biological molecules Flashcards
2.7 - 2.14B
1
Q
2.7 the chemical elements present in carbohydrates
A
carbon, hydrogen and oxygen
(C,H,O)
2
Q
2.7 the chemical elements present in proteins
A
carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)
3
Q
2.7 the chemical elements present in lipids (fats&oils)
A
carbon, hydrogen and oxygen
(C,H,O)
4
Q
2.8 starch and glycogen is from
A
simple sugars
5
Q
2.8 protein is from
A
amino acids
6
Q
2.8 lipids are from
A
fatty acids and glycerol
7
Q
2.8 a monosaccharide is a …
A
simple sugar like glucose
8
Q
2.8 a disaccharide is made when
A
two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose
9
Q
2.8 a polysaccharide is formed when
A
lots of monosaccharides join together
10
Q
2.8 polysaccharides starch, glycogen or cellulose are all formed when
A
lots of glucose molecules join together
11
Q
2.8 most fats (lipids) in the body are made up of
A
triglycerides
12
Q
2.8 lipids basic unit is
A
one glycerol molecule chemically bonded to three fatty acid chains
13
Q
2.8 proteins are formed from
A
long chains of amino acids
14
Q
2.8 when amino acids are joined together
A
a protein is formed
15
Q
2.9 what is the test for starch?
A
iodine solution
16
Q
2.9 explain the test for starch
A
- place food sample on a spotting tile
- add a few drops of iodine solution to the sample
- blue - black colour indicates starch
17
Q
2.9 what is the test for glucose / reducing sugars?
A
benedicts solution
18
Q
2.9 explain the test for glucose / reducing sugars?
A
- place food sample in a boiling tube
- add benedict’s solution to the sample of food in solution
- place in a water bath at 80*c for 5 minutes
- a change from blue to brick red if present
(if green, yellow or orange means less sugar present)
19
Q
2.9 what is the test for protein?
A
biuret test
20
Q
2.9 explain the test for protein
A
- place food sample in a boiling tube
- add enough biuret solution for colour to be pale blue
- if protein is present colour will change to mauve / purple
21
Q
2.9 what is the test for lipids?
A
emulsion test
22
Q
2.9 explain the test for lipids?
A
- place food sample in a test tube
- add small amount of ethanol and shake to dissolve any lipid in the alcohol.
- add equal volume of water
- cloudy white colour (emulsion will form) indication presence of lipid
23
Q
2.9 benedicts solution is used to test for
A
reducing sugars (glucose)
24
Q
2.9 benedicts solution colour change
A
blue to brick red
25
2.9 how do I remember benedicts solution
christmas sugar
26
2.9 iodine is used to test for
starch
27
2.9 iodine solution colour change
orange to blue-black
28
2.9 how do I remember iodine
bumblebee
29
2.9 biuret is used to test for
protein
30
2.9 biuret solution colour change
(light)blue to pale purple
31
2.9 how do I remember biuret
snowflakes
(et) proTEin biurET
32
2.9 emulsion is used to test for
lipids
33
2.9 emulsion colour change
colourless to a cloudy white emulsion
34
2.9 how do I remember emulsion
snowing
35
2.10 enzymes are biological
catalysts
36
2.10 a catalyst is a ........
chemical which increases the rate of a reaction without being used up itself in the reaction
37
2.10 the theory for understanding how enzymes work is the
lock and key theory
38
2.10 what is the lock and key theory
the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don't fit - so they are released,
the enzyme is free to catalyse the next reaction
39
2.10 the active site has a particular shape which is ... to the shape of the substrates
complementary
40
2.10 because the shape of the active site is complementary to that of the substrates, this means
each enzyme can only catalyse one reaction
41
2.11 as temperature increases the enzyme & substrate have more
kinetic energy
so they move faster and there are more successful collisions
42
2.11 high temperatures and changes of pH cause the shape
to change
43
2.11 when the shape changes we say this is
the protein being denatured
44
2.11 when the active site changes shape it is no longer
complementary to the substrate
45
2.12 practical for investigating effect of temperature on enzymes
place spots of iodine into each dip of a spotting tile
add 5cm^3 of starch suspension into a boiling tube w/ a syringe
with a different syringe add 5cm^3 of amylase solution into another tube
fill a beaker w/ water at 20*C & place both boiling tubes inside for 5 minutes
pour amylase solution into the starch suspension leaving it in the water bath
take a sample w/ pipette & add a drop to the iodine solution in the spotting tile
record colour change of the solution in the tile
repeat every 30 seconds for 10 minutes
until the iodine solution remains orange indicating the starch is used up
repeat the experiment with the water bath at diff temps between 20*C & 60*C
46
2.13 what is the optimum pH for most enzymes
7
47
2.13 which enzymes have a lower pH than 7
those produced in acidic conditions e.g. the stomach
- pH 2
48
2.13 which enzymes have a higher pH than 7
those produced in alkaline conditions e.g. the duodenum - pH 8/9
49
2.13 what happens if the pH is too high or too low
the bonds that hold the amino acid chain together can be disrupted / destroyed
this changes the shape of the active site
so the substrate can no longer fit into it
this reduces the rate of activity
moving too far away from the pH - the enzyme will denature
50
2.14B practical investigating how enzyme activity can be affected by changes in pH
add a drop of iodine to each well of a spotting tile
use a syringe to place 2cm^3 of amylase into a test tube
add 1cm^3 of buffer solution (at pH2) to the same test tube using a syringe
in another test tube add 2cm^3 of starch solution
pour the starch solution into the amylase and buffer solution
start a stopwatch whilst mixing the solution using a pipette
every 10 seconds transfer a droplet of the solution to a new well of iodine solution which should turn blue black
repeat every 10 seconds until the iodine solution stops turning blue-black
meaning the amylase has broken down all the starch
record the time taken for reaction to be completed
repeat the investigation with buffers at different pH values from pH3 - pH7
51
2.14B practical amylase is an enzyme that breaks down
starch into maltose
52
2.14B practical what does it mean when the iodine solution remains orange - brown
that all the starch has broken down
53
2.14B practical what will this investigation show
at the optimum pH the iodine stopped turning blue-black within the shortest amount of time
54
2.14B practical why does the iodine remain orange in the shortest amount of time
because the enzyme is working at its fastest / optimum rate and has digested all of the starch
55
2.14B practical what will happen at a higher or lower pH
the iodine will take longer to stop turning blue-black
56
2.14B practical what is a control variable
the starch and amylase solutions should be placed in a water bath at the optimum temperature before being used
57
2.14B practical name one tool that can be used to measure the progress of the reaction more accurately
using a colorimeter
58
2.14B practical CORMS
C - changing the pH of the environment
O - not relevant - no organism
R - repeat several times to ensure reliability
M - measure time taken for iodine to stop turning blue-black
S - control the concentration & volume of the amylase, iodine and starch solution
