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Life: The Science of Biology 11th Edition > Chapter 11. The Cell Cycle and Cell Division > Flashcards

Chapter 11. The Cell Cycle and Cell Division Flashcards

1
Q

Key Concept 11.1 - All Cells Derive from Other Cells

A
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2
Q

What roles does cell division play in organisms?

A
  • It builds the organism from a single cell.
  • It allows tissues to grow and it repairs tissues.
  • It builds the gametes organisms need for reproduction.

11.1 All Cells Derive from Other Cells

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3
Q

What broad steps does cell division follow in eukaryotes and prokaryotes?

A
  1. A reproductive signal - An intracellular or extracellular signal that initiates cell division in that cell.
  2. Replication of DNA - The cell’s DNA must be replicated so that the two new cells produced by cell division can each receive the exact same genetic material.
  3. Segregation of DNA - The replicated DNA must be distributed equally between the two cells.
  4. Cytokinesis - This allows the two cells to split from each other.

11.1 All Cells Derive from Other Cells

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4
Q

In prokaryotes, cell division produces the entire single-celled organism/more cells for the multicellular organism.

A

The entire single-celled organism.

All prokaryotes are single-celled organisms.

11.1 All Cells Derive from Other Cells​

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5
Q

Give a brief description of binary fission

A
  • The cell increases in size.
  • DNA replication occurs
  • Cytoplasm and nuclei separate to form two new cells.

11.1 All Cells Derive from Other Cells​

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6
Q

Name common external factors that act as reproductive signals in prokaryotes.

A

Environmental factors and nutrient factors.

Nutrients such as carbohydrates and mineral nutrients cause Bacillus subtillis to divide every 120 minutes and E.coli to divide every 20 minutes.

11.1 All Cells Derive from Other Cells

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7
Q

Name two regions of the prokaryotic chromosome essential for cell division.

A
  1. ori: the site where replication of the circular chromosome starts (the origin of replication)
  2. ter: the site where replication ends (the terminus of replication)

11.1 All Cells Derive from Other Cells

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8
Q

Most prokaryotes have how many chromosomes?

A

Just one!

11.1 All Cells Derive from Other Cells

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9
Q

What takes place while DNA replication occurs?

A

Anabolic metabolism. This allows the cell to grow in size.

11.1 All Cells Derive from Other Cells

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10
Q

What happens to the two daughter DNA molecules after DNA replication?

A

They separate from each other and move towards opposite poles.

11.1 All Cells Derive from Other Cells

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11
Q

What happens after DNA replication in binary fission?

A

Cytokinesis occurs splitting the one big elongated cell into two daughter cells. The cell pinches to form a ring of fibres. The ring of fibres is composed mainly of a protein called FtsZ (pronounced Fit-Zee).

11.1 All Cells Derive from Other Cells

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12
Q

Binary fission overview (picture of binary fission on back of card)

A

11.1 All Cells Derive from Other Cells

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13
Q

Eukaryotic cells divide when environmental conditions are adequate like prokaryotes

True/False

A

False

11.1 All Cells Derive from Other Cells

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14
Q

In which type of cell (eukaryotic or prokaryotic) is cell division more complex? Suggest reasons for your choice.

A

Cell division is more complicated in eukaryotes.

  1. This is because many eukaryotic cells contain way more chromosomes than a typical prokaryotic cell (46 in humans for example) and a chromosome’s pair of sister chromatids must go to each new cell.
  2. The genetic information of a eukaryotic is stored in the nucleus so there must be measures taken to break down the nucleus to get access to the chromosomes.
  3. The DNA molecules are much larger in eukaryotes.

11.1 All Cells Derive from Other Cells

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15
Q

Mitosis is also known as _____ _______and cytokinesis is also known as _______ _________.

A

nuclear division; cell division

11.1 All Cells Derive from Other Cells

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16
Q

Cytokinesis is different in plant cells than to animal cells. Suggest why.

