Unit 5: The Cell Cycle

Question 1

Every cell contains the same DNA in an individual but depending on how these instructions are expressed…

Answer 1

it will lead to a variety of cell types (such as blood cells, neurons, and muscle cells).

Question 2

What is the cell cycle?

Answer 2

New cells are formed by
splitting of pre-existing cells

Question 3

What type of cells does meiosis create?

Answer 3

Meiosis produces reproductive cells, called gametes.

Question 4

What type of cells does mitosis create?

Answer 4

Mitosis produces all other cell types—somatic cells

Question 5

Mitosis and meiosis are usually accompanied by __________.

Answer 5

cytokinesis

Question 6

What is cytokinesis?

Answer 6

Division of cytoplasm into two daughter cells.

Question 7

What is mitosis?

Answer 7

Genetic material is copied and divided equally between two
cells (cellular replication).

Question 8

In mitosis, daughter cells are ___________ to the parent cell and to each other.

Answer 8

In mitosis, daughter cells are genetically identical to parent cell and to each other.

Question 9

What does meiosis produce?

Answer 9

Produces daughter cells with only half of the hereditary material as
parent cell (four cells created).

Question 10

For life to exist, cells must _________.

Answer 10

replicate

Question 11

What are the three basic steps in cellular replication?

Answer 11

1. Copying DNA
2. Separating copies
3. Dividing cytoplasm to create two complete cells.

Question 12

What is chromatin?

Answer 12

Refers to a mixture of DNA and proteins that form the chromosomes.

Question 13

What are chromosomes?

Answer 13

Refers to the condensed form of chromatin.

Question 14

What are chromosomes made of?

Answer 14

Consists of double helix of DNA wrapped around proteins called histones. Consists of two sister chromatids.

Question 15

What is a chromatid?

Answer 15

Each double-stranded DNA copy is called a
chromatid.

Question 16

What are genes?

Answer 16

Region of DNA in chromosome. Codes for specific RNA to be transcribed which is then translated to a specific protein

Question 17

Before cellular division, each chromosome is _________.

Answer 17

replicated

Question 18

Before cellular division, chromosomes _________ into ___________.

Answer 18

Before cellular division, chromosomes condense into compact structures.

Question 19

In mitosis, one _____ of each chromosome is distributed to each of the two ___________.

Answer 19

One copy of each chromosome is distributed to each of the two daughter cells.

Question 20

Once mitosis begins, chromosomes are attached only at _________.

Answer 20

centromere

Question 21

Cells can alternate between the dividing and non-dividing phases. What is the dividing phase and the nondividing phase?

Answer 21

• M (mitosis) phase- dividing phase
• Interphase- non-dividing phase

Question 22

What is the M phase?

Answer 22

Dividing phase: cells in process of separating their chromosomes.

Question 23

What is interphase?

Answer 23

Nondividing phase: chromosomes are uncoiled/uncondense. Cells are growing/preparing to divide.

Question 24

What are the four phases of the cell cycle?

Answer 24

1. Interphase consisting of G1, S, and G2.
2. M phase consisting of mitosis/meiosis

Question 25

What are gap phases?

Answer 25

During which no DNA synthesis occurs.

Question 26

What is the S phase?

Answer 26

Chromosome replication occurs only during interphase, specifically during the S phase.

Question 27

What are two distinct events that occur during M phase?

Answer 27

1. Mitosis 2. Cytokinesis

Question 28

What is cytokinesis?

Answer 28

Division of cytoplasm that forms two daughter cells.

Question 29

When does mitosis begin?

Answer 29

Begins when chromatin condenses.

Question 30

What do sister chromatids do during mitosis?

Answer 30

During mitosis, two sister chromatids separate to form independent daughter chromosomes

Question 31

How many copies does each daughter cell get during mitosis?

Answer 31

One copy of each chromosome goes to each of the two daughter cells.

Question 32

What are the five subphases of mitosis?

Answer 32

1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase

Question 33

What is prophase?

Answer 33

Chromosomes condense, and spindle apparatus begins to form.

