Cancer cells

Question 1

What are the phases of mitosis

Answer 1

Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 2

Explain what happens in prophase

Answer 2

Chromosomes become shorter and thicker into distinct individual chromosomes, nuclear membrane disintegrates (prometaphase), nucleolus disappears, centrioles

Question 3

Explain what happens in Metaphase

Answer 3

The chromosomes are arranged on the equatorial plane of the spindle

Question 4

Explain what happens in anaphase

Answer 4

Sister chromatids separate and are pulled towards opposite poles as the spindle fibers contract

Question 5

Explain what happens in telophase

Answer 5

Chromatids have reached the poles, a nuclear membrane appears, the nucleoli form, and cytokinesis takes place

Question 6

Explain what happens in cytokinesis

Answer 6

The division of the cytoplasm into two cells

Question 7

Explain cancer

Answer 7

• All cancers begin when a gene mutation
  gives rise to a faulty protein that participates in the process of cell reproduction.
• Uncorrected errors are passed from parent cell to daughter cells
• Accumulate as each generation of cells produces more nonfunctional proteins from uncorrected DNA damage
• Positive cell cycle regulators
• Negative cell cycle regulators

Question 8

What genes are involved in cancer

Answer 8

• Proto oncogenes
• Tumor suppressor

Question 9

What is the purpose of Proto oncogenes
and Tumor suppressor

Answer 9

• Proto oncogenes = drives cell division; gene Cdk is for cell regulation
• Tumor suppressor = supposed to stop uncontrolled division; acts like a roadblock

Question 10

What is cancer

Answer 10

Uncontrolled division and growth of cells when the mechanisms controlling cell division have been “destroyed”

Question 11

What happens to those who develop cancer

Answer 11

• Of these affected individuals one-third of the females and one-quarter of the males will ultimately die of the cancer mutation of proto-oncogenes,i.e. genes that stimulate cell division but are usually inactivated in fully differentiated non-dividing cells,
• Mutations leads to the proto-oncogenes to become oncogenes that are active all the time
• Tumor suppressor genes normally suppress cell division when this begins to occur abnormally

Question 12

Explain genes implicated in cancer

Answer 12

• Inactive tumor suppressor genes and active oncogenes will lead to uncontrolled cell division and thus tumor development
• The production of specific transcription factors by proto-oncogenes and tumor suppressor genes is required to ensure normal cell development and differentiation as well as the process of apoptosis, i.e. programmed cell death

Question 13

Explain P53 for cancer

Answer 13

• Tumor suppressor gene that codes for a transcription factor, it tends to mutate easier than other genes
• Mutation of this gene interferes with apoptosis and results in uncontrolled cell divisions

Question 14

Explain oncogene

Answer 14

• A mutated proto-oncogene is an oncogene (mutated variants of genes that normally stimulate cell division)
• Oncogenes speed cell division and mutated tumor suppressor genes fail to stop excess cell division
• Mutations in cancer-related genes may be inherited or acquired during a person’s lifetime
• Several lifestyle factors influence cancer risk

Question 15

Explain cancer cells break through cell cycle controls

Answer 15

• Tumors can result from excess cell divisions or deficient apoptosis.

A benign tumor (usually slow-growing) does not spread,

But a malignant tumor invades nearby tissues and metastasizes if it reaches the bloodstream or lymph.

