Meiosis and Mitosis

Chromosome

Histones

protein molecules around which DNA is tightly coiled in chromatin

Chromatin

Lose clusters of DNA

Centromere

Area where the chromatids of a chromosome are attached

Chromatids

one of two identical "sister" parts of a duplicated chromosome

Haploid

n

Diploid

2n

Autosomes

Non-sex chromosomes

Homologous chromosomes

Pair of chromosomes that are the same size and same genes.

Spindle fiber

help pull apart the cell during mitosis and meiosis

Centriole

What does DNA wind itself around?

Histones (protein)

What phase does a cell spend most of its time in?

Interphase (90-95%)

Gap 1

The first part of interphase: the cell grows and functions takes place

Synthesis

DNA replication

Gap 2

additional growth and normal functions

Parts of interphase

G1 --> S --> G2 --> Mitosis/Meiosis

How do you count chromosomes?

by centromeres

Mitosis

Cell division where a parent cell divides into two identical daughter cells

Mitosis function

Growth and repair

Meiosis

Cell division that produces four daughter reproductive cells each with half the of chromosomes as the parent cells

Meiosis function

sexual reproduction

Crossover

Exchange of genetic information between a homologous pair

Nondisjunction

Error in meiosis in which homologous chromosomes fail to separate causing to many or too few chromosomes in daughter cells

What causes down syndrome?

an extra chromosome 21

law of independent assortment

Each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random

Prophase (mitosis)

chromosomes condense and spindle fibers begins to form

Metaphase (mitosis)

Chromosomes line up in the middle of the cell (m for middle)

Anaphase (mitosis)

sister chromatids are pulled apart (A for away)

Telophase (Mitosis)

Separation the duplicated genetic material into two identical daughter cells. Nucleus reforms and chromosomes de-condense forming chromatin

Cytokenisis (Mitosis)

division of the cytoplasm

Prophase 1

Chromosomes condense and spindle fibres begins to form; chromosomes find their homologous pairs and crossing over occurs!!

Metaphase 1

Paired homologous chromosomes line up randomly across the middle of the cell

Anaphase 1

Homologous chromosome pairs separate

Telophase 1

Cytoplasm divides, 2 daughter cells are formed

Prophase 2

Chromosomes condense and spindles form in each new cell. (No crossover or homologous pairs)

Metaphase 2

Centromeres of chromosomes line up at the middle of each cell

Anaphase 2

sister chromatids separate

Telophase