http://go.hrw.com/resources/go_sc/hbio/hx
8_ss_10_crp_cm.swf
Chapter review
Mitosis and Reproduction
Why reproduce?
• Too big
• Grow—need to make more cells
• Heredity—pass on the genes to another
generation
• Replace worn out or destroyed parts
– Blood cells constantly being made to replace used
ones. Get destroyed by constant squeezing of heart
– Stomach cells get destroyed by acid
– Regeneration: Sea stars—if loose leg, grow new
ones.
Asexual Reproduction
Definition
Method
1. _______ 1. ___________
Example
1. __________
2. _______ 2. ___________
2. __________
3. _______ 3. ___________
3. __________
4. _______ 4. ___________
4. __________
https://www.youtube.com/watch?v=DY9DN
WcqxI4
Bacterial fission
Types of Asexual Reproduction:
Budding
ex. Yeasts
Binary Fission
ex. Bacteria
Fragmentation
ex. Starfish
Parthenogenesis ex. Crustaceans (shrimp,
lobsters, crabs)
Sexual Reproduction:
Requires and egg and a sperm (gametes).
Egg: XX chromosomes
Sperm: XY chromosomes
10.1 Limits to Cell Growth
2 reasons for the limit to how big a cell can get
a. The larger a cell gets the more difficult it is for the
cell to produce the necessary proteins for the cell
b. When the volume of the cytoplasm gets bigger
than the cell surface (at a faster rate) there isn’t
enough cell membrane to exchange O2, H2O,
food, and CO2. Think of a city whose population
grows too fast for the garbage removal
companies.
Before a cell becomes too big and dies, it divides to
increase the surface area/volume ratio again. This is
called Cell Division and produces 2 cells called
daughter cells which are identical to the “parent” cell.
Some general concepts:
• plants: cell division takes place in the tips of
roots & stems
• animals: cell division takes place all over the
body to produce many different kinds of cells
• the timing of cell division is critical to
development of tissues & organs
• DNA must be replicated & equally divided
otherwise it can lead to birth defects, cancer or
serious disease
10.2 Cell Cycle
A. Chromosomes:
* organisms have genetic information coded in a
molecule called DNA
* 2 forms of DNA
In dividing cell the DNA coiled into structures
called – Chromosomes
In a nondividing cell the DNA is called Chromatin
- the genetic code is the same, just in
different forms so the cell can divide easily
* organisms have a set number of
chromosomes –
humans have 46! Fruit flies have 8!!
* When a cell divides, DNA replicates and
chromatin condenses, forming visible strands
called chromosomes
* Each chromosome is now made of two
strands called chromatids attached in the
middle by a protein bundle called a centromere
centromere
Sister
chromatids
* When a cell divides, chromatids separate and
each cell gets a copy of the DNA
B. Cell Cycle
* The period of time between one cell division,
growth of the cell, and the next cell division.
* During the cell cycle:
• a cell grows
• prepares for division
• divides to form two daughter cells, each of
which begins the cycle again
• The sequence of the cycle is the same in all
cells but some cells spend more time in
certain stages
• Most cells in an adult multicellular organism
are in G0 – “resting”.
* 2 Phases of the cell cycle – each broken further
1. Interphase: the period between cell divisions
G1 – 1st Gap
S – DNA synthesis
G2 – 2nd Gap
G0 - resting
cell cycle animation
2. Mitosis: nuclear division
Prophase
Metaphase
Anaphase
Telophase
cytokinesis: division of the cytoplasm
5.
1.
4.
2.
3.
Phases 1-3 are together called__________.
Draw in the 3 Checkpoints as traffic lights.
Actual cell division occurs
Only in Phase #_____.
5.C
1. G1
4.M
2. S
3. G2
Phases 1-3 are together called__________.
Draw in the 3 Checkpoints as traffic lights.
Actual cell division occurs
Only in Phase #_____.
1. Interphase….a little more
• Once a cell enters the S phase, it usually
completes the rest of the cell cycle
– * longest part of cell cycle – 75%?
• G1: cells grow & make new proteins &
organelles
• GO: some cells enter a prolonged period
where they are just carrying out normal
cell processes
• S: DNA replicates (synthesize) –
– DNA is copied so that each new cell will get a
copy.
G2: organelles and molecules (enzymes)
needed for mitosis are made
cell is ready for mitosis…division
Interphase
Normal Somatic (body) Cells
are DIPLOID (“2n”)
Cell cycle (S phase) in
Somatic cells
Mitosis of DIPLOID (“2n”)
Somatic cells
• Prophase
Mitosis of DIPLOID (“2n”)
Somatic cells
Mitosis of DIPLOID (“2n”)
Somatic cells
• Metaphase
Mitosis of DIPLOID (“2n”)
Somatic cells
• Anaphase
Mitosis of DIPLOID (“2n”)
Somatic cells
• Telophase
Mitosis of DIPLOID (“2n”)
Somatic cells
• Cytokinesis
http://go.hrw.com/resources/go_sc/interact
Online/hx/hxcrp_io.swf
Mitosis interactive
http://science.education.nih.gov/supplemen
ts/nih1/cancer/activities/activity2_animation
s.htm cell cycle and cancer