BIO230H1 Lecture Notes - Lecture 5: Cyclin A, Cyclin E, Cell Growth

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Lecture Ten: Cell Cycle

Eukaryotic Cell Cycle:

• Life requires cell growth and division

• The cell cycle is the repeated duplication

of the cell’s contents and division of

these components into two

• A critical aspect of cell division is the

fidelity with which the cell duplicates

and segregates its genome

Cell Cycle:

1. Interphase:

a. G1 Phase:

• Cell growth and partially

doubling proteins and

organelles

b. S Phase:

• DNA replication

c. G2 Phase:

• Cell growth and remaining

doubling of proteins and

organelles

2. M Phase:

a. Mitosis:

• Nuclear division

b. Cytokinesis:

• Cytoplasmic division

Successful completion of cell cycle requires the temporal coordination of many processes

(aka checkpoints)

1. Start Checkpoint:

• Is the environment favorable?

o Yes – will enter S phase

o No – will wait

2. G2/M Checkpoint:

• Is all the DNA replicated?

• Is the environment favorable?

o Yes – will enter M phase

o No – will wait

3. Metaphase-to-Anaphase Transition:

• Are all chromosomes attached to spindles?

o Yes – will trigger anaphase and proceed cytokinesis

o No – will wait

There are 3 major

checkpoints – other

cells may have more

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NEVER have the same

or different CDK with

the SAME Cyclin

o Phosphorylation of lamin leads to nuclear envelope breakdown

o Regulates proteins required for chromosome condensation

o Phosphorylates microtubule regulators (important for making the mitotic spindle)

Checkpoint Regulation: Cdks (Cyclin Dependent Kinases)

• Cdks are the traffic lights of the cell cycle control system

• Cdks are protein kinases with targets that

control the cell cycle

• Their activity gives the “green light” to pass

through a check point

• Cyclin binding is require for activity – one

way to switch from a red to green light

a) If we have a cdk it requires a cyclin and an activating phosphate

b) If it has all the requirements it will use ATP to phosphorylate a target

• Different cyclin-Cdk checkpoints act at different

stages of the cell cycle

o Cdk requires a cyclic and activating phosphate

and ATP to work

▪ There are different types of cyclic to phosphate

different targets at each stage:

• For budding yeasts, they have the same

CDK and the activity is controlled by different Cyclin

• For vertebrates, they can have the same CDK with

different Cyclin or different CDK with different Cyclin

Activation of Cdk:

• Requires Cyclin and Activating Phosphate

A. Cdk is Inactive

• ATP is the ATP binding site

(for when it phosphorylates)

T-loop is part of the protein

B. Cdk is Partially Active

• Cyclin comes in and moves

the t-loop which opens up

the active site

• Extremely low activity

(still known as inactive)

C. Cdk is Fully Active

• Cdk – Activating Kinase (CAK) will come in and phosphorylate the t-loop which

forms the activating phosphate

S-Cdk Activity:

• Inhibits an inhibitor of the origin recognition complex promoting DNA replication

M-Cdk Activity:

• Phosphorylates multiple targets required to start mitosis

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Document Summary

Cell cycle: interphase, g1 phase, cell growth and partially doubling proteins and organelles, s phase, dna replication, g2 phase, cell growth and remaining doubling of proteins and organelles, m phase, mitosis, nuclear division, cytokinesis, cytoplasmic division. Successful completion of cell cycle requires the temporal coordination of many processes (aka checkpoints: start checkpoint: Is the environment favorable: yes will enter s phase, no will wait, g2/m checkpoint: Is the environment favorable: yes will enter m phase, no will wait, metaphase-to-anaphase transition: There are 3 major checkpoints other cells may have more: are all chromosomes attached to spindles, yes will trigger anaphase and proceed cytokinesis, no will wait. Never have the same or different cdk with the same cyclin and atp to work: there are different types of cyclic to phosphate different targets at each stage, for budding yeasts, they have the same.

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

Question 1

The process by which RNA is synthesized using DNA as a template is â¦

Select one:

a. replication

b. transcription

c. translation

d. inspiration

Question 2

Which of the following occurs during meiosis but not mitosis?

Select one:

a. DNA condenses into chromosomes

b. nuclear envelop disappears

c. homologous chromosomes separate

d. sister chromatids separate

Question 3

Which part of the animal life cycle is haploid?

