Cell Cycle

Question 1

What are the 4 reasons why cells divide?

Answer 1

1. Efficiency : as cell grows bigger demand for transport across membrane is too great
2. DNA overload: as cell grows bigger, DNA can’t send out instructions fast enough to instruct organelles on work to do
3. Growth
   4: Cells divide to replace word out or damaged cells

Question 2

What is cell division called in prokaryotes ?

Answer 2

Binary Fission

Question 3

What happens in Binary Fission?

Answer 3

DNA is copied then cell divides

Question 4

What is cell division called in Eukaryotes ?

Answer 4

Mitosis

Question 5

What happens in mitosis?

Answer 5

cell grows and copies its DNA before it can divide

Question 6

What is the cell cycle?

Answer 6

The series of events that cell go through as they grow and divide

Question 7

What are the two phases of the cell cycle?

Answer 7

Interphase and “m” phase

Question 8

What does the “m” phase include?

Answer 8

mitosis-division of the nuclei
cytokinesis-division of the cytoplasm

Question 9

What are the steps in Interphase?

Answer 9

-G1(Growth /Gap 1)-cell grows in size, makes new organelles and performs assigned function; DNA is relaxed in chromatin and is not visible

-S phase (synthesis) :duplicates DNA to prepare for mitosis

-G2(growth/Gap 2) -cell prepares for mitosis

Question 10

chromatin

Answer 10

DNA “scrunched up” in the nucleus and is not visible / DNA is relaxed; DNA appears as chromatin during interphase

Question 11

Chromosome

Answer 11

cell structure that carries the genetic material/ visible DNA during mitosis

Question 12

Sister chromatids

Answer 12

identical halves of the duplicated parent chromosome

Question 13

centromere

Answer 13

cell structure that joins the 2 sisters chromatids of chromosome

Question 14

What happens during prophase?

Answer 14

1) DNA organizes
- chromatin condense into visible chromosomes
-chromosomes are paired with their identical copies and are called sister chromatids
- sister chromatids are held together as a pair by centromere

2) ;nuclear membrane and nucleolus disappear

3) spindle fibers form between the pairs of centrioles, which have moved to opposite ends of the cell

Question 15

What happens during metaphase ?

Answer 15

• chromosomes line up on the middle of the cell
• each chromatid is attached to a separate spindle fiber by its centromere

Question 16

What happens during anaphase ?

Answer 16

• sister chromatids are pulled apart to opposite poles of the cell

Question 17

What happens during telophase ?

Answer 17

• nucleolus and nuclear membrane reappear ,chromosome begin to uncoil and relax back into chromatin

Question 18

What happens during cytokinesis?

Answer 18

-cytokinesis occurs as the plasma membrane pinches in along the equator
- 2 identical daughter cells are formed

Question 19

What happens in plants because they have a cell all and cannot pitch off their plasma membrane?

Answer 19

• a structure known as the cell plate forms across the cells equator

Question 20

What happens after mitosis ?

Answer 20

• each new daughter cells is an identical copy of the parent cell . Both cells enter interphase to carry out the assigned function until they are ready to divide

Question 21

Where do cells spend the most time ?

Answer 21

Interphase

Question 22

What are cells life span like ?

Answer 22

Some cells have a short life span and can divide ( ex: skin cells )

While others must last your entire life and cannot divide (ex :heart cells )

Question 23

What is G0 phase ?

Answer 23

It is the cell’s resting phase where it doesn’t divide. Cells can go back into the cell cycle if needed

Question 24

What happens when the genes that control cell division become damaged ? And some cells do not respond to the signals that regulate growth ?

Answer 24

Result : uncontrolled cell growth . Aka cancer

Question 25

- cigarette and tobacco use - radiation exposure ( x-ray and UV light ) - genetics - some viruses Are examples of

Answer 25

Causes of cancer

Question 26

What are stem cells ?

Answer 26

Unspecialized cells

Question 27

Through ____ ____stem cells become specialized in structure and function

Answer 27

Cell differentiation

Question 28

What are the two kinds of stem cells ?

Answer 28

Embryonic and adult stem cells