A

Since plant cells have cell walls and animal cells do not.

11.1 All Cells Derive from Other Cells

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17
Q

Describe the nature of the DNA belonging to the two resulting daughter cells formed by mitosis.

A

The DNA in both of the daughter cells are identical in number and kind (exact same alleles of genes).

11.1 All Cells Derive from Other Cells

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18
Q

Name the other nuclear division process that is responsible for the formation of gametes in eukaryotes.

A

Meiosis (my-oh-sis)

11.1 All Cells Derive from Other Cells

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19
Q

Key Concept 11.2 - The Eukaryotic Cell Division Cycle Is Regulated

A
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20
Q

Key Concept 11.3 - Eukaryotic Cells Divide by Mitosis

A
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21
Q

Key Concept 11.4 - Cell Division Plays Important Roles in the Sexual Life Cycle

A
22
Q

Key Concept 11.5 - Meiosis Leads to the Formation of Gametes

A
23
Q

Key Concept 11.6 - Cell Death Is Important in Living Organisms

A
24
Q

State the two ways a cell can die?

A
  • Necrosis
  • Apoptosis

11.6 Cell Death Is Important in Living Organisms

25
Q

What are the definitions of necrosis and apoptosis?

A

Necrosis - When a cell dies by mechanical injury, toxins or because it was starved of oxygen or nutrients.

Apoptosis - This is programmed cell death.

11.6 Cell Death Is Important in Living Organisms

26
Q

Recall the two possible reasons a cell might undergo apoptosis

A
  1. The cell is no longer needed by the multicellular organism. Example - before a human fetus is born is has webbing between its fingers. Apoptosis helps to eliminate those cells that compose the webbing between the fingers.
  2. The cell has received too much total radiation which increases the chance of DNA damage and thus cancer which would harm the organism.

11.6 Cell Death Is Important in Living Organisms

27
Q

Describe the stages of Apoptosis

A
  1. The cell becomes detached from neighbouring cells.
  2. External signals or internal signals binding to mitochondria releasing other signals activates caspases.
  3. Caspase hydrolyses nucleosomes resulting in apoptosis.
  4. The cell forms membranous blebs that break up into fragments
  5. Neighbouring cells ingest the cell’s fragments by apoptosis.
  6. Engulfed fragments are digested by the cells lysosome organelle and the products of this digestion is recycled.

11.6 Cell Death Is Important in Living Organisms

28
Q

Name the important defence mechanism in plants that utilises apoptosis

A

The defence mechanism is called the hypersensitive response.

More information about this response can be found in chapter 38.

11.6 Cell Death Is Important in Living Organisms

29
Q

How is apoptosis initiated in the first place?

A

By internal and external signals. These can be any of hormones, viral infection, growth factors, intense DNA damage or certain toxins.

The signals (internal or external) bind to receptors that triggers a signal transduction pathway that activates caspases.

11.6 Cell Death Is Important in Living Organisms

30
Q

Suggest why the ability of a multicellular organism to carry out apoptosis could be a selective advantage

A

Apoptosis may be a way to eliminate cells that might develop mutations causing the cell to be harmful to the organism, such as a normal cell turning into a cancer cell. In addition, as an organism develops, organs must be a defined size and shape. Apoptosis may eliminate excess cells that would make an organ too big or misshapen.

11.6 Cell Death Is Important in Living Organisms

31
Q

Key Concept 11.7 - Unregulated Cell Division Can Lead to Cancer

A
32
Q

Put very simply, what is cancer?

A

Cancer is a disease characterised by an abnormal increase in the number of cells.

11.7 Unregulated Cell Division Can Lead to Cancer

33
Q

Name two ways in which cancer cells differ from normal cells.

A
  1. Cancer cells no longer have control over its own cell division.
  2. Cancer cells have the ability to invade neighbouring cells or migrate to other locations in the body.

