Biology 1000 - Mitosis and the Cell Cycle

When does chromosome replication occur?

Before cell division.

What type of reproduction is Prokaryotic binary fission?

Asexual.

How do Bacteria reproduce?

Binary fission.

What is Binary fission?

the process of producing clones by replicating chromosomes and separating them and divides the cell using Cytoskeletal proteins.

Starting with 1 cell, how many cells would there be after 5 rounds of divisions?

32.

What is mitosis used for in Eukayotes?

Asexual reproduction, growth and development, and tissue renewal.

What are the 2 sections that the cell cycle can be divided into?

Mitosis and interphase.

What is the time spent not dividing in the cell called?

Interphase.

What are the 3 phases of interphase?

G1 phase, S phase, and G2 phase.

What is the G1 phase and what happens during it?

It is the “first gap” in the cell cycle, happens after mitosis and before DNA synthesis. In this phase the cell produces protein, RNA, and lipids etc., and prepares for DNA synthesis.

What is the S phase and what happens durring it?

DNA synthesis occurs; Happens after G1 phase and before G2 phase.

What is the G2 phase and what happens during it.

It is the “second gap”; Happens after S phase and before mitosis. In this phase, the cell grows, produces RNA, protein, and lipids etc., and makes molecules required for mitosis.

What happens in DNA synthesis of S phase?

Centrioles replicate, DNA replicates, and chromosomal proteins are synthesized.

What shape is the Eukaryotic chromosome?

A linear double helix of DNA.

What is the centromeres function in a Eukaryotic chromosome?

To link a pair of sister chromatids.

What is a telomere?

A region of repetitive DNA sequences at the end of a chromosome.

What results from S phase DNA replication?

Sister chromatids.

Where are the centromeres located?

In the middle of each DNA strand.

Does the chromosome number and amount of DNA change following S phase?

Chromosome number stays the same but amount of DNA changes.

If a cell has 2 chromosomes before S phase, how many sister chromatids is there after S phase?

4 (2x the amount of DNA).

Is a pair of sister chromatids considered 1 or 2 chromosomes?

1 chromosome.

What are sister chromatids physically held together by?

Thousands of cohesions proteins.

How many chromatids are in a replicated chomosomes?

2.

Hoe many chromatids are in a unreplicated chromosome?

1.

True or false; both a pair of sister chromatids and a single chromatid is considered a chromosome?

True.

What is Karyokinesis?

Division of the chromosomes.

What is Cytokinesis?

Division of the cytoplasm.

In animals and plants what does cell divsion require the loss of?

The nuclear membrane.

What is the M phase of the cell cycle?

Mitosis; Division of one nucleus into 2 genetically identical nuclei.

What are the phases of mitosis?

Interphase, Prophase, Prometaphase, Metaphase, Anaphase. Telophase, and Cytokinesis.

What happens in Interphase?

DNA replication and preperation for mitosis.

What happens in Prophase of mitosis?

Chromosomes condense and early spindles form.

What is a centrosome?

A structure made of centrioles and microtubules.

Where are centrioles?

At the center of a centrosome, connected to microtubules.

How is a miotic spindle formed?

The centrosome duplicates its centriole pairs, and moves both a parent and daughter centriole to opposite sides of the nucleus, connected by a mass of microtubules forming the early spindle.

What structures are formed in Phrophase?

Sister chromatids, miotic spindle, and Kinetochores.

What is Codensin’s function in Prophase?

Promotes chromosome condensation (forms rings).

How are Centromeres and Kinetochores related?

The Centromere is a narrow region on the chromosome where Kinetochores (protein structures that format the centromere and bind spindle microtubules), will form and where sister chromatids attach tightly.

What happens during Prometaphase of mitosis?

Starts with loss of nuclear membrane, then mitotic spindle continuous to form as microtubules elongate and some of their microtubules begin to attach to Kinetochores. Chromosomes begin to move.

What are the 3 types of microtubules in mitosis?

Kinetochore microtubules, Non-kinetochore microtubes (polar microtubules), and Astral microtubules.

What do Kinetochore microtubules do in mitosis?

Connect to a chromosome.

What do Non-kinetochore microtubules (polar microtublues) do in mitosis?

Extends outwards and overlap with other non-kinetochore microtubules extending from the opposite pole.

What do Astral microtubules do in mitosis?

Radiate towards plasma membrane.

How many chromosomes and chromatids will there be in a cell with 20 chromosomes in G1?

20 chromosomes and 20 chromatids.

What happens in late Prometaphase?

Spindle matures and chromosomes settle at metaphase plate.

What happens during metaphase of mitosis?

Sister chromatids line up at metaphase plate (done via microtubules), miotic spindle is complete, centrosomes are at poles, and Kinetochores of each sister chromatid attached to microtubules oriented to opposite poles (spindle fibers).

What happens during Anaphase of mitosis?

Proteins holding sister chromatids together (cohesions) are cleaved by enzymes, sister chromatids separate and move to opposite poles (via microtubules and motor proteins), Kinetochore fibers shorten/disassemble, and cell lengthens for division.

Do Kinetochore microtubules shorten from the + or - end?

the + end.

What do Kinetochore microtubules do in spindle separation?

They move chromatids toward the poles.

What do the non-Kinetochore microtubules do in spindle separation?

They overlap at the cell midpoint pushing poles further apart to lengthen the cell in preparation for cytokinesis.

What happens during Telophase of mitosis?

Chromosomes reach poles, nuclear membrane starts to reform, chromosomes begin to de-condense, mitotic spindle reverts to Interphase Centrosomes and Cytokinesis occurs.

How does Cytokenesis occur in Animal cells?

Division of Cytoplasm via contractile ring (actin myosin at equator contracts pinching the cell in 2), causing a cleavage furrow.

How does Cytokinesis occur in plant cells?

A new membrane called the cell plate forms at the equator, separating the cytoplasm of 2 daughter cells, and the cell plate lays down the cell wall for ach daughter cell.

What do plants form in place of centrioles in mitosis?

Multiple microtubule nucleation sites along nucleus.