Cell Cycle

What happens during prophase?

The DNA condenses into chromosomes, and appear as two chromatids joined by a centromere.

What is the cell cycle?

A series of events that takes place in a cell, leading to its division and replication. The cell division cycle is a vital process by which a single-celled, fertilized egg develops into a mature organism, as well as the process by which many cells are renewed.

What is stage 1 of DNA replication?

An enzyme unwinds the parent DNA strand by breaking the hydrogen bonds between bases (this exposes the base pairs) while another enzyme stops the unwinding strands from becoming knotted.

What is stage 5 of DNA replication?

At the end of DNA replication two new molecules of DNA are produced. Both are exact copies of the original molecule. Each winds up forming a helix, but they remain attached by a centromere.

How do environmental factors affect the rate of mitosis?

Because mitosis involves enzymes, the rate of mitosis is affected by the same factors that affect enzymes, such as temperature (low temperatures result in slow reactions, high temperature result in denaturing the enzyme), pH (enzymes have an optimum pH level at which they work best), and salts.

Why is DNA replication called 'semi-conservative' duplication?

Because one half of the new DNA molecule is an intact strand from the old 'parent' DNA molecule.

What happens during anaphase?

Chromatids of each chromosome get torn apart by the microtubules.

What happens during metaphase?

Chromosomes line up randomly at the cell equator, while a network of fibres called 'microtubules' has formed across the cell to control division.

What are new cells called after cell division?

Daughter cells.

What are the different stages of the cell cycle?

Gap 1 (G1), S, Gap 2 (G2), and M. (However, in cells with a nucleus, it's easier to seperate the cell cycle into two stages: Interphase and Mitosis.)

What are the different phases of mitosis?

Interphase, prophase, metaphase, anaphase, telophase (and cytokinesis).

What is mitosis?

Mitosis is the growth and the repair of tissues. The process begins with a cell that contains a set of 46 chromosomes and ends with two daughter cells, each with their own full set of chromosomes.

How do location of cells affect the rate of mitosis?

Mitosis occurs fastest in area where most growth and replacement is taking place. (Eg hair follicles, bone marrow, skin cells, mucous membrane, etc)

How does the stage of life affect the rate of mitosis?

Mitosis occurs most in cells undergoing growth or repair. (Eg during infancy and puberty or following damage to the organism when repair of tissues is necessary).

How does availability to nutrients and energy affect the rate of mitosis?

Mitosis requires energy, enzymes, and certain substances in order to build new organelles and cell components - replication is slowed or prevented if these nutrients are not available.

What is stage 2 of DNA replication?

New deoxyribonucleotides are brought in. They bond with the bases of the parent DNA strand according to complimentary base pair rules. (A=T, G=C)

What is stage 4 of DNA replication?

Replication is fragmented on the lagging strand. The fragments of nucleotides (known as Okazaki Fragments) are bonded together using the enzyme DNA ligase to form the complementary side of the lagging strand.

What is stage 3 of DNA replication?

Replication of the leading strand is continuous - an enzyme working only in a specific direction bonds deoxyribonucleotides directly to the leading strand.

What factors affect the rate of mitosis?

SALE: Stage of life, availability of nutrients and energy, location of cells, and environmental factors.

What happens during interphase?

The cell is engaged in metabolic activity and is preparing for mitosis. Chromosomes appear in the nucleus as long chromatin threads.

What happens during the G1 phase?

The cell prepares for division and copies organelles.

What happens during the S phase?

The cell's DNA is copied in the process of DNA replication.

What are the two parent strands of DNA called?

The leading strand (3') and the lagging strand (5'). These strands run anti-parallel.

What happens during telophase?

The microtubules retract and a nucleus forms around each set of chromosomes. (After this, cytokinesis pulls them apart to create the two daughter cells.)

What happens during interphase?

The phase in which cells grow, accumulating nutrients needed for mitosis and replicating its chromosomes. (Interphase consists of the G1, S and G2 phases of the cell cycle.)

What is DNA replication?

The process by which the DNA is copied before a cell divides to ensure that every new cell has its own complete copy of the genetic code. It is controlled by enzymes and affect by the same factors that affect mitosis.

What happens during the G2 phase?

This phase ensures that any errors in the chromosomes are repaired and that the cell is ready to proceed before it moves on to the next phase in the cycle.

What happens in the M (mitosis) phase?

This phase includes both mitosis and cytokinesis, during which the chromosomes are sorted and separated to ensure that each daughter cell receives a complete set. After this, cytokinesis divides the cell in two.