BIO221 FALL - Eukaryotic Cell Cycle, Mitosis, Meiosis

What is ‘Cell Theory’

All cells come from a pre-existing cell

What is ‘karyokinesis’

Segregating replicated chromosomes

What is cytogenetics

Study of the structure and function of chromosomes

What is a karyotype:

Number and structure of chromosomes for given organism

What are autosomes

Non-sex chromosomes

What does ‘diploid’ mean

2 complete sets of chromosomes

What does ‘haploid’ mean

1 of each type of chromosome

How many cells does the mother cell have in G1 of mitosis

6 chromosomes; 2 sets of 3 each (diploid)

What type of ploidy is the mother cell in during G1

Diploid

What phase of the mitosis cycle does chromosome replication produce 6 pairs of sister chromatids

S Phase

What happens in G2

Cell prepares to divide

What phase does the cell prepares to divide in

G2

What happens in the M phase of the mitotic cycle

• Nucleus breaks apart and replicated chromosomes condense in preparation for mitosis

  • Sister chromatids separate into two nuclei, 2 cells formed in cytokinesis

What phase in the mitotic cycle does the nucleus break apart and replicated chromosomes condense in preparation for mitosis

M phase

What phase in the mitotic cycle do sister chromatids separate into two nuclei, 2 cells formed in cytyokinesis

M Phase

What happens in the G1 checkpoint

Cell growth, prepare for cell division

What happens during G1 restriction

Determines if cell division should occur

What is the criteria for cell division

Size, contact, chromosome integrity

Why would a cell fall into G0?

Didn’t meet requirements of G1 checkpoint

What is the state of the cell in the G0 checkpoint

The cell is active

What happens in the S Phase checkpoint

DNA replication

What doubles in the S phase checkpoint

DNA content

Does the chromosome number change or stay the same during the S phase checkpoint

STAYS THE SAME

What do the replicated chromosomes consist of

Sister chromatids

What happens during the G2 checkpoint

Checks for DNA damage, determines if all DNA is replicated, monitors levels of proteins needed for M phase

What happens during the M phase checkpoint

Mitosis stops until chromosomes are properly aligned

What is the state of the chromosomes at the start of mitosis

Compact

When are chromatids attached

During mitosis

What is each chromatid

A double-stranded DNA molecule

Which cyclin is made during the G1 checkpoint

The G1 cyclin: Cyclin E; Forms cyclin+cdk complex

What happens to the G1 cyclin during S phase

It is degrade

What is a CDK

Cyclin-dependent kinase

What happens to the CDK during the G2 phase

Continues to move forward in cycle, binds to mitotic cyclin (Cyclin B): Mitotic cyclin+CDK complex

What happens to the mitotic cyclin during M phase

It is degraded as the cell progresses during mitosis

What order do the cyclins work in?

EAB

Which cyclin is continuously used during the whole cycle

Cyclin D

What do cyclin-CDK

Promote progression through the cell cycle

What happens when you bind a cyclin to a CDK

Activates the kinase

How is a kinase activated

Cyclin binds to CDK

What happens once the kinase is activated

• Dephosphorylation of proteins

• Differential gene expression

• Cyclin-CDK complexes can be activated/inactivated

What can G1 mean

Growth

What is the goal in the G1 phase

Big enough cell for division, DNA is ready

Are the genes needed for s phase transcribed?

NO

What is ‘Rb’

Retinoblastoma protein

What happens to MDM2 when it is phosphorylated?

It is inactive

What is P53

Causes cell-cycle arrest and apoptosis

What happens when the cell meets P53

Cell is prevented from progressing further in the cell cycle

What is mitiosis

A type of karyokinesis

What is the result of mitosis

Two genetically identical daughter cells

What is maintained in mitosis

The chromosome number!!

What occurs in diploid AND haploid cells

Mitosis!

Can mitosis occur in diploid and haploid cells?

Yes!!

When does mitosis occur

After S phase

What order does mitosis phases occur?

