BIOLOGICAL MOLECULES - AQA A LEVEL BIOLOGY

what are the three categories of molecules?

lipids, proteins and carbohydrates

what is a molecules if its based on carbon?

organic

what group does DNA belong too?

nucleic acids

what is a one unit carbohydrate called?

monosaccharide

what is a monosaccharide with three carbons called?

triose monosaccharide

what is a monosaccharide with five carbons called?

pentose monosaccharide

give an example of a triose monosaccharide?

glyceraldehyde

give an example of a pentose monosaccharide?

ribose (found in nucleic acids e.g. dna and rna)

what is the name of a six carbon monosaccharide?

hexose monosaccharide

give 3 examples of a hexose monosaccharide

glucose, fructose, galactose

what is the formula for hexose monosaccharides?

C6 H12 O6

what is two monosaccharides joined together?

disaccharide

what is maltose made up of?

glucose and glucose

what is sucrose made up of?

glucose and fructose

what is lactose made up of?

glucose and galactose

how do you test for non reducing sugars?

benedicts solution in boiling water bath

what monosaccharide is a non-reducing sugar?

sucrose

why does a colour change take place during the test for reducing sugars?

because copper sulfate is being reduced

what factors cause oxidation?

add oxygen, loose hydrogen, loose electrons

what factors cause reduction?

loose oxygen, gain hydrogen, gain electrons

how is a disaccharide formed?

glycosidic bond

what reaction takes place to join a disaccharide?

condensation

what is the difference between a-glucose and b-glucose?

a - same, B - opposite

what are the two types of lipids?

triglycerides and phospholipids

what are triglycerides made up of?

glycerol and 3 fatty acids

what are phospholipids made up of?

glycerol, 2 fatty acids and a phosphate group

what is a fatty acid with no double bonds called?

saturated fatty acid

what is a fatty acid with one double bond called?

mono unsaturated fatty acid

what is a fatty acid with more than one double bond called?

poly unsaturated fatty acid

what is the test for lipids?

alcohol and shake, water and emulsion forms

is cellulose branched or unbranched?

unbranched

what is cellulose made up of?

two beta glucose molecules

is glycogen branched or unbranched?

very branched

how branched is starch?

highly branched

what is starch made from?

amylose and amylopectin

what are branched structures good for?

energy storage

what is the test for starch?

iodine in potassium solution turns blue

how may levels of protein structure are there?

4

what is the primary structure like?

a sequence of amino acids

what is the secondary structure like?

folding of amino acid chains in alpha-helices and beta-pleated sheets

what is tertiary structure?

detailed spacial arrangements of amino acids/a-helices/b-pleated

what is quaternary structure?

more than one polypeptide makes up the protein

give an example of a quaternary structured protein?

haemoglobin made up of 4 polypeptide chains

what is an amino acid made up of?

carboxyl, R group and nitrous

how are amino acids joined in chains?

peptide bonds via condensation reaction

what do secondary and tertiary structures do?

help to maintain an active site

what are hydrogen bonds?

forms between R groups, weak, stronger than van der waals forces

what are ionic bonds?

form between groups with opposite charged, stronger than hydrogen bonds

what are disulphide links?

form between cysteine side chains, strong covalent bonds between sulphur molecules

what four factors effect the rate of change?

enzyme concentration, substrate concentration, pH, temperature

what are competitive inhibitors?

molecular shape, non permanent bond

what are non-competitive inhibitors?

attack enzyme and change its shape

what does DNA stand for?

deoxyribonucleic acid

what does DNA do?

stores genetic information

what kind of genetic information does the DNA store?

all the information an organism needs to grow and develop from a fertilised egg to a fully grown adult.

what does RNA stand for?

Ribonucleic acid

what is RNAs structure?

similar to the structure of DNA

what is the main function of RNA?

to transfer genetic information from the DNA to the ribosomes.

what are ribosomes known as?

the bodies protein factories

what do ribosomes do?

read the RNA to make polypeptides in a process called translation

what are ribosomes made up of?

RNA and proteins

what is a nucleotide made out of?

a pentose sugar, a nitrogen-containing organic base and a phosphate group

what does organic mean?

it contains carbon

what do nucleotides to?

monomers that make up DNA and RNA

what is the name of the sugar in DNA?

deoxyribose

what does each DNA nucleotide have the same of?

same sugar and phosphate group

what in a nucleotide can vary?

the base?

what are the four possible bases?

adenine, thymine, cytosine and guinine

what is the sugar in RNA?

ribose

how are the four bases of RNA different to the four bases of DNA?

uracil replaces thymine

what is a polynucleotide?

it is a polymer of nucleotides

give examples of nucleotides?

DNA and RNA

how do the nucleotides join together to form a polynucleotide?

via a condensation reaction between the phosphate group of one and the sugar group of the next

what bond does the condensation reaction to form a polynucleotide form?

a phosphodiester bond

what does the phosphodiester bond consist of?

the phosphate group and two ester bonds

the chain of sugars and phosphates is known as the?

sugar-phosphate backbone

to form the double helix structure how do the two DNA polynucleotides join together?

via hydrogen bonding between the bases

what is it called when each base can only join with one particular partner?

complementary base pairing

which bases pair together?

T-A, G-C

how many hydrogen bonds form between A and T?

2

how many hydrogen bonds form between C and G?

3

how are the polynucleotide strands situated to form the double-helix?

they run antiparallel

when was DNA first observed?

1800s

when DNA was first observed what was the scientists thoughts?

doubted that it could carry genetic code because of its relatively simple chemical composition

in 1800s what did scientists think carried the genetic information instead?

proteins

when was it that experiments proved that DNA was the genetic information carrier?

1953

what year did Watson and Crick determine the double helix structure?

1953

RNA is made from a?

single polynucleotide chain and is shorter than most DNA polynucleotides

what does DNA do before cell division?

copies itself

why does DNA copy itself before cell division?

so that each new cell has the full amount of DNA

what is the name of the process when DNA replicates itself before cell division?

semi-conservative replication

why is it called semi-conservative replication?

because half of the strands are from the original DNA and half of them are new

what does semi-conservative replication mean for the cells?

that there is genetic continuity between generations of cells

what enzyme breaks the hydrogen bonds to make the helix unwind?

DNA helicase

each original strand acts as what for the new strand?

a template

what does complementary base pairing mean for semi-conservative replication?

that the free-floating DNA nucleotides are attracted to their complementary exposes bases on each original template strand

what joins the nucleotides of the new strands together?

condensation reactions catalysed by the enzyme DNA polymerase

what bonds form between the bases of the original and new strands of DNA?

Hydrogen bonds

what are the neds of DNA strand called?

3' (three prime) and 5' (five prime) ends

in DNA helix the strands run in opposite directions meaning they are?

antiparallel