Cancer is a family of diseases characterised by malignant cells

Question 16

How is DNA organised

Answer 16

• Protein help as scaffolds around which DNA entwines, helping to pack the DNA inside the cell
• Chromatin is organised into units called nucleosomes, each containing a stretch of DNA wrapped around eight proteins (histones)
• A continuous thread of DNA connects nucleosomes like beads on a string

Question 17

Explain apoptosis fully

Answer 17

• Is different from necrosis, which is accidental cells death that follows a cut or bruise
• The process of Apoptosis begins when a ‘death receptor’ protein on a doomed cell’s membrane receives a signal to die
• Within seconds apoptosis-specific ‘executioner’ proteins begin to cut apart the cell’s proteins and destroy the cell. Immune system cells descend and the cell is soon gone

Question 18

What is necrosis

Answer 18

A sudden and traumatic, but apoptosis results from a precisely coordinated series of events that dismantle a cell

Question 19

Explain apoptosis in animals

Answer 19

• animal cells serve to eliminate excess cells carving out functional structures such as fingers, toes etc. Secondly to weed out aging or defective cells that might otherwise harm the organism
  Plants cells also die, but are digested by enzymes in their own vacuoles when the vacuole bursts

Question 20

Explain the process of apoptosis

Answer 20

• Normal cell rounds up and nucleus collapses
• Chromatin condenses and nucleus fragments
• Plasma membrane blister, and blebs form
• Cell fragments contain DNA fragments

Question 21

How can you reduce the risk of cancer

Answer 21

• Eat a healthy diet
• Avoid obesity
• Avoid and reduce tobacco use
• Avoid UV radiation
• Use self tests for early detection
• Use protection to avoid viruses that cause cancer

Question 22

Explain what cancer cells lack

Answer 22

• A cancer cell lacks :
  • Contact inhibition (the ability to stop dividing when cells touch one another in a one-cell-thick layer) and
  • Anchorage dependence – normal cells only divide when attached to a surface, cancer cells lack this requirement,
  • May not undergo apoptosis and
  • secretes chemicals that stimulate the growth of blood vessels
    
    • Angiogenesis

Given enough nutrients, cancer cells can divide continuously and uncontrollable

Question 23

How do cancer cells differ from normal cells

Answer 23

• Cancer cells look different from normal cells
• Some cancer cells have many nuclei
• Telomeres can be seen as cellular clocks, everytime a cell divides the telomeres become shorter.
• When telomeres (the non-coding DNA at the tips of eukaryotic chromosomes) become very short, division ceases in normal cells.
  - An enzyme called telomerase adds DNA to telomeres in some cells
  
  • Cancer cells produce telomerase so they retain long telomeres and divide continually
• Normal cells divide only in response to the presence of external signals called growth factors (proteins that stimulate cell division)
  - Cancer cells can continue to divide even after growth factors are depleted

Question 24

Explain the gene NOEY2

Answer 24

• Paternally expressed and maternally imprinted gene in humans
• 2 sets of chromosomes one from mum and one from dad
  There are two genes present for each protein
• Loss of the expression of the gene NOEY2 is linked to an increased risk of ovarian and breast cancers
• In 41% of breast and ovarian cancers the protein encoded by NOEY2 is not expressed

Functions as a tumor suppressor gene

Question 25

Explain when a cell is damaged with irradiation

Answer 25

Cell that has dysfunctional p53, it becomes damaged with irradiation, there is no p53 therefore the cell is not dismantled and allowed to replicate resulting in more abnormal cells

Question 26

How do cancer cells behave

Answer 26

• Certain genes associated with the development of cancers especially if mutations occur.
• Mitosis plays a major role in the development of cancer as it results in cancerous cells multiplying in the same way normal cells would……
• Applying our knowledge of how cells replicate and divide or undergo apoptosis allows us to understand why cancers develop and how to treat to them…

Question 27

Explain chemical signals regulating cell division

Answer 27

• Cell cycle control checkpoints ensure that each stage of the cell cycle is complete before the next begins.
• The cell must pause briefly to repair errors, but if the damage is too great to repair apoptosis is triggered

Question 28

Explain the cancer cell cycle

Answer 28

• Single cell = death and division controls lost
• Uncontrollable cell division
• Tumor may develop
• Each cancerous cell passes on the lack of cell cycle control to daughter cells
• Growing tumor
• Damages organs = crushing; blocking passageways; diverting nutrients away from healthy cells