Biology Chapter 12 Flashcards
Mitosis is a type of cell division that
leaves two identical copies of a cell
In mitosis, the chromosome number is
Unchanged
Most cells divide by
Mitosis (skin, blood, kidney)
Why is nerve and brain damage usually permanent?
Nerve and brain cells rarely divide after childhood
Interphase
The cell grows and DNA replicates
Interphase is followed by
Mitosis
Mitosis
The cell divides into two
What are the stages of mitosis?
Prophase,
metaphase,
anaphase,
telophase
Prophase
The spindle forms. The chromosomes are visible scattered at random
What is the spindle, that forms during prophase, made of?
Microtubules
Metaphase
Chromosomes line up in the center of the cell
Anaphase
Centromeres divide. The chromosomes move to opposite ends of the cell (V shape)
Telophase
Two nuclei form. The cytoplasm divides (cytokinesis)
During telophase in animals, how does it divide?
The cell membrane pushes inwards from the outer edge making a cleavage furrow, so the center is the last part that divides
During telophase in plants, how does it divide?
The cytoplasm separates from the center of the cell towards the outside by forming a cell plate
When do normal cells divide?
When the correct growth factor is present.
When each cell is not completely surrounded by other cells.
What do proteins inside the cell control?
The cell cycle
What do cyclins in the nucleus control?
The replication of DNA
The 2001 Nobel prize was awarded to
The people who discovered cyclins
What do protein kinases switch on?
Proto-onco genes that start mitosis
A mutation in a proto-onco gene can turn it into
An oncogene that causes cancer (uncontrolled cell division)
Tumor suppressor genes
Prevent mitosis and make abnormal cells kill themselves
What is an example of a tumor suppressor gene?
p53
Why is cancer more common in older people?
Most cancers have mutations in the tumor suppressor genes and as you get older the chance of mutation increases
Cancer cells keep dividing even if
Surrounded by other cells
A benign tumor
Is limited to one site and cannot spread
A malignant tumor
Cancer cells spread around the body in the blood
Metastasis
The cancer has spread
What is cell division needed for?
Growth, reproduction, and to replace dead cells
What are causes of cancer?
Environment,
Genetics
Environment
- Carcinogens (chemicals which cause cancer)
- Radiation
- Ultra-violet (UV) light causes skin cancer
- Virus (the virus HPV causes cancer of the cervix)
Genetics
Some cancers have a high genetic risk
What are high risk cancers?
Prostate, colon, breast, skin, ovary
What are low risk cancers?
Lung, pancreas, testicles, uterus
What are some cancer treatments?
Surgery, chemotherapy, radiation
Surgery
Removes cancer cells. Best for benign tumors
Chemotherapy
Chemicals that kill dividing cells. Standard for malignant tumors
What is a problem with chemotherapy?
Side effects. Kills all cells that are dividing.
Radiation
Kills all the cells in one spot. Standard for malignant tumors
What are problems with radiation?
Kills all cells in the area, whether cancerous or not, causes side effects.
Can cause new cancer to start.
Prostate cancer
39,000 annual deaths
93% 5 year survival rate
Early detection through exam and blood
Breast cancer
44,000 annual deaths
85% 5 year survival rate
Early detection through self exam and mammogram
Colon cancer
57,000 annual deaths
62% 5 year survival rate
Early detection through exam and blood
Lung cancer
160,000 annual deaths
14% 5 year survival rate
No early detection
What are cancer survival rates from lowest to highest?
Lung,
Colon,
Breast,
Prostate
Most cancer research is done using human cells grown in the lab called
HeLa cells
Who are HeLa cells named for?
Henrietta Lacks
What cells have telomerase?
Cancer cells
Telomerase
An enzyme that repairs the telomeres on the ends of the chromosomes
Cancer researchers are developing
Inhibitors against telomerase
Inhibitors that stop cancer cells from producing new blood vessels
Medications that boost the immune system
Asexual reproduction
Offspring are identical (clones)
Only one parent
Cells divide by mitosis
What are examples of asexual Reproduction?
Bacteria, banana
Sexual reproduction
Offspring vary
2 parents
Sex cells have one set of chromosomes, compared to two sets in a normal cell
What are sex cells called?
Gametes
Gametes are produced by
Meiosis
Diploid cells
Have 2 sets of chromosomes (2n)
Examples of diploid cells
Skin, stomach, liver
Regular body cells are also called
Somatic cells
In humans, diploid cells have how many chromosomes?
46 chromosomes
Haploid cells
Have one set of chromosomes (n)
Examples of haploid cells
Sperm and egg (called the gametes or sex cells)
In humans, haploid close have how many chromosomes?
23 chromosomes
What are sources of genetic variations?
Independent assortment
Crossing over
Random fertilization
Independent assortment
Picking 23 chromosomes from 46 in humans
In a species with 3 chromosomes in gametes it gives
8 genetic combinations
How many independent assortment combinations are in humans?
8 million
Crossing over
Changes the combinations of genes that are inherited. May give thousands of different combinations (exact number is unknown)
Random fertilization
The sperm that fertilizes the egg is chosen at random
In a species with 3 genetically different gametes it gives
9 combinations
How many random fertilization combinations are in humans?
70 trillion
