cell growth and division

Question 1

what cells in the body don’t undergo cell division

Answer 1

• gametes
• red blood cells
• most neurons
• some muscle cells

Question 2

somatic cells

Answer 2

general term for a body cell and all human cells except for the cells that produce eggs and sperm (germ cells)
- contain 2 copies of each of their chromosomes (one copy received from each parent)

Question 3

homologous

Answer 3

• pair of chromosomes is the two copies of single chromosome found in each somatic cell

Question 4

diploid organism

Answer 4

• humans are!
• have 23 homologous pairs of chromosomes in each of the somatic cells

Question 5

diploidy

Answer 5

condition of having pairs of chromosomes

Question 6

Interphase

Answer 6

• period of cell cycle during which the cell is not dividing
• majority of cells are in interphase

Question 7

mitosis

Answer 7

division of genetic material during which cell nucleus breaks down and two new fully functional nuclei are formed

Question 8

cytokinesis

Answer 8

divides the cytoplasm into two distinctive cells

Question 9

what are the two general phases of the cell cycle

Answer 9

• interphase
• mitosis and cytokinesis

Question 10

what are the phases in interphase?

Answer 10

• g1 phase: growth phase (spend most of time here)
• s phase: synthesis phase, cell replicates its dna, dna doubles
• g2 phase: cell continues to grow and makes necessary preparations for mitosis
  g0 phase: resting phase of cell cycle, cells temporarily stop dividing and are resting, and those who have permenantly stopped dividing (nerve cells)

Question 11

what are each copies of the chromosome called

Answer 11

sister chromatid

Question 12

centromere

Answer 12

structure that attaches one sister chromatid to another
- 46 chromosomes (92 chromatids)

Question 13

Mitotic Phase - what are the 2 parts?

Answer 13

1. complete mitosis (contents of nucleus are equally pulled apart and distributed)
2. cytokinesis (divides cytoplasm and cell body into 2 new cells)

Question 14

what are the 4 major stages of mitosis?

Answer 14

prophase, metaphase, anaphase, and telophase

Question 15

prophase

Answer 15

• first phase of mitosis
  -loosely pascked chromatin coils and condenses into visible chromosomes
• chromosomes become visible with identical partner attached
• forms x shape of sister chromatids
• nucleolus disappears early in this phase
• nuclear envelope also disintegrates
• centrosomes begin to move apart during prophase
• centrosomes migrate to different sides of the cell
• microtubules extend from each ends like fingers

Question 16

centrosome

Answer 16

• a pair of centrioles together
• cell has 2 centrosomes side to side

Question 17

mitotic spindle

Answer 17

structure composed of centrosomes and their emerging microtubules

Question 18

mitotic phase

Answer 18

• cell typically takes between 1-2 hrs
• ## cell undergoes 2 major processes: mitosis and cytokinesis

Question 19

mitosis

Answer 19

• the contents of the nucleus are equitably pulled apart and distributed between its two halves
• four major stages after interphase: prophase, metaphase, anaphase, telophase

Question 20

cytokinesis

Answer 20

divides the cytoplasm and cell body into two new cells

Question 21

describe prophase

Answer 21

1. prophase
   - chromosomes condense and become visible w a partner attached (forms x-shaped sister chromatids)
   - spindle fibers emerge from centrosomes
   - nuclear envelope breaks down
   - centrosomes move toward opposite poles
   - becomes an important structure that contains the site for microtubules growth.

Question 22

2. prometaphse

Answer 22

• chromosomes continue to condense
• kinetochores appear at the centrosomes
  -mitotic spindle microtubules attach to kinetochores

Question 23

3. metaphase

Answer 23

• chromosomes are lined up at metaphase plate
• each sister chromatid is attached to a spindle fiber originating from opposite poles

Question 24

4. anaphase

Answer 24

• centrosomes split in two and forms individual chromosomes
• sister chromatids (now called chromosomes) are pulled towards opposite poles by kinetochores as microtubules shorten
• certain spindle fibers begin to elongate the cell
• each end of cell receivves one parter from each pair os sister chromatids

Question 25

5. telophase

Answer 25

- chromosomes arrive at oppostive poles and begin to decondense - nulear envelope material surrounds each set of chromosomes - new nucleoli from around nuclei - the mitotic spindle breaks down - spindle fibers continue to push poles apart - cell begins to split in half

Question 26

6. cytokinesis

Answer 26

- animal cells: a cleavage furrow separates the daughter cells - plant cells: a cell plate the precursor to a new cell wall, separates the daughter cells

Question 27

Centrosome

Answer 27

- a pair of centrioles together -each cell contains 2 side-by-side - move apart during prophase -

Question 28

centrioles

Answer 28

- cellular structures that serve as origin points from which microtubules extend

Question 29

mitotic spindle

Answer 29

- a structure composed of centrosomes and their emerging microtubules

Question 30

kinetochore

Answer 30

protein structure on the centromere that is the point of attachment between the mitotic spindle and sister chromatids

Question 31

metaphase plate

Answer 31

the name for the plane through the center of the spindle on which the sister chromatids are posisitoned

Question 32

cleavage furrow

Answer 32

- contractile band made up of microfilaments that form around midline of cell during cytokinesis - microfilaments made up of actin - squeezes the two until they seperate

Question 33

Cyclin

Answer 33

one of primary classes of cell control molecules

Question 34

cyclin-dependent kinase (CDK)

Answer 34

one group of molecules that work together with cyclins to determine progression past cell checkpoints