11.7 Unregulated Cell Division Can Lead to Cancer

34
Q

Most cells in the body divide only if they are exposed to _________ _______ such as ______ _______. Cancer cells _____ ____ respond to these controls and instead divide more or less continuously, ultimately forming _______ (large masses of cells).

A

Extracellular signals: growth factors; do not; tumours

11.7 Unregulated Cell Division Can Lead to Cancer

35
Q

Name the two types of tumours that exist

A
  1. Benign
  2. Malignant

11.7 Unregulated Cell Division Can Lead to Cancer

36
Q

What is meant by a benign tumour?

A

A benign tumour is a mass of cells that look very similar to their neighbouring normal cells, they grow very slowly and always stay in the location they first grew.

Benign tumours are not cancers (since cancers cells have the ability to move to other locations in the body). However, they must be removed if they stop an organ from functioning properly.

11.7 Unregulated Cell Division Can Lead to Cancer

37
Q

What is meant by a malignant tumour?

A

Malignant tumour cells do not look anything like their parent cells. Malignant cells can have different nucleus sizes and shapes.

Malignant cancer cells can invade surrounding and spread to other locations in the body by travelling through the bloodstream or lymphatic ducts. When they become lodged in a new location in the body they will continue growing like nothing happened to create new tumours in more than one location in the body.

This formation of new tumours in different sites of the body is called metastasis and it results in organ failures and makes malignant cancers very hard to treat.

11.7 Unregulated Cell Division Can Lead to Cancer

38
Q

Name a positive regulator of the cell cycle

A

Growth factors

Growth factors are like the gas pedals of the car and make the car (the cell cycle) go

11.7 Unregulated Cell Division Can Lead to Cancer

39
Q

Name a negative regulator of the cell cycle

A

Retinoblastoma (Rb)

Rb is like the brake pedal of a car and it stops the car (the cell cycle) from moving forward; progressing.

11.7 Unregulated Cell Division Can Lead to Cancer

40
Q

The proteins expressed by oncogenes are negative/positive regulators of the cell cycle?

A

Positive regulators

11.7 Unregulated Cell Division Can Lead to Cancer

41
Q

The mutated version of a proto-oncogene is a _______.

A

Oncogene

Point mutations such as deletions and insertions (other mutations can give rise to the creation of oncogenes such as chromosomal mutations) to a proto-oncogene can cause the proto-oncogene to become an oncogene.

Good website: https://www.news-medical.net/life-sciences/What-are-Proto-Oncogenes.aspx

11.7 Unregulated Cell Division Can Lead to Cancer

42
Q

In terms of their actions what makes oncogenes more dangerous than proto-oncogenes?

A
  • Express an overactive protein (caused by insertions and deletions in a proto-oncogene)
  • Transcription of the normal positive cell cycle regulator proteins increases (caused by insertions and deletions in a proto-oncogene)
  • The number of copies of a proto-oncogene (now become an oncogene after mutations) increases (caused by gene amplification)
  • Chromosomal translocation that causes a proto-oncogene to move to a different chromosomal site associated with increased expression
  • Chromosomal translocations that cause a proto-oncogene to fuse with another gene to produce a protein that has oncogenic activity.

11.7 Unregulated Cell Division Can Lead to Cancer

43
Q

Name the type of gene products produced by oncogenes

A

An Oncogenes could express any one protein kind from the following:

  1. Growth factors (positive regulators of the cell cycle)
  2. Receptors for the growth factors
  3. Other components in signal transduction pathways (chapter 7 has more information on signal transduction pathways)

11.7 Unregulated Cell Division Can Lead to Cancer

44
Q

Name the well-known example of an oncogene protein featured in the Life book 11th edition.

The picture below is a hint.

A

HER2

It’s a growth factor receptor found on the surface of breast cells. Normal breast cells have relatively low numbers of HER2 on their surface but in a breast cell with the HER2-coding oncogene, the gene has greatly increased expressivity and will express more HER2 so that the cell’s surface has lots of HER2.

