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OCR Biology A2 F214/F215 exams June 2016

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Original post by Dominator1
HDLs transport cholestrole from the body tissues to hepatocytes, where they bind to their complementary cell receptors.

cheers
do nerve cells respire, especially in the brain? if so how does O2 and nutrients reach these nerve cells in the brain? is it due to glial cells?
Original post by axle1234
do nerve cells respire, especially in the brain? if so how does O2 and nutrients reach these nerve cells in the brain? is it due to glial cells?

Nerve cells take up nutrients and release waste products through tissue fluid maybe
Original post by axle1234
do nerve cells respire, especially in the brain? if so how does O2 and nutrients reach these nerve cells in the brain? is it due to glial cells?


My guess would be yes, I think the brain is covered in capillaries bringing blood with high concentrations of oxygen and nutrients and they just go down their corresponding concentration gradients . I would presume that the cell body of the neuron has lots of mitochondria since very they're many active processes taking place in neurons. No idea what glial cells are though.
how does a trained athlete have larger mitochondria in his/her muscle tissue?
Original post by Superbubbles
how does a trained athlete have larger mitochondria in his/her muscle tissue?


I'm guessing because a trained athlete has a high requirement for ATP in their muscles, which releases signals for the muscle cells to produce more mitochondria (e.g. they may replicate their mitochondria), so that the next time they exercise, they can support aerobic respiration for longer (provided O2 concentration is high enough/constant supply of O2)
Original post by Superbubbles
how does a trained athlete have larger mitochondria in his/her muscle tissue?


I'm not sure if they necessarily have larger mitochondria; I think they may have a higher concentration of mitochondria in their cells though?
What are the advantages and disadvantages of Somatic and Germ-line gene therapy?
Specific example of taxis and kinesis and escape behaviours in animals and their advantages?
Original post by Don Pedro K.
I'm not sure if they necessarily have larger mitochondria; I think they may have a higher concentration of mitochondria in their cells though?


That's what I thought but it says larger on page 86 of the OCR textbook
Original post by Superbubbles
That's what I thought but it says larger on page 86 of the OCR textbook


Oh yeah, that's true...hmm well, in that case, I am not entirely sure xD I wouldn't worry too much about it though! Also, it might be an error in the book, because they've made some errors elsewhere too!
Original post by Superbubbles
In oxidative phosphorylation where does the oxygen come from?


Just present in the matrix, from when we breathe it in? Idk
Original post by axle1234
What are the advantages and disadvantages of Somatic and Germ-line gene therapy?


Advantages Somatic Therapy and germ line:
Prolonging life, if life-threatening genetic disorder
Better quality of life, can cure/reduce symptoms
Advantages Germ line therapy:
Technically simpler to achieve, as you only have to do it on one or few cells
Can have a baby without that genetic disorder, passed on through generations
Doesn't require multiple treatments
Disadvantages:
Somatic more technically difficult, have to do it on a lot more cells.
Can be difficult to get an allele into a specific body cell
Requires multiple treatments.(somatic therapy)
Allele could be overexpressed, causing more problems
Allele inserted into wrong place in the DNA, possibly causing cancer
Only some genetic disorders with few genes involved can be treated
The body could identify vectors as foreign bodies and start an immune response against them.
Expensive to do
Not yet achieved, people believe money could be better spent on other treatments which have passed clinical trials.

There is also a lot of ethical issues as well, with both gene therapy
Original post by yoda123
Specific example of taxis and kinesis and escape behaviours in animals and their advantages?


Taxis directional response to a stimulus. Woodlice when exposed to light they will run away from it(when you turn a stone over), to prevent them being seen by predators, which increasing their chances of survival

Kinesis non-direction response to a stimulus.Woodlice when they reach an area which is very dry they will start moving in random directions until they reach an area of soil which is more humid. This reduces water loss and so increases their chances of survival

Escape behaviour I presume you mean a reflex response . Cockroaches run away when your foot is about to squash them. Increases their chance of survival.
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Im gonna do a f215 revision after i stop procrastinating from stats.
Original post by axle1234
What are the advantages and disadvantages of Somatic and Germ-line gene therapy?


(DISCLAIMER: I'm kind of basing this off my memory so it may not be 100% correct.)

