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Reply 20
TX22
are these summaries helping?


Yep thanks ! :yes:
Reply 21
carbon monoxide can lead to atherosclerosis and CHD. it really easy to learn.

emphysema, lung cancer normally caused by tar.

Tar relates to emphysema chronic bronchitis, and lung cancer

carbon monoxide, nictotine related to CHD

also diet like cholesterol, lipoproteins, high salt intake relates to CHD.




HumanNature1992
The more important stuff for smoking is in terms of diseases, like atherosclerosis, CHD, stroke, lung cancer, Chronic Bronchitits and Emphysema.:confused:
TX22
carbon monoxide can lead to atherosclerosis and CHD. it really easy to learn.

emphysema, lung cancer normally caused by tar.

Tar relates to emphysema chronic bronchitis, and lung cancer

carbon monoxide, nictotine related to CHD

also diet like cholesterol, lipoproteins, high salt intake relates to CHD.


Don't worry, I know this stuff, sitting this for a third time:p:

Stroke, are also caused by nicotine, as nicotine create blood clots and a blood clot to the brain causes a stroke. And carbon momoxide irreversibly combines with haemoglobin making less o2 availabe for the brain.

Also Lung cancer, caused by carciongens in the smoke --->uncontrolled cell growth ---> malignant tumour--->blocks air flow--->decreases gas exchange and leads to shortness of breath.
Reply 23
Hydrolysis

H20 added
Covalent bond broken
Large molecule split into smaller molecules (seen in digestion)

Condensation

H20 released (H on one molecule, OH on other molecule)
Covalent bond formed (-O-)
Small molecules built into larger molecules (seen in muscle growth)


Overview of the roles and functions of biological molecules

Carbohydrates: Energy storage and supply, structure

Proteins: Enzymes, antibodies, hormones, transport, structure

Lipids: Membranes, energy supply, thermal insulation

Vitamins & Minerals: Metabolic reactions, coenzymes

Nucleic acids: Information molecules that carry the instructions for life

Water: Support, transport, medium for metabolism



Structural differences between a-glucose and b-glucose

ABBA

A-glucose = Below

B-glucose = Above

In a-glucose, the OH bond is below the the plane of the ring structure whereas in b-glucose, the OH bond is above the plane of the ring structure.



CARBOHYDRATES

Two monosaccharides of a-glucose form a disaccharide called maltose.

Lots more a-glucose molecules forms a polysaccharide called amylose.


Starch: energy storage in plants

Amylose is present in starch.
It's a long, unbranched chain.
The angles of the glycosidic bonds cause amylose to coil.
This makes it more compact, making it a good storage molecule, as more substance can be put into a small space.

Starch is also made up of amylopectin.
This is a long, branched chain.
These branches allow enzymes to access the glycosidic bonds with ease so glucose can be released quickly.

Starch is also insoluble in water which is vital as it means it does not affect the water potential of the plant cell and cause water to enter by osmosis (which would cause the plant cell to swell)


Glycogen: energy-storage in animals

Similar structure to amylopectin.
Also made on a-glucose subunits.
Differs to amylopectic as it has MORE side brances.
This makes it even more compact than starch.

Same properties as starch in that it's insoluble in water and it's branches allow glucose to be released quickly.


Cellulose

Made of b-glucose which forms long, straight chains.

Hydrogen bonds form between the different cellulose chains to form macrofibrils.
Macrofibrils can criss-cross and run in all directions to give the wall even more strength.

Cellulose has great mechanical strength and structural support.
Reply 24
Proteins

Monomers: amino acids

Amino acids consist of an amino group, carboxyl group and an R group bonded to a carbon

Condensation reaction takes place between the carboxyl group on one and the amino group on the other. The bond formed is a peptide bond


Levels of protein structure

Primary - sequence of amino acids. Involves peptide bonds

Secondary - the coiling of polypeptide chains to form an alpha helix or the folding of polypeptide chains to form beta plated sheets. This involves hydrogen bonds (hold the coils/folds together)

Tertiary - the coils and folds then coil and fold themselves.
This is the final 3D structure for proteins made of one polypeptide chain
This involves:

Disulfide bonds (between sulfur on one cysteine molecule and sulfur on another) sulfur is a type of amino acid.

Ionic bonds (between +ve R group and -ve R group)

Hydrogen bonds between +ve molecule and -ve hydrogen

Hyrophobic and hydrophillic interactions.


