Cell Division (Mitosis)

BIOLOGY EXAM 2

Interphase

The cycle where a cell grows, replicates its DNA, and prepares for division.

*The cell is not dividing.

The four phases of the cell cycle

G1, S, G2, M.

G1

The cell recovers from previous division ,grows larger, and makes new proteins.

S phase

The cell duplicates its genome (DNA replication).

G2 Phase

Cell is confirming DNA is completely replicated and preparing for division.

Mitosis

The cell replicates its chromosomes and divides to produce two genetically identical daughter cells.

Telomere

-End of a linear chromosome

-Have repetitive DNA that protects chromosome from losing genetic material during replication.

-shortens after each replication.

Telomerase

The enzyme that lengthens and shortens the telomeres.

Pair of sister chromatids

Joined copies of the original chromosomes

Considered a single chromosome.

Chromosomes

Long thin fiber of chromatin (DNA) that has been condensed.

Centomere

Repetitive sequence in DNA where the sister chromatids are joined.

Chromatin

Loosely packed DNA.

Prophase

Chromosomes condense

Mitotic spindles develop from centrosomes.

Prometaphase

Nuclear membrane Breaks

Spindle fibers (microtubules) attach to the chromosomes via kinetichore proteins at the centromere

Metaphase

All chromosomes and their centromeres allign at the metaphase plate (dashed line).

Anaphase

Sister chromatids and daughter chromosomes move to opposite poles.

Telophase

Daughter nuclei reform

Spindles break down

Cytokenesis occurs and splits in to two daughter cells

Cytokensis

Division of the cytoplasm and its contents.

splits in to two daughter cells

Cytokenesis in plant cells

Vesicles from the golgi apparatus move to midline,

Fuse and deposit cell wall materials creating a cell plate.

Completely divides the wall.

Cytokenesis in Animal cells

Cleavage furrows of actin

Packaging DNA

Chromatins→Nucleosomes+Octomere Histones→Chromosomes

Histones

The histone octamer is made up of eight individual histone protein subunits, H3,H4, H2A, H2B.

wraps around DNA nucleosomes

Nucleosomes

the basic structural unit of a chromatin. Wraps together with histones to form a chromosome.

Diploid

two sets/copy of chromosomes

Haploid

One set/copy of a chromosome