BABS1201 Lecture Notes - Lecture 10: Centriole, Microtubule, Metaphase

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rubysalmon926

28 May 2018

School

UNSW, UNSW Sydney

Department

Biotechnology & Biomolecular Sciences

Course

BABS1201

Professor

All

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Cell Division and Reproduction

Binary fission

• The cell division in bacteria

• DNA replication starts at the origin of replication

• Each origin becomes attached separately to the plasma membrane

o Proteins bind at the origin and attach to the plasma membrane

• After replication is completed, the plasma membrane grows inward to separate the two new

daughter cells

•

Cell division

• Large numbers of cells must replication often to produce the adult human

• It is essential that this process is precisely regulated

o Uncontrolled growth = cancer

The cell cycle

• Cell cycle times vary for different cell types

•

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• Two phases:

Interphase

• Growth and replication of cellular components

o G1 stage - growing and carrying out metabolic function

o S (DNA synthesis) - DNA replicates

o G2 - growth of other organelles

Mitotic phase (M)

• Split into two daughter cells

o Nucleus divides

o Mitosis - chromosomes are distributed to daughter cells

o Cytokinesis - cytoplasm divides into two daughter cells

▪ Cyto = cell, kinesis = movement

▪ (cell separation)

Stage S

• DNA is replicated

• Packaged with proteins (chromatin)

• Condensed for cell division

•

o One double helix becomes two double stranded helices

o Each double helix is packaged with proteins (histone)

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•

o Chromatin loops to form two sister chromatids

o Centromere - where sister chromatids are attached

▪ Sister chromatids split during cell division

o Chromosome is only visible during cell replication

Mitotic cell division

• G2 of Interphase

o Centrosomes (with centriole pairs)

o G2

▪ DNA has been replicated

▪ Not condensed

o DNA replicated within the nucleus

• Prophase

o Centrosomes - moving apart, fibres are extending from them

o Condense chromosomes - packaged with proteins

•

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Document Summary

Large numbers of cells must replication often to produce the adult human. It is essential that this process is precisely regulated: uncontrolled growth = cancer. The cell cycle: cell cycle times vary for different cell types, two phases: Interphase: growth and replication of cellular components, g1 stage - growing and carrying out metabolic function, s (dna synthesis) - dna replicates, g2 - growth of other organelles. Split into two daughter cells: nucleus divides, mitosis - chromosomes are distributed to daughter cells, cytokinesis - cytoplasm divides into two daughter cells, cyto = cell, kinesis = movement (cell separation) Sister chromatids split during cell division: chromosome is only visible during cell replication. Cytokinesis in animal and plant cells: animal cells, rings of microfilaments cleave the membrane, separating into two daughter, cells, plant cells, pla(cid:374)ts do(cid:374)"t have flexible (cid:373)e(cid:373)bra(cid:374)es, lays down new cell wall, cell plate fuses with the cell wall.

Related Questions

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.

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?

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BABS1201 Lecture Notes - Lecture 10: Centriole, Microtubule, Metaphase

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