Chapter 3- Biological Molecules and Chapter 4- Enzymes Flashcards
How does hydrogen bonding occur in water?
H2O is a polar molecule
different molecules of water interact between positive and negative ends
What are carbohydrates made up of?
C,H,O
What are lipids made up of?
C,H,O
What are proteins made up of?
C,H,O,N,S
What are nucleic acids made up of?
C,H,O,N,P
Structure of glucose
Glucose is a monosaccharide, composed of six carbons and therefore a hexose monosaccharide, when forming a polymer creates a polysaccharide
What is an alpha glucose
Hydroxyl group on same side
What is a beta glucose?
Hydroxyl group above not below on 1st carbon
Properties of glucose
Polar and soluble in water
What do two glucose molecules form
Forms maltose and water
Maltose contains a 1,4 glycosidic bond
Other hexose monosaccharides
Fructose and galactose
What forms sucrose?
Fructose + glucose
What forms lactose?
Galactose + glucose
Two important pentose sugars
Ribose sugar
Deoxyribose sugar
Difference between a hexose and pentose monosaccharide
Hexose contains 6 carbons
Pentose contains 5 carbons
How is starch formed?
Formed by many alpha glucose molecules
One of the polysaccharides in starch is called amylose. Amylose is formed by alpha glucose molecules joined together only be 1,4 glycosidic bonds. The angle of the bond means that this long chain of glucose twists to form a helix which is further stabilises by hydrogen bonding. This makes the polysaccharide more compact , and much less soluble
What other type of starch can be formed?
When 1,6 glycosidic binds form , this starch is known as amylopectin
Key properties of amylopectin and glycogen
Insoluble, Branched, and compact
Hydrolysis reaction
Addition of water molecules
Converts starch to glucose
Cellulose structure and how it’s formed
Beta glucose molecules , alternate beta glucose molecule turned upside down.
Unable to coil or branch
Cellulose make hydrogen bonds with each other forming microfibrils, there microfibrils combine to produce fibres. These fibres are strong and are used to make cell walls.
Roles of glycogen and amylopectin
Insoluble, Branched and compact. These properties mean it is ideally suited to the storage roles that they carry out
What is a triglyceride made up of?
One glycerol molecule
Three fatty acids
What is a phospholipid made up of?
Phosphate group
Two fatty acids
Glycerol molecule
The phosphate ions have extra electrons so are negatively charged making them soluble in water.
Roles of lipids
Membrane formation
Hormone production
Electrical insulation
Waterproofing
Synthesis of peptides
Amino acids join when the amine and carboxylic acid groups connected to the central carbon atoms react. The r groups are not involved at this point. The hydroxyl in the carboxylic acid group of one amino acid reacts with a hydrogen in the amine group of another amino acid. A peptide bond is formed between two amino acids
Primary structure
Sequence in which the amino acids are joined. It is directed by information carried within DNA. The particular amino acids in the sequence will influence how the polypeptide folds to give the proteins final shape.The only bonds involved in primary structure are peptide bonds.
Secondary structure
The oxygen, hydrogen and nitrogen atoms of the basic , repeating structure of amino acids interact. Hydrogen bonds may form within the amino acid chai, pulling it in to a coiled shape called an alpha helix. Can also form beta pleated sheets.
Tertiary structure
Folding of the protein into its final shape Interaction between r groups Hydrophobic and hydrophilic interactions Hydrogen bonds Ionic bonds Disulfide bonds
Quaternary structure
The association of two or more individual proteins called subunits
Breakdown of peptides
Requires addition of a water molecule
Globular protiens
Compact water soluble and usually roughly spherical in shape. They form when proteins fold into their tertiary structure in such a way that the hydrophobic r groups on the amino acids are kept away from the aqueous environment
Haemoglobin
Red oxygen carrying pigment found in red blood cells
Made up of four polypeptides
Two alpha and two beta subunits
Each subunit contains a prosthetic haem group
Able to pick up oxygen
Catalase
An enzyme which speeds up the breakdown of hydrogen peroxide
Fibrous protiens
Formed from long insoluble molecules. This is due to the presence of a high proportion of amino acids with hydrophobic r groups in their primary structures. They contain a limited range of amino acids, usually with small r groups. Primary structure usually quite repetitive. They tend to make strong, long molecules which are not folded into 3D shapes.
Keratin
A group of fibrous protiens present in hair, skin and nails. Contains many strong disulphides bridges
Elastin
Fibrous protein found in elastic fibres. Elastic fibres are present in the walls of blood vessels and in the alveoli of the lungs.
Collagen
Is another fibrous protien. It is a connective tissue found in skin, tendons, ligaments and the nervous system
Has a strong rope like structure and is long.
What does a nucleotide contain?
A pentose monosaccharide
A phosphate group
A nitrogenous base
How are nucleotides linked together?
