Topic 10- Cell Cycle and Division

Question 1

What are the roles of cell division?

Answer 1

1. Reproduction
2. Growth and development
3. Tissue renewal

Question 2

Chromatid vs Chromosome

Answer 2

A chromatid is each individual molecule of DNA while a chromosome is molecule with a specific genetic sequence.

Question 3

What is asexual reproduction?

Answer 3

Creation of off spring from a single parent.

Question 4

Haploid vs. Diploid

Answer 4

Haploids have one set of chromosomes, ex sperm and eggs
Diploids have 2 sets, pretty much everything else

Question 5

What are gametes vs somatic cells?

Answer 5

Gametes are cells for reproduction, somatic cells are everything else.

Question 6

what is a zygote?

Answer 6

A cell made when the sperm fertilizes the egg and it continues to do mitosis over and over.

Question 7

What is a homologous pair of chromosomes?

Answer 7

the same chromosome from each parent.
-same size
-genes are in the same location.

Question 8

Describe the steps of the cell cycle

Answer 8

1. Interphase
   -G1: cell growth
   -S: synthesis phase, copy DNA and making sister chromatids
   -G2 More growth and division prep.
2. Mitotic phase.
   -Prophase:
   chromosomes condense
   nucleolus disappears
   centrosomes start forming spindles
   -Prometaphase:
   nuclear membrane dissolves
   microtubules attach to the centromeres
   -Metaphase:
   moment when chromosomes are lined up at the down the middle at the metaphase plate
   -Anaphase:
   sibling chromatids are cleaved apart
   microtubules pull each chromatid towards their half
   -Telophase:
   spindle disassembles and nucleus reforms.
   Cytokinesis- when the cell divides

Question 9

What is mitosis?

Answer 9

The division of the nucleus

Question 10

What is Meiosis?

Answer 10

The creation of gametes

Question 11

How does cytokinesis change for plants and animals?

Answer 11

Animals
ring of microfilaments go around the middle and squeeze it in half creating a cleavage furrow.

Plants
forms a cell plat down the middle that is created by material carried in vesicles. It is then anchored down to create a new cell.

Question 12

Describe the steps of Meiosis

Answer 12

Meiosis 1
-Prophase 1:
Chromosomes duplicate to create sister chromatids
pairs up with corresponding homologous pair to form a tetrad.
when they line up they begin crossing over, mixes up.
-Metaphase 1:
The pairs line up in the center.
Due to independent assortment either chromosome can be on either side of the middle line.
-Anaphase 1:
spindle fibers reach out and separate the homologous chromosomes.
-Telophase 1:
nucleus reforms and and spindle fibers disapear

Meiosis 2:
Same as Mitosis, results in 4 genetically different haploid cells.

Question 13

How to calculate how many possible variations there can be?

Answer 13

2^n N= # of chromosomes

Question 14

What causes genetic variation

Answer 14

Crossing over and independent assortment

Question 15

What is apoptosis

Answer 15

when the immune system identifies and kills a cell

Question 16

What are the checkpoints in cell division

Answer 16

G1- Red light until it receives a signal. If it is a red light it stays in G0 phase which allows a cell to just do it function and not replicate. Usually happens when it is at its perfect size.

M- Checks for proper attachment of microtubules to chromosomes. If it is not connected it sends a signal that stalls for time. If it takes to long apoptosis will occur.

G2- checks for proper duplication and if the DNA is damaged. If it is not connected it sends a signal that stalls for time. If it takes to long apoptosis will occur.

Question 17

What is Nondisjunction? When does it happen in both stages of meiosis?

Answer 17

Nondisjunction is when the chromosomes do not separate properly during division.

In meiosis 1, one cell will have an extra homologous pair while the other is missing one

In meiosis 2, half will be fine but one will have an extra sibling chromatid while one will be missing an extra sibling chromatid.

Question 18

What is trisomy?

Answer 18

Why you have 3 sets of a chromosome instead of 2

Question 19

Which chromosome determines sex?

Answer 19

The Y chromosome

Males have XY while Females have XX

Question 20

What is cancer? What is a tumor? Why does likely hood increase with age?

Answer 20

Cancer is a disease that involves abnormal cell growth that can spread. The tumor is the lump of abnormal cells. Likely hood increases with age because your cells have gone through more division which increases the chances that mutations have happened. You need several mutations in a variety of genes. Also, more exposure to cancer risks.

Question 21

What are the treatments for cancer

Answer 21

Chemotherapy
Puts a toxin into your body that kills rapidly diving cells.

Radiation
Beams of radiation are shined on a tumor causing it to shrink

CAR-T therapy
T cells are genetically modified to hunt down and kill cancer cells.

Question 22

What are the changes needed for cancer

Answer 22

Initial Tumor development
1. evading apoptosis
- ability to hide from the immune system
2. Self sufficient in growth signals
- tells it self to keep on growing
3. insensitivity to anti growth signals
-ignores the signal that tells it to stop growing

Additional capabilities
4. tissue evasion and metastasis
- Tumor cells get in the blood stream and spread.
5. limitless replication potential
- Instead of dying when its damaged or old it keeps on duplicating which can lead to even more mutations
6. sustained angiogenesis
- Blood gets pumped into tumor to supply it with nutrients