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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

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Can someone please tell me in note forms if possible everything we need to know for suppressor Tumour genes.

Thanks :biggrin:

Reply 2101

sienna5

Original post by Med_me

Please could someone explain what fluorescent gene markers are and how/why they are used? I just can't seem to understand them!

A fluorescent marker is basically a marker gene that codes for fluorescence. And the point of a marker gene is to identify cells that have been transformed ( the host cells that's actually taken up the vector and Dna)

Reply 2102

sienna5

Original post by propagation

Can someone please tell me in note forms if possible everything we need to know for suppressor Tumour genes.

Thanks :biggrin:

I'm certain all you need to know is that there a gene that control cell division (slow cell division by producing a protein to stop cells dividing) and if you get a mutated tumour suppresser gene, they inactive and therefore no protein made so the cell division can't be slowed. This is how tumour formed due to uncontrollable division

Reply 2103

ActaNonVerba

Original post by bad8oy

Lool yeah aha it's chilled probably would mean less turns it makes more sense??

Is there a markscheme from a question on a past paper which would tell us

Posted from TSR Mobile

starting past papers today since they are in limited supply, I'll post it if It does pop up though

Reply 2104

currydud

Original post by Mocking_bird

Gosh, there's always a rude person on every single biology unit thread theres been.

Unfavourable conditions = less turning / more movement.

"Don't argue you're wrong".

why wouldnt there be less movement and less turning in a favourible condition?

Reply 2105

F1's Finest

The more unpleasant the stimulus, the more movement to try and find an area that is more pleasant.

Is this taxes or kinesis?

Reply 2106

Mocking_bird

Original post by James A

The more unpleasant the stimulus, the more movement to try and find an area that is more pleasant.

Is this taxes or kinesis?

Kinesis.

Reply 2107

Mocking_bird

Original post by currydud

why wouldnt there be less movement and less turning in a favourible condition?

More turning allows them to ensure they stay in favourable conditions

Reply 2108

F1's Finest

Original post by Mocking_bird

Kinesis.

So taxes is moving their whole body to a favourable area? (Directional stimulus)

Reply 2109

prolapse

Just done an essay, if anyone could glance through it and let me know what they think it is worth I would appreciate it.

CO2 may affect organisms directly or indirectly. Describe and explain these effects.

More co2 in the atmosphere will lead to an increased amount of global warming, infra-red radiation is absorbed by the C=o bond, causing heat to be released as the bond vibrates due to the extra kinetic energy, this extre kinetic energy is released as heat. This increase in global temperatures may indirectly lead to changes in many enzyme controlled reactions, such as respiration, as enzymes have an optimal temperature at which they operate, and going either above or below this set optimal temperature leads to a lower rate of reaction.

In the long term this climate change may have some very severe consequences on animal distribution and genders, in certain animals the incubation temperature of the eggs determines the sex of the offspring, too many males of females will lead to a bottleneck, and possible extinction of the species. Colonies of insects such as mosquitoes may emigrate to different countries due to the new and more favourable conditions, spreading with them many forms of tropical diseases.

Carbon dioxide is a product of aerobic respiration, where it is released as a waste gas, it is produced in the link reaction where pyruvate combines with coenzyme a to form acetyl coenzyme a and a mollecule of waste CO2, and also in the krebs cycle where a 6c sugar is reduced to a 5c sugar and then to a 4c sugar, in each step a mollecule of CO2 is released. This co2 accumulates in the blood as carbonic acid, which lowers the PH of the blood, this decrease in pH is detected by chemoreceptors in the carotid artery, which leads to an electrical impulse being sent to the cardioacceleratory section of the medulla, causing more frequent impulses to be sent along the sympathetic pathways, resulting in noradrenaline being released onto the SAN, causing the heart rate to increase, allowing more CO2 to be removed via diffusion in the lungs due to more bloodflow to the lungs. An increase in CO2 also leads to an effect called bohr shift, whereby the haemoglobin in the blood has a lower affinity for oxygen at all partial pressures - it dissociates more readily to provide more oxygen, this is advantageous for example in respiring muscle cells which are producing a lot of co2 but also have a high o2 demand.

CO2 is a vital substance required in the light independant stage of photosynthesis, it is used in fixation where it combines with RUBP to form 2x3c gp molecules, which are then further reduced to 2x3c tp molecules, the 2x3c tp molecules are reformed to the 5C RUBP, leaving 1 carbon worth of organic materials left over that are used to build up glucose, 6 molecules of co2 are required to form 1 molecule of glucose via this method.

CO2 is taken in by plants, however by burning fossil fuels and decreasing the number of plants due to deforestation, we are allowing more CO2 to accumulate in our atmosphere. CO2 conc is usually a limiting factor in photosynthesis, however more means that photosynthesis can occur at a higher rate, meaning a greater yield of crops.

i very much appreciate it.

(edited 10 years ago)

Reply 2110

Mocking_bird

Original post by James A

So taxes is moving their whole body to a favourable area? (Directional stimulus)

Indeed.
Taxes - directional stimulus
Kineses - related to intensity of stimulus

Reply 2111

currydud

Original post by Mocking_bird

More turning allows them to ensure they stay in favourable conditions

thanks

Reply 2112

ahmmm

can someone have a look at question 2b in the jun12 paper and tell me how you work out these magnification questions !! pleeeeeeeeeeeease :biggrin:

Reply 2113

SamEastie

are core sequences of introns different lengths in the same person? or just vary in length between people?

Reply 2114

Lizzie232

Original post by James A

So taxes is moving their whole body to a favourable area? (Directional stimulus)

Yeah, well a more favourable area than the one they're in. I think of it like a taxi takes you somewhere you want to go directly :smile:

And I just remember that kinesis is random movement...

Edit: Random in that they turn randomly...they still want to get to a favourable area :smile:

(edited 10 years ago)

Reply 2115

ahmmm

question 2b from jun2012 anybody????

Reply 2116

medlou

Original post by stoppy123

Yep, it isn't disrupted :smile:

It says at the top above the flow chart "Sheep can be genetically engineered to produce factor IX in their milk produced by their mammory glands"

Ok I think I misunderstood the question, thanks again

Reply 2117

medlou

Can someone clarify the difference between a DNA probe and a DNA primer? is the probe just a labelled primer?

Reply 2118

Mocking_bird

Original post by ahmmm

question 2b from jun2012 anybody????

1) Measure sarcomere with your ruler in cm to find image size
2) Convert cm to um (x 10,000)
3) Magnification = image/actual

I can't put the figures in because I don't have a print out and it doesnt work if I measure it off my screen :P

Reply 2119

SamEastie

Original post by medlou

Can someone clarify the difference between a DNA probe and a DNA primer? is the probe just a labelled primer?

primer is provides a starting sequence for dna polymerase to begin copying (it can only add nucleotides to an existing strand)- has complementary bases to a section of the dna near the start of a target gene.
a probe is a complementary sequence of bases to part of a gene whose position you are trying to locate. it can be labelled as you said.. but essentially, they're both short sequences of nucleotides complementary to part of dna.