Module 2 Control of the Cell Cycle

Question 1

The Tumor suppresors (3)

Answer 1

Retinoblastoma protein:
p53
p21

Question 2

Typical cell cycle duration in Human Cell Maintained in culture

G1 (GAP 1)

G0

S (DNA Synthesis)

G2 (GAP 2)

M (Mitosis)

Answer 2

G1 (GAP 1)
5 hrs

G0
Variable lengths of time

S (DNA Synthesis)
7 hrs

G2 (GAP 2)
3 hrs

M (Mitosis)
1hr

Question 3

Cell turnover:

early embryonic cells

epithelial cells

Specialized cells

Answer 3

early embryonic cells
Few hours

epithelial cells
Two to five days

Specialized cells
Entire human lifespan

Question 4

Examples of specialized cells (2)

Answer 4

Cortical neurons

Cardiac muscle cells

Question 5

Regulation by external events:

Both the ___ and ____of cell division are triggered by events external to the
cell when it is about to begin the replication process.

Answer 5

initiation

inhibition

Question 6

Regulation by external events:

Whatever the source of the message, the cell receives the ____

a series of events within the cell allows it to proceed into ____

Moving forward from this ____ point, every parameter required during each cell cycle phase must be met or the cycle cannot progress.

Answer 6

signal

interphase

initiation

Question 7

Regulation by external events:

The ____ of a nearby cell

The release of ____ hormones such as ____

____ of cells can also inhibit cell divisions

The ____ of the cell can also initiate cell division. This is because the cell becomes inefficient thanks to its ____ ratio wherein it needs to eventually divide.

Answer 7

Death

Growth-promoting hormones
HGH, Human Growth Hormone

Crowding

Size
Surface-to-Volume Ratio

Question 8

____ are proteins that stimulate cell division

Answer 8

Growth Factors

Question 9

Regulation by external events:

A lack of HGH or Human Growth Hormone can result in ____

An excess of HGH or Human Growth Hormone can result in ____

Answer 9

Dwarfism

Gigantism

Question 10

Regulation by Internal Checkpoints:

Mistakes in the duplication or distribution of the chromosomes lead to ____ that may be passed forward to every new cell.

To prevent this, there are ____ that operate at _____.

Answer 10

Mutation

Internal Control Mechanisms

Three Main Cell Cycle Checkpoints

Question 11

Regulation by Internal Checkpoints:

____ one of the several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable

Location of these occur at the (3)

Answer 11

Checkpoint

End of G1

G2/M transition

During Metaphase

Question 12

Regulation by Internal Checkpoints:

The integrity of the DNA is assessed at the ___

Proper _____ is assessed at the ____

Attachment of each ____ to a _____ is assesed at the ____

Answer 12

G1 checkpoint

chromosome duplication
G2 Checkpoint

Kinetochore
Spindle Fiber
M checkpoint

Question 13

G1 checkpoint:

Also called ____(in yeast) determines whether all conditions are favorable for cell division to proceed

It is a point where the cell ____ to the cell division process

Answer 13

Restriction point

Irreversibly commits

Question 14

G1 checkpoint:

Checks the following:

Adequate ___ and ___

Check for ___ at the G1 checkpoint which is then regulated by the ___ protein causing ____

Answer 14

Protein reserves and cell size

Genomic DNA damage
p53 protein
Apoptosis

Question 15

G1 checkpoint:

If failed to meet the conditions, the cell cannot fo into the ____

The cell can halt the cycle and attempt tor emedy the condition or it can advance into ___ and await when conditions improve

Answer 15

S phase

G0 Phase

Question 16

G2 checkpoint:

Bars entry into the ____ phase if certain conditions are not met.

This checkpoint ensures that all of the ____ have been duplicated without damage

Upon failure it either attempts to complete ___ or ___ it

Answer 16

Mitotic phase

Chromosomes

DNA replication
Repair

Question 17

M checkpoint:

Occurs near the ___ stage of ____

It is also known as the ____ because it determines whether the ___ are attached correctly to the ____

Answer 17

Metaphase stage of Karyokinesis

Spindle Attachment Checkpoint
Sister Chromatids
Spindle microtubules

Question 18

In addition to the checkpoints, there are ___ that regulate the cell cycle.

