Download Cell cycle, Mitosis and Cancer

Mitosis and Cancer
Study Guide
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Describe the roles of mitosis in living organisms.
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Describe the basic structure of a chromosome,
and explain how chromosomes are duplicated through DNA replication
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Describe the key events of each phase of the cell cycle.
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Describe the key events of each phase of mitosis.
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Compare the processes of cytokinesis in animal and plant cells.
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Describe how the cell cycle control system normally functions and explain the
consequences of errors in this system.
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Explain how cancer cells are different from normal cells of the body.
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Explain how you can reduce your risks of developing cancer.
Each of us began as a single cell,
so one important question is:
How did that single cell develop into
the present trillions of cells in our body?
Zygote (one cell)
Multicellular person
Mitosis for growth
Before a cell divides, what does it need to do?
Grows in size and Copies its DNA
so that enough cell materials
can be split between daughter cells
The Cell Cycle is the life of a cell
from its birth to its division
Interphase
G1: cell growth
S phase: Chromosomes are copied
by DNA replication
G 2: cell growth
Cell division phase
Two overlapping steps:
Mitosis: DNA (chromosomes)
distributed in to two nuclei
Cytokinesis: cytoplasm divides in two
During _____ , both the contents of the nucleus and the cytoplasm are divided.
1. G2
2. mitosis
3. S
4. the cell division phase
5. G1
During _____, the cell grows and replicates both its organelles and its
chromosomes.
1. G2
2. Interphase
3. S
4. the cell division phase
5. G1
What controls the cell’s cycle?
External and internal signals (molecules)
tell the cell whether to divide or not
These signals “turn on” certain genes
The proteins produced will
Promote cell division
Inhibit cell division
If there is a mutation in these
genes,
how will that affect that cell’s cycle?
Genes associated with cancer
Proto-oncogenes:
normal: stimulate cell division
mutated: uncontrollable cell division
Tumor suppressor genes:
normal: inhibit cell division
mutated: does not inhibit cell division
These genes normally are able to control
the cell division
but when mutated
they lead to uncontrollable cell division
1. A proto-oncogene becomes cancer causing or oncogenic, when a mutation
makes the gene inactive
True or False
2. Tumor suppressor genes can cause cancer when both copies of a particular
suppressor gene are inactivated
True or False
Cancer results after multiple mutations
in the same line of cells
2/3 of cancers are due to random mutations on DNA
66 % of cancers were due to random mistakes,
29 % of cancers were due to environmental factors or people's lifestyles,
and 5 % of cancers were due to inherited mutations
Most brain and prostate cancers are
Are due to random mutations
Most lung and skin cancers are due to
Environment,
A combination of random mistakes,
plus mistakes due to environmental
factors eventually turns the cell cancerous
For example, skin cells have a baseline
level of mutations due to random mistakes,
and exposure to ultraviolet light can add even more mutations,
leading to cancer,
Carcinogens
cause mutations on the DNA that lead to cancer
Closer look at S phase and Cell division
S phase
Process: DNA replication
Both strands are used as template
Semi conservative process:
each new molecule of DNA
has an old strand and a new strand
Who is involved?
original DNA
DNA polymerase
individual nucleotides
Accuracy: 1 error/billion  name for the error?
why are these errors important?
In what part of the cell does DNA replication take place?
After DNA replication is completed, _____.
1. each new DNA double helix consists of one old DNA strand and one new
DNA strand
2. one DNA double helix consists of two old strands and one DNA double helix
consists of two new strands
3. there are four double helices
4. each of the four DNA strands consists of some old strand parts and some
new strand parts
5. each new DNA double helix consists of two new strands
During replication, ______ are responsible for joining the nucleotides of a new
DNA strand together.
1. RNA polymerase
2. DNA ligases
3. DNases
4. DNA polymerases
5. Restriction enzymes
DNA replication occurs in mitosis.
True or False
Cell showing chromosomes
How many chromosomes
after the S phase
does this cell have?
Chromosome
Centromere
Sister chromatids
Cell division Phase:
Mitosis and Cytokinesis
Purpose:
create two daughter cells identical to mother cell
Separate chromatids so that each new cell
gets a copy of all the chromosomes
Method: a dance of chromosomes
dance directors: two centrosomes
Footstep guides: microtubules
(form mitotic spindle)
Mitosis phases:
Interphase
technically not part of mitosis
Chromosomes (DNA) as chromatin
Animation
Prophase: Preparation
Metaphase: Middle
Anaphase: Apart
Telophase-Cytokinesis:
Two nuclei (telophase)
Cut cytoplasm (cytokinesis)
Mitosis Table
STAGES
G2 of interphase
(Prior to mitiosis)
Prophase
Metaphase
Anaphase
Telophase
What happens to the
Chromosomes?
Other Cellular details
Indicate the correct order for the stages of
mitosis by labeling each stage 1-5
Two Nucleoli (plural for nucleus) are present at the end of _____.
1. metaphase
2. interphase
3. prophase
4. telophase
5. anaphase
Chromosomes become visible during _____.
1. metaphase
2. interphase
3. prophase
4. telophase
5. anaphase
Sister chromatids separate during _________.
1. metaphase
2. interphase
3. prophase
4. telophase
5. anaphase
Cytokinesis varies
in animals cells and in plants cells
by Cleavage Furrow
by Cell Plate
Slime molds cells undergo several mitosis
without undergoing cytokinesis. What would
result from this?
Why do cells divide by mitosis?
Lab test on Wednesday
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Using the microscope
Observing cells
Diffusion and Osmosis
Enzymes
Photosynthesis and Respiration
DNA evidence