11.7 Unregulated Cell Division Can Lead to Cancer

45
Q

How is cervical cancer caused?

A

Cervical cancer is caused by a virus called HPV (human papillomavirus) that expresses a protein called E7 that binds to and inactivates the tumour suppressor Rb (retinoblastoma) allowing the cell cycle to proceed.

Look up HPV genome on google images and you’ll be able to see the E7 gene that produces the E7 protein.

11.7 Unregulated Cell Division Can Lead to Cancer

46
Q

Does it take more than one active oncogene to cause cancer in an organism?

True/False

A

True

There are two important oncogenes in mouse cells cause myc and ras that are required to be active to cause cancer in the mice.

11.7 Unregulated Cell Division Can Lead to Cancer

47
Q

In the formula,

Growth rate of cell population = rate of cell division – rate of apoptosis

Would the value of growth rate of a healthy cell population be 0, positive or negative?

What would it be for an organism with cancer?

How about an organism with a neurodegenerative disease?

A

Health cell population - A value of 0 since the rate of cell division should equal the rate of apoptosis.

An organism with cancer - A positive value for cell growth rate.

An organism with a neurodegenerative disease - A negative value.

11.7 Unregulated Cell Division Can Lead to Cancer

48
Q

According to Life 11th Edition, what is the most successful treatment for cancer?

A

Surgery

11.7 Unregulated Cell Division Can Lead to Cancer

49
Q

Despite surgery being the most successful type of treatment for cancer according to the Life book 11th edition why is surgery often not curative?

A

Surgery is unlikely to be curative because:

  1. It is difficult for a surgeon to remove all the tumour cells (in just 1 centimetre of a tumour there are a billion tumour cells)
  2. A tumour is usually embedded in normal cells.
  3. There is a probability that a part of an original tumour has broken off and metastasized to other locations in the body.

11.7 Unregulated Cell Division Can Lead to Cancer

50
Q

What is another treatment apart from surgery mentioned in 11.7 and what goals do the treatments have to stop cancer?

A

Drugs that target the cell cycle.

The drugs aim to either decrease cell division or increase apoptosis.

11.7 Unregulated Cell Division Can Lead to Cancer

51
Q

Name some specific drugs and explain how they work? Talk about radiation treatment and explain how that works too.

A
  • 5-fluorouracil - stops the synthesis of the Thymine base in DNA. This DNA damage activates checkpoint(s) (I believe the S checkpoint) and thus triggers apoptosis in this cell.
  • Paclitaxel - prevents the functioning of the mitotic spindle during mitosis. This may also trigger apoptosis in the cell by activating the M checkpoint although I’m not too sure.
  • Herceptin - binds to HER2 receptors without activating them stopping the natural growth factor from binding and activating them (in other words, acts as an agonist). If a growth factor was to bind to the HER2 receptor it would trigger a signal transduction pathway that would eventually lead to cyclin synthesis. Greater production of cyclin means more cyclin-CDK complexes are formed and so tumour suppressors like Rb get phosphorylated by the cyclin-CDK complexes allowing the cell to progress through the cell cycle.
  • Radiation therapy - causes extensive DNA damage triggering apoptosis.

11.7 Unregulated Cell Division Can Lead to Cancer

52
Q

What is one advantage specific drugs have over general cell cycle drugs such as 5-fluorouracil and Paclitaxel?

A

Specific drugs would be able to target altered proteins only tumour cells would produce whereas the general cell cycle drugs affect the cell cycle of every kind of dividing cell (tumour cells and normal cells). This can have an impact on the circulatory system and immune system as healthy RBCs and WBCs targeted by the drugs will die of apoptosis and the person suffering from a tumour may develop anaemia (from lack of RBCs) or become immunosuppressed (from lack of WBCs).

11.7 Unregulated Cell Division Can Lead to Cancer

Life: The Science of Biology 11th Edition (60 decks)

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