OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

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noodlecookie

I can't find your question lol what was it?

I asked if an allele was produced from a mutation in a gene, how many mutations would there have to be in that particular gene for it to be a completely new gene and not just an allele

Reply 3221

PJ991

Archen

can anyone outline the disadvantages of tissue culture/cloning in plants?

it makes it hard for farmers in poorer countries to farm year after year as the technology isn't available to them.

expensive.

then the usual disease once they're planted make them all susceptible.

Reply 3222

ratherbesurfing

had english this afternoon and i've got history tomorrow afternoon after bio... feeling swell? yeah..

Reply 3223

toxik_apple

I'm thinking questions are going to be retarded. From looking at past questions they often don't even make sense until after you read it five times :rolleyes:

And Hardy-Weinberg will definitely come up, I think anyway.....but that's simple(ish) :ninja:

The person asking about neuromuscular junctions and their compare/contrast features with synapses, in the back of the OCR textbook is an answer to exactly that. There are more points you can make though...

Beating Around The Bush

>Homeobox genes. I know that they control the body plan and development or organisms including polarity and positioning of organs, as well as they are similar in plant, animals and fungi. Is there anything else needed to be known about these?

>Genetic drift, could someone describe what it is and it's consequences, I know it vaguely but a little bit confused.

>Phylogenetic species concept, know the definition but I don't get where it goes on about clades, monophyletic etc

>The book goes on about sequencing the genome on page 166 what the difference between this and the sequencing on page 172??

>Whats the deal with the human dopahmine? What do I need to know for this?

I'm gonna have a go at answering these :biggrin:

You don't specifically have to remember all that stuff about fly homeobox genes. Just the different genes and what they do.
Basically you've got the maternal-effect genes, these determine the polarity of anterior and posterior
Then you have segmentation genes which after the action of maternal-effect genes determine the polarity of your segments
Homeobox selector genes SELECT the identity of each segment...
Homeobox genes are morphogens, they aid in the specific shape/pattern development of the embryonic cells in ALL animals.
Evidence of which comes from inserting a human eye into a fly genome, it was expressed on random parts of the body so you had eyes on its ass.

Genetic drift occurs when you get huge changes in allele frequencies in a population due to various speciation/environmental pressures.
Say if a country suddenly became very cold, and you have white rabbits and black rabbits. The white rabbits would naturally outcompete the black rabbits as they're capable of 'blending in' with the background, don't get eaten and thus survive to reproduce. Therefore the black rabbits die. The allele frequency for black fur becomes virtually extinguished, it disappears and the prevalent allele will become that for white fur.

With phylogenetic stuff, don't ask. I have no idea :sad:

Sequencing a genome: the different pages are different in that the first explains it in a basic manner, the other is more complex. But not by much.
Putting the genomes sheared into fragments into BACs is basically just putting them into a library...
When you need to sequence them you identify, expand and extract.
Put into a reaction mixture your single stranded DNA along with DNA polymerase, DNA nucleotides flagged with a fluorescent base, primers and DNA nucleotides (normal ones)
The primers need to be allowed to anneal with the 3' end of the DNA
When this has happened DNA polymerase joins the nucleotides to the exposed bases on the DNA single strand according to the complementary base pairing rules (A with T, C with G)
This occurs UNTIL the DNA polymerase adds a nucleotide flagged with the fluorescent base. It then gets thrown off
Electrophoresis then separates the DNA fragments according to their length
A laser beamed through the sample with determine the sequence of the fluorescent colours, and thus the DNA sequence :smile:

Dopamine: You need to know about drugs, effects of reduced and increased dopamine levels in the brain and hint about relevant research into OCD.
Drugs include L-dopa, which increased the amount of dopamine production in the brain, this can treat Parkinson's disease, but may cause adverse Schizophrenic symptoms
Phenothiazines reduce the symptoms of Schizo by reducing the activity of the dopamine receptors
L-dopa has also been shown to induce addiction, gampling and risk taking in individuals. This suggests the excitatory activity of dopamine in the brain
OCD may be caused by unbalanced levels of serotonin, a precursor for dopamine.

There are various variants of the DRD dopamine receptor, five of them are DRD1 - 5, and there are about 50 of the most crucial one, DRD4. They variants are named number variation tandem repeats.

I believe this is mostly what you need to know, if not feel free to kill me :biggrin:

Reply 3224

steph_v

Varciani

I just got my mum to ask me questions from my notes... her pronunciation's hilarious 'enzeem' hahaha

I got my boyfriend to do the same, he hates biology, he's very much a physicsy person, and he really couldn't pronounce anything, especially beta-galactosidase, that was funny. It's helped me remember, though!

Reply 3225

Just-Some-Guy

Hey guys, i posted a mini revision guide near the bottom of 149, its a compilation of stuff, it may help with some of your queries check it out. im off now best of luck to everyone!!! p.s get some REMs!!!!

Reply 3226

steph_v

greywacke

http://www.cnpg.com/video/flatfiles/539/

Haha, this is brilliant.

Reply 3227

SaBzY

greywacke

http://www.cnpg.com/video/flatfiles/539/

I was gonna post this!
So funny :biggrin:

Reply 3228

noodlecookie

clad in armour

I asked if an allele was produced from a mutation in a gene, how many mutations would there have to be in that particular gene for it to be a completely new gene and not just an allele

I'll answer this then I'm going to sleep lol!
I don't think we have to learn that... I think we only have to learn the types of mutations and the cystic fibrosis example...

Reply 3229

hollowpoint

What topics do you think are most likely to come up for the high mark qs?

Reply 3230

Tinkerbelle ♥

Ok so can someone just check I've got this right.

p + q = 1 is for the different alleles

p would be one allele, eg R for red flowers and q would be another eg r for white flowers.

p2 + 2pq + q2 = 1 is for the different genotypes

p2 would be for RR for red
2pq would be Rr for red
q2 would be rr for white

Reply 3231

Jemmmx

Right, Good Luck for tomorrow.
Given up on revision, will look a little bits in the morning.

Just think, 12hrs and it will all nearly be over...

Reply 3232

Jemmmx

ratherbesurfing

can people please give examples of similarites/differences between the normal synaptic junction and the muscle synaptic junction?

THIS.

Reply 3233

The TSR Star.

If they say which part of the brain controls voluntary movement of muscles, and it's a one marker, do you say cerebrum or cerebellum?

Reply 3234

conorf199

do we need to know about wheat in any detail? anddd, ive completely left translation and transcription assuming they wont come up because of the 10 marker in the specimen

Reply 3235

conorf199

The TSR Star.

If they say which part of the brain controls voluntary movement of muscles, and it's a one marker, do you say cerebrum or cerebellum?

id go for cerebrum, because of (voluntary)

Reply 3236

Summerdays

For those of you who have attempted the specification paper (either on your own or in class), what did you get? I think I got either 75-80%, depending on harsh the examiner is.

Reply 3237

SaBzY

Summerdays

For those of you who have attempted the specification paper (either on your own or in class), what did you get? I think I got either 75-80%, depending on harsh the examiner is.

I did it as a mock in class, got 84% :smile:

Reply 3238

blueberry123

conorf199

id go for cerebrum, because of (voluntary)

i thought cerebellum coordinates movement and balance whereas cerebrum deals with ,emotion, consious thoughts judgement and intelligence .
so i would have gone for cerebellum