Biological molecules Flashcards
Bases in DNA
Cytosine
Guanine
Thymine
Adenine
Bases in RNA
Cytosine
Guanine
Uracil
Adenine
What are pyrimidines?
Smaller
1 carbon ring
C and T/U
What are purines
Larger
2 carbon ring
G and A
Describe a nucleic acid
A large polymer
Describe a nucleotide
A monomer
Differences between DNA and RNA
DNA-
Long double strand (helix)
Deoxyribose sugar
A, C, G & T
RNA-
Single short strand
Ribose sugar
A, C, G & U
Similarities of DNA and RNA
Pentose sugars
Polymers
Made of nucleotides (monomers)
What are the complementary base pairings?
A and T/U = 2 hydrogen bonds
C and G = 3 hydrogen bonds
What bond is present in DNA?
Phosphodiester bond
What carbon do the phosphate groups attach?
Number 5
Covalent bond
Two atoms share a pair of electrons
What bond forms between glucose molecules
Glycosidic bond
What makes maltose
2 Glucose alpha
1,4
What makes lactose
Glucose beta and galactose
1,4
What makes sucrose
Glucose alpha and fructose
1,5
Another name for glucose molecules
Monosaccharide
Another name for maltose/sucrose etc. Molecules
Disaccharides
What makes cellulose
2x alpha beta
1,4
Properties of water
Temp constant- coolant (hydrogen bonds) Transport medium Minerals soluble in water Transparent to light Cohesion Polar
What makes up amylose
Alpha glucose
(1,4)
(Helical)
What makes up amylopectin
Alpha glucose
(1,4) and (1,6)
(Branched)
What makes up glycogen
Alpha glucose
(1,4) and (1,6) every 25
(Branched and helical)
Another name for glycogen/amylose/amylopectin/cellulose
Polysaccharides
Bond in lipids?
Ester bond
What is a triglyceride molecule made up of?
A glycerol molecule
3 fatty acids
What is a phospholipid made up of
Phosphate Group
Glycerol
Fatty acids
What is the reaction forming lipids called
Esterification
Test for lipids
Emulsion test
Add ethanol- white emulsion forms
What are polysaccharides
Polymers made of monosaccharides
Joining together of lots of glucose molecules creates what?
A store of energy
What are characteristics of glycogen
1-4 and 1-6 carbon bonds
Chain formation with branches
Less tendency to coil
Easier to remove monomer units as has more ends
Why are polysaccharides good energy stores?
Compact
Less soluble than monosaccharides
Why is it important that polysaccharides are less soluble in water
If they dissolved it would disrupt the cells water potential
Why are polysaccharides less soluble
Because of their size (larger)
Through what reaction are glycosidic bonds formed
Condensation
When bonded together what form does cellulose take
Straight chain
What prevents spiralling in cellulose
The alternate invention of the beta glucose molecules
What bonds prevent spiralling
Hydrogen bonds between rotated beta glucose molecules
What are micro fibrils made up of
Beta glucose molecules
What are macro fibrils made of
Microfibrils
Why is cellulose hard to digest
The glycosidic bonds are hard to break
Define lipids
A group of substances that are soluble in alcohol rather than water
Define macromolecule
Large biological molecule
Define phospholipid
A molecule consisting of glycerol, two fatty acids and a phosphate group
Characteristics of a lipid
Contain large amount of carbon and hydrogen and a small amount of oxygen
Insoluble in water
Soluble in alcohol
what do fatty acids contain
A carboxyl group at one end
Hydrocarbon tail
Why are fatty acids, acids?
The carboxyl group can ionise hydrogen therefore it is an acid and can produce free H+ ions
What does the carbon bond in an unsaturated fatty acid inhibit
Hydrogen atoms can’t bond to the molecule
What do double bonds do
Provide a kink making the molecule more fluid
When does an ester bond appear
During the condensation reaction the water is given off creating a covalent bond between the glycerol and fatty acids
Five functions of lipids
Energy source Energy store Insulation Buoyancy Protection
What is different in the structure of a phospholipid to a triglyceride?
