Cellular Signals

Question 1

Signalling molecules

Answer 1

Transmit information about an internal or external stimulus to other cells.

Question 2

Animal hormones

Answer 2

Hormones are produced by animal organs or glands. Involve autocrine, paracrine or endocrine modes of transmission.

Question 3

Neurotransmitters

Answer 3

Transmit signals to various types of cells that form synapses with neurons. Hydrophilic and paracrine transmission mode.

Question 4

Cytokines

Answer 4

Produced by immune cells (macrophages and lymphocytes).

Question 5

Pheromones

Answer 5

Excreted outside the organism and diffuse through the air to other individuals of the same. Species.

Question 6

Abscisic acid

Answer 6

Visible effect: seed and bud dormancy, drought tolerance and apical dominance.

Question 7

Auxins

Answer 7

Visible effect: shoot tip bends towards the light, roots grow downwards, apical dominance.

Question 8

Cytokinins

Answer 8

Visible effect: growth of lateral branches

Question 9

Gibberellins

Answer 9

Visible effect: elongation of stems, leaf expansion, seed germination, fruit and flower mutation.

Question 10

Ethene

Answer 10

Visible effect: increases sugar content of fruit (ripening), fruit and leaf drop off.

Question 11

Signal transduction

Answer 11

The process of transmitting a signal into or out of a cell, or changing the form of a signal into another form. (Second messengers, when signalling molecules bind to a cell surface receptor and the conversion of an action potential to neurotransmitters).

Question 12

Signal transduction steps

Answer 12

1. Reception
2. Transduction
3. Cellular response

Question 13

Hydrophilic receptors location

Answer 13

On the membrane.

Question 14

Hydrophilic receptors location

Answer 14

In the cytosol

Question 15

Apoptosis

Answer 15

Programmed cell death

Question 16

Mitochondrial pathway

Answer 16

Apoptosis triggered by cell damage; signal comes from within the cell.

Question 17

Death receptor pathway

Answer 17

Triggered by cytokines; signal comes from within the cell.

Question 18

Cascades

Answer 18

Enzymes that physically break down the components of te cell during apoptosis.

Question 19

Steps of apoptosis

Answer 19

1. Separation from adjacent cells.
2. Collapse of cell’s cytoskeleton
3. Cell shrinkage.
4. Breakdown of organelles and nucleus.
5. Blabbing of the plasma membrane.
6. Budding of plasma membrane-bound vesicles called apoptosis bodies.
7. Phagocytosis of the apoptotic bodies by macrophages etc.

Question 20

Inhibited apoptosis examples

Answer 20

Syndactyly & cancers.

Question 21

Cancer

Answer 21

Unregulated and abnormal cell growth and division.

Question 22

Excessive apoptosis example

Answer 22

Alzheimer’s disease