Objectives1) Name three parts of the cell cycle. 2) Name four major parts of mitosis.3) Identify important parts of a dividing cell.4) Discuss important similarities and

differences between mitosis and meiosis.

The cell cycle has three major parts:

1. Interphase

2. Mitosis (Karyokinesis)

(Mitosis has four major sub-parts)

1) Prophase

2) Metaphase

3) Anaphase

4) Telophase

3. Cytokinesis

InterphaseCharacterized by:1. Intact nuclear envelope2. Visible nucleolus3. Although you can’t tell it,

the cell’s DNA and other cell components are undergoing a process called replication (duplication process); chromosomes become double-stranded.

4. Three sub-phases: G1, S, and G2

Nuclear envelope

Nucleolus

ProphaseCharacterized by:1. Disappearing nuclear envelope

and nucleolus2. Chromosomes (46* in each

human cell) coil and condense

3. Spindle fibers (microtubules)form and chromosomes become attached by way of centromeres

4. Newly formed centrioles move to opposite ends of the cell

Condensed chromosomes(chromatin fibers)

*23 pairs of chromosomes

Mitosis = Karyokinesis

Metaphase Characterized by:

1. Chromosomes align across the “equator” or metaphase plate

2. Centrioles stop at oppositeends of the cell

3. Spindle apparatus is fully formed

Metaphase plateCentrioles

CentriolesSpindle

apparatus

Mitosis = Karyokinesis

AnaphaseCharacterized by:1. Spindle fibers (microtubules)

shorten and separate the chromosomes at the metaphase plate

2. In the human cell, 46 single-stranded chromosomes movein opposite directions toward each pole

Centrioles Centrioles

Shortening microtubules(spindle fibers)

Mitosis = Karyokinesis

Can you name structures in the dividing cell?

single-stranded chromosome centromere

centrioles

spindle fiber (microtubule)

TelophaseCharacterized by:1. Cleavage furrow forms2. Nuclear envelopes begin to

form around two daughter nuclei

3. Chromosomes decondense4. Spindle disappears

cleavage furrow

daughter nuclei

Mitosis = Karyokinesis

Cytokinesis (Division of cytoplasm and contents into two cells)

This figure represents an overview of the cell cycle.

This figure represents an overview of meiosis (human male)

This figure represents an overview of meiosis (human female)

MITOSIS MEIOSIS

All chromosomes align at metaphase plate

Homologous pairs of chromosomes align

One set of divisions:

P – M – A – T

Two sets of divisions:

PI - MI – AI – TI

PII – MII – AII – TII

2 daughter cells 4 daughter cells (male)

1 cell and polar bodies (female)

daughter cells diploid (2n; same as original cell)

daughter cells haploid (n; half chromosomes as original cell)

Growth and repair Formation of sex cells

Similarities and Differences