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Biology A Level > Biological Molecules - Protiens Digestion And Absorption > Flashcards

Biological Molecules - Protiens Digestion And Absorption Flashcards

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1
Q

What is the equation for Rf values?

A

What is the equation for Rf values?

Rf value = distance moved by solute / distance moved by solvent

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2
Q

An amino acid consists of which elements?

A

An amino acid consists of which elements?

Carbon
Hydrogen
Oxygen
Nitrogen

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3
Q

Draw the structure of an amino acid

A

Draw the structure of an amino acid

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4
Q

Draw a dipeptide and label the bond between the amino acids

A

Draw a dipeptide and label the bond between the amino acids

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5
Q

Describe how a peptide bond is formed between 2 amino acids

A

Describe how a peptide bond is formed between 2 amino acids

Condensation reaction (1)
Between amine and carboxylic acid group (1)
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6
Q

Describe a biochemical test to show if a solution contains protein

A

Describe a biochemical test to show if a solution contains protein

Add biuret reagent (1)
Purple = positive result (1)

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7
Q

Describe the primary structure of a protein (1)

A

Describe the primary structure of a protein (1)

Sequence of amino acids

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8
Q

Describe the secondary structure of protein (2)

A

Describe the secondary structure of protein

Hydrogen bonding