One of the fatty acids is replaced with a phosphate group
What part of a phospholipid is hydrophillic
Head
Why are fatty acids hydrophobic
They are non polar
What describes the properties of phospholipids in water
Amphiphatic
In a phospholipid bilayer where are the heads and tails
Tails in heads out
Cholesterol is what
A steroid alcohol or sterol
A type of lipid made without fattyacids or glycerol
Where is cholesterol found
Within the phospholipid bilayer
Define amino acids
Monomers of all proteins
Define peptide bond
A covalent bond formed when two amino acids are joined by a condensation reaction
What are proteins
Large polymers consisting of long chains of amino acids
Three functions of proteins
Form structural components
Tendency to adopt specific shapes and make into enzymes
Act as carriers in membrane
Structure of an amino acid
Amino group at one end
R group and an added hydrogen in the middle
Carboxyl group on the end
What enzyme breaks down peptide bonds
Protease
When two amino acids bond what is it called
Dipeptide
When a long chain of amino acids join together what is it called
Polypeptide
What is used to test for starch
Iodine
What colour change happens if starch present
Blue/black
What is used to test for reducing sugars
Benedicts reagent
Colour change if reducing sugars present
Red
Define a reducing sugar
Sugar which gives electrons to other molecules
What test for non reducing sugars
Benedicts solution
Colour change for non reducing sugars (low to high)
Blue Green Yellow Orange Red
Test for proteins
Biurent reagent
Light blue to lilac
What are glycosidic bonds
Formed between monosaccharides by a hydrolysis reaction
Characteristics of monosaccharides
Soluble in water
Quaternary structure
Protein consists of more than one polypeptide chain
Secondary structure
Coiling or folding of an amino acids chain
Main forms of secondary structure
Helix and beta pleated sheet
Tertiary structure
3D shape of a protein molecule
If a protein adopts a supercoiled shape what is this called
Fibrous protein
If a protein adopts a spherical shape what is this called
Globular protein
Where are disulphide links
Between the R groups
What is a fibrous protein
Thin long structure
Insoluble in water
What is a globular protein
Molecules with spherical shape
Soluble in water
Prosthetic group
Non protein component
Describe a fibrous protein
Regular repetitive sequences of amino acids
Insoluble in water
What do fibrous proteins do
Form fibres which form a structural role
Characteristics of amylose
Coils into spiral shape
Binds on carbons 1 and 4
Hydroxyl group on carbon 2 for hydrogen bonds
Globular proteins tend to fold up into what shape
Sphere
Two enzymes that carry out dna replication
DNA helicase
DNA polymerase
What is a nucleotide made up of
Pentose monosaccharide
Phosphate Group
Base
How many hydrogen bonds does A & T form
2
How many hydrogen bonds can C & G/U make
3
What is Adenosine triphosphate made up of
Base
Pentose sugar (ribose)
3 phosphate groups
Releasing energy through ATP is what reaction
Hydrolysis
Storing energy through ATP is what reaction
Condensation
DNA vs RNA
differences- dna 2 long strands vs 1 short strand
Deoxyribose vs ribose
A,C, G and T vs A, C, G and U
Define transcription
Copying of the genetic code from DNA into mRNA
Define translation
Assembly of a polypeptide from the genetic code on the mRNA
Where is the codon and anti codon
Codon on ribosome
Anticodon on tRNA
What is the triplet code
Sequence of 3 based- the codon
Sense strand
Runs from 5’ to 3’
Antisense strand
Acts as template strand
Runs from 3’ to 5’
In an amino acid which two groups combine to form a peptide link?
1 and 3
What does ethanol do to a lipid
Dissolves it
what is the formulae of a fatty acid
Cn H2n
