Lecture 26

Question 1

Explain the two theory of cell division and aging (hayflick limit and
telomere theory)

Answer 1

Hayflick Limit:
Cells have a limited capacity for division.
Replicative senescence occurs after a certain number of divisions.

Telomere Theory:
Telomeres at chromosome ends shorten with each division.
Shortened telomeres contribute to cellular aging and eventual senescence.

Question 2

What is abnormal in the cell cycle of a cancer cells? How do they react to growth factors signals?

Answer 2

Abnormalities in Cancer Cell Cycle:
Uncontrolled and rapid division.
Loss of checkpoint control and genetic instability.

Reaction to Growth Factor Signals:
Heightened responsiveness, autonomous growth, and resistance to inhibition.

Question 3

What are Hela cells? What is the importance and legacy of Henrietta Lacks?
Why is it relevant to science and cancer cells?

Answer 3

HeLa Cells:
Human cancer cells from Henrietta Lacks’ tumor (1951).
Widely used in scientific research.

Legacy:
Unintentional contribution to breakthroughs in cell biology, vaccines, and cancer research.

Relevance:
Crucial for understanding genetics and cell biology.
Key in polio vaccine development.
Significant in cancer research and therapy advancements.

Question 4

How is a tumor different from a hyperplastic tissue or an hypertrophic tissue?

Answer 4

Tumor:
Uncontrolled cell mass, can be benign or malignant.

Hyperplastic Tissue:
Controlled increase in cell number.

Hypertrophic Tissue:
Enlargement due to increased cell size, not cell number.

Question 5

What are the steps of cancer formations?

Answer 5

Initiation:
Genetic mutations occur.

Promotion:
Altered cells form a pre-malignant or benign tumor.

Progression:
Further mutations lead to malignancy, with invasive and metastatic potential.

Question 6

What are the six hallmarks of cancer? Explain each one and their
implication

Answer 6

Uncontrolled Proliferation:
Cancer cells trigger their own growth signals.
Implication: Continuous cell division leads to tumor formation.

Resistance to Growth Suppression:
Cancer cells resist signals inhibiting growth.
Implication: Loss of growth control allows unchecked cell division.

Evasion of Cell Death:
Cancer cells resist programmed cell death (apoptosis).
Implication: Surviving cells contribute to tumor growth.

Immortal Replication:
Cancer cells can divide indefinitely.
Implication: Prolonged cell division supports tumor growth.

Stimulation of Angiogenesis:
Cancer cells promote new blood vessel formation.
Implication: Improved blood supply sustains tumor growth and aids metastasis.

Invasion and Metastasis:
Cancer cells can invade tissues and spread to distant organs.
Implication: Invasion and metastasis contribute to cancer’s lethality.