Select one:

a. gamete

b. zygote

c. sporophyte

d. spore

Question 4

Single celled eukaryotic organisms are â¦

Select one:

a. viruses

b. bacterial

c. archaea

d. protists

Question 5

Which type of cellular division results in the formation of diploid cells from a diploid parent cell?

Select one:

a. mitosis

b. meiosis

c. interphase

d. A and B but not C

e. all of the above

Question 6

A sequence of DNA that codes for a single protein is a â¦

Select one:

a. gene

b. ribosome

c. mRNA

d. none of the above

Question 7

Which of the following is characteristic of animals?

Select one:

a. heterotrophic

b. sexual reproduction

c. embryonic development

d. all of the above

Question 8

All genes have only two possible alleles.

Select one:

True

False

Question 9

The presence of membrane-bound organelles is characteristic of â¦

Select one:

a. prokaryotes

b. viruses

c. bacteria

d. eukaryotes

Question 10

What are the building blocks of proteins?

Select one:

a. fatty acids

b. amino acids

c. nucleic acids

d. all of the above

Question 11

During which phase of the cell cycle does DNA replication occur?

Select one:

a. Mitosis

b. Interphase

c. Meiosis

d. Replicosis

Question 12

Which of the following characteristic is shared among fungi and animals?

Select one:

a. autotrophic

b. heterotrophic

c. cell walls

d. absorb nutrients

Question 13

A error in DNA replication that goes unrepaired is a â¦

Select one:

a. chromosome

b. chromatid

c. mutation

d. none of the above

Question 14

Alternate forms of a gene are called ________.

Select one:

a. chromatids

b. chromosomes

c. ribosomal subunits

d. alleles

Question 15

The physical expression of a genotype is the phenotype.

Select one:

True

False

Question 16

In complete dominance, a heterozygous genotype results in â¦

Select one:

a. a recessive phenotype

b. a dominant phenotype

c. a third and unique phenotype

d. none of the above

Question 17

Which theory explains the evolution of eukaryotes from prokaryotes?

Select one:

a. phagocytosis

b. endosymbiosis

c. pinocytosis

d. none of the above

Question 18

Which scientist experimented with plants to describe patterns of inheritance?

Select one:

a. Mendel

b. Chase

c. Einstein

d. Watson

Question 19

Which cellular organelle contains aerobic cellular respiration?

Select one:

a. chloroplasts

b. mitochondria

c. nucleus

d. lysosome

Question 20

Which of the following statements is false?

Select one:

a. Haploid gametes are formed by meiosis

b. Mitosis forms genetically identical daughter cells

c. Mitosis results in the formation of four daughter cells from a single parent cell

d. Mitosis forms diploid daughter cells from a diploid parent cell

Question 21

The first forms of life on Earth were ________.

Select one:

a. plants

b. microorganisms

c. birds

d. dinosaurs

Question 22

Which of the following is used to separate chromosomes during nuclear division?

Select one:

a. cytoskeleton

b. microtubules

c. actin and myosin

d. amoeboid movement

e. all of the above

Question 23

Which generation is most dominant in more primitive plants?

Select one:

a. bryophyte

b. sporophyte

c. gametophyte

d. androphyte

Question 24

Which of the following is characteristic of plants?

Select one:

a. autotrophic

b. contain chloroplasts

c. multicellular

d. all of the above

Question 25

During which phase of mitosis do chromosome line up along the middle of the cell?

Select one:

a. prophase

b. metaphase

c. anaphase

d. telophase

Question 26

During which phase of mitosis does DNA condense into distinct chromosomes?

Select one:

a. prophase

b. metaphase

c. anaphase

d. telophase

Question 27

The process by which DNA is used as a template to make new DNA is â¦

Select one:

a. translation

b. replication

c. transcription

d. allocation

Question 28

Which of the following is characteristic of plant but not animal cells?

Select one:

a. chloroplasts

b. water vacuole

c. cell wall

d. all of the above

Question 29

Which meiotic division is most like mitosis?

Select one:

a. Meiosis I

b. Meiosis II

c. Meiosis III

d. Meiosis IV

Question 30

Which enzyme catalyzes replication?

Select one:

a. DNA polymerase

b. RNA polymerase

c. Ribosome

d. all of the above

BIO230H1 Lecture Notes - Lecture 5: Cyclin A, Cyclin E, Cell Growth

BIO230H1 Full Course Notes

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