Cell cycle

Question 1

What does cell division allow for?

Answer 1

1. Reproduction of cells
2. Growth of cells and tissue repair

Question 2

Cell cycle definition

Answer 2

The life of a cell from it’s formation until it divides

Question 3

What do cells have to do before division?

Answer 3

1. Organize and package their DNA
2. DNA associates with and wraps around proteins known as histones to form nucleosomes
3. Strings of nucleosomes form chromatin, which after DNA replication condenses to form a chromosome
4. Each chromosome has a duplicated copy due to DNA replication which joint together to form sister chromatids

Question 4

Centromere

Answer 4

The region on each sister chromatid where they are most closely attached

Question 5

Kinetochore

Answer 5

Proteins attached to the centromere that link each sister chromatid to the mitotic spindle

Question 6

Genome

Answer 6

All of a cells genetic info (DNA)

Question 7

Eukaryotes

Answer 7

One or more linear chromosomes

Question 8

Homologous chromosomes

Answer 8

Two chromosomes (one from mom and one from dad) that are the same length , have the same centromere position, and carry genes controlling the same characteristics

Question 9

Somatic cells

Answer 9

-Body cells
-Diploid (2n): two sets of chromosomes, one set from each parent (46)
-Divide by mitosis

Question 10

Gamete cells

Answer 10

-Reproductive cells (eggs/sperm)
-Haploid (n): one set of chromosomes (23)
-Divide by meiosis

Question 11

What does the cell cycle consist of?

Answer 11

Alternating phases of interphase and mitosis

Question 12

Interphase

Answer 12

-Longest portion of the cell cycle
G1 “first gap” phase- Cell grows and carries out normal functions
S “synthesis” phase-DNA replication and chromosome duplication occurs
G2 “second gap” phase- Final growth and prep for mitosis

Question 13

M phase

Answer 13

Mitosis: nucleus divides- results in two identical diploid daughter cells
Cytokinesis- Cytoplasm divides

Question 14

Phases of mitosis

Answer 14

-PPMAT
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telephase and cytokinesis

Question 15

Prophase

Answer 15

-Chromatin condenses
-Nucleoli disappears
-Duplicated chromosomes appear as sister chromatids
-Mitotic spindle begins to form
-Centrosomes move away from each other

Question 16

Prometaphase

Answer 16

-Nuclear envelope fragments
-Microtubules enter area and attach to kinetochores

Question 17

Metaphase

Answer 17

-think middle
-Centrosomes are at opposite poles
-Chromosomes line up at the metaphase plate
-Microtubules are attached to each kinetochore

Question 18

Anaphase

Answer 18

-Sister chromatids separate and move to opposite ends of the cell due to microtubules shortening
-Cell elongates

Question 19

Telephase

Answer 19

-Two daughter Nuclei form
-Nucleoli reappears
-Chromosomes become less condensed

Question 20

Cytokinesis

Answer 20

-cytoplasm divides
Animals: Cleavage furrow appears due to a contractile ring of actin filaments
Plants: Vesicles produced by the golgi travel to the middle of the cell and form a cell plate

Question 21

Regulation of the cell cycle

Answer 21

-Throughout the cell cycle there are checkpoints
-Control points that regulate the cell cycle
-Cells receive stop/go signals

Question 22

G1 Checkpoint

Answer 22

-Most important checkpoint
-Checks for cell size, growth factors and DNA damage

Question 23

Stop/go signals

Answer 23

Stop- Cell enters a nondividing (quiescent) stage known as G0
Go- Cell completes the whole cell cycle

Question 24

G0

Answer 24

-Some cells stay here forever (muscle/nerve cells)
-Some cells can be called back into the cycle

Question 25

G2 checkpoint

Answer 25

-Checks for completion of DNA replication and DNA damage
-“go”- Cell proceeds to mitosis
-“stop”-Cell cycle stops and the cell will attempt to repair damage
*If damage cannot be repaired the cell goes through programmed death known as apoptosis

Question 26

M (spindle) checkpoint

Answer 26

-Checks for microtubule attachment to chromosomes
at the kinetochores at metaphase
-“go”- cell proceeds to anaphase and completes mitosis
-“stop”- cell will pause mitosis to allow for spindles to finish attaching to chromosomes

Question 27

Internal cell regulators

Answer 27

1. Proteins known as cyclins
2. Enzymes known as cyclin-dependent kinases (CDK’s)-concentration remains constant. Active only when it’s specific cyclin is present
   -Each CDK has a specific regulatory effect
   *active CDK complexes phosphorylate target proteins, which help regulate key events in the cell cycle

Question 28

External cell cycle regulators

Answer 28

1. Growth factors
2. Contact inhibition
3. Anchorage dependence

Question 29

Growth factors

Answer 29

Hormones released by cells that stimulate cell growth
-Signal transduction pathway initiated
-CDK’S activated leading to progression through the cell cycle

Question 30

Contact inhibition

Answer 30

Cell surface receptors recognize contact with other cells
-Initiates signal transduction pathway that stops the cycle in G1 phase

Question 31

Anchorage dependence

Answer 31

Cells rely on attachment to other cells or the extracellular matrix to divide

Question 32

Cancer cells

Answer 32

-Dont follow checkpoints, evade apoptosis and continue dividing, divide infinitely

Question 33

How do normal cells become cancerous?

Answer 33

Through DNA mutations

Question 34

Tumors

Answer 34

-Uncontrollable growth of cells can lead to a tumor
-benign- not cancerous
-Malignant- cancerous
-Metastasis- when cells separate from the tumor and spread elsewhere in the body