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

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Reply 2920
Avatar for aimz08
aimz08
13
Lac operon confusion.
What does RNA polymerase bind to - operator or promoter (these are the control elements yes?)

Can someone provide me a simple but correct explanation of the lac operon? Because I am getting confused...thanks
Falcon91
Gametes can be single letters, just think about it as Monohybrid crosses but they can be on a certain chromosome, in my example that chromosome was C, however they will always give you an idea whether u need to put the chromosome letter or not in the stem of the question. If not then just use the allele letters e.g. if you have A and B, then write AB. Thats all.
PSC = Peter Symonds College

thank you, and everyone else, think i kinda understand it now :biggrin: btw, i dont :biggrin: wt gave u dat idea
aimz08
Lac operon confusion.
What does RNA polymerase bind to - operator or promoter (these are the control elements yes?)

Can someone provide me a simple but correct explanation of the lac operon? Because I am getting confused...thanks


RNA polymerase binds to promoter.
Reflex
if its AaBb then you look at it like this (A+a)(B+b) and multiply out the brackets to get AB Ab aB ab for all possible genotypes.

thanks, understand dat :biggrin:
Someone run me down the Galapagos Islands stuff please?
Guys any notes for this unit pks :wink:?will rep.
noodlecookie
Get a bit of each letter, e.g. parental genotype is AaBb (the big letter-litle letter combo usually comes up the most because it's the most friggin' complicated one).

Gametes are AB, ab, Ab and aB.

As long as you go through this step-by-step procedure instead of jumping the gun you shouldn't get it wrong:

Write down the genotypes.
Figure out the gametes.
Draw out a cross table and work it out, e.g. AB x ab = AaBb
Figure out each phenotype, e.g. pink wings/dodgy eye; green wings/normal eye
Tally them up and you get the phenotypic ratio.

thanks
Reply 2927
Avatar for Falcon91
Falcon91
Archen
which part of the DNA is negative that causes it to be pulled towards the anode in electrophoresis?

Phosphoryl/phosphate groups.
Reply 2928
Avatar for aimz08
aimz08
13
noodlecookie
Get a bit of each letter, e.g. parental genotype is AaBb (the big letter-litle letter combo usually comes up the most because it's the most friggin' complicated one).

Gametes are AB, ab, Ab and aB.

As long as you go through this step-by-step procedure instead of jumping the gun you shouldn't get it wrong:

Write down the genotypes.
Figure out the gametes.
Draw out a cross table and work it out, e.g. AB x ab = AaBb
Figure out each phenotype, e.g. pink wings/dodgy eye; green wings/normal eye
Tally them up and you get the phenotypic ratio.


Thats dihybrid inheritance right? So when it's monohybrid each parent has two letters? e.g. NN x nn so to get gametes split the genotypes;
N N n n then insert these into punnet cross to get Nn x4?
Archen
which part of the DNA is negative that causes it to be pulled towards the anode in electrophoresis?


The phosphate group makes it negative :smile:


EDIT: note to self, read for other posts before posting just to feel like a smartarse :|
Reply 2930
Avatar for aimz08
aimz08
13
win2kpro
RNA polymerase binds to promoter.


Ah thanks - mistake in my notes :rolleyes:
Perfect timing to figure that out day before exam and all
Reply 2931
Avatar for Falcon91
Falcon91
student92
Someone run me down the Galapagos Islands stuff please?

Man im spamming this thread, i should go revise synoptics but i just dont think its worth it lol

Anyway
-Giant Tortoises used for food and taken from island, endangered i.e. lonesome george
-Overfishing of sea cucumbers and shark fins
-Pollution due to oil spill
-Land clearance for agriculture and buildings are population increased

-Species introduced such as feral goats, outcompete tortoises, trample + eat a unique species of plant + overlap in niche so compete
-Goats also cause forest to be destroyed and turns to grass field so soil erosion takes place
-Foreign pests
-Red quinine tree outcompetes man native trees and so species diversity lost

Measures to counter:
-Quarantine system, any boats etc arriving on island are checked
-Education of local and encouraging conservation 'culture'
-Exploitation of control release of certain predators to remove certain pests
-Culling of feral goats

Btw lol noodlecookie, im just panicking like no tomorrow now, answering everyons questions ASAP. :P gna go revise methinks -.-
aimz08
Ah thanks - mistake in my notes :rolleyes:
Perfect timing to figure that out day before exam and all


Haha no worries :smile:

The repressor proteins bind to the operator though :wink2: - By doing so it also covers a part of the promoter and thats the reason why RNA polymerase isnt able to bind anymore.
Parental blood groups : AB and O. Parental genotypes IAIB x IOIO but why is the baby blood group B???
aimz08
Lac operon confusion.
What does RNA polymerase bind to - operator or promoter (these are the control elements yes?)

Can someone provide me a simple but correct explanation of the lac operon? Because I am getting confused...thanks


lactose present:
lactose binds to repressor protein and changes shape of active site
RNA polymerase binds to promoter region
allows transcription of Mrna and translation of beta-galactosidase and lactose permease which increases lactose uptake and breaks lactose into galactose and glucose to be used in respiration to release energy.

No lactose
regulatory gene synthesises repressor protein
binds to operator region and slightly blocks active site of promoter region.
RNA polymerase cannot bind
No translation and transcription of enzymes
aimz08
Thats dihybrid inheritance right? So when it's monohybrid each parent has two letters? e.g. NN x nn so to get gametes split the genotypes;
N N n n then insert these into punnet cross to get Nn x4?


Pretty much, yeah.

Oh and the cross table that I'm talking about is a punnet square, sorry for the confusion, I forgot what it was called :biggrin:
Reply 2936
Avatar for Falcon91
Falcon91
student92
Parental blood groups : AB and O. Parental genotypes IAIB x IOIO but why is the baby blood group B???


Gametes: IA or IB times by Io
F1 possibilities - IAIO or IBIO (O is recessive so Baby is B or A, 50% chance of either)
Reply 2937
Avatar for aimz08
aimz08
13
noodlecookie
Pretty much, yeah.

Oh and the cross table that I'm talking about is a punnet square, sorry for the confusion, I forgot what it was called :biggrin:


No confusion - thought that's what you meant :P Yay at least one thing I dont have to cram :smile:
Would anyone care to explain the bread wheat stuff to me? How you artificially select bread wheat or something?
Reply 2939
Avatar for Sakujo
Sakujo
14
student92
Parental blood groups : AB and O. Parental genotypes IAIB x IOIO but why is the baby blood group B???


IO is recessive.

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