Bio chap 12

The continuity of life is based on the reproduction of cells or

cell division

In unicellular organisms, the division of one cell reproduces what?

The entire organism

Multicellular eukaryotes depend of cell division for?

• Development from a fertilized cell

• Growth

• Repair

Cell cycle

The life of a cell from formation to its own division

Reproduction

Growth and development

Tissue renewal

Genome

All of the DNA in a cell

DNA molecules in a cell are packaged into?

Chromosomes

A genome can consist of

A single DNA molecules (prokaryotic) or a number of DNA molecules (eukaryotic)

Centrosome

Organelle that produces microtubules

Centriolles

Factory site of microtubule production

Microtubules are

Spindle fibers

One portion of the chromosome is called

A sister chromatid

A sister chromatid after being replicated and copied becomes what?

A chromosome

Chromatin

A complex of DNA and protein that condenses during cell division

Somatic cells

(nonreproductive cells) have two sets of chromosomes

Gametes

(reproductive cells: sperm and eggs) Have half as many chromosomes as somatic cells

How is a nucelosome extended?

By being wrapped around histones, which then becomes a DNA complex

centromere

The attachment site of chromosomes

What happens to sister chromatids during cell division?

They separate and move into two nuclei

One separate, the sister chromatids are called?

Chromosomes

Eukaryotic cell division consists of

Mitosis and cytokinesis

Mitosis

The division of genetic material in the nucleus

Cytokinesis

The division of the cytoplasm

Cell cycle phases

• Mitotic phase

• Interphase- G1 phase, S phase, and G2 phase

Mitotic phase

Mitosis and cytokinesis

Interphase

Cell growth and copying of chromosomes in preparation for cell division

Which phase is about 90% of the cell cycle?

Inrerphase

G1 phase

First gap

S phase

Synthesis

G2 phase

Second gap where chromosomes are duplicated

Telophase and cytokinesis

Anaphase

Metaphase

Prometaphase

Prophase

First step of cellular division before prophase

G2 of interphase

First step of cellular division

Prophase

Second step of cellular division

Prometaphase

Third step of cellular division

Metaphase

Forth step of cellular division

Anaphase

Fifth step of cellular division

Telophase and cytokinesis

Mitotic spindle

A structure made of microtubules that controls chromosome movement during mitosis

In animal cells, assemble of spindle microtubules begins in?

The centrosome; The microtubule organizing center

What replicated during interphase?

The centrosome, forming two chromosomes

Centrioles

Mirrotubule

Aster

A radial array of short microtubules that extends from each centrosome

Aster

Early mitotic spindle

Centromere

Chromosome

Prometaphase

Some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosome

Kinetochores

Protein complexes associated with centromeres

Metaphase

Chromosomes are line up at the metaphase plate

Metaphase plate

A plane midway between the spindle’s two poles

Separase

Cleaves cphesions in anaphase

Anaphase

Sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell

Depolymerizing

Shortens microtubules at their kinetochore ends during telophase

Kinetochore

Nonkinetochore microtubules from opposite poles during anaphase

Overlap and push against each other, elongating the cell

Kinetochore

A structure composed of several proteins that associate with the centromere region of a chromosome and bind to spindle microtubules

Telophase

Genetically identical daughter nuclei form at opposite ends of the cell

When does cytokinesis begin?

During anaphase or telophase and the spindle eventually disassembles

Similarity between plant and animal cell division?

The identical cells will be at the end

Difference between plant and animal cell division

Plant cells have a cell wall and cell plate while animal cells have the cleavage furrow

In animal cells, cytokinesis occurs by a process know as cleavage. What does this form?

Cleavage furrow

Binary fission

Chromosome replicates, and two daughter chromosomes actively move apart

The plasma membrane in binary fission of bacteria

It pinches inward, dividing the cell in two

Prokaryotes reproduce binary fission

True

Step one of mitosis

Chromosome replication begins

Step 2 of mitosis

One copy of the origin is now at the end of the cell

Step 3 of mitosis

Replication finishes

Step 4 of mitosis

Two daughter cells result

Mitosis evolved from binary fission

True

This type of cell division occurs where?

In bacteria

This type of cell division occurs where?

Dinoflagellates

This type of cell division occurs where?

Diatoms and some yeasts

This type of cell division occurs where?

Most eukaryotes

Cell cycle control system

Directs the sequential events of the cell cycle

The cell cycle control system is regulated by?

Internal and external controls

Checkpoinds

Areas where the cell cycle stops until a go-ahead signal is received

M checkpoint

Ensures that the spindle fibers attach properly during metaphase

G1 checkpoint

Inhibits S-phase entry in G1 cells that have not yet committed DNA replication

G2 checkpoint

Ensures that the cell has completed DNA replication and that the replicated DNA is undamaged before entering mitosis

Cyclins and Cyclin-dependent kinases

Regulatory proteins involved in cell cycle control

With changes in concentration of its cyclin partner, what happens to Cdk?

The activity rises and falls

Maturation-promoting factor (MPF)

Cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase

Fluctuation of MPF activity and cyclin concentration during cell cycle

Molecular mechanisms that help regulate the cell cycle

Checkpoints register signals from outside the cell

True

Most important checkpoint

G1

G0 phase

If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state

Example of an internal signal

Cells will not being anaphase until all chromosomes are properly attached to the spindle at the metaphase plate

Integral signal ensures?

That daughter cells have the correct number of chromsomes

Growth factors

Released by certain cells and stimulate other cells to divide

Platelets form what?

Platelet-derived growth factor (PDGF)

Platelets

Blood cell fragments

Density-dependent inhibition

Crowded cells will stop dividing