Transcript Chapter 10 Cell Growth and Division
Chapter 8 Cell Growth and Division
Biology
10-1 Cell Growth
Adults don’t have bigger cells than kids… they just have MORE of them
Why don’t cells just grow bigger?
DNA overload….DNA would need extra copies to handle “information demand” Too difficult to get enough nutrients and oxygen IN and waste products OUT
The world's tallest man in 2007 7’9”, Bao Xishun and his 5’6” wife… most people with acromegalic gigantism eventually die because of complications from heart problems. "Keeping the blood going round such an enormous circulation becomes a huge strain for the heart,"
What would happen?
Calculate ratio of surface area to volume L * W * # of sides= surface area L * W * H= Volume Practice problem: if cell was a cube and its sides were 1cm each ….figure SA?
Figure V… What if the cell were 3cm? SA? V?
What is the ratio?
Volume increases faster than surface area
1*1*6=6 SA 1*1*1=1 V Ratio 6:1 in and out.
3*3*6=54 SA 3*3*3=27 V Ratio 54:27 reduce… 2:1 The decrease in ratio of SA to V- makes it harder for the cell to move needed products
Cell division solves…
The problem of information storage… because each daughter cell gets it’s own DNA The problem of being too big and inefficient because although the cell grows some… parent daughter cells will still be smaller than the
10-2 Cell Division : is mitosis
4 sections of the cell cycle: G phases, S phase, mitosis, cytokinesis
Cell Division Mitosis Cytokinesis Division of the nucleus Division of the cytoplasm
In Bacteria …prokaryotes
Have circular DNA And only 1 piece of DNA called plasmid The process by which bacteria reproduce is called binary fission (not mitosis)
10-2 Cell Division
In eukaryotes the chromosomes carry the genetic information and they live inside the nucleus Chromosomes are made up of DNA and proteins (called histones)
Centromere is made of protein Spindle fibers are made of microtubules sister chromatids are duplicate halves
Karyotype-
Tells # of chromosomes in that body cell
Growth & Repair
Interphase
Baby Cell (daughter cell)
grows and matures here…and
eventually is mature enough to divide a.k.a.…time in between cell division
3 steps of Interphase
1.
2.
3.
G1- cell grows, and organelles and makes new proteins
S phase- DNA is replicated
G2 - molecules and organelles cell division are produced.
needed for
Now ready for Mitosis
PMAT
Prophase longest,
chromosomes become visible/
centrioles go to the poles Spindle fibers start to form Nuclear envelope starts to break down
Mitosis….
Metaphase (middle) Last only a few minutes Chromosomes line up across the MIDDLE of the cell Centromeres connect to the spindle fibers
Mitosis…
Anaphase (the fingers) Centromeres split , splitting chromosomes into 2 sets
Chromosomes move away from each other to the poles being pulled by spindle fibers
Mitosis
Telophase (the peanut) Chromosomes begin to disappear from view Nuclear envelope re forms Spindles break apart Nucleolus reforms …end mitosis
Cytokinesis
Nucleus and contents have split but what about the rest of the cell….?
Cell membrane is drawn inward until cytoplasm is eventually pinched into two equal parts In plants cell plate eventually becomes the cell wall
Cell plate >
http://www.biostudio.com/d_%20Mitosis.htm
10-3 Regulating the Cell Cycle
Cell growth and cell division are carefully controlled
Cells grow when there is space , then when they bump into other cells they stop
A cut in your hand?
http://www.pearsonsuccessnet.com/snp app/iText/products/0-13-181118 5/ch10/sb4501f1.html
What signals the cell to start dividing?
A set of proteins called cyclins control the timing of cell division…
Internal Regulators- tell cell to divide based on what is happening inside the cell (PMAT timing) External Regulators- tell cell to divide based on what is happening outside the cell (wound healing , embryonic development)
Cancer
A disorder in which some of the body’s own cells (whose DNA is damaged) lose the ability to control growth… Cells grow out of control and form masses called tumors
Sometimes these cells break free and spread throughout the body These cells lack the proteins that tell them to stop growing and ignore the bordering cells telling them to stop
Causes of Cancer
Viral Infection (commercial) Radiation (sun, x-rays ) Smoking tobacco Anything known to cause cancer cells to develop is called a carcinogen….
Identifying the Number of Chromosomes…
Not all living things have the same number of chromosomes..
Humans: 46 Fruit flies: 8 Carrots: 18 **worksheet
Haploid vs Diploid
Haploid: half Diploid: Double But first figure out where you are at?
Body cell(regular cell) is already Diploid Sperm/egg cell (sex cell) is already Haploid
Differences between animal and plant cells Plants have a cell wall and a cell membrane- so when they pinch…it’s called a cell plate.
The cell plate becomes the cell membrane – then the cell wall develops next.
Cell plate >