Biochem Amino Acids And Lipids

Question 1

What type of molecules are lipids?

Answer 1

Macromolecules

Question 2

How much energy do lipids store (relative to carbohydrates)

Answer 2

Double

Question 3

Functions of lipids:

Answer 3

Thermal Insulation - reduce heat loss
 energy storage - adipose tissue - protections
 hormone production
cell signalling 
buoyancy.

Question 4

What groups make up an amino acid?

Answer 4

An amine group, variable r group and a carboxyl group

Question 5

When are peptide bonds formed?

Answer 5

The condensation of two amino acids.

Question 6

What makes up a protein?

Answer 6

One or more polypeptide chains.

Question 7

What is primary structure of a protein?

Answer 7

Straight line of amino acids - simple polypeptide chain

This is the sequence in which amino acids are joined.

Question 8

What is the secondary structure of a protein?

Answer 8

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.

Question 9

What is tertiary structure of a protein?

Answer 9

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)

Question 10

What is Quaternary structure of proteins.

Answer 10

Several polypeptide chains form the structure. All bonds occur, it is more stable than tertiary; more interactions occur because r-groups closer together.

Question 11

What is insulin?

Answer 11

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.

Question 12

What is collagen?

Answer 12

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.

Question 13

What is keratin?

Answer 13

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.

Question 14

What is haemoglobin?

Answer 14

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.

Question 15

ATP groups?

Answer 15

3 phosphate, one Pentose sugar (ribose) and a nitrogenous base (adenine)

Question 16

How does ATP release energy?

Answer 16

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.

Question 17

Why is ATP not used for storage?

Answer 17

ATP is not as stable as fats, because it easily hydrolyses in water.

Question 18

Cholesterol determine the … of membranes

Answer 18

Moderate the fluid properties - maintains integrity and mechanical stability. (ANIMAL CELL MEMBRANES)

Question 19

Cholesterol is used to synthesise…

Answer 19

steroid hormones and bile.

Question 20

Why are the fatty acid tails of triglycerides important for the storage of energy?

Answer 20

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?)

Question 21

What bond is hydrolysed in triglyceride molecules?

Answer 21

The ester bonds between the glycerol head and fatty acid tails.

Question 22

Mixing a substance with water and ethanol tests for what?

Answer 22

Lipids

Question 23

What is the positive test result when testing for lipids?

Answer 23

The formation of a white precipitate.

Question 24

What’s the difference between fats and oils? (properties)

Answer 24

Fats are solid at room temp, whereas oils are liquids at room temperature.

Question 25

What’s the difference between fats and oils? (Structure)

Answer 25

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.

Question 26

What groups make up a phospholipid?

Answer 26

Phosphate, glycerol and 2 fatty acid tails.

Question 27

True or False: Cholesterol is soluble

Answer 27

False, it’s carried around the body by lipoproteins.

Question 28

What varies in a lipids?

Answer 28

Whether they are saturated or not

Question 29

What is the name of the test for Lipids?

Answer 29

Emulsion test.

Question 30

What does the emulsion test involve?

Answer 30

Add distilled water and ethanol to substance - shake - if cloudy lipids present.

Question 31

What are beta pleated sheets formed by?

Answer 31

Hydrogen bonds forming between parallel polypeptide chains.

Question 32

What processes do globular proteins regulate?

Answer 32

Chemical reactions, immunity, muscle contraction and many more

Question 33

What are conjugated proteins?

Answer 33

Globular proteins that contain a prosthetic group.

Question 34

Give 2 categories that are made up by conjugated proteins:

Answer 34

Glycoprotein and lipoprotein

Question 35

Summarise everything about fibrous proteins: (Exclude examples)

Answer 35

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.

Question 36

Haemoglobin:

Answer 36

Quaternary globular protein made of 2 alpha and 2 beta sub units. Has haem prosthetic group.

Question 37

Describe collagen in terms of flexibility

Answer 37

A fibrous protein which is flexible but not stretchable.

Question 38

Describe insulin in terms of flexibility

Answer 38

Globular protein with a specific fixed shape

Question 39

Describe elastin in terms of flexibility

Answer 39

Fibrous protein which recoils after being deformed

Question 40

Describe haemoglobin in terms of flexibility

Answer 40

Globular protein which can change shape.

Question 41

Test for lipids?

Answer 41

Emulsion test: add ethanol to sample, mix with water and shake white precipitate positive result.

Question 42

Globular proteins:

Answer 42

spherical ,compact, water-soluble, hydrophobic r-groups sheltered away from an aqueous environment. a-helix

Question 43

Identification of proteins?

Answer 43

Biuret Test: Add copper sulfate, test should form a violet colour.

Question 44

Summarise everything about globular proteins:

Answer 44

Soluble, spherical tertiary proteins with a hydrophilic outside. They may have conjugated groups and can be sensitive to temperature of pH.