Quaternary structure - How different polypeptide chains are assembled/held together.
Involves all the bonds above.
Final 3D structure for proteins made of more than one pp chain.


Structure of collagen

3 polypeptide chains wound in a triple helix held by hydrogen bonds

35% of its primary structure is made of glycine.
Glycine contains sulfur so it can form disulfide bridges = strong.

Collagen + another collagen molecule -> fibril.
Many fibrils make a fibre.
Different collagen molecules are held together by covalent bonds
(between amino acid group & carboxyl group)


SHOT GUN POINTS

Carbohydrate monosaccharides: glucose, fructose, galactose

Carbohydrate disaccharides: sucrose (glucose+fructose), lactose(glucose+galactose), maltose (glucose+glucose)

Carbohydrate polysaccharides: amylose, amylopectin

Bond formed in condensation is glycosidic.

Test for starch: iodine test, turns blue-black if present



Protein monomer: amino acids

Joining of amino acids forms a peptide bond.

Test for protein: Biuret test, goes purple if protein present
Reply 25
these were posted on another thread by someone else. Thought i would just paste it here
About comparing the structure and functions of collagen and haemoglobin.. I can compare their structures but what would you say for their functions? Just one line about how collagen is strong and supportive, a fibrous protein but haemoglobin is a globular transport? Or would you have to relate the structure to the function?
I'm doing (and flopping :biggrin:) this exam...

haven't really started revision as I have psychology and chemistry which are loooong ass units...

should be interesting to see though :biggrin:
Reply 28
Can someone please help me!!

I'm stuck on:

Nucleaic Acids - DNA + RNA

Replication

Immune system

Smoking + disease

ro.
Can someone please help me!!

I'm stuck on:

Nucleaic Acids - DNA + RNA

Replication

Immune system

Smoking + disease



What exact part in each of those topics?
serious question guys, i need 84% to get an A, do you think that is do-able?
annieareyouokay
serious question guys, i need 84% to get an A, do you think that is do-able?


With hard work and determination, yes. :yes:
Reply 32
Does anyone have the OCR Biology January Unit 2 2010 paper with mark scheme??
Emy8643
Does anyone have the OCR Biology January Unit 2 2010 paper with mark scheme??


Here:

http://www.thestudentroom.co.uk/showthread.php?p=25489187#post25489187
Emy8643
Thank youu! :smile:


Dont thank me, thank them :wink:
Reply 36
Wow these notes are really great!
Reply 37
Marshmellow.
What exact part in each of those topics?


I've got neculeaic acids and immune system down now, but i dont understand anything on protein synthesis, like i don't even understand what it says in my revision guide on it.

And i understand smoking somewhat , but i just cant seem to remember it.
Reply 38
ro.
I've got neculeaic acids and immune system down now, but i dont understand anything on protein synthesis, like i don't even understand what it says in my revision guide on it.

And i understand smoking somewhat , but i just cant seem to remember it.


I'll explain protein synthesis to you if you want. :smile: What revision guide do you have?

Pretty much, think of protein synthesis in a step-by-step process like this: DNA --> RNA --> CYTOPLASM --> RIBOSOME --> PROTEIN.

DNA is found in the nucleus. To make a protein, it must first leave the nucleus. But, DNA is too large to move out of the nucleus. So, DNA copies itself into RNA, which is a smaller molecule (it has a single polypeptide chain, DNA has a double). RNA leaves the nucleus and joins with a ribosome in the cytoplasm. Ribosomes are the organelles that look like jelly babies and are the site where proteins are made. A protein is synthesised here. There you go! :smile: Any questions?
Just to add to that.. the DNA gives the RNA a sequence to follow. It puts all the free floating RNA nucleotides in the same order (as is on the DNA) so it's effectively a replicate (just single stranded so it's able to leave the nucleus)
After it's all in order, the RNA single strand will peel away from the DNA molecule and leave the nucleus via the nuclear pore as stated above. The ribosome's job is to translate the base sequences of RNA (which the DNA gave it) so the amino acids can be brought in the along in the correct order. Three bases code for an amino acid so a different order of bases will produce a different amino acid.
The amino acids undergo condensation reactions to join up.. forming peptide bonds.. the chain of amino acids produces a protein.

I suggest you watch a video of protein synthesis on youtube if you don't understand it. :smile: I find videos helpful for such subjects like DNA, RNA and immune response - just puts it all into context.

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