Chapter 12: The Cell Cycle

Question 1

Cell Cycle

Answer 1

sequence of events in the life of a cell
(Interphase- G1, S, and G2)
(M phase- Mitosis and Cytokinesis)

Question 2

Genome

Answer 2

the genetic material of an organism or virus

Question 3

Chromosomes

Answer 3

One DNA molecule and associated protein molecules

Question 4

Chromatin

Answer 4

the complex of DNA and proteins that make up eukaryotic chromosomes

Question 5

Somatic Cells

Answer 5

Body cells, everything but gametes

Question 6

Gametes

Answer 6

Sex Cells; haploid reproductive cells formed by meiosis

Question 7

Mitosis

Answer 7

Cell division/replication

Question 8

Cytokinesis

Answer 8

The cytoplasm splitting after mitosis, meiosis 1, and meiosis 2

Question 9

Interphase

Answer 9

The stage of the cell cycle where the cell does not divide, it works and duplicates chromosomes and organelles. 90% of cell cycle

Question 10

Centrosome

Answer 10

In the cytoplasm, micro-tubule-organizing center (produces spindle fibers)

Question 11

Binary Fission

Answer 11

Asexual reproduction method; cell grows to twice its size and then divides into 2 cells

Question 12

G0 Phase

Answer 12

A non dividing state occupied by cells that have left the cell cycle (sometimes reversible)

Question 13

Growth Factors

Answer 13

A protein that must be present in the extracellular environment for the growth and normal development of certain cells

Question 14

Density-dependent inhibition

Answer 14

the phenomenon observed in normal animal cells that causes them to stop dividing when they come in contact with each other

Question 15

Anchorage Dependence

Answer 15

the requirement that a cell must be attached to a substratum in order to initiate cell division

Question 16

Benign tumor

Answer 16

mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of tumor origin

Question 17

Metastatic tumor

Answer 17

tumor that will spread away from tumor site

Question 18

Metastatic tumor

Answer 18

tumor that will spread away from tumor site

Question 19

What do Eukaryotes depend on Cell Division for?

Answer 19

Cell division is crucial in multicellular-eukaryotes for renewal and repair. Think of a child with a scraped knee. You clean the area, bandage it, and over the next few days a scab is formed, and voila brand new skin just the same as before. This is because of cell division. Your body replicated the tissue that was missing to repair and renew it.

Question 20

Most cell division results in what? What is an exception to this?

Answer 20

Most cell division results in 2 identical daughter cells.
The DNA is replicated, and then split into two separate cells. The exception is meiosis, who’s two daughter cells produce 2 more daughter cells, for a total of 4 daughter cells, each with unique genetic make-up.

Question 21

How is cytokinesis different in animal and plant cells?

Answer 21

In animal cells, cytokinesis happens quickly through a cleavage furrow formed during mitosis, along the metaphase plate. Motor proteins pull the cleavage inward like a drawstring, causing the cytoplasm to split and form two new cells.

In plant cells, their is no cleavage furrow. Instead, vesicles derived from the golgi apparatus move to the middle of the cell, where they produce a “cell-plate”. Vesicles transfer their materials (phospholipids, right?) until a new cell wall is formed and the cell is split into two daughter cells.

Question 22

Discuss how the G1, G2, and M checkpoint in the cell cycle work.

Answer 22

G1 is the growth phase of the cell. Is the cell growing well? Any damaged DNA? (wouldn’t wanna replicate that!). Does it have the resources to move onto S phase. It grows, checks itself, and then moves to S phase where it replicates it’s DNA.
G2 is the second growth phase. It checks if the DNA was replicated correctly, if the cell is growing well enough, and does it have the resources to continue. Then it moves to M phase.
The M phase checkpoint occurs in metaphase and checks that the chromosomes are aligning properly, and attached to the spindle.

Question 23

There are internal and external factors that influence cell division. What are three external factors discussed in class? Describe each and their influence on the cell cycle.

Answer 23

External factors influencing cell division are the “checkpoints” such as G1, G2, and M. G1 is the first checkpoint and occurs during Interphase. During this time, the cell is growing to prepare itself for mitosis. G1 is a checkpoint to ensure that the cell is growing properly and has enough energy and other resources to move on into the synthesis phase of interphase. After the cell has duplicated it’s DNA in S phase, it enters into G2, another checkpoint. G2, like g1, ensures the cell is growing adequately, but also checks for any mutations in the DNA, any inadequate DNA (like too few or too many), and if there is enough resources to move into mitosis. If the cell passes all of these checkpoints, then it moves into Mitosis, where it comes to the M checkpoint (metaphase checkpoint), which ensure that the chromosomes are aligned properly and all attached to the spindle fibers, confirming that their will be no missing or extra chromosomes in the daughter cells.

Question 24

Which type of external factors on cell division do cancer cells lack? Which of these two aid cancer cells in metastasis?

Answer 24

Density dependent inhibition and anchorage dependence. Anchorage dependence means that the cell needs to be attached to a substrate to divide. Metastatic cancer cells do not need this because they can bind and be viable for growth at any site.

Question 25

Why don’t cancer cells need growth factors to grow and divide?

Answer 25

Cancer cells lack growth factors either because they produce their own, or they have an abnormality in their signal pathway that acts as a growth factor signal, even when their is no growth factor.