Biochem Amino Acids And Lipids Flashcards
What type of molecules are lipids?
Macromolecules
How much energy do lipids store (relative to carbohydrates)
Double
Functions of lipids:
Thermal Insulation - reduce heat loss energy storage - adipose tissue - protections hormone production cell signalling buoyancy.
What groups make up an amino acid?
An amine group, variable r group and a carboxyl group
When are peptide bonds formed?
The condensation of two amino acids.
What makes up a protein?
One or more polypeptide chains.
What is primary structure of a protein?
Straight line of amino acids - simple polypeptide chain
This is the sequence in which amino acids are joined.
What is the secondary structure of a protein?
Hydrogen bonds form between amino acids. If the bonds are intramolecular then it will form an alpha helix. Otherwise if hydrogen bonds from between chains it will form a beta pleated sheet.
What is tertiary structure of a protein?
The protein in folded further forming a 3D shape. Ionic bonds, disulphide bonds, hydrophilic/hydrophobic interactions and hydrogen bonds effect shape. (all these interactions stem from/ are dependent on r-groups)
What is Quaternary structure of proteins.
Several polypeptide chains form the structure. All bonds occur, it is more stable than tertiary; more interactions occur because r-groups closer together.
What is insulin?
Insulin is a polypeptide hormone involved in the controlling of blood glucose concentration, by signalling to cells to take in more glucose from the environment. It is soluble and so can be transported through the blood.
What is collagen?
3 polypeptides in a triple helix, forming a long rope structure. It is a fibrous protein and use on tendons, ligaments, and skin. Covalent bonds link chains and minerals bind to it to increase rigidity. triple helixes cross-link and wound to form microfibril.
What is keratin?
Polypeptide containing a large proportion of sulphur containing amino acids; this causes it to form strong disulphide bonds to create an inflexible material ( seen in fingernails). The number of disulphide bonds determine flexibility.
What is haemoglobin?
Polypeptide containing a prosthetic iron (haem) group. Binds to oxygen in blood, soluble in water, it’s a quaternary protein, it’s a red pigment, contains 2 alpha units and 2 beta units.
ATP groups?
3 phosphate, one Pentose sugar (ribose) and a nitrogenous base (adenine)
How does ATP release energy?
ATP requires a small amount of energy to break the hydrogen bonds on the last phosphate group. A large amount of energy is then released as the phosphate forms new bonds, whilst the phosphate is removed through hydrolysis. Because these reactions happen simultaneously it is a coupled reaction.
Why is ATP not used for storage?
ATP is not as stable as fats, because it easily hydrolyses in water.
Cholesterol determine the … of membranes
Moderate the fluid properties - maintains integrity and mechanical stability. (ANIMAL CELL MEMBRANES)
Cholesterol is used to synthesise…
steroid hormones and bile.
Why are the fatty acid tails of triglycerides important for the storage of energy?
The fatty tails are non-polar and are therefore hydrophobic/ insoluble; This causes the fatty acid tails to group within globules, which are surrounded by a ring of glycerol heads. The tails being sheltered from the water causes the globule to be very stable and a long lasting storage for energy. (Interactions between tails maybe?)
What bond is hydrolysed in triglyceride molecules?
The ester bonds between the glycerol head and fatty acid tails.
Mixing a substance with water and ethanol tests for what?
Lipids
What is the positive test result when testing for lipids?
The formation of a white precipitate.
What’s the difference between fats and oils? (properties)
Fats are solid at room temp, whereas oils are liquids at room temperature.
What’s the difference between fats and oils? (Structure)
Unsaturated fatty acids have bent tails. This means they are not able to be tightly packed and results in oils that are liquid at room temperature. Whereas fats have straight tails and can be compact.
What groups make up a phospholipid?
Phosphate, glycerol and 2 fatty acid tails.
True or False: Cholesterol is soluble
False, it’s carried around the body by lipoproteins.
What varies in a lipids?
Whether they are saturated or not
What is the name of the test for Lipids?
Emulsion test.
What does the emulsion test involve?
Add distilled water and ethanol to substance - shake - if cloudy lipids present.
What are beta pleated sheets formed by?
Hydrogen bonds forming between parallel polypeptide chains.
What processes do globular proteins regulate?
Chemical reactions, immunity, muscle contraction and many more
What are conjugated proteins?
Globular proteins that contain a prosthetic group.
Give 2 categories that are made up by conjugated proteins:
Glycoprotein and lipoprotein
Summarise everything about fibrous proteins: (Exclude examples)
Fibrous proteins are formed from long, insoluble molecules; they are insoluble due to their high proportion of amino acids with hydrophobic R-groups in their primary structure. The sequence is repetitive, leading to an organised structure; this cause most fibrous proteins to make strong, long and flexible molecules.
Unlike other proteins, Fibrous proteins are NOT FOLDED INTO COMPLEX 3D SHAPES.
Haemoglobin:
Quaternary globular protein made of 2 alpha and 2 beta sub units. Has haem prosthetic group.
Describe collagen in terms of flexibility
A fibrous protein which is flexible but not stretchable.
Describe insulin in terms of flexibility
Globular protein with a specific fixed shape
Describe elastin in terms of flexibility
Fibrous protein which recoils after being deformed
Describe haemoglobin in terms of flexibility
Globular protein which can change shape.
Test for lipids?
Emulsion test: add ethanol to sample, mix with water and shake white precipitate positive result.
Globular proteins:
spherical ,compact, water-soluble, hydrophobic r-groups sheltered away from an aqueous environment. a-helix
Identification of proteins?
Biuret Test: Add copper sulfate, test should form a violet colour.
Summarise everything about globular proteins:
Soluble, spherical tertiary proteins with a hydrophilic outside. They may have conjugated groups and can be sensitive to temperature of pH.
