CH 17

Question 1

Cell theory(Cell Reproduction)

Answer 1

-All cells come from pre-existing cells
-You get more cells by cell reproduction

Question 2

Why do we need to make new cells:

Answer 2

• For growth
  -repair and replace old cells
  -without growth they cant mature

Question 3

What parts do you need to make a new cell?

Answer 3

Lipid bilayer, organelles, and genetic material

Question 4

Two types of cell reproduction:

Answer 4

1. Mitosis – new diploid (somatic) cells
2. Meiosis – generates haploid (germ) cells

Question 5

Two major phases of the cell cycle

Answer 5

1. Interphase: Occurs between cell divisions
2. Mitotic Phase: When the cell actually divides

Question 6

Period between cell division

Answer 6

Interphase

Question 7

3 stages of interphase

Answer 7

-G1 (1st growth period)
Primary growth phase. very active growing while still doing its function

-S (Synthesis)
Makes a second copy of DNA before the next cell division (DNA Replication)

-G2 (2nd growth period)
Final growth phase, prepares the cell to divide

Question 8

Stages of Mitotic Phase

Answer 8

Nuclear division: The nucleus inside the cell divides

Cytoplasmic Division: Division of the cytoplasm into two daughter cells

Question 9

How long is the cell cycle

Answer 9

-18-24 hours in mammals
-different for every cell

Question 10

What’s the G0 Phase

Answer 10

This stops cells from proliferating unnecessarily

Question 11

Genetically identical to parent cell

Answer 11

Daughter cells (Offspring) –

Question 12

Phases of Mitosis

Answer 12

1. Prophase
   First appearance of chromosomes
2. Metaphase
   thechromosomesbecome attached to thespindlefibers
3. Anaphase
   thechromosomesmove away from one another to oppositepolesof thespindle
4. Telophase
   the final phase of cell division, thechromatidsorchromosomesmove to opposite ends of the cell and twonucleiare formed

Question 13

-Mitotic spindle forms from centrioles
-Chromatin condenses into visible chromosome
-Nuclear membrane dissolves

Answer 13

Prophase

Question 14

-Chromosomes form a single line across the equator of the cell
-No separation occurs as they are still held together by the centromeres

Answer 14

Metaphase

Question 15

-The daughter chromatids are pulled in opposite directions

-Duplicate DNA molecules separate and are pulled away by microtubules of the mitotic spindle

-Cytokinesis usually begins at this time

-Shortest phase of mitosis lasting only minutes

Answer 15

Anaphase

Question 16

-Two sets of chromosomes arrive at opposite poles of the cell

-Mitotic spindle disintegrates

-Nuclear membrane re-forms around the chromosomes

-Chromosomes uncoil and revert to chromatin

Answer 16

Telophase

Question 17

Two daughter cells that are formed

Answer 17

Cytokinesis

Question 18

Meiosis includes two successive cell divisions:

Answer 18

Meiosis I: produces two haploid daughter cells, but chromosomes are still in duplicated state.

Meiosis II: each of the two daughter cells from Meiosis I goes through Meiosis II,

Question 19

At the end of Meiosis 2..

Answer 19

In males - four haploid sperm cells result; all are viable,

In females – one haploid egg cell and 3 polar bodies result; only the egg is viable.

Question 20

Whats the purpose of meiosis

Answer 20

Allows the sperm and egg to each contribute
-one set of haploid chromosomes

-to the formation of a new organism

Question 21

How many chromosomes does a human have

Answer 21

46 chromosomes