Recall Questions 4 Flashcards
(17 cards)
Explain how a change in the primary structure of a globular protein may result in a different 3D structure (3)
- change in sequence of amino acids changes the tertiary structure
- change of folds and bonds formed
- bonds formed in different places
Explain why an enzyme only breaks down a specific substrate
- tertiary structure of enzyme gives it a specific shape
- active site complimentary to substrate
- induced fit:
Active site not completely complimentary to substrate. Active site changes shape to fit around substrate - enzyme is a catalyst and lowers activation energy
- can form enzyme substrate complexes
Name a type of reaction that joins carbohydrates together. What is released
Condensation
- water
Describe how you could use the emulsion test to show that a seed contains lipids
- crush the seeds
- dissolve in alcohol then add water
White emulsion = lipid present
Biochemical test to show a solution contained protein
- buiret test
- colour change from blue to PURPLE, protein present.
(Buiret test: NaOH soln & dilute CuSO4 soln)
Test for starch
Add iodine solution to sample
Should turn blue/black
Explain the ways in which starch molecules are adapted for their function in plant cells (6)
Insoluble - doesn’t affect water potential
Helical and coiled - compact and can be stored in small spaces
Large molecule - cannot leave the cell
Explain how decreasing pH affects enzyme activity
- decrease in pH, increases H+ ions which are attracted to amino acids
- hydrogen bonds disrupted and changes tertiary structure
- active site changes shape, e-s complexes can’t form
- decreasing rate of reaction
What is an unsaturated fatty acid
Double bond between the carbon atoms
What is the bond formed between two amino acids
What is produced
Peptide bond
Dipeptide
Describe the induced fit model
Substrate and active site not complimentary to each other
When substrate binds in e active site, the active site changes shape to fit around the substrate.
Describe the structure of proteins
- polymer of amino acids formed by condensation reaction
- joined by peptide bonds
- primary structure, sequence of amino acids
- secondary structure, hydrogen bonds fold polypeptide chains, alpha helix and beta pleated sheets
- tertiary structure, 3D shape due to further folding, hydrogen bonds, ionic bonds disulphide bridges
- quaternary structure, more than 2 polypeptide chains
Describe one way which lock and key model differs from induced fit model
Active site is rigid and doesn’t change shape in lock and key model
Explain how increasing temperature affects enzyme activity
Increasing temperature increases kinetic energy between molecules
Increasing collisions between enzyme and substrates
Increasing the rate of reaction for more enzyme-substrate complexes formed
Biochemical test to show reducing sugar is present
Benedicts test.
Heat the sample with Benedictus reagent
Red precipitate formed if reducing sugar is present
Describe competitive and non competitive inhibition of an enzyme (6)
Inhibitors reduce binding of enzyme to substrate. Reduces e-s complexes.
Competitive inhibition;
- inhibitor similar shape to substrate
- binds into active site of enzyme
- can be over come by adding more substrate
Non competitive inhibition;
- binds on the site of enzyme, NOT active site
- changes shape of the active site
- can’t be overcome by adding more substrate
Explain how cellulose molecules are adapted for their function in plant cells (3)
Long and straight chains
Linked by many hydrogen bonds to form microfibrils
Provides strength for cell wall
