OCR Biology F214 Communication, Homeostasis and Energy Wed 25 Jan 2012

Original post by VQG

Could someone explain the terms:

Glycogenolysis
Glycogenesis
Glucogenesis

And whether we need to know these terms in our specifications. Thanks.

There always on the mark scheme for anything that asks about what happens if blood glucose conc rises or falls.

Make sure you can spell them right as there always underlined in the mark scheme too.

Glycogenesis is the conversion of glucose to glycogen (when blood glucose conc high)
Glycongenlysis is the conversion of glycogen back to glucose (when blood glucose conc low)

Gluconeogenesis is the conversion of Amino Acids and Fats to glucose (when blood glucose conc is low)

Reply 382

glitterphobia

16

Original post by Yasin-Ali

Someone help:
The liver is responsible for the excretion of nitrogenous waste from the body right?
Can someone correct/improve on my wording:
Nitrogenous ~~waste~~ compounds need to be removed from the body because in large quantities it they cause a toxic environment in the ~~body~~ liver. When there's a large quantity of amino acids in the ~~body~~ liver their amine groups are toxic so they are broken down by ~~reaction with oxygen~~deamination to produce keto acids (to be respired/stored as glycogen) and ammonia...blah blah.

What other nitrogenous waste is there? I know about Uric acid too which is from the break down of dna right?

For nitrogenous compounds you just need to know about the deamination and the ornithine cycle. Remember, if you're talking about nitrogenous compounds being broken down, it only happens in the liver because ammonia isn't safe to be in the bloodstream - it's too toxic. You could talk about carbon dioxide that's produced by cells in the body because of respiration. It's passed into the bloodstream in the form of hydrogencarbonate ions to the lungs where it diffuses from the capillaries into the alveoli and excreted when we breathe out.

Reply 383

sumsum123

2

Original post by Yasin-Ali

Can someone tell me a bit about oxireductase enzymes please aswell.

Hey,

They are enzymes involved in reduction and oxidation. In the inner membrane (cristae) of the mitochondria you got enzyme carriers. They are assosciated with a co-factor that contains a haem group which has iron. Iron can become reduced to iron 2+ and oxidised to iron 3+ . So that is why they are called oxidoreductase enzymes

Reply 384

kimmey

7

does the keto acid enter respiration after deamination ?

Reply 385

High VOLTAGE

What is the role of aquaporins ?

Reply 386

VQG

Original post by undertaker1

u need to know the terms

Glycogenolysis is glycogen to glucose when we have low blood glucose levels
Glycogenesis is glucose to glycogen why we have high blood glucose levels
Gluconeogenesis is amino acids and fats to glucose when we have low blood glucose levels

Original post by atman7

There always on the mark scheme for anything that asks about what happens if blood glucose conc rises or falls.

Make sure you can spell them right as there always underlined in the mark scheme too.

Glycogenesis is the conversion of glucose to glycogen (when blood glucose conc high)
Glycongenlysis is the conversion of glycogen back to glucose (when blood glucose conc low)

Gluconeogenesis is the conversion of Amino Acids and Fats to glucose (when blood glucose conc is low)

Thanks a lot, was just a bit unsure over them. Are any of you sitting Chemistry on Thursday?

Reply 387

kimmey

7

Original post by High VOLTAGE

What is the role of aquaporins ?

gets inserted into the plasma membrane of the collecting duct. basically makes the walls more permeable to water so water can be reabsorbed into the blood by osmosis. so you dont get dehydrated. as a result you produce urine of small volume and high concentration

Reply 388

High VOLTAGE

Original post by kimmey

gets inserted into the plasma membrane of the collecting duct. basically makes the walls more permeable to water so water can be reabsorbed into the blood by osmosis. so you dont get dehydrated. as a result you produce urine of small volume and high concentration

Thank you

, so when ADH is released does it place aquaporins in the plasma membrane or not?

Reply 389

VQG

Original post by High VOLTAGE

Thank you

, so when ADH is released does it place aquaporins in the plasma membrane or not?