They either promote progress of the cell into the next phase called ____

Or they halt the cycle called ____

Answer 18

Regulatory molecules

Positive regulation

Negative regulation

Question 19

Regulatory molecules:

The failure of a single regulator may have almost no effect on the cell cycle, especially if more than one mechanism controls an event

However, the effect of a deficient or ____ can be wide-ranging ang possibly fatal if multiple processes are involved

Answer 19

Non-functioning regulator

Question 20

Positive regulation:

There are two types of proteins which are responsible for the progress of the cell through various checkpoints

However, the ___ only regulate when bound to the ___

A ____ is an enzyme that transfers a phosphate group onto a protein through phosphorylation

Answer 20

Cyclins

Cyclin-Dependent Kinases (Cdks)

Kinase

Question 21

Initiation of Mitosis:

____ The protein complex which initiates the mitotic phase of the cell cycle

It is made up of :

____ Oscillates in quality during the cell cycle. High concentrations necessary to enter M phase, low concentration necessary to leave M phase

_____ Constant quantity and encoded by the ___ gene. Only functional when bound to its cyclin.

Answer 21

Mitosis-promoting Factor

Cyclin B

CDC2 Kinase
CDC2

Question 22

Initiation of Mitosis:

Once mitosis has been initiated, the ___ decrades the Cyclin B protein of the Mitosis Promotion Factor

It also causes the separation of ___ at the start of ___

Answer 22

Anaphase-Promoting Complex (APC)

Sister Chromatids
Anaphase

Question 23

Negative regulation:

Best understood ____ are (3):

___ a group of tumor-suppresor proteins common in many cells

The number designations refer to the functional molecular masses of the proteins known as _____

Answer 23

Negative Regulatory Molecules

Rb
p53
p21

retinoblastoma protein

Kilodaltons

Question 24

Negative regulation:

A faulty copy of a regulatory protein may cause cells to replicate uncontrollably becoming ____

Rb, p53, p21 primarily act at the ____

Answer 24

cancerous

G1 checkpoint

Question 25

Cancer cells can become tumors

___ remain clustered and can be removed

____ are able to ___ or break away and form new tumors

____ are substances that promote cancer

Answer 25

Benign tumors

Malignant tumors
Metastasize

Carcinogens

Question 26

Negative regulation:

____ acts when there is damaged DNA in cells undergoing preparatory processes in G1

It halts the cell cycle and recruits ___ to repair the DNA and if it cannot be repaired, it triggers ___ to prevent the duplication of damaged chromosomes

Answer 26

p53

Enzymes
Apoptosis

Question 27

Negative regulation:

As ___ levels rise, the production of ___ is triggered which enforces the halt of the cell cycle by binding and inhibiting the activity of ____

As a cell is exposed to more stress, higher levels of these proteins accumulate making it less likely that a cell will move into ____

Answer 27

p53

p21
cdk/cyclin complexes

S phase

Question 28

Negative regulation:

____ exerts its regulatory influence on other positive regulator proteins.

It usually monitors cell size.

It binds to proteins called ____, namely the one called ____ which “turn on” specific genes to produce certain proteins.

Answer 28

Rb Retinoblastoma Tumour Suppressor Protein

Transcription Factors
E2F

Question 29

Negative regulation:

As the cell increases size, the RB is phosphorylated by ____ / ____ In turn, RB releases E2F which activates the ____ also known as ____

Answer 29

Cyclin D + CDK4
Cyclin D + CDK 6

Transition Protein
Cyclin E

Question 30

Apoptosis is also known as ____

It occurs in normal development when cells are temporarily required for a maturation process. It also occurs in genetically damaged cells.

An example being (2)

Answer 30

Programmed Cell Death

Embryonic Development
Metamorphosis

Question 31

Apoptosis:

A well-known example of apoptosis is in the animal ____

It is signaled by the ____ which causes the animal to digest their tail cells, reabsorbing and recycling the digestion products into new structures

Answer 31

Frog

Thyroid hormone

Question 32

Cells that die from an unexpected injury undergo ____ which is an accidental death.

Answer 32

Necrosis

Question 33

Key differences between apoptosis and necrosis:

In nectrotic cells, the ____ does not shrink or fragment

In necrotic cells, ____ form but fuse

In necrotic cells, the ____ bursts to release the cell contents into the extracellular environment

Answer 33

Nucleus

Blebs

Cell membrane

Question 34

Key differences between apoptosis and necrosis:

Nucleus in this case does ____

In cells undergoing apoptosis, the blebs turn into ____ and the cell contents are not released into the extracellular environment

Answer 34

fragment

Apoptotic bodies