topic 10 (part 1)

Question 1

7list the stages of the cell cycle

Answer 1

1. G1 phase
2. S phase
3. G2 phase
4. M phase

Question 2

the cell cycle consists of _____ and _____?

Answer 2

interphase and mitosis

Question 3

what is G0 phase also known as?

Answer 3

quiescent phase

Question 4

what occurs during G0 phase?

Answer 4

non-dividing cells enter this phase and rest

Question 5

cells exit G1 and enter G0 in order to _____

Answer 5

differentiate

Question 6

differentiated cells enter from G0 to G1 after the action of _____?

Answer 6

growth factors (mytogens)

Question 7

what are 3 types of cells differentiated according to their cell division potential?

Answer 7

• post-mitotic cells
• cells that divide upon appropriate stimulation (signals)
• cells with high mitotic activity

Question 8

what are post-mitotic cells?

Answer 8

terminally differentiated cells which have lost their ability to replicate (permanently arrested at G0)

Question 9

what is an example of a post-mitotic cell?

Answer 9

neural cells, RBCs, cardiac muscle cells

Question 10

what is an example of cells that divide upon appropriate stimulation (signals)

Answer 10

lymphocytes upon antigenic presentation

Question 11

what is an example of cells with high mitotic activity?

Answer 11

germ cells, stem cells, epithelial cells

Question 12

what occurs during G1 phase? how long does it last?

Answer 12

• preparation for DNA replication
• protein synthesis/organelle production
• 5-6 hrs

Question 13

what occurs during S phase? how long does it last?

Answer 13

• DNA synthesis
• 10-12 hrs

Question 14

what occurs during G2 phase? how long does it last?

Answer 14

• preparation for mitosis
• (same as G1)
• 4-6 hrs

Question 15

what are the 2 types of cells?

Answer 15

• somatic (diploid cells)
• gametes (haploid)

Question 16

what are homologous chromosomes?

Answer 16

chromosomes that carry the same genes at the same positions

Question 17

what occurs during interphase?

Answer 17

• chromosomes are not condensed

G1 - each chromosomes consists of one chromatid (not yet replicated)

S - DNA is replicated

G2 - each duplicated chromosome has 2 sister chromatids

Question 18

what is the difference between sister chromatids and homologous chromosomes?

Answer 18

sister chromatids - are genetically identical and used in cell division

homologous chromosomes - composed of two different chromosomes that are not genetically identical despite containing the same sets of genes

Question 19

what occurs during mitosis (cell division)?

Answer 19

• the chromosomes condense
• sister chromatids separate (each future daughter cell receives one chromatid)

Question 20

the mitotic phase (M phase) consists of _____ and _____

Answer 20

• mitosis (division of the nucleus)
• cytokinesis (division of the cytoplasm)

Question 21

mitosis consists of 5 phases

Answer 21

• prophase
• prometaphase
• metaphase
• anaphase
• telophase

Question 22

prophase

Answer 22

1. chromatin condenses into distinct chromosomes
2. nucleoli disappear/nuclear membrane degrades
3. mitotic spindle begins forming (composed of centrosomes & microtubules)

Question 23

prometaphase

Answer 23

1. fragments of the nuclear envelope are seen
2. microtubules extending from each centrosome can invade the nuclear area and bind to the chromosomes

Question 24

metaphase

Answer 24

1. chromosomes become aligned at the metaphase plate
2. centrosomes are now at opposite poles

Question 25

anaphase

Answer 25

1. each sister chromatid of a chromosome moves towards opposite poles 2. by the end, the two poles of the cell have equivalent collections of chromosomes (chromatids)

Question 26

telophase

Answer 26

1. nucleoli reappear/nuclear envelope reforms 2. chromosomes decondense 3. two daughter nuclei form 4. mitosis is complete

Question 27

cytokinesis

Answer 27

occurs in animal cells by a process called cleavage, where a cleavage furrow forms, and cells are completely separated

Question 28

mitotic spindle begins to form by

Answer 28

polymerization of mictrotubules

Question 29

microtubule polymerization starts from

Answer 29

the centrosome

Question 30

kinetochores

Answer 30

protein structures found at the centromere of each chromosome

Question 31

_____ attach to the kinetochores of the chromatids to move chromosomes towards the metaphase plate

Answer 31

mitotic spindle microtubules

Question 32

kinetochores are also the attachment point for

Answer 32

motor proteins

Question 33

3 types of mitotic spindle microtubules

Answer 33

1. astral microtubules 2. kinetochore microtubules (or chromosomal) 3. polar microtubules

Question 34

astral microtubules

Answer 34

- radial (star-like) structure around the centrosome - helps in positioning of the spindle in the cell

Question 35

kinetochore microtubules

Answer 35

- join the centrosome with the kinetochores of the chromosomes - helps in chromosomal movement

Question 36

polar microtubules

Answer 36

- start from the centrosome but do not attach to the chromosomes - interact with other polar microtubules projecting from the other pole - help maintain the integrity of the spindle

Question 37

nuclear lamin

Answer 37

intermediate filaments present in the nuclear lamina

Question 38

nuclear lamin phosphorylation

Answer 38

nuclear envelope degradation and packaging into vesicles

Question 39

begins upon degradation of nuclear envelope

Answer 39

prometaphase

Question 40

in prometaphase chromosomes move towards the cell center (metaphase plate) by

Answer 40

polymerization/depolymerization of kinetochore microtubules

Question 41

if chromosomes are not aligned correctly in metaphase

Answer 41

cell cycle arrest signal is activated

Question 42

endoplasmic reticulum and golgi apparatus are degraded and packaged into vesicles during _____ and reformed during _____

Answer 42

prophase, telophase

Question 43

prokaryotes reproduce by

Answer 43

binary fission

Question 44

compared to eukaryotic cell cycle, binary fission is

Answer 44

much faster and more simple (1-3 hrs)

Question 45

binary fission being much quicker is important to

Answer 45

allow rapid evolution of bacteria

Question 46

multiple fission

Answer 46

some unicellular eukaryotes exhibit types of cell division intermediate between mitosis and binary fission that is usually followed by multiple cytokinesis