Chapter 7 - cell cycles

Question 1

what is cell growth and division important for?

Answer 1

• Increasing population size (single-celled organisms)
• Growing new tissues (e.g. new leaves during plant development)
• Asexual reproduction (bacteria, fungi, corals, many others)
• Replacement of lost cells (lining of gut) and/or damaged cells (wound repair)

Question 2

what is binary fission ?

Answer 2

• Involves coordinated cytoplasmic growth, DNA replication, and cell division
• Results in two daughter cells from an original single parent cell
• DNA replication occupies most of the cell cycle in rapidly dividing prokaryotic cells

Question 3

what is The Bacterial Cell Cycle?

Answer 3

Replication of the bacterial chromosome
consumes most of the time in the cell cycle

Question 4

where does the bacterial cycle begin?

Answer 4

single site called the origin of replication (ori) through reactions catalyzed by enzymes located in the middle of the cell

Question 5

Mitotic Cell Division

Answer 5

Eukaryotes : Genome: multiple, large, linear chromosomes , DNA in nucleus
Prokaryotes : Genome: one small, circular chromosome ,
DNA in cytoplasm

Question 6

what is the cell cycle?

Answer 6

A period of growth followed by nuclear division and cytokinesis

Question 7

what is the purpose of mitosis?

Answer 7

divides replicated DNA equally and precisely
* Ensures the two cells resulting from a cell division have the same genetic information as the parent cell entering division

Question 8

Mitosis is the basis for ?

Answer 8

• Growth and maintenance of body mass in multicellular
  eukaryotes
• The reproduction of many single-celled eukaryotes

Question 9

how is the DNA of eukaryotic cells divided?

Answer 9

divided among individual, linear chromosomes

Question 10

number of chromosome sets of a cell or species is called

Answer 10

Ploidy

Question 11

Haploid

Answer 11

a cell with one complete set of chromosomes

Question 12

Diploid

Answer 12

a cell with two complete sets of chromosomes

Question 13

what are sister chromatids ?

Answer 13

Replication of DNA of each individual chromosome
creates two identical molecules

Question 14

Chromosome segregation

Answer 14

Equal distribution of daughter chromosomes to each of two cells resulting from cell division

Question 15

phases of the eukaryotic cell cycle

Answer 15

interphase , prophase, metaphase, anaphase, telo phase

Question 16

what is interphase?

Answer 16

is the first stage of the cell cycle; it begins immediately
after mitosis (& cytokinesis) and continues until the beginning of the next mitosis

Question 17

three phases of interphase

Answer 17

1. G1 phase: The cell carries out its function(s), and in
   some cases grows, during this initial “gap” phase
2. S phase: DNA replication and chromosome
   duplication occur
3. G2 phase: A second “gap” in the cell cycle when cell
   growth continues and the cell prepares for mitosis
   and cytokinesis

Question 18

mitotic cell cycle :

Answer 18

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 19

Stage 1: Prophase

Answer 19

• Chromosomes condense into compact, rod-like structures
• Spindle forms in the cytoplasm

Question 20

Stage 2: Prometaphase

Answer 20

• Nuclear envelope breaks down
• Spindle enters former nuclear area
• Microtubules from opposite spindle poles attach to two kinetochores of each chromosome

Question 21

Stage 3: Metaphase

Answer 21

• Spindle is fully formed
• Chromosomes align at spindle midpoint
  * Moved by spindle microtubules

Question 22

Stage 4: Anaphase

Answer 22

• Spindle separates sister chromatids and moves them to opposite spindle poles
• Chromosome segregation is complete

Question 23

Stage 5: Telophase

Answer 23

• Chromosomes decondense
  
  • Return to extended state typical of interphase
• New nuclear envelope forms around chromosomes

Question 24

what is cytokinesis?

Answer 24

completes cell division by dividing the cytoplasm between daughter cells

Question 25

Cytokinesis in animals

Answer 25

- proceeds by furrowing - Band of microfilaments forms just inside the plasma membrane, forming belt - Microfilaments slide together and tighten band, constricting cell and forming furrow in plasma membrane - Gradually separates cytoplasm into two parts

Question 26

plant cytokinesis

Answer 26

* Cell wall material is deposited along the plane of former spindle midpoint * Deposition continues until continuous new wall (cell plate) separates daughter cells

Question 27

centrosomes

Answer 27

contain a pair of centrioles that divide and move apart

Question 28

Microtubules

Answer 28

radiate outwards from centrosomes to form the spindle

Question 29

Plant cells do not contain centrosomes. true or false

Answer 29

TRUEEEEE

Question 30

Kinetochore microtubules

Answer 30

Connect chromosomes to spindle poles

Question 31

Nonkinetochore microtubules

Answer 31

- Extend between spindle poles without connecting to chromosomes - At spindle midpoint, microtubules from one pole overlap with those from opposite pole

Question 32

Kinetochore Movement

Answer 32

* Chromosomes move by sliding over or along kinetochore microtubules * Microtubules disassemble as kinetochore passes over them