Cell Growth, Division, and

Reproduction

Human Development: Mitosis and Meiosis

Division of the Cell

Before a cell grows too large, it divides into two new “daughter” cells in a

process called cell division. Cell division reduces cell volume. It also results

in an increased ratio of surface area to volume, for each daughter cell.

Asexual Reproduction

Asexual reproduction is

reproduction that involves

a single parent producing

an offspring. The offspring

produced are, in most

cases, genetically identical

to the single cell that

produced them.

Sexual Reproduction

In sexual reproduction,

offspring are produced by the

fusion of two sex cells – one

from each of two parents.

These fuse into a single cell

before the offspring can

grow.The offspring produced

inherit some genetic

information from both

parents.

The Process

of Cell Division

Terms to Know

1. Cell Cycle

2. G1 Phase

3. S Phase

4. G2 Phase

5. M Phase

6. Mitosis

7. Cytokinesis

8. Prophase

9. Metaphase

10.Anaphase

11.Telophase

12.Chromatids

13.Centrioles

14.Cytokinesis

Chromosomes –

structures in the

nucleus that contain

genetic material.

Prokaryotic Chromosomes

• Prokaryotic cells lack nuclei. Instead, their DNA molecules are found in the

cytoplasm.

• Most prokaryotes contain a single, circular DNA molecule, or chromosome,

that contains most of the cell’s genetic information.

Eukaryotic Chromosomes

In eukaryotic cells, chromosomes are located in the nucleus, and are made up

of chromatin. Chromatin is composed of DNA and histone proteins.

The nucleosomes interact with one another to form coils

and supercoils that make up chromosomes.

Level of organization from big to small

Chromosomes Nucleosomes Histones DNA

The Prokaryotic Cell Cycle

• Most prokaryotic cells begin to replicate, or copy, their DNA once they have grown to a certain size.

• When DNA replication is complete, the cells divide through a process known as binary fission.

• Binary fission is a form of asexual reproduction during which two genetically identical cells are produced.

The Eukaryotic Cell Cycle

The Eukaryotic Cell Cycle

The eukaryotic cell cycle consists

of four phases: G1, S, G2,

and M.

Interphase – is a period of growth

that includes G1, S, and G2

phases.

M phase or Mitosis - is cell

division.

G1 Phase: Cell Growth

In the G1 phase, cells

increase in size

and synthesize

new proteins and

organelles.

S Phase: DNA Replication

In the S (or synthesis) phase,

new DNA is synthesized

when the chromosomes are

replicated.

G2 Phase: Preparing for Cell Division

In the G2 phase, many of the

organelles and molecules

required for cell division are

produced.

M Phase: Cell Division

In eukaryotes, cell division

occurs in two stages:

mitosis and cytokinesis.

Mitosis is the division of the

cell nucleus.

Cytokinesis is the division of

the cytoplasm.

Mitosis

Mitosis – Prophase

Mitosis – Metaphase

Mitosis – Anaphase

Mitosis – Telophase

Important Cell Structures Involved in Mitosis

• Chromatid – each strand of a duplicated chromosome

• Centromere – the area where each pair of chromatids is joined

• Centrioles – tiny structures located in the cytoplasm of animal cells that help

organize the spindle

• Spindle – a fanlike microtubule structure that helps separate the chromatids

Prophase

• During prophase, the first

phase of mitosis, the

duplicated chromosome

condenses.

• The centrioles move to

opposite sides.

• The spindle forms and DNA

attaches at a point called the

centromere.

• The nuclear envelope breaks

down.

Metaphase

• During metaphase, the

second phase of mitosis, the

centromeres of the

duplicated chromosomes

line up across the center of

the cell.

• The spindle fibers connect

the centromere of each

chromosome to the two

poles of the spindle.

Anaphase

• During anaphase, the third

phase of mitosis, the

centromeres are pulled apart

and the chromatids separate

to become individual

chromosomes.

Metaphase Anaphase

Telophase

• During telophase, the fourth

and final phase of mitosis, the

chromosomes spread out.

• A nuclear envelope re-forms.

• Cytokinesis completes the

process of cell division – it

splits one cell into two.

The Stages of the Cell Cycle

Cell Specilization

• The process by which

cells become specialized

is known as

differentiation.

• Stem cells are

unspecialized cells from

which differentiated cells

develop.

• There are two types of

stem cells: embryonic and

adult stem cells.

Video on cell processes

Crash Course on Mitosis:

http://youtu.be/L0k-enzoeOM

3D Animation of Mitosis:

http://youtu.be/JcZQkmooyPk