Post on 30-Dec-2015
description
Chromosomes
Contain genetic information – DNA
DNA is arranged in segments called genes Determine
characteristics, or traits Humans have 46
chromosomes in their cells – 23 from each parent
Chromosomes
Sister chromatids: Each half of the X, contains identical copies of DNA
Centromere: at the center of the chromosome where the sister chromatids attach
The Cell Cycle
Cells reproduce by growing and dividing
WHY?? Cell division
prevents the cell from becoming too large
To replace other cells
For asexual reproduction
To allow multicellular organisms to grow
3 Main Stages:
InterphaseMitosis
Cytokinesis
Interphase
G1: The cell is growing, carrying out normal cell functions, and preparing to replicate DNA. Occurs immediately after the cell divides.
S: The cell copies its DNA in preparation for cell division.
G2: The cell prepares for the division of its nucleus.
Mitosis Process that
divides the nucleus of one cell into two nuclei
Purpose is to create two daughter cells with identical genetic information
Each daughter cell receives the exact same # and type of chromosomes, it’s like photocopying the cell!
Prophase
Beginning phase, the longest phase
Chromatin tightens, or coils, into chromosomes
In this phase the chromosomes are shaped like an X
Nuclear envelope disappears
Centrioles migrate to poles
Spindle fibers form
Metaphase
Changing phase, one of the shortest stages
Chromosomes are pulled to center of cell and lined up
Ensures there are accurate copies of the chromosomes
Anaphase
Anew phase The spindle
fibers pull the sister chromatids apart into two identical chromosomes
The chromosomes are pulled to opposite ends of the cell
Telophase
Ending phase Chromosome
s reach the poles of the cell and begin to unwind
Two new nuclear membranes begin to form
Nuclei reappear
Cytokinesis
Towards the end of mitosis, the cell undergoes cytokinesis
This divides the cytoplasm
The cytoplasm is pinched (the furrow)
Creates two new cells
The Cell Cycle
Cell Cycle Regulation
The cell cycle has built-in checkpoints that monitor the cycle and can stop it if something goes wrong.
Abnormal Cell Cycle
CANCER: the uncontrolled growth and division of cells
Cancer cell can kill an organism by crowding out normal cells, resulting in the loss of tissue function
Cancer
THE CANCER CELL CYCLE IS MUCH FASTER THAN THE NORMAL CELL CYCLE:
Interphase: 120 minutes
Prophase: 60 minutes Metaphase: 10
minutes Anaphase: 3 minutes Telophase: 12 minutes
CHICKEN STOMACH CELLS
Interphase: 16 minutes
Prophase: 15 minutes Metaphase: 2 minutes Anaphase: 1 minute Telophase: 3 minutes
Causes
The changes that occur in the regulation of cell growth and division of cancer cells are due to mutations.
Inherited Carcinogen
s Radiation
Apoptosis
Programmed cell death
Cells going through this apoptosis actually shrink and shrivel in a controlled process