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

5. Cytokinesis

Please Mind Aunt Tina Chang

MITOSIS: What happens during interphase?

Chromosomes have already replicated during interphase

MITOSIS: What happens during mitiosis

Sister chromatids condense

Mitotic spindle starts to form

Nuclear envelope begins to dissociate into vesicles

Nucleolus no longer visible

What phase do the sister chromatids condense?

Prophase

What phase does the mitotic spindle start to form

Prophase

What phase does the nuclear envelope being to dissociate

Prophase

Can the spindle fibers attach to chromosomes?

No!

What happens during prometaphase of mitiosis

Nuclear envelope has complete dissociated into vesicles, mitotic spindle fully formed. Sister chromatids attach to the spindle via kinetochore microtubules

When has the nuclear envelope completely dissociated into vesicles

Prometaphase

When has the mitotic spindle fully formed

Prometaphase

When has the sister chromatids attached to the spindle via kinetochore microtubules

Prometaphase

What is the centromere bound by

Kinetochore proteins

What type of microtubules are attached to chromosomes at the kinetochore

Kinetochore microtubules

What happens during metaphase of mitosis

Sister chromatids align along metaphase plate in single file fashion

When do sister chromatids align along metaphase plate in single file fashion

Metaphase

How do the sister chromatids align along the metaphase plate

Microtubules lengthen and shorten

What happens during anaphase of mitosis

Sister chromatids separate, individual chromosomes move toward the poles as kinetochore microtubules short. Polar microtubules lengthen and push the poles apart

When do the sister chromatids separate in mitosis

Anaphase

When do individual chromosomes move toward the poles as kinetochore microtubules lengthen and push the poles apart

Anaphase

How do the chromosomes move toward the poles in anaphase

Kinetochore microtubules shorten

How are the poles pushed apart

Polar microtubules lengthen

What happens during Telophase of mitosis

Chromosomes decondense, nuclear envelope re-forms. Cytokinesis separates the mother cell into two daughter cells, beginning with cleavage furrow

When do chromosomes decondense in mitosis

Telophase

When does cytokinesis separate the mother cell into two daughter cells

Telophase

Where are cleavage furrows ONLY found in

Animal cells

What happens during telophase of mitosis

Reformation of nuclear membranes around each set of chromosomes

When are the nuclear membranes reformed around each set of chromosomes

Telophase

When do spindle fibers start to break down

Telophase

What type of ploidy do the daughter cells have in mitosis

Haploid

What happens during Anaphase A

Chromosomes are pulled poleward

What happens during Anaphase B

Poles move apart

What is ‘Meiosis’?

A type of karyokinesis only occurring in germ cells

What type of cells does meiosis only occur in

Germ cells

What type of ploidy are cells in during meiosis

Diploid to haploid

What does genetic recombination mean in meiosis

Homologous chromosomes can exchange genetic information

What is the result of meiosis

Daughter cells have HALF the number of chromosomes as the original germ cell and are genetically different

What happens during prophase I of meiosis

Homologous chromosomes synapse to form bivalents, crossing over occurs. Chromosomes condense, nuclear envelopes begin to dissociate into vesicles

When do homologous chromosomes synapse to form bivalents, resulting in crossing over?

Prophase I of meiosis

When do chromosomes condense in meiosis?

Prophase I

When does the nuclear envelope begin to dissociate into vesicles in meiosis?

Prophase I

What are paired up homologous chromosomes referred to as?

Tetrad

Are paired up homologous chromosomes essential for genetic recombination?

Yes!

What happens in prometaphase I of meiosis?

Nuclear envelope completely dissociates into vesicles, bivalents become attached to kinetochore microtubules

When does nuclear envelop completely dissociate into vesicles in meiosis

Prometaphase I

When do the bivalents become attached to the kinetochore microtubules in meiosis?

Prometaphase I

What happens in metaphase I in meiosis

Bivalents randomly align along the metaphase plate. Each pair of sister chromatids is attached to one pole

When do bivalents randomly align along the metaphase plate in meiosis?

Metaphase I