Cell Cycle

What is the best way to distnguish living things from non-living matter?

Ability of organisms to reproduce

What is the contuinity of life based on?

Reproduction of cells

Why do Cells divide?

To pass on genetically identical info to offspring

What is the Cell Cycle?

Life of a cell from formation until its own division

How much of the cell cycle does ccell division make up?

Small part

How important is cell division in unicellular organisms?

Division of 1 cell reproduces entire organism

What do Multicellular organisms depend on cell division for?

Development from fertilised cell, growth, repair

What does most cell division result in?

Daughter cells w/ identical DNA

What is the relationship btwn genome and DNA?

All DNA in a cell constitues cell’s genome

What can a genome consist of?

1 or more DNA molecules

How are DNA molecules in cells packaged?

Into chromosomes

What are Somatic Cells?

Non-reproductive cells that have 2 sets of chromosomes

How do the number of chromosomes in Gametes compare to Somatic Cells?

Have ½ as many

What do Eukaryotic Chromosomes consist of? (C, D, P)

Chromatin, DNA complex, protein that condense during cell division

Why does the ploidy of daughter cells remain the same after cytokinesis?

Each daughter cell contains 4 chromatids

Why doesn’t single stranded chromatid not affect the ploidy of daughter cells?

Cells will undergo DNA replication and have double stranded chromosomes - sister chromatids

What does each duplicated chromosome have?

2 sister chromatids, separate in cell division

What is the Centromere?

Narrow waist of the duplicated chromosome, where 2 chromatids are most closely attached

What is Mitosis?

Division of the nucleus

What is Cytokinesis?

Division of the cytoplasm

How are Gametes produced?

By variation of cell division (meiosis)

What does Meiosis yield?

Non-identical daughter cells that have only 1 set of chromosomes

What is the Mitotic (M) Phase?

Mitosis and Cytokinesis

What is Interphase?

Cell growth and copying of chromosomes in prep for cell division

What are the steps of the Cell Cycle?

• G1/2 - Gaps

• S - DNA Synthesis

• Cytokinesis

• Mitosis

How do the lengths of the Cell Cycle compare to each other?

G1 > G2 > S > Mitosis and Cytokinesis

What are the 5 phases of Mitosis?

Prophase, Prometaphase, Metaphase, Anaphase, Telophase

What is the Mitotic Spindle?

Apparatus of microtubules that control chromosome movement during mitosis

What is the MTOC’s role in Prophase?

Assmebly of spindle microtubules begins in the centrosome

What is the result of Centrosome replication?

Forms 2 centrosomes that migrate to opposite ends of cell as spindle microtubules grow out from them

What is the Aster?

Radial array of short microtubules, extends from each centrosome

What does the spindle include?

Centrosomes, spindle microtubules, asters

What happens to spindle during prometaphase?

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

What happens to chromosomes in Metaphase?

Lined up at metaphase plate

What is the metaphase plate?

Midway point between spindle’s 2 poles

What is the Mitotic Spindle made of?

Tubulin

What is the relationship of the Mitotic Spindle and Centrosome?

Mitotic spindle radiates out from centrosome

What is the relationship of Chromosomes and Kinetochores?

Chromosomes bind to spindle via kinetochores

Where is the Kinetochore bound to?

Centromeric DNA

What happens to Sister Chromatids in Anaphase?

Separate and move along kinetochore microtubules toward opposite ends of cell

How do Microtubules shorten?

Depolymerising at their kinetoc

How do we know which end the microtubules shorten from during Anaphase?

Microtubules labelled fluorescently

What is Photobleaching used to do?

Decolour a section of the microtubule

What happens as chromosomes moved toward poles?

Pole-side MTs stayed same length, kinetochore side MTs shorten

How do Microtubules shorten during Anaphase?

At kinetochore spindle pole ends

How do Microtubules depolymerise?

At kinetochore end and wlak chromosome towards ends of the cell

What do Non-kinetochore microtubules do?

Non-kinetochore MTs from opposite poles overlap and push against each other, elongating cell

What happens to daughter nuclei in telophase?

Form at opposite ends

How does Cytokinesis occur in animal cells?

Cleavage, forming cleavage furrow

What forms during Cytokinesis in Plants?

Cell plate