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Copy of Mitosis

Honors Biology mitosis and cell cycle. Image credits: Biology Life on Earth 8th ed

Heidi Montgomery

on 5 May 2016

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Transcript of Copy of Mitosis

Why do cells divide?
Cell cycle control
Early prophase
Late prophase
Cell Cycle and Mitosis
DNA begins to condense into chromosomes
Nuclear membrane begins to break down
Centrosomes move to opposite poles
Spindle fibers form
DNA is fully condensed
Nuclear membrane is gone
Chromosomes are attached to spindle fibers
Spindle fibers position chromosomes along middle of cell
Spindle fibers shorten
Sister chromatids are pulled apart
Chromatids reach the poles
Cytokinesis begins
Nuclear membrane reforms
Cell is pinched in two
Daughter cells separate
All done!
Back to interphase...
Most of a cells life spent here
Divided into stages
G1: Growth or Gap 1
s: DNA Synthesis
G2: Growth or Gap 2
Cytokinesis in Plant Cells
Characteristics of Interphase Cells
DNA is in a loose state called chromatin
DNA is replicated during S phase
Cell is "doing its job"
Chromosome Structure
Chromosomes are complexes of DNA AND protein
During S phase the DNA replicates to form sister chromatids
Sister chromatids are exact copies of each other
Chromatids are held together at the centromere
Humans have 46 chromosomes, arranged in 23 pairs

Why pairs?
This picture is called a karyotype
Why do cells divide?
When is mitosis used for reproduction?
How does a cell control when it divides?
What happens when cells divide uncontrollably?
How are mitosis and meiosis diffferent?
Asexual Reproduction
The cell cycle is controlled by checkpoints
If a cell does not correctly fufill checkpoint requirements, cell cycle is stopped
Problem can be fixed, or cell can eliminate itself (apoptosis)
R Point
Major checkpoint
If cell gets past this, will most likely complete rest of cell cycle
Checkpoints are controlled by the activity of cdk proteins

Cyclin Dependent Kinases

Cyclins cycle during cell cycle
SC.912.L.16.14 Describe the cell cycle, including the process of mitosis. Explain the role of mitosis in the formation of new cells and its importance in maintaining chromosome number during asexual reproduction.
Reproduce by binary fission
Reproduce by binary fission or budding
Reproduce by budding
Reproduce by binary fission
Binary fission
Means "divide in two"
A type asexual reproduction- similar to mitosis
How prokaryotes reproduce
DNA is replicated and the cell divides in two
You have 2 daughter cells that are exactly like the original cell - no genetic diversity
The chromosome number is maintained
There are about 100 Trillion cells in an adult human
Only about 37 Trillion of those are human cells
The rest are bacteria
Did you know we lose 30,000 to 40,000 dead skin cells every minute?
Did you know the body makes about two million red blood cells every second
Cells with high mechanical use get worn out quickly
Some cells like nerve and brain cells divide rarely, if ever.
Replacement of worn out Cells
Cancer Is Uncontrolled Cell Growth
Instead of dying, cells continue to divide and form new, abnormal cells
Cancer cells form disorganized clumps called tumors.
Benign tumors remain clustered and can be removed.
Malignant tumors metastasize, or break away, and can form more tumors.
Cancer cells do not carry out necessary functions.
Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.
SC.912.L.16.8 Explain the relationship between mutation, cell cycle, and uncontrolled cell growth potentially resulting in cancer.
SC.912.L.16.17 Compare and contrast mitosis and meiosis and relate to the processes of sexual and asexual reproduction and their consequences for genetic variation.
At the end of mitosis you have 2 exact copies (daughter cells) of original or parent cell.
If parent cell has 38 chromosomes to begin with, how many chromosomes will the daughter cells have?
Meiosis is division of germ cells to produce sex cells (gametes) in eukaryotes.
Meiosis starts with a diploid cell
diploid is where there are 2 copies of every chromosome
Meiosis ends with 4 haploid daughter cells, only one of each chromosome.
The result of meiosis is the mixing up of chromosomes through random assortment of chromosomes and crossing over
Producing a clone or exact replica - only one parent ...no genetic diversity
Vegetative Reproduction
Used by some plants
Parent plant sends out runners
Parthenogenesis is a type of asexual reproduction in which the offspring develops from unfertilized eggs.
Common in insects and other arthropods
Can also be found in some species of fish, amphibians, birds, and reptiles, but not in mammals.
Offspring are clones.
Body cells which reproduce by mitosis are called
Somatic cells.
Sex cells are called
Sex cells need to have
the number of chromosomes so that when they meet another gamete in fertilization (sexual reproduction), there will be the correct (diploid) number of chromosomes.
Sexual reproduction results in
genetic diversity
and individuals with variations that may be beneficial to certain environmental conditions (adaptation).
Mitosis and meiosis are processes involved in cellular reproduction. Which of the following describes and event that results from mitosis but NOT meiosis?
A. two stages of cell division
B. replication of cellular genetic material
C. daughter cells that are identical to the parent cell
D. four daughter cells that are produced from each parent cell
How are sexual reproduction and asexual reproduction
from each other?
A. sexual reproduction requires two parents and asexual reproduction requires only one parent
B. asexual reproduction requires two parents and sexual reproduction requires only one parent
C. mutation rates are lower in sexual reproduction than in asexual reproduction
D. asexual reproduction occurs only in multicellular organisms
Quiz Question
Which type of reproduction leads to
increased genetic variation
in a population?
A. Parthenogenesis
B. asexual reproduction
C. Sexual reproduction
D. Vegetative reproduction
Quiz Question
Which of the following phrases
best describes cancer?
A. absence of cyclins in the DNA
B. multiple gene mutations on a chromosome of DNA
C. uncontrolled cell growth caused by mutations in genes that control the cell cycle
D. presence of genetic defects caused by hereditary disorders
Quiz Question

Which of the following correctly describes the process being illustrated?
A. mutation in which the DNA content of the gene is altered
B. segregation of sister chromatids
C. condensation and segregation of alleles
D. crossing-over in which alleles are exchanged
Quiz Question
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