BIO230H1 Lecture Notes - Lecture 10: Cyclin A, Cyclin E, Cyclin-Dependent Kinase 1

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BIO230

Lecture 10

The$cell$cycle$

$Cell$cycle$–$the$repeated$duplication$of$the$cell's$contents$division$of$these$components$

into$two.$$

Eukaryotic$cell$cycle$involved:$

1) Cell$growth$and$Chromosome$replication;$

2) Chromosome$Segregation;$

3) Cell$Division;$

Phases$of$the$eukaryotic$cell$cycle:$

PHASE$

PROCESSES$

G1$

Cell$growth$and$partial$doubing$of$proteins$

and$organelles$

DNA$replication$

G2$

Cell$growth$and$remaining$doubling$of$

proteins$and$organelles$$

Mitosis$and$cytokinesis$

Mitosis$–$nuclear$division$

Cytokinesis$–$cytoplasmic$division$$

Checkpoints,used,to,control,cell,cycle:,

CHECKPOINT$

LOCATION$IN$THE$CELL$

CYCLE$

QUESTION$ASKED$

Start$checkpoint$$

Before$S$Phase$

Is$environment$favourable?$

G2/M$checkpoint$

Before$M$phase$(mitosis)$

Ia$environment$favourable?$

Is$all$DNA$replicated?$

Metaphase-to-anaphase$

transition$

Before$anaphase$(in$M$

phase)$

Are$all$chromosomes$

attached$to$the$spindle$

$$$Cyclin-dependent$protein$kinases$(Cdks)$–$protein$kinases$with$targets$that$control$

cell$cycle$(ensures$a$«Green$light»).$Their$activity$ensures$passing$through$the$checkpoint.$

The$binding$of$cyclin$is$required$for$Cdk$to$be$active.$$$

$$$The$entire$action$of$Cdk$is$dependent$on$the$nature$of$cyclin.$That$means$that$the$same$

cyclin$can$trigger$different$checkpoints,$if$it$is$bound$to$different$cyclins.$$

Ex:,

Cdk1$–$the$Cdk$of$the$budding$yeast$which$controls$all$the$checkpoints$in$the$cell$cycle$of$

budding$yeast$when$boudn$to$different$cyclins.$$

- in$eukaryotes,$it$is$a$little$bit$more$complicated.$Usually$different$Cdks$combine$with$

different$cyclins$to$determine$the$stage$of$the$cell$cycle.$$

Cdk-activating$kinase$(CAK)$–$kinase$that$phorphorylates$Cdk,$thereby$activating$it.$$

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BIO230H1 Full Course Notes

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Document Summary

Cell cycle the repeated duplication of the cell"s contents division of these components into two. Eukaryotic cell cycle involved: cell growth and chromosome replication, chromosome segregation, cell division; Cell growth and partial doubing of proteins and organelles. Cell growth and remaining doubling of proteins and organelles. Cyclin-dependent protein kinases (cdks) protein kinases with targets that control cell cycle (ensures a green light ). The binding of cyclin is required for cdk to be active. The entire action of cdk is dependent on the nature of cyclin. That means that the same cyclin can trigger different checkpoints, if it is bound to different cyclins. Cdk1 the cdk of the budding yeast which controls all the checkpoints in the cell cycle of budding yeast when boudn to different cyclins. in eukaryotes, it is a little bit more complicated. Usually different cdks combine with different cyclins to determine the stage of the cell cycle.

Related Questions

Part A:

In prokaryotes and eukaryotes cell reproduction is similar in that it requires some kind of signal to proceed, DNA replication, careful separation of the DNA into two equal portions, and division of the cytoplasm. How is cell reproduction different in prokaryotes and eukaryotes?

Select one:

a. In a eukaryotic organism, the signals for cell division are usually not related to the environment but to the function of the entire organism.

b. Eukaryotic cells constantly divide whenever environmental conditions are adequate and the cells are large enough.

c. The linear chromosomes in prokaryotes are constantly being updated.

d. Prokaryotic cell division requires cytokinesis before mitosis because of their small size.

e. The sexual phase of most prokaryotes (bacteria) is essential to the rapid cell division required for infection.

Part B:

What does the name Cyclin Dependent Kinase stand for?

Select one:

a. A protein important to the cell cycle that is dependent on DNA synthesis.

b. An enzyme that cuts DNA so that chromosomes can segregate.

c. An enzyme that phosphorylates other proteins using ATP only when the protein Cyclin is bound to the enzyme.

d. An enzyme that rolls along microtubules dragging a vesicle.

e. An enzyme that connects chromosomes to the spindle fiber.

