Phenotype

An organism's physical appearance, or visible traits.

A

dominant

a

recessive

Meiosis

-Cell division that produces reproductive cells in sexually reproducing organisms

-reproduction

Tetrad

structure containing 4 chromatids that forms during meiosis

Prophase I

The chromosomes condense, and the nuclear envelope breaks down. crossing-over occurs.

Metaphase I

Pairs of homologous chromosomes move to the equator of the cell.

Anaphase I

Homologous chrmosomes move to the oppisite poles of the cell.

Telophase I

Cytoplasm divides, 2 daughter cells are formed

Mitosis

-division of the nucleus

-4 daughter cells

-1/2 DNA of parents

-heals cuts

Independent assortment

Independent segregation of genes during the formation of gametes

Gametes

reproductive cells

Law of segregation

Mendel's 1st law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

Law of Independent Assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

Mutation

change in a DNA sequence that affects genetic information

Cell Partitioning

the division of a single cell into two or more smaller cells during cell division

Somatic cells

-Any cells in the body other than reproductive cells

-more errors (mutations)

Germline cells

cells that produce gametes

Mutation rate

the probability that a gene will mutate when a cell divides

Sperm

- More likely for errors to occur

Pleiotropy

The ability of a single gene to have multiple effects.

Morphological mutations

changes in visible appearance

Lethal Mutants

-Cause premature death of an organism. Usually in the early stages of life

-usually recessive

conditional mutants

a mutant whose phenotype depends on the environmental conditions, such as a temperature-sensitive mutant

Central Dogma

DNA-transcription-RNA-translation-protein

Recombination

the genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division

XX

Female

XY

male