View
232
Download
0
Category
Tags:
Preview:
Citation preview
Cell Division
The Cell Cycle:InterphaseMitosisCytokinesis
Cell Cycle
When a cell grows to a certain---predetermined size—it divides in to two cells.
One ‘parent’ cell divides into two ‘daughter’ cells
There are three main stages to this process.
Stage 1: Interphase
Period BEFORE cell division occurs. Cell grows to its mature stage. Cell makes a copy of its DNA
(chromosomes). Cell prepares to divide into two
cells.
Stage 1: Interphase-continued
Replication—this is when the DNA in the nucleus reproduces itself with an exact copy.
If the DNA (chromosomes) did not reproduce itself….then each new cell would only have ½ of the chromosomes it should have………
Stage 2: Mitosis
In this stage, one copy of the DNA (chromosomes) is distributed into each of the two new ‘daughter’ cells.
Prophase---Metaphase---Anaphase---Telophase
Stage 2: Mitosis--continued
Prophase: Chromosomes look like fishing line wrapped around a ball.
Each chromosome is made up of the doubled strand (chromatid) held together by a centromere.
Stage 2: Mitosis--continued
Metaphase: Chromosomes line up across the middle of the cell.
Each chromosome attaches to a spindle fiber that holds them together.
Stage 2: Mitosis--continued
Anaphase: The two chromatids of the Chromosome separate and each moves to the opposite end.
The cell appears stretched out.
Stage 2: Mitosis--continued
Telophase: The chromosomes begin to stretch out and lose their appearance.
A new nuclear membrane starts to appear and divides the nucleus into two different but identical nuclei.
Stage 3: Cytokinesis
This refers to when the cell membrane pinches in around the middle of the cell.
This separates the cell into two different but identical cells.
All organelles are evenly distributed to the new cells.
Stage 3: Cytokinesis-continued
Cytokinesis starts around the time of Telophase.
Structure of DNA
“double helix’ refers to a ladder that has sugars and phosphates
as the sides and nitrogen bases as the steps.
Recommended