Part C:

The Cell Cycle is divided into Mitosis, Cytokinesis, and Interphase. Mitosis can be ordered into the following phases:

Select one:

a. Prophase/Prometaphase/Metaphase/Anaphase/Telophase

b. Anaphase/Prometaphase/Metaphase/Prophase/Telophase

c. Metaphase/Anaphase/Telophase/Prophase/Prometaphase

d. Telophase/Prophase/Prometaphase/Metaphase/Anaphase

e. Anaphase/Telophase/Prophase/Prometaphase/Metaphase

Part D:

The Cell Cycle is divided into Mitosis, Cytokinesis, and Interphase. Interphase can be ordered into the following phases:

Select one:

a. S/G1/G2

b. G2/G1/S

c. G1/S/G2

d. G2/S/G1

e. G1/G2/S

amethystyak657

Question 3 (5 points)

Match the terms to the definitions provided.

Question 3 options:

	telophase II
	meiosis II
	telophase I
	anaphase I
	anaphase II

1.	Division, beginning without DNA replication, that resembles and produces four haploid cell.s
2.	Phase of meiosis when chiasmata are broken as spindle fibers shorten and homologous pairs are pulled apart.
3.	Phase of meiosis when sister chromatids are pulled to opposite poles of the cells.
4.	Phase of meiosis in which homologues cluster at the poles of the cells and the nuclear envelope reforms.
5.	Phase of meiosis in which four different haploid cells are present.

Question 4 (7 points)

Match the terms to the definitions provided.

Question 4 options:

	G0
	telophase
	G2
	mitosis
	cytokinesis
	cell cycle
	S

1.	The phase in which the cell synthesizes a replica of its genome
2.	The overall process of genome duplication
3.	The phase in the cell cycle during which mitochondria and other organelles replicate.
4.	The phase in mitosis when chromosomes are clustered at opposite poles and the spindle apparatus disappears
5.	A resting state that cells often enter before resuming cell division.
6.	The phase in the cell cycle when the cytoplasm divides creating two daughter cells.
7.	The phase in the cell cycle in which the spindle apparatus assembles and sister chromatids move apart.

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Question 5 (6 points)

Put the events of a MAP kinase cascade in the correct order.

Question 5 options:

	MAPKKK phosphorylates and activates another kinase
	MAPKK phosphorylates and activates MAPK
	Binding of MAPKKK to Ras
	External signal binds to membrane receptor and activates receptor kinase.
	MAPK phosphorylates an inactive response protein and activates it.
	Phosphorylation of receptor kinase and interaction with RAS

1)What experiment was performed that allowed for scientists to finally agree that DNA is the genetic material within living organisms?

a.Understand the materials and scientific techniques used to come to this result.

2)What group of experiments led to the discovery of the mechanism used in DNA replication?

a.Understand the materials and scientific techniques used to come to this result.

i.What is a cesium chloride gradient?

ii.Where do 14N and 15N respectively fall along this gradient?

b.The results revealed that DNA replicates using which of the three proposed models?

i. Describe the mechanism of each model.

3)What is the role of the following proteins in DNA replication?

a.Helicase

b.Single strand binding proteins

c.Topoisomerase

d.DNA polymerase III

e.DNA polymerase I

f.Primase

g.Ligase

4)What extra steps are taken to be sure the lagging strand does not shorten each time DNA is replicated?

a.What is the role of telomerase in these âstepsâ?

5)In DNA repair, which enzyme has âproof-readingâ capabilities?

1)Which type of cells within our bodies use mitosis to reproduce?

2)Does mitosis create a cell that is different or the same as the parent cell undergoing division?

3)Describe the DNA found in sister chromatids.

4)Describe the DNA found in homologous chromosomes.

5)What occurs during the following stages of the cell cycle?

a.G₁ Phase

b.S Phase

c.G₂ Phase

d.M Phase

What are the phases of mitosis? What events occur in each phase?

1)Does mitosis separate homologous chromosomes, sister chromatids, or both?

2)What is cytokinesis?

a.Which fibers of the cytoskeleton contract to pinch parent and daughter cells apart from one another in animals?

b.How do microtubules move chromosomes to the two poles of a dividing cell?

3)How are centrioles involved in this process?

a.How do plants form two complete cells during cytokinesis?

4)How do bacterial cells reproduce?

5)The cell cycle is controlled at âcheckpointsâ. What occurs at each of the following checkpoints?

a.G₁ Checkpoint

b.G₂ Checkpoint

c.M Checkpoint

6)How do cyclin and cdk act to control the G2 checkpoint?

7)If presented with the schematic of the M checkpoint, you should be able to explain perturbations to the system as well as if the cell will divide or stall at metaphase.

8)Cancerous cells form when the cell cycle checkpoints do not function correctly and continues to divide even though it is damaged in some way. How does the protein p53 function to keep these cells from dividing?

9)Normal cells follow certain rules of growth that cancerous cells do not follow. What are these rules (provide a short definition for each as well)?

10)What is the difference between a benign tumor and a malignant tumor?

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BIO230H1 Lecture Notes - Lecture 10: Cyclin A, Cyclin E, Cyclin-Dependent Kinase 1

BIO230H1 Full Course Notes

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