Growth, Development & Aging

Question 1

Three effects of aging

Answer 1

• The pituitary gland shrinks and becomes more fibrous with old age. Thus, the production and secretion of growth hormones decline significantly. This results in a decrease in lean muscle mass, an increase in fat mass, and a decrease in bone density.
• Aging correlates with a loss of neurons, and a reduction in brain size. THis leads to memory loss, slower reaction times, diminished hearing and vision, and loss of fine motor skills
• An increase in aberrant cells, correlating to an increase in cancers as a result of accumulation of cellular damage. Tumours of the endocrine organs are particularly common amongst the elderly.

Question 2

Ethical Issue of Euthanasia

Answer 2

• People of higher wealth can afford travelling to countries with euthanasia, while those from lower income backgrounds cannot.
• Many religious views do not support euthanasia. They regard life as sacred and belonging to God, thus considering assisted suicide unethical.
• If euthanasia becomes legal, it can become overused by many young people. They are still young with long futures ahead. No one knows what will happen in the future, so would assisted suicide in teens taking away their hope?

Question 3

Legal Issue of Euthanasia

Answer 3

• Is illegal in most countries. If patients from these nations travelled to those in which euthanasia is legal, in order to take euthanasia, can the law of the patient’s country still apply?
• The borderline between euthanasia and murder can be very vague; making it difficult for authorities to determine justice.
• Euthanasia process must be recorded on tape for authorities to determine its just. This could result in privacy breaches.

Question 4

Apoptosis

Answer 4

Programmed cell death, occurring as a natural and healthy process of the body to regulate and maintain healthy cells.

Question 5

Why do cells undergo apoptosis?

Answer 5

Cells undergo apoptosis when their DNAs are damaged beyond repair. They are safely disposed of to protect other cells.

Question 6

What regulates apoptosis?

Answer 6

Apoptosis is regulated by proto-oncogenes (cell division and development) and tumor suppressor genes (inhibits division).

Question 7

What happens when proto-oncogenes mutate?

Answer 7

Proto-oncogenes mutate into oncogenes, leading to uncontrollable cell growth (cancer)

Question 8

What happens when tumour suppressor genes mutate?

Answer 8

Also leads to cancer.

Question 9

Example of tumour suppressor genes?

Answer 9

p53

Question 10

Hayflick limit

Answer 10

When telomeres are too short and cells enter replicative senescence (active but not dividing). Occur after around 50 divisions.

Question 11

What are telomeres?

Answer 11

Structures composed of DNA sequences and proteins located at the end of chromosomes. Protects the ends of chromosomes. Each time a cell divides, the telomeres shorten until cells can no longer divide.

Question 12

What is telomerase?

Answer 12

An enzyme that can extend telomeres and prevent them from shortening.