Biomacromolecules 2
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Transcript of Biomacromolecules 2
Biomacromolecules 2
Nucleic acids
• RNA and DNA. What’s the D and the R???
• Deoxyribonucleic acid• Ribonucleic acid
The sugars
The nucleotide monomer
Nitrogen base
HO H
C 5’ O
Negative charge
C 1’
C 2’C 3’
C 4’
Phosphate group
Phosphate Group
OH
P-O O
O
C 5’
What’s this?
Hydroxyl group!
Nitrogen base
HO H
5’ O
1’
2’3’
4’
OH
P-O O
ONitrogen base
HO H
5’ O
1’
2’3’
4’
OH
P-O O
O
How will they bond?
OH
Nitrogen base
OH
5’ O
1’
2’3’
4’
OH
P-O O
O
H
Nitrogen base
HO OH
5’ O
1’
2’3’
4’
P-O O
O
O
Phosphodiester bond. One ester bond was
there already. A new one has formed between the phosphate on the 5’ end and the oxygen on the
3’end.
What type of reaction is this?
Condensation polymerisation!
• Nucleotides can only be added to the 3’ end of the newly forming strand.
• This results in elongation of the new strand in a 5'-3' direction.
S sugar
P
B
Phosphate group
Nitrogen base
The molecule grows from the 5’ end to the 3’ end
Base PairingThere are 4 different bases in DNA .
• Adenine• Thymine• Guanine• Cytosine
• A always pairs with T and C with G
• A &T and C & G are complementary bases
• A & G are Pyrimidines• C & T are Purines
• Two hydrogen bonds form between A and T
• Three hydrogen bonds form between C and G
• DNA forms a double helix
• IN RNA, T is replaced by Uracil
DNA is an information molecule
• Information is carried in the order of the bases in DNA
• The information tells the cell which proteins to make
• The information is carried outside the nucleus by mRNA and proteins are built using tRNA and rRNA
• RNA is not a double helix
Lipids
• Fats, oils, waxes, steroids• Functions
– Energy storage– Structural components of
membranes– Transmission of chemical
signals within and between cells
• Lipids are not polymers
Triglycerides• Triglycerides have
a three (tri) fatty acid chains attached to a glycerol
• These are the fats used as energy stores
Only 3 OH groups so only 3 fatty acid chains. Not
polymers
Fat or oil?• Fats are solid at room temperature• Oils are liquid• This is determined by the structure of the fatty acid
chains• Saturated fatty acids have no double bonds in the
fatty acid chain (the chains are saturated with hydrogen atoms)
• Unsaturated have some double bonds• Unsaturated have some kinks in the fatty acids chains
Saturated Unsaturated
Cannot pack as tightly and so is liquid at higher temperatures
Phospholipids
• Phosphate is added to the glycerol instead of another fatty acid chain
• Phosphate group is polar, making it hydrophilic
• Fatty acid chains are non-polar and therefore hydrophobic
I water
I h8 water!
• Phospholipids will naturally form a bilayer in water
• The hydrophilic ends will point towards the water
• The hydrophobic ends will point to each other
Lets form a bilayer. It’s the only way to
keep both of us happy.
Glycolipids
• A carbohydrate group is added to the glycerol instead of a third fatty acid chain
• Project from plasma membranes and act as signal receptors
Steroids are lipids• Cholesterol is a
steroid• It is an important
structural component of many membranes
• It is the starting point for the synthesis of all steroid hormones e.g. oestrogen and testosterone
Group work
• Groups of 2• Each group do a different biomacromolecule• Heading will be your biomacromolecule• Content will be subunits, examples, function
where they’re found• Any other pertinent information• Include diagrams
Macromolecule Building blocks
Carbohydrates monosaccharides
Proteins Amino acids
Nucleic Acids nucleotides
Fatty acids and glycerolLipids
Examples
Glycogen, starch
Haemoglobin,