ADVANTAGES OF SOMATIC GENE THERAPY:

Allows curing of a recessive genetic disorder, or the alleviation of symptoms caused by that disorder, such as with cystic fibrosis.
Extend life span.
Provides a better quality of life.
Currently legal (I guess you could consider this an advantage?)

DISADVANTAGES OF SOMATIC GENE THERAPY:

Treatments are short lived - if a modified virus is used as the vector for example, the body will develop immunity to the virus after the first treatment so the virus becomes ineffective after the first treatment.

The virus vector could also cause a viral disease in the patient.

Germline not affected - allele which causes the genetic disorder may still be passed onto offspring.

Getting the allele to the cell can be an invasive procedure - e.g. removing and replacing bone marrow.

This is one for both - the allele could mutate with unknown consequences.

ADVANTAGES OF GERM-LINE GENE THERAPY (CURRENTLY ILLEGAL):

Allele is easier to get into target cell compared with somatic gene therapy.

Since alleles are inserted into germ-line cells (e.g. sperm/egg/zygote/embryo), the allele will be present in every single cell of the patient and will be expressed (transcribed and translated) to produce the desired polypeptide wherever needed.

As a result, the allele can also be passed onto offspring.

DISADVANTAGES OF GERM-LINE GENE THERAPY:

Permanent modifications to our genome raises many ethical, social and moral issues.

It may interfere with the evolution of our species in an unexpected way.

It could lead to the creation of a new human disease.

Even if the target defect is treated within the embryo, a new defect could be introduced into the embryo.

This new defect (and any other modifications) can be passed onto offspring, who would not have gotten a choice as to whether or not they wanted the modification(s).

People might start to want to enhance certain aspects of their baby as opposed to just treating defects - 'designer babies' issue.

That's all I can think of :smile:! Hope it helps.
is ATP used to convert hexose phosphate to triose phosphate in glycolysis?
Original post by Superbubbles
is ATP used to convert hexose phosphate to triose phosphate in glycolysis?


nope, its just splits into 2 triose phosphates
Original post by student__1001
nope, its just splits into 2 triose phosphates


thats what I thought too but this ms says it does
pp.jpg57.3KB
ms.jpg79.4KB
Original post by Don Pedro K.
(DISCLAIMER: I'm kind of basing this off my memory so it may not be 100% correct.)

ADVANTAGES OF SOMATIC GENE THERAPY:

Allows curing of a recessive genetic disorder, or the alleviation of symptoms caused by that disorder, such as with cystic fibrosis.
Extend life span.
Provides a better quality of life.
Currently legal (I guess you could consider this an advantage?)

DISADVANTAGES OF SOMATIC GENE THERAPY:

Treatments are short lived - if a modified virus is used as the vector for example, the body will develop immunity to the virus after the first treatment so the virus becomes ineffective after the first treatment.

The virus vector could also cause a viral disease in the patient

Germline not affected - allele which causes the genetic disorder may still be passed onto offspring.

Getting the allele to the cell can be an invasive procedure - e.g. removing and replacing bone marrow.

This is one for both - the allele could mutate with unknown consequences.

ADVANTAGES OF GERM-LINE GENE THERAPY (CURRENTLY ILLEGAL):

Allele is easier to get into target cell compared with somatic gene therapy.

Since alleles are inserted into germ-line cells (e.g. sperm/egg/zygote/embryo), the allele will be present in every single cell of the patient and will be expressed (transcribed and translated) to produce the desired polypeptide wherever needed.

As a result, the allele can also be passed onto offspring.

DISADVANTAGES OF GERM-LINE GENE THERAPY:

Permanent modifications to our genome raises many ethical, social and moral issues.

It may interfere with the evolution of our species in an unexpected way.

It could lead to the creation of a new human disease.

Even if the target defect is treated within the embryo, a new defect could be introduced into the embryo.

This new defect (and any other modifications) can be passed onto offspring, who would not have gotten a choice as to whether or not they wanted the modification(s).

People might start to want to enhance certain aspects of their baby as opposed to just treating defects - 'designer babies' issue.

That's all I can think of :smile:! Hope it helps.



damn you guys are too good, thanks alot aha!!!

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