By phosphodiester bonds
Difference between deoxyribose and ribose
Deoxyribose contains one less oxygen
Description of DNA
Made up of two strands of polynucleotides coiled into a helix
The two strands of double helix joined together by hydrogen bonds
Run in opposite directions-anti parrallel
Different number of bonds between C and G , A and T
C and G 3 bonds
A and T 2 bonds
What bases are pyrimidines
Cytosine and Guanine
What bases are purines?
Anadine and guanine
How does RNA differ from DNA
Ribose, U instead of A
What does semi conservative replication mean
One old strand, one new
Double helix is unzipped, the free dna nucleotides will pair with complimentary base pairs.
Role of DNA helicase
Breaks down the hydrogen bonds
Role of DNA polymerase
Forms phosphodiester bonds
What enzyme breaks down start to maltose
Amylase
What enzyme breaks down maltose to glucose?
Maltose
What enzyme breaks down hydrogen peroxide?
Catalase
Enzyme to breakdown proteins into smaller peptides
Trypsin
What is temperature coefficient?
Measure of how much the rate of reaction increases with a 10 degrees rise in temperature.
How are enzymes affected by temperature?
As the temperature increases the vibrations increase until the bonds strain and then break. The breaking of these bonds results in a change in the precise tertiary structure of the protien. The enzyme has changed shape and is said to have been denatured.
How does pH affect enzyme activity?
Hydrogen bonds ams ionic bonds between amino acid r groups hold protiens in their precise 3D shape. A change in pH refers to a change in hydrogen ion concentration. More hydrogen ions are present in low pH acid environments and fewer hydrogen ions are present in high pH alkaline environments
What is competitive inhibition?
A molecule that has similar shape to substrate of enzyme and can fit into active site
Blocks the substrate from entering the active site
The enzyme cannot carry out its function and is said to be inhibited
What is non competitive inhibition?
Inhibitor binds to the enzyme at a location other than the active site. Known as a allosteric site.
Define a cofactors
A non protien helper component in order to carry out their function as biological catalysts. They may transfer atoms or groups from one reaction to another in a multi step pathway or they may actually for, part of the active site of an enzyme
What is a prosthetic group?
Required by certain enzymes to carry out the catalytic function
In what reaction are zinc ions important?
Form an important part of the structure of carbonic anhydrase an enzyme necessary for metabolism of CO2
How does hydrogen bonding occur in water
The O takes a negative charge
The two Hydrogens take a positive charge
The hydrogens are attracted to other oxygens from other water molecules
Roles of water
Solvent
Transport medium
Coolant
A habitat
Benedictus test for reducing sugars
Place sample in boiling tube Add an equal volume of benedict reagent Heat the mixture gently for 5 minutes A brick red precipitate forms if positive and reduces Cu2+ to Cu+ A blue precipitate forms if negative
Benedictus test for non reducing sugars
Sucrose is an example
However if sucrose is heated with HCl first it is hydrolysed glucose and fructose which are both reducing sugars
Iodine test
A few drops of iodine dissolved in potassium iodide solution are mixed with a sample.
If the solution changes from yellow/brown to purple/black starch is present
What is a colorimeter?
A piece of equipment used to quantitvely measure the absorbance, or transmission, of light by a coloured solution. The more concentrated the solution the more light it will absorb and less it will transmit.
What is a biosensor?
Use biological components to determine the presence and concentration of molecules such as glucose
Molecular recognition
Transduction
Thin layer chromatography method
Draw a pencil line on the chromatography plate about 2cm above from the bottom.
Four equally spaced points are marked along the pencil line
The amino acid solution is added to a spot on the pencil line using a capillary tube
The three remaining marks were spotted with three known amino acids
Plate was then placed into a jar containing the solvent.
The plate was then left until the solvent was 2cm from the top
The plate was then allowed to dry
The plate is then sprayed with ninhydrn spray
Define genetic code
DNA must code for a sequence of amino acids
Define a triplet code
A sequence of three bases, called a codon.
Each codon codes for a amino acid
A section of DNA which codes for a whole protien is known as a gene
It is universal all organisms use this code
Define Degenerate code
Stop codons
Start codons
Several codons code for same amino acid
Precursor activation
When enzyme is produced in an inactive form. Precursor enzymes often have to undergo a change in shape to the tertiary structure, particularly to the active site , to be activated. This can be achieved by the addition of a co factor.
Examples of fibrous proteins
Keratin
Elastin
Collagen
Structure of elastin
Link many soluble tropoastin
Makes a cross linked stable insoluble structure
Able to stretch and recoil without breaking
Structure of collagen
Three polypeptide chains wound around each other forms a triple helix structure
Every third amino acid in chain is glycine
Many boyfriends bonds form between the polypeptide chains forming long quaternary proteins
Produce strong fibers
The r groups repel one another increasing stability
Lipid emulsion test
Sample mixed with ethanol Then water Shaken If white emulsion forms indicates present of lipid If remains clear negative
Identifications of proteins
Bitter test
3cm of liquid sample mixed with an equal volume of sodium hydroxide
1% copper sulfate solution was then added a few drops at a time until the sample turned blue
The solution was mixed and left to stand for five minuteman minutes
