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 PreparationCell increases in sizeMakes the proteins and

molecules needed for the cell to function

Interphase

S- ReplicationDNA 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,