lipids Flashcards
during respiration saturated fatty acids yield more energy than unsaturated fatty acids * saturated fatty acids have higher melting points than unsaturated fatty acids
* lipases in seeds act more rapidly on liquid substrates.
-population 1 grew longer at warm routes whereas 2 at cooler temperatures
population 1 has more saturated fatty acids so more energy available(break into glycerol)
-population 2 grew cooler climates because liquid fatty acids so more lipase activity
What does it mean for a lipid to be unsaturated
they’re liquid
E. coli has no cholesterol in its cell-surface membrane. Despite this, the cell maintains a constant shape. Explain why.
-cell wall unable to change shape
-cell has a cell wall
-rigid and made from murein
Use the diagram to explain what is meant by an unsaturated fatty acid.
-double bonds present
-not equal distribution between carbon and hydrogen molecules
Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst.
Substrate binds to the active site/enzyme
-ctive site changes shape (slightly) so it is complementary to substrate
-Active site changes shape (slightly) so distorting/breaking/forming bonds in the substrate;
Reduces activation energy;
A competitive inhibitor decreases the rate of an enzyme-controlled reaction.
Inhibitor similar shape to substrate;
Fits/binds to active site;
Prevents/reduces enzyme-substrate complex forming;
Lyxose binds to the enzyme.
Suggest a reason for the difference in the results shown in the graph with and without lyxose.
(Binding) alters the tertiary structure of the enzyme ;
-if lyxose acting as an inhibitor
-(This causes) active site to change (shape);
3. (So) More (successful) E-S complexes form (per minute)
(a) Give two other factors the technician would have controlled.
Concentration of enzyme Volume of substrate solution pH.
(b) A decrease in temperature decreases the kinetic energy of molecules in a solution. Explain how a decrease in temperature decreases the rate of an enzyme-controlled reaction.
molecules moving less / slower; reduces chance of collision (between enzyme and substrate) / of enzyme-substrate complexes being formed; (reject converse)
Urea breaks hydrogen bonds. Explain how the addition of urea would affect the rate of an enzyme-controlled reaction.
these bonds hold / maintain tertiary / globular structure (of enzyme); enzyme denatured / tertiary structures destroyed; (shape of) active site distorted / changes;
substrate no longer fits / enzyme-substrate complex not formed;
(d) Different times:
1. Higher temperature / 60 °C causes denaturation of all of enzyme;
Accept converse for 37 °C
2. Reaction stops (sooner) because shape of active site changed;
Reject if active site on substrate
Different concentrations of product (at 60 °C)
3. Substrate still available (when enzyme denatured);
4. But not converted to product.
Suagest one advantade of the different percentage of cholesterol in red blood cells
compared with cells lining the ileum.
-more red blood cells can flow freely in blood .
-not supported by other cells so cholesterol helps
to maintain shape;
Why are fatty acids important in the creation of new cells ?
-Fatty acids used to make phospholipids and so plasma membranes made
-thyere respired to release eergy
-made triglycerides =more energy released
-energy used for cell production
how many molecules is a triglyceride made from
4
other than ethical reasons why were cats used to test for milk and lipids
-small enough to keep in labs
-large number of them
-same physiological systems as babies
why are hydrogen bonds important for cellulose molecules
-holds cellulose molecules toghtehr
-hydrogen bonds are strong in large numbers
