signalling molecules

Question 1

endocrine signalling

Answer 1

• Long distance.
• hormones
• travels through the blood stream

Question 2

paracrine siganlling

Answer 2

• travel to nearby cells

- local mediators

Question 3

autocrine siganlling

Answer 3

• has effect on itself

- eg T cells

Question 4

direct cell-to-cell contact

Answer 4

from one cytosol to another

Question 5

what’s apoptosis

Answer 5

programed cell death

Question 6

What are the 5 things that happen to the cell during apoptosis?

Answer 6

1. shrinkage
2. blebbing
3. nuclear fragmentation
4. Chromatin Condensation
5. Chromosomal Dna fragmentation

Question 7

homeostasis

Answer 7

the body’s tendency to maintian a constant internal environment.
-relatively stable equilibrium

Question 8

negative feedback.

Answer 8

response feeds back and countereacts the change from the set point.

Question 9

negative feedback in terms of blood glucose levels.

Answer 9

• BG levels arr too high
• receptors on pancreas (beta cells) detect, and insulin is produced.
• insulin stimulates glucose uptake, and the liver converts it to glycogen= lower BG levels
• BG levels are too low
• receptors on pancreas (alpha cells) detect, and glucagon is secreted.
• glucagon stimulates the breakdown of glucogen in the liver, and BG levels increase.

Question 10

blebbing

Answer 10

cell membrane shows irregular budding

Question 11

cell shrinkage

Answer 11

cell gets smaller and loses its shape

Question 12

chromatin condensation

Answer 12

nuclear DNA forms patches against the nuclear membrane

-chonmatin swells up (like in mitosis)

Question 13

Hormones

Answer 13

Influeces other cells in body. Travel using the bloodstream.

Question 14

Types of hormones.

Answer 14

–can be: amino acid derivatives (hydrophillic), lipid-derived hormones (hydrophobic), and peptide and protein hormones (hydrophillic).

Question 15

Properties of hormones (hydrophillic)

Answer 15

can dissolve readily in the water in the blood plasma. it binds to receptor sites on the cell’s surface. Eg: epinephrine.

Question 16

Porperties of hormones (hydrophobic)

Answer 16

can’t dissolve readily in blood, and therefore uses protien carries to travel to the target cell. It binds to receptor sites inside the target cell. Eg: cortisol

Question 17

Characteristics of cell undergoing apoptosis

Answer 17

-blebbing, cell shrinkage, nucleus fragmenting, apoptotic bodies (the little vesicles). chromatin condensation, etc.

Question 18

Intrinsic (mitochondrical) apoptosis pathway

Answer 18

• Depends on factors released by the mitochondria.
• Occurs due to cellular stress.
• Cytochrome C is released from mitochondrial pores, and aggregates other compounds in the cytoplasm to activate caspase 9.
• caspase 9 then activates other caspases (executioners) to “systematically dismantle” the cell.
• after dismantlment, the cell contents are packaged into apoptotic bodies an engulfed by phagocytic cells

Question 19

Examples of cellular stress?

Answer 19

DNA damage, low O2 levels, viral infection, deprivation of growth factors.

Question 20

Why does the cell need to be packaged into apoptotic bodies?

Answer 20

To prevent the immune respone from being triggered due to presense of infection.

Question 21

Caspase

Answer 21

protien digestor enzyme

Question 22

Extrinsic (death receptor) pathway

Answer 22

• molecules bind to death receptor OUTSIDE cell.
• signal sent when cell’s no longer needed, are being replaced by other cells, or are in excess of current needs.
• a cascade of reactions results in the activation of the executioner caspases, same as inrinsic.
• note that the extrinsic can activate the “intrinsic” response too.

Question 23

Examples of plant hormone responses?

Answer 23

ripening, growth (size), development (form),