The Cell Cycle

Question 1

What are the three processes needed for a single fertilized egg to become a multicellular organism?

Answer 1

1. Apoptosis
2. Cell proliferation
3. Differentiation

Question 2

Apoptosis (+3 reasons)

Answer 2

Programmed cell death
-3 reasons: During development, maintenance, or unfixable damage

Question 3

Cell Proliferation (+5 reasons)

Answer 3

Cell growth and division
-5 reasons: Growth and development, maintenance, repair, asexual reproduction, sexual reproduction

Question 4

Differentiation

Answer 4

the process of a stem cell specializing in function and structure changes to reflect function

Question 5

Epigenetics

Answer 5

When cells differentiate, they only express the relevant genes.

Question 6

Interphase

Answer 6

Growth and replication
- G1, S, G2, G0

Question 7

M-Phase

Answer 7

Nuclear and cytoplasm division
- prophase, metaphase, anaphase, telophase, cytokinesis

Question 8

G1

Answer 8

Cell grows to mature size
- checkpoint after G1

Question 9

Checkpoint

Answer 9

Points in division in which cell pauses to check for proper and determine next step

Question 10

S

Answer 10

After G1 if cell ‘decides’ to divide; Chromosomes are replicated in preparation for division. Each chromosome will consist of 2 sister chromatids
-checkpoint after S

Question 11

G0

Answer 11

After G1 if cell ‘decides’ NOT to divide; maintaining status quo and has exited the cell cycle.

Question 12

G2

Answer 12

After S; Cell continues to grow larger the mature size and replicated cell structures outside the nucleus.
-checkpoint after G2

Question 13

Prophase

Answer 13

Chromatin condenses into chromosomes and nuclear membrane breaks down. Microtubules form and attach to chromosomes. In cells that have centrioles, they move to opposite ends of the cell.

Question 14

Metaphase

Answer 14

Microtubules line chromosomes up single-file in center of cell.

Question 15

Anaphase

Answer 15

Sister chromatids are separated and pulled to opposite ends of the cell.

Question 16

Telophase

Answer 16

Occurs at the same time as cytokinesis. Nuclear membrane and nucleolus reform. Chromosomes de-condense.

Question 17

Cytokinesis

Answer 17

Occurs at the same time as telophase. In animal cells, cytoplasm divides by forming a cleavage furrow. In plant cells, a cell plate forms in the center which extends the cell wall.

Question 18

Meristems

Answer 18

Regions of actively dividing undifferentiated cells in plants at the tips of roots, shoots, and buds; as a ring along the circumference of roots and shoots; and in some plants, at the junction between the roots and shoots.

Question 19

Cancer

Answer 19

The unregulated and continuous growth of abnormal (mutated) cells

Question 20

What are the 4 main reasons increased exposure to alcohol can lead to higher risk of cancer?

Answer 20

1. Ethanol forms DNA-damaging molecules
2. Impairs the body’s ability to absorb vitamins for proper enzyme function
3. greater chance of mutation due to the higher rate of cell division to replace directly and indirectly damaged cells.
4. Causes epigenetic changes: can prevent apoptosis or proliferation

Question 21

DNA replication: step 1

Answer 21

Initiation:
an enzyme ‘unzips’ DNA and binds proteins to prevent strands from rejoining

Question 22

DNA replication: step 2

Answer 22

RNA primers are placed on the DNA strands to start the replication process

Question 23

DNA replication: step 3

Answer 23

An enzyme places DNA nucleotides off the RNA primers

Question 24

DNA replication: step 4

Answer 24

Lagging stand is created as the enzyme from step 1 continues to ‘unzip’ the DNA. Okazaki fragments form on lagging strand.

Question 25

DNA replication: step 5

Answer 25

Termination:
The RNA primers are replaced with DNA nucleotides.

Question 26

DNA replication: step 6

Answer 26

Bonds in sugar-phosphate backbone are repaired.

Question 27

Okazaki Fragment

Answer 27

Segments of newly copied DNA and the attached RNA primer

Question 28

Which way can nucleotides be placed?

Answer 28

5’->3’
off the 3’ end

Question 29

Ploidy: Diploid v.s Haploid

Answer 29

Diploid: 2 copies of each chromosome
Haploid: 1 copy of each chromosome

Question 30

Homologous chromosomes

Answer 30

Chromosomes with same genes but inherited from a different parent; possibly with different alleles.