Unit 6: Cell Cycle

Question 1

How can cells grow?

Answer 1

1) Dividing
2) Growing in size - there is a limit

Question 2

Growth in cells is limited because:

Answer 2

1) cell will eventually not have enough DNA - as when the cell increases in size, it is more demanding of DNA (this DNA does not increase in size with the cell, thus there will not be enough info/ instructions needed).

2) It becomes less efficient in moving nutrients and waste materials across its membrane (there is an optimum SA: V ratio)

Question 3

Asexual + Sexual Reproduction

Answer 3

• sexual reproduction - 2 parent cells fuse to form the first cell of a new organism
• asexual reproduction - a single organism splits into 2 genetically identical cells (very rapid process)

Question 4

How Surface Area to Volume Ratio impacts cell transport

Answer 4

The larger the SA: V ratio is, the faster the rate at which substances can pass through the membrane is.
- the smaller the cell, the bigger this ratio is

Question 5

Why cells replicate

Answer 5

• Reproduction
• Growth
• Regeneration

Question 6

cell division

Answer 6

A parent cell duplicated its genetic material + divides into two similar cells.

Question 7

Interphase

Answer 7

OVERALL: preps. for cell to divide + is the longest stage of cell cycle

G1 - the cell grows and begins duplicating all of its cellular components

S - “DNA Synthesis” - DNA is copied

G2 - cell continues this growing + copying in order to prep. for division

Question 8

Centromere

Answer 8

What attaches the duplicated strands of DNA together.

Question 9

Centriole

Answer 9

Structure which forms spindle fibers.

Question 10

Spindle Fibers

Answer 10

What attach to chromosomes during Metaphase, to later break the sister chromatids back apart during anaphase.

Question 11

Chromosomes

Answer 11

Combination of the original DNA + its copy.

Question 12

Sister Chromatids

Answer 12

The organized version of the copied DNA.

Question 13

Nuclear Envelope

Answer 13

• Contains chromosomes
• begins to fade in prophase and reforms in telophase

Question 14

Prophase

Answer 14

• duplicated chromosomes become visible + are attached in the center by a centromere
• centrioles begin forming spindle fibers
• nuclear membrane begins to fade

Question 15

Metaphase

Answer 15

• chromosomes meet in the middle of the cell
• spindle fibers connect to the centromeres of each chromosome

Question 16

Anaphase

Answer 16

• spindle fibers pull sister chromatids apart into individual chromosomes on opposite sides of the cell

Question 17

Telophase

Answer 17

• nuclear envelope reforms around each “cluster” of chromosomes
• spindle begins to break apart
• cell begins to look like it will form 2 new cells

Question 18

Cytokinesis

Answer 18

The division of the large cell containing duplicated chromosomes into 2 new cells.

Question 19

How cell growth is regulated

Answer 19

• Cells stop dividing when coming into contact with other cells
• Cell growth can be turned on and off - regulatory proteins control both inside and outside the cell.

Question 20

What happens when cell growth is no longer able to regulate

Answer 20

When there is no response to the signals that regulate the growth of most cells, the cells divide uncontrollably, causing cancer.

Question 21

Two types of protein regulators, and how they affect the cell cycle

Answer 21

Internal regulators (ex: cyclin): Respond to things happening inside the cell

• Cyclin allows cell cycle to proceed only after certain events have occurred

External Regulators (ex: growth factors): Proteins that respond to things happening outside the cell

• Growth factors stimulate the growth and division of cells, causing cells to slow down or stop their cell cycles.