ch 14,15,16 Response to changes in environment

Question 1

What is homeostasis?

Answer 1

Maintaining a constant internal environment

Question 2

What surrounds each cell, supplies nutrients and removes waste?

Answer 2

Tissue fluid

Question 3

What is the ability to return to the optimum point when deviations occur?

Answer 3

Homeostasis

Question 3

Where do fluctuations occur around?

Answer 3

the optimum point

Question 4

Why is homeostasis important for enzymes?

Answer 4

Enzymes are sensistive to changes in pH and temperature.
-These enzymes control chemical reactions and other proteins.
-Any changes to these variables will reduce RoR or may denature them.
-Maintaining a constanst internal environment means that reactions can take place at a suitable rate.

Question 5

Why is homeostasis important to maintain constant blood glucose conc?

Answer 5

Blood glucose conc affects the water potential of the tissue fluid.
-Changes to water potential can cause cells to shrink or burst due to water movement by osmosis.
-Constant blood glucose conc also ensures a reliable source of glucose for respiring cells.

Question 6

Why is homeostasis important?

Answer 6

-Enzymes are sensitive to changes in pH and temperature.
-Blood glucose conc will affect tissue fluid conc.
-Organisms with the ability to maintain a constant interal environment are more independent of changes to the external environment.

Question 7

Describe how bacteria can be modified to produce human insulin.

Answer 7

Use mRNA and reverse transcriptase to produce cDNA.
Use restriction endonuclease to cut out the insulin gene from the cDNA.
Use the SAME restriction endonuclease to cut open the plasmid.
This ensures complimentary ‘sticky ends’.
Plasmid and DNA fragement are joined using DNA ligase.
The modified/recombinant plasmids are taken up by the bacteria.

Question 8

Which hormone release when blood glucose too low?

Answer 8

Glucagon

Question 9

Where is glycogen stored?

Answer 9

liver

Question 10

which hormone breaks glycogen to glucose?

Answer 10

glucagon

Question 11

Explain how the events of blood glucose control can be described as negative feedback

Answer 11

A change to the optimum initiates a response which acts against the change

Question 12

Describe the role of glucagon in gluconeogenesis.

Answer 12

Glucagon attaches to receptors on target cells and stimulates enzymes.
Turns glycerol/FA/AA into glucose.

Question 13

Explain how increasing the cells sensitivity to insulin will lower the blood glucose conc.

Answer 13

More insulin to bind to the receptors on the surface of target cells.
Stimulates uptake of glucose by channel/transport proteins.

Question 14

Which enzyme is involved in the second messenger model?

Answer 14

Adenylate cyclase

Question 15

What does adenylate cyclase do?

Answer 15

Catalyses reaction of ATP-> cAMP.
cAMP then activates kinase… glycogen–> glucose

Question 16

Explain how inhibiting adenylate cyclase will help lower blood glucose conc.

Answer 16

ATP will not be converted to cAMP. So there will be no cAMP to activate kinase. No kinase activated. So glycogen will no be converted to glucose. No glucose produced.