Question 34

What is prometaphase?

Answer 34

Nuclear envelop breaks down, and microtubules contact chromosomes at kinetochores.

Question 35

What is metaphase?

Answer 35

Chromosomes migrate to middle of cell.

Question 36

What is anaphase?

Answer 36

Sister chromatids separate into daughter chromosomes, which are pulled to opposite poles of spindle apparatus.

Question 37

What is telophase?

Answer 37

Nuclear envelopes reforms, chromosomes de-condense.

Question 38

What is cytokinesis?

Answer 38

Actin-myosin ring causes the plasma membrane to being pinching in. Two daughter cells form.

Question 39

What are kinetochores?

Answer 39

The structures on sister chromatids where microtubules attach.

Question 40

What are centrosome?

Answer 40

The microtubule-organizing center in animals and certain plants and fungi. Each pole in the spindle apparatus is a centrosome.

Question 41

What are micotubules?

Answer 41

Cytoskeletal filaments that form the spindle apparatus.

Question 42

How does bacteria divide?

Answer 42

Bacteria divide via binary fission.

Question 43

What is binary fission similar to?

Answer 43

Process similar to eukaryotic M phase.

Question 44

What are the three steps to binary fission?

Answer 44

1. Bacterial chromosomes are replicated. 2. Protein filaments attach to replicated bacterial chromosomes. 3. Filaments pull chromosomes apart.

Question 45

What affects cell-cycle length?

Answer 45

Mostly due to variation in length of G1 phase.

Question 46

What phase do rapidly dividing cells eliminate?

Answer 46

Rapidly dividing cells essentially eliminate G1 phase.

Question 47

What phase do nondividing cells get stuck in?

Answer 47

Nondividing cells get permanently stuck in G1 phase.

Question 48

What is the arrested state?

Answer 48

Arrested state is called the G0 state.

Question 49

Variations in cell-cycle length suggest that cell cycle is _________.

Answer 49

regulated

Question 50

What are cell-cycle checkpoints?

Answer 50

Critical points in cell cycle that are regulated.

Question 51

What are regulatory molecules?

Answer 51

Regulatory molecules at each checkpoint allow cell to “decide” whether to proceed with division

Question 52

What happens if regulatory molecules are defective?

Answer 52

If these regulatory molecules are defective, checkpoint may fail. Cells that divide without control may form a tumor.

Question 53

What is the G1 checkpoint?

Answer 53

The cell growth checkpoint. Establishes if cell will continue through cell cycle and divide.

Question 54

What is the G2 checkpoint?

Answer 54

DNA synthesis checkpoint.

Question 55

What is the G3 checkpoint?

Answer 55

Mitosis checkpoint

Question 56

What are the four factors that affect passage through G1 checkpoint?

Answer 56

1. Size 2. Availability of nutrients 3. Social signals from other cells 4. Damage to DNA

Question 57

What is the p53 tumor suppressor?

Answer 57

If DNA is physically damaged, p53 activates proteins that pause cell cycle until damage can be repaired.

Question 58

What is apoptosis?

Answer 58

If cell can't be repaired, p53 initiates apoptosis, programmed cell death.

Question 59

What happens if the p53 gene is damaged?

Answer 59

Damage to the p53 gene can lead to uncontrolled cell division.

Question 60

Where does the G2 checkpoint occur?

Answer 60

Second checkpoint occurs after S phase.

Question 61

What is the G2 checkpoint?

Answer 61

If chromosome replication has not proceeded properly or if DNA is damaged, cells remain in G2 phase.

Question 62

How many M phase checkpoints are there? Where do they occur?

Answer 62

Final two checkpoints occur during Mitosis. One occurs between Metaphase and Anaphase the other between anaphase and telophase.

Question 63

What does the mitosis checkpoint between metaphase and anaphase check for?

Answer 63

Ensures that sister chromatids do not split until all kinetochores are attached to the spindle apparatus

Question 64

What does the mitosis checkpoint between anaphase and telophase check for?

Answer 64

Ensures that chromosomes have fully separated.