Biology 101 Lab 9: Cell Division

Gene

-Specific nucleotide sequence of DNA and codes everything a polypeptide

Genome

-Complete set of an organisms genes

Mitosis

-Results in two daughter cells that are identical to the parent cells

Somatic Cells

-Body Cells

-Used by mitosis

Meiosis

-Occurs in germ cells and results in gametes (sex cell) which are four daughter cells that are unique from the parent cells

Meiosis

-Chromosome number is divided in half

-Reduces the chromosome number to 46 to 23

Homologous Chromosomes

-A pair of chromosomes with similar length, and genes in similar locations

-One inherited from the father and one inherited from the mother

Sister chromatids

-Two copies of a duplicated chromosome; therefore they are identical

-Only found when a cell is preparing to divide

Centromere

Region where two sister chromatids “connect”

Haploid

• (n)

• A cell containing one set of chromosomes

Diploid

• 2n

• A cell containing two sets of chromosomes, one set inherit from each parent

Interphase

-Cell actively prepares for the next stage by growing, acquiring nutrients, and replicating DNA

-Three stages: G1, S, G2

G1 Phase

-Cell acquires energy from its environment along with molecules needed to build additional DNA and Proteins

S Phase

-Duplication of the chromosomes by the cell

-Then each chromosome is now made up of two sister chromatid

G2 Phase

-Cell replenishing energy and protein stores

Prophase

-Chromosomes condense

-Nuclear envelope breaks down

-Spindle begins to form

Prometaphase

-Chromosomes continue to condense and are more visible

-Kinetochores appear at the centromere, and kinetochore microtubules attach

-Centrosomes continue to more towards opposite poles

Metaphase

-Sister chromatids line up at metaphase plate

Anaphase

-Chromosomes (sister chromatids) are pulled to opposite plates

Telophase

-Chromosomes reach opposite poles

-Chromosomes decondense

-Nuclear envelope assembles around chromosomes

-Spindle Breaks down

Cytokinesis

-Division of the cytoplasm occurs

Cleavage Furrow

-In animal cells

-A rip before it is split into two cells

Cell Plate

-In plate cells

-Forms between the two daughter cells to separate them.

Meiosis

-Cellular division that produces gametes and reduces the chromosome number by half

-Diploid cells divide to produce haploid cells

Anaphase I

-Separates homologous chromosomes

Anaphase II

-Separates sister chromatids

Synapsis

-Occurs in Prophase I

-A pair of homologous chromosomes are zipped together

Crossing Over

-Occurs in Prophase I

-Genetic material is swapped between the two chromosomes at a point where they cross called the chiasma

Recombinants

-New sets of homologous chromosomes after synapsis and crossing over

Independent Assortment

-Event that increases genetic variation during meiosis.

-Occurs during Metaphase I, homologous chromosomes align at the metaphase plate independently of one another