ADH is a hormone- messenger molecule secreted by the neurosecretery cells in the posterior pituitary gland. It binds to the receptors on the surface of the distal convuluted tubule- (mechanism of inducing secondary messages in the cells) which result in vesicles fusing with the cell membrane to form channels in the distal convuluted tubule and collecting duct.

Reply 390

High VOLTAGE

Original post by VQG

ADH is a hormone- messenger molecule secreted by the neurosecretery cells in the posterior pituitary gland. It binds to the receptors on the surface of the distal convuluted tubule- (mechanism of inducing secondary messages in the cells) which result in vesicles fusing with the cell membrane to form channels in the distal convuluted tubule and collecting duct.

oh right, thank you (Y)

Reply 391

kimmey

7

Original post by High VOLTAGE

Thank you

, so when ADH is released does it place aquaporins in the plasma membrane or not?

yep thats right and when water potential increases the aquaporins are removed and any adh still in the blood gets broken down by the liver

Reply 392

Leah.94

for the photosynthesis or experiment questions, what are usually the limitations and improvements for reliability etc. because i've a feeling this may come up :/

Reply 393

Maple

Original post by sumsum123

Yerh that would be one, erm for anabolic reactions... protein synthesis perhaps?

there's a few examples:
neurotransmitter synthesis
Cellulose synthesis from B-glucose
steroid from cholesterol
and even photosynthesis as you are going from simple inorganic molecules to complex organic molecules such as glucose like you said.

Reply 394

Maple

Original post by VQG

Alright thanks- anymore hunches on what will come up? I can't remember the ornithine cycle coming up much? Nor fatty liver?

Has the respirometer come up in recent papers?

yeah the respirometer, that hasn't come up in all the papers I've done. I need to revise the green pages as there's bound to be practical questions. Also evaluating the evidence for chemiosmosis - that's hardly come up.

There's not been any questions that I can remember about countercurrent multiplier systems and the advantage of them. You find them in dialysis, loop of henle and many other places.

(edited 12 years ago)

Reply 395

Original post by VQG

Thanks a lot, was just a bit unsure over them. Are any of you sitting Chemistry on Thursday?

Yup I got it Thursday and then the f325 paper on the 31st. How's your preparation going for Thursday? I hate how they always make biology and chemistry so close it would have been nice to have a day gap inbetween.

About the respirometer is it in the AS book? I have a question in front of me on it involving maggots, it's from the central concepts jan 04 if anyone wants to take a look at it.

Reply 396

sumsum123

2

Original post by atman7

Yup I got it Thursday and then the f325 paper on the 31st. How's your preparation going for Thursday? I hate how they always make biology and chemistry so close it would have been nice to have a day gap inbetween.

About the respirometer is it in the AS book? I have a question in front of me on it involving maggots, it's from the central concepts jan 04 if anyone wants to take a look at it.

F325 is on 1st right... :s , I don't even know when it is :rolleyes:

& yerh upload it or pass the link please :smile:

Reply 397

VQG

Original post by atman7

Yup I got it Thursday and then the f325 paper on the 31st. How's your preparation going for Thursday? I hate how they always make biology and chemistry so close it would have been nice to have a day gap inbetween.

About the respirometer is it in the AS book? I have a question in front of me on it involving maggots, it's from the central concepts jan 04 if anyone wants to take a look at it.

Ah good luck, pretty poor to be honest. Biology's taken up all my time, but I've pretty much got the organic and amino acids on lockdown (had an amazing teacher teaching me that). Now I've got to sort out the polymers and analysis, and also squeeze in some uses for the organic products.

I don't think respirometers in the text book, but its in the CGP revision guide. I'll try and scan the relevant page in tomorrow, if you want. But my scanners been a bit dodgy recently, not as sharp as it should be.

Reply 398

Original post by sumsum123

F325 is on 1st right... :s , I don't even know when it is :rolleyes:

& yerh upload it or pass the link please :smile:

I had it printed but I got a pack that I can upload its got all the questions for old spec well most of them without the stuff you don't need from F215. Is it the first? I can't even remember LOL I haven't touched that side of chemistry this week.

Just give me a few minutes and I'll upload everything

Reply 399