Chapter 8 - The Developing Cell

Question 1

What happens during Growth 1 in interphase?

Answer 1

• cell increases in size and mass
• all metabolic processes remain active
• organelles replicated (except mitochondria and chloroplasts)
• increased protein synthesis occurs

Question 2

What happens during the synthesis phase of interphase?

Answer 2

• DNA is replicated

- using SCR

Question 3

What happens in Growth 2 in interphase?

Answer 3

• chloroplasts and mitochondria increase in size and divide
• energy stores are increased
• spindle fibers start to form

Question 4

What are the 4 stages of mitosis?

Answer 4

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

Question 5

What is cytokinesis?

Answer 5

Equal division of cytosine and organelles

Forms 2 genetically identical daughter cells

Question 6

What is the importance of mitosis?

Answer 6

• growth of multicellular organisms
• repair of damaged tissues
• replacement of cells
• asexual reproduction

Question 7

What happens in prophase?

Answer 7

• longest phase of mitosis
• chromosomes shorten and thicken
• centrioles move towards poles
• microtubules form
• nucleolus breaks down
• nuclear envelope breaks down

Question 8

What happens in metaphase?

Answer 8

• chromosomes line up on the equator

- spindle fibres attach to the centromere

Question 9

What happens in anaphase?

Answer 9

• spindle fibres contract
• pulling force on centromeres
• centromeres split
• daughter chromosomes pulled to opposite poles

Question 10

What happens in telophase?

Answer 10

• daughter chromosomes reach poles
• chromosomes uncoil and lengthen
• spindle fibres disintegrate
• centrioles replicate
• nuclear envelope reforms around chromosomes at each pole
• nucleolus reforms

Question 11

What happens in cytokinesis in animal cells?

Answer 11

• cell surface membrane invaginates
• cleavage furrow forms in the middle of the cell
• cell surface membrane pinches until 2 sides can meet
• cytoplasm divides equally
• organelles divide equally

Question 12

What happens in cytokinesis in plant cells?

Answer 12

• vesicles from golgi apparatus assemble on the equator
• this is the cell plate
• vesicles fuse with each other and with the cell surface membrane
• new sections of cellulose cell wall form along the new sections of membrane (middle lamella)
• cytoplasm divides equally in 2
• organelles divide equally in 2

Question 13

Why is it important that a cell wall is formed along the middle lamella before the 2 daughter cells are separated in plant cells?

Answer 13

to prevent osmotic lysis from the surrounding aqueous environment.

Question 14

What is apoptosis?

Answer 14

• programmed cell death in multicellular organisms

- ordered and controlled process

Question 15

What is necrosis?

Answer 15

• unregulated cell death after trauma
• cell surface membrane ruptures
• hydrolytic enzymes released

Question 16

Events in apoptosis

Answer 16

1. cell shrinks and chromatin in nucleus condenses
2. enzymes break down the cytoskeleton and cell contents
3. cytosol becomes denser
4. cell surface membrane changes and ‘blebs’ form
5. nuclear envelope breaks down
6. DNA fragments
7. cell breaks down into fragments within vesicles
8. phosphatidylserine binds to receptors on macrophages
9. macrophages engulf cell fragments
10. cell debris is removed

Question 17

What is apoptosis essential for?

Answer 17

• developing fetus (distinct fingers and toes)
• puberty
• formation of connections between neurones in the brain
• development of the immune system
• production of xylem tissue in plants

Question 18

What are totipotent stem cells?

Answer 18

Stem cells than can differentiate into all the types of cell within an organism

Question 19

Where are totipotent stem cells found?

Answer 19

• very early embryos

- meristematic tissue in plants

Question 20

What are pluripotent stem cells?

Answer 20

Stem cells that can give rise to any cells of the organism except extra-embryonic cells

Question 21

Where are pluripotent stem cells found?

Answer 21

• the inner cell mass of the blastocyst (embryos that are ~5 days old)

Question 22

What are multipotent stem cells?

Answer 22

Adult stem cells that can give rise to a limited number of cell types related to their origin tissue

Question 23

Where are multipotent stem cells found?

Answer 23

• bone marrow stem cells
• epithelial stem cells
• bone stem cells
• umbilical cord blood