Module 1 Centrosome cycle

Question 1

___ Phase.

Occurs after the M phase of the previous cycle.

A resting phase, also known as the ___ phase since no ___ takes place during this stage.

Also called the ___ phase, since it involves synthesis of ___, ___ and ___ which leads to the growth of ___ and ___ of each daughter cell towards their mature size.

Answer 1

G1

First gap
DNA synthesis

First growth
RNA, proteins, and membranes
Nucleus
Cytoplasm

Question 2

During G1 phase, ___ is ___ and not distinguishable as discrete chromosomes.

Answer 2

Chromatin (DNA and protein)

fully extended

Question 3

G1 involves the transcription of these RNAs (3)

Answer 3

rRNA - ribosomal

tRNA - transfer

mRNA - messenger

Question 4

rRNA synthesis is indicated by the appearance of ___ in the interphase (G1 phase) nucleus.

Answer 4

Nucleolus

Question 5

Proteins synthesized during G1 phase are (3)

Answer 5

Regulatory proteins that control events in mitosis

Enzymes like DNA polymerase for DNA synthesis of next stage

Tubulin (form microtubules, a skeletal structure) and other mitotic apparatus proteins

Question 6

G1 phase is the most variable as to duration; it either occupies __ to __ percent of total time in cell cycle or entirely lacking or abesnt in ___ or ___ that no longer divide.

Answer 6

30 to 50

rapidly dividing cells
terminally differentiated somatic cells

Question 7

Examples of Rapidly dividing cells (2)

Examples of Terminally Differentiated Somatic Cells (2)

Answer 7

Blastomeres of early embryo in frogs and mamamls

Neurons, striated muscle cells

Question 8

___ phase.

Synthetic phase of interphase.
___ and ___ occur.

Answer 8

S

Replication of DNA
Synthesis of histone proteins (structural proteins of chromosome)

Question 9

To provide ___, large amounts of ___ are needed. Thus, each chromosome has two DNA molecules and a duplicate set of genes.

Answer 9

Nucleosomes

Histones

Question 10

S phase occupies roughly ___ to ___ percent of the cell cycle.

Answer 10

35 to 45

Question 11

__ phase.

This is a second gap or ___ phase of interphase. Synthesis of ___ and ___ continues which is required for cell growth.

Answer 11

G2

growth/resting

RNA and proteins

Question 12

Interphase cells have distinct ___ complete with ___, well demarcated from the rest of the cell.

Answer 12

nuclei

intact nuclear envelope

Question 13

In animal interphase cells, a daughter pair of ___ originates near the existing one and thus an interphase cell has two pairs of them which are positioned ___ to each other.

Answer 13

centrioles

perpendicular

Question 14

T or F: Net membrane biosynthesis slows down just before cell division. This is because there is extra membrane stored as ___ on the surface of the cells about to divide.

Answer 14

False, net membrane is FASTER and is THEN stored as blebs.