Activity Complete 5-1A: From One Cell to Many

Cells

Cell Cycle Divided into three stages

Interphase Mitosis Cytokinesis

Interphase Longest stage of the cell cycle Carries out its functions

Example: stomach cells are making enzymes needed to digest food

3 phases1. G1 -Growth and Preparation2. S- Replication3. G2-Continued Growth and

Preparation

Interphase G1 – Growth and Preparation

Cell increases in sizeMakes the proteins and

molecules needed for the cell to function

Interphase S- Replication

DNA copies itselfCell temporarily has two sets

of DNATo replicate itself the DNA

molecule unwinds and the steps of the ladder break apart.

Interphase G2-Continued Growth and

PreparationCell continues to grow and

prepare for mitosis.DNA is in a loosely coiled formOrganelles such as

mitochondria and chloroplasts will be duplicated

Mitosis Second Stage of the cell cycle Usually the shortest stage Process when the contents of a cell’s

nucleus divide. Division results in two daughter cells

identical to the parent cell.

Mitosis Early Prophase

Chromosomes pair up into X shaped structures. Protein fibers known as spindle fibers begin to form.

Mitosis Late Prophase

Protein fibers complete forming Attach to the chromosomes at a point called

the centromere Nuclear membrane breaks down

Mitosis Metaphase

Chromosomes are pulled to the middle (equator) of the cell.

Mitosis Anaphase

Protein fibers contract and pull the chromatids to opposite poles of the cell.

Mitosis Telophase

One complete set of chromosomes is now at each pole of the cell

Nuclear membrane forms around each set of chromosomes.

Now there are two nuclei in one cell

Cytokinesis Final stage of the cell cycle Cell membrane pinches together to

divide the cell’s cytoplasm and organelles.

Checkpoints Checkpoints in the cell cycle monitor cell

activities and instructs the cell whether or not to divide.

Cells will not divide if: There are not enough nutrients to support cell

growth. DNA within the nucleus has not been

replicated DNA is damaged.

Cell Cycle and Cancer If a mutation occurs in a gene producing

the instructions for a checkpoint protein, cell cycle control will be lost.

A damaged cell may divide uncontrollably which is called cancer.

Cancer cells also have large, abnormal nuclei

Check Your Understanding Complete questions p. 151

#1, 2, 4, 6, 8, 9, 11

Asexual Reproduction Only one parent is required to produce

offspring. Offspring look identical to the parent

Can you name some organisms which reproduce through asexual reproduction?

• Bread Mould• Trees• Potatoes• Tulip bulbs

Types of Asexual Reproduction

Binary Fission A single parent cell reproduces itself

and divides into two equal parts Example: Amoeba and Bacteria

E Coli Bacteria

Types of Asexual Reproduction

Budding Occurs when part of the

cell pushes outward to form a growth or bud.

Pinches off from the parent cell to form a new organism identical to the parent. Example: yeast, hydra,

sponges

Types of Asexual Reproduction

Fragmentation Some animals can reproduce

asexually from fragmentsExample: Starfish, Japanese

Knotweed

Types of Asexual Reproduction

Vegetative Reproduction Occurs when special cells, usually in

the stems and roots divide repeatedly to form structures that will develop into a new plant.

Types of Asexual Reproduction

Spore Formation A spore is a reproductive cell

that grows into a new individual by mitosis. Ex: Bread Mould

Spores are lightweight and rely on wind and water to carry the spores away from the parent. Why is it important to carry the

spores away from the parent?

Asexual ReproductionAdvantages Disadvantages

p. 161

Checkpoint Complete questions p. 165

# 1, 3, 4, 7, 9, 11, 13 P. 166-167

#3, 4, 5, 6, 10, 15, 16, 17,19,