BIOL 1010 Lecture Notes - Lecture 2: Microtubule Organizing Center, Rudolf Virchow, Sister Chromatids

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3 May 2018

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The Cell Cycle

October 2, 2014

In 1855, Rudolf Virchow (a German doctor) added the last part of the Cell Theory:

Cells can only arise by division from a pre-existing cell.

Genetic Material Organization

Genome – total of the entire DNA in a cell

DNA is organized as chromatin inside the nucleus. DNA can either be relaxed or condensed.

The total length of DNA in your body would be able to go to the sun and back.

Chromosomes are made up of chromatin. When the cell is getting ready to divide, the

chromatin condenses and chromosomes become visible.

Cell Division

Mitosis – division of genetic material after replication

Cytokinesis – division of the cytoplasm

Chromosomes duplicate before cell division.

After duplicating, each chromosome consists of two sister chromatids (each a piece of linear

DNA) held together at the centromere. These chromatids are identical.

The two sister chromatids will ne separated by separase during mitosis and cytokinesis.

Microtubules provide the machinery for mitosis. The centrosome is the microtubule-

organizing center of the cell.

Interphase (G2)

• DNA (chromatin) still unwound

• Centrosomes have been duplicated

• Chromosomes duplicate

• Cells prepare for division

Phases of Mitosis:

1. Prophase

• Chromatin starts to condense

• Centrosomes move to opposite poles

• Spindle fibres form

2. Prometaphase

• Chromosomes have finished condensing

• Two centrioles are at opposite sides of the nucleus

• Nuclear envelope disintegrates

• Microtubules capture chromosomes by attaching to kinetochores

3. Metaphase

• Chromosomes line up in the middle of the cell at the metaphase plate

• Confirms that there is a microtubules attached to every kinetochore

• Centrioles are at opposite poles

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Document Summary

In 1855, rudolf virchow (a german doctor) added the last part of the cell theory: Cells can only arise by division from a pre-existing cell. Genome total of the entire dna in a cell. Dna is organized as chromatin inside the nucleus. The total length of dna in your body would be able to go to the sun and back. When the cell is getting ready to divide, the chromatin condenses and chromosomes become visible. Mitosis division of genetic material after replication. After duplicating, each chromosome consists of two sister chromatids (each a piece of linear. The two sister chromatids will ne separated by separase during mitosis and cytokinesis. The centrosome is the microtubule- organizing center of the cell. Interphase (g2: dna (chromatin) still unwound, centrosomes have been duplicated, chromosomes duplicate, cells prepare for division. Cytokinesis (splitting of the cytoplasm: a cleavage furrow forms which pinches two daughter cell apart.

Related Questions

What is the difference between chromatin and chromosomes?

Question options:

	chromatin is one of two identical strands of DNA.
	chromosomes are chromatin that has been tightly packed and coiled.
	chromosomes are composed of nucleosomes and chromatin is composed of sister chromatids.
	chromosomes are important in mitosis and chromatin is essential to meiosis.

Bacterial cells only reproduce asexually and cannot exchange genetic material.

Question options:

	True, because they undergo binary fission.
	False, because they transfer genetic material with other bacterial cells.
	True, because they have a cell wall that prevents sharing of genetic material.

After a visit to a specialist, Dan was diagnosed with liver cancer. Six months later additional tumors were found in his stomach and small intestine. This is an example of

Question options:

	malignant tumors.
	benign tumors.
	Both malignant tumors and metastasis are correct.

Which of the following does NOT occur during mitosis?

Question options:

	DNA is replicated.
	Replicated chromosomes divide.
	Cells line up along the equator of the cell.

Which of the following is INCORRECTLY matched?

Question options:

	prophase -- mitotic spindle forms
	metaphase -- chromosomes line up along the equator
	telophase -- cytoplasm divides

Why is hair loss a common side effect of cancer treatments?

Question options:

Hair cells are at the surface of the body so die easily.

Hair cells divide rapidly and so are targeted by the cancer drugs.

Cancer drugs often target and kill random cells within the body.

From "Investigating Life: Cutting Off a Tumor's Supply Lines in the War on Cancer," how are endostatins used to treat cancerous cells?

Question options:

	They prevent angiogenesis by cancerous cells.
	They promote growth of new blood vessels to feed cells.
	They bind to receptors on cancerous cells and prevent cells from reproducing.

1)What experiment was performed that allowed for scientists to finally agree that DNA is the genetic material within living organisms?

a.Understand the materials and scientific techniques used to come to this result.

2)What group of experiments led to the discovery of the mechanism used in DNA replication?

a.Understand the materials and scientific techniques used to come to this result.

i.What is a cesium chloride gradient?

ii.Where do 14N and 15N respectively fall along this gradient?

b.The results revealed that DNA replicates using which of the three proposed models?

i. Describe the mechanism of each model.

3)What is the role of the following proteins in DNA replication?

a.Helicase

b.Single strand binding proteins

c.Topoisomerase

d.DNA polymerase III

e.DNA polymerase I

f.Primase

g.Ligase

4)What extra steps are taken to be sure the lagging strand does not shorten each time DNA is replicated?

a.What is the role of telomerase in these âstepsâ?

