REPAIRS BROKEN BONES, BURNS, CUTS, AND SCRAPES?

CAUSES CANCER?TRANSFORMS US FROM 2 CELLS TO 20 BILLION?

Allows organisms, including you, to GROW

Replace old cellsIncreases the number of cells

Every day billions of red blood cells in your body are destroyed and need to be replaced --- HOW?

MITOSIS During the time it takes to read this sentence, 6

million new red blood cells were produced!

Individual cells follow the same life cycle

Cell Cycle: series of events that takes place from one cell division to the next

Not the same for all cellsExamples▪Bean Plants 19hours▪Animal Embryos 20 min

1. INTERPHASE2. MITOSIS

1. PROPHASE2. METAPHASE3. ANAPHASE4. TELOPHASE

Period of growth &development

Before a cell can divide, a copy of its hereditary material must be made So each new cell can receive a copy

Nucleus divides & cytoplasm separates

Mitosis: nucleus divides to form two identical nuclei

Steps1. Prophase2. Metaphse3. Anaphase4. Telophase

A Chromosome is a structure that contains the cell’s hereditary material (DNA)

Found inside the nucleus

When cells are ready to divide, each duplicated chromosome condenses into thick strands called chromatids

Chromatids: duplicated chromosomes formed during interphase that are thick and coiled together Needed for mitosis

Centromere

Chromatids are tightly coiled together

Nucleolus and nuclear membrane disintegrate

Spindle fibers begin to stretch across the cell

The chromatid pairs line up along the equator (or middle) of the cell

Pairs of chromosomes are separated

Each half of the chromatid is pulled to an opposite side of the cell

Spindles disappear

Chromosomes uncoil

New nucleus forms

Mitosis ends

After mitosis Cytoplasm

separatesCell membrane

moves inward and pinches off = TWO

separate cells

Cytokinesis

Division of the nucleusProduces two new nuclei that are identical to each other and the original cell

Each cell in your body has 46 chromosomes or 23 pairsEach new cell also has 46 chromosomes

Sexual reproduction requires two organisms

Asexual reproduction: a new organism is produced from one parent

Produces offspring that are identical to parent

Reproduce asexually

Produce horizontal stems called runners that create new strawberries

Bacteria CANNOT reproduce by mitosis

They are prokaryotic – NO Nucleus

Reproduce by fission Used by cells with no

nucleus to copy genetic information and divide

New organism grows from the body of the parent

When the bud is large enough it breaks away to live on its own

Some organisms can regrow damaged or lost body parts

Sea Stars

Cancer is the result of errors during mitosis

Normally healthy cells being reproducing out of control and can grow into structures called tumors