Genetics Bio

DNA

the molecule that stores and carried genetic information in cells.

Gene

A section of DNA that carries information for a biological function, which may be used to make a protein

Chromosome

A long DNA molecule packaged with proteins that contains genes. DNA →contains genes → DNA+proteins → chromosome

Chromatid

one copy of a chromosome. Before replication: 1 chromosome = 1 chromatid. After replication: 1 chromosome = 2 sister chromatids.

Centromere

Region that connects diste chromatids and where the kinetochore forms for spindle attachment during cell division

G1 Phase

cell grows and prepares for DNA replication

S Phase

DNA replication occurs, producing 2 sister chromatids for each chromosome

G2 Phase

Cell prepares for mitosis and checks that DNA replication has no errors

Mitosis

A cell separates its duplicated chromosomes into 2 nuclei

cytokinesis

divided the cytoplasm to form two separate daughter cells

Checkpoints in cell cycle

Control points in the cell cycle that detect problems and can pause cell division until corrected (G1,G2, Spindle)

Order to mitosis

G1,S,G2,Mitosis, cytokinesis

Process of mitosis

Prophase → Prometaphase → Metaphase → anaphase → telophase

Prophase (mitosis)

Chromosomes condense and become visible. The multicellular spindle begins forming and centrosomes move apart.

Prometaphase (mitosis)

The nucleus envelope breaks down, and spindle fibers attach to the kinetochores on the chromosomes.

Metaphase

Chromosomes line up in the middle of the cell at the metaphase plate. Sister chromatids remain attached.

Anaphase

Sister chromatids separate and move towards opposite sides of the cell. Once separated, each chromatid is considered a chromosome.

Telophase

Chromosomes reach opposite ends, new nuclear envelopes form, and the chromosomes begin to uncoil

to remember mitosis

pack, attach, middle, apart, two, divide

Mitosis vs. Meiosis

Mitosis makes identical body cells. Meiosis makes genetically different sex cells (gamete). Mitosis has 1 division to end up with 2 identical diploid cells and Meiosis has 2 divisions to end up with 4 genetically different haploid cells

Homologous chromosomes

matching chromosome pairs that carry the same genes at the same loci but can have different alleles. (dad chromosome + mom = homologous pair)

Diploid (2n)

A cell that contains two complete sets of chromosomes , one from mom and one from dad

Haploid (n)

a cell that contains one complete sets of chromosomes, half the chromosome number of a diploid cell. Sperm and egg cells are haploids

Incomplete dominance

A pattern of inheritance in which neither allele is dominant, resulting in a heterozygous offspring with blended phenotype. Ex: Red x White → Pink

Co-dominance

A pattern of inheritance in which both alleles are fully and equally expressed in the heterozygous offspring. Ex: Type AB blood

Epistasis

A pattern of inheritance in which one gene masks or modifies the expression of another gene at a different location. Ex: a gene prevents a labrador from getting black or brown fur.

Allele

a different version of a gene

Ex: white flowers vs. red (Rvs.r)

Homologous chromosomes

matching pair. one chromosome inherited from each parent

Sister chromatids

replicated copies. They usually carry identical DNA before recombination and contain the same alleles