5)In DNA repair, which enzyme has âproof-readingâ capabilities?

1)Which type of cells within our bodies use mitosis to reproduce?

2)Does mitosis create a cell that is different or the same as the parent cell undergoing division?

3)Describe the DNA found in sister chromatids.

4)Describe the DNA found in homologous chromosomes.

5)What occurs during the following stages of the cell cycle?

a.G₁ Phase

b.S Phase

c.G₂ Phase

d.M Phase

What are the phases of mitosis? What events occur in each phase?

1)Does mitosis separate homologous chromosomes, sister chromatids, or both?

2)What is cytokinesis?

a.Which fibers of the cytoskeleton contract to pinch parent and daughter cells apart from one another in animals?

b.How do microtubules move chromosomes to the two poles of a dividing cell?

3)How are centrioles involved in this process?

a.How do plants form two complete cells during cytokinesis?

4)How do bacterial cells reproduce?

5)The cell cycle is controlled at âcheckpointsâ. What occurs at each of the following checkpoints?

a.G₁ Checkpoint

b.G₂ Checkpoint

c.M Checkpoint

6)How do cyclin and cdk act to control the G2 checkpoint?

7)If presented with the schematic of the M checkpoint, you should be able to explain perturbations to the system as well as if the cell will divide or stall at metaphase.

8)Cancerous cells form when the cell cycle checkpoints do not function correctly and continues to divide even though it is damaged in some way. How does the protein p53 function to keep these cells from dividing?

9)Normal cells follow certain rules of growth that cancerous cells do not follow. What are these rules (provide a short definition for each as well)?

10)What is the difference between a benign tumor and a malignant tumor?

indigohedgehog242

1)What are the inputs of photosynthesis?

2)What are the outputs of photosynthesis?

3)Light-Dependent Reactions

Where does the first stage of photosynthesis, the light-dependent reactions, occur within a chloroplast?

Where does the energy come from that drives these reactions?

What molecule donates an electron to the reaction center of photosystem II?

How is the energy of an electron changed as it moves along the ETC?

How does the electrical charge of the thylakoid membrane affect protons (H+) within the chloroplast?

Where does the electron that is donated to photosystem I come from?

What are the final products of this series of reactions?

What happens to each of the final products from this series of reactions?

4)Light-Independent Reactions (Calvin Cycle)

a.Where does the second stage of photosynthesis, the Calvin Cycle, occur within a chloroplast?

b.What are the direct inputs for these reactions?

c.What are the three steps to the Calvin cycle?

d.What are the final products of this reaction?

e.What role does rubisco play in the Calvin Cycle?

1)What experiment was performed that allowed for scientists to finally agree that DNA is the genetic material within living organisms?

a.Understand the materials and scientific techniques used to come to this result.

2)What group of experiments led to the discovery of the mechanism used in DNA replication?

a.Understand the materials and scientific techniques used to come to this result.

i.What is a cesium chloride gradient?

ii.Where do 14N and 15N respectively fall along this gradient?

b.The results revealed that DNA replicates using which of the three proposed models?

i. Describe the mechanism of each model.

3)What is the role of the following proteins in DNA replication?

a.Helicase

b.Single strand binding proteins

c.Topoisomerase

d.DNA polymerase III

e.DNA polymerase I

f.Primase

g.Ligase

4)What extra steps are taken to be sure the lagging strand does not shorten each time DNA is replicated?

a.What is the role of telomerase in these âstepsâ?

5)In DNA repair, which enzyme has âproof-readingâ capabilities?

1)Which type of cells within our bodies use mitosis to reproduce?

2)Does mitosis create a cell that is different or the same as the parent cell undergoing division?

3)Describe the DNA found in sister chromatids.

4)Describe the DNA found in homologous chromosomes.

5)What occurs during the following stages of the cell cycle?

a.G₁ Phase

b.S Phase

c.G₂ Phase

d.M Phase

What are the phases of mitosis? What events occur in each phase?

1)Does mitosis separate homologous chromosomes, sister chromatids, or both?

2)What is cytokinesis?

a.Which fibers of the cytoskeleton contract to pinch parent and daughter cells apart from one another in animals?

b.How do microtubules move chromosomes to the two poles of a dividing cell?

3)How are centrioles involved in this process?

a.How do plants form two complete cells during cytokinesis?

4)How do bacterial cells reproduce?

5)The cell cycle is controlled at âcheckpointsâ. What occurs at each of the following checkpoints?

a.G₁ Checkpoint

b.G₂ Checkpoint

c.M Checkpoint

6)How do cyclin and cdk act to control the G2 checkpoint?

7)If presented with the schematic of the M checkpoint, you should be able to explain perturbations to the system as well as if the cell will divide or stall at metaphase.

9)Normal cells follow certain rules of growth that cancerous cells do not follow. What are these rules (provide a short definition for each as well)?

10)What is the difference between a benign tumor and a malignant tumor?

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BIOL 1010 Lecture Notes - Lecture 2: Microtubule Organizing Center, Rudolf Virchow, Sister Chromatids

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