what…..??????? repairs broken bones, burns, cuts, and scrapes? causes cancer? transforms us...
TRANSCRIPT
REPAIRS BROKEN BONES, BURNS, CUTS, AND SCRAPES?
CAUSES CANCER?TRANSFORMS US FROM 2 CELLS TO 20 BILLION?
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!
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
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
Chromatids are tightly coiled together
Nucleolus and nuclear membrane disintegrate
Spindle fibers begin to stretch across the cell
Pairs of chromosomes are separated
Each half of the chromatid is pulled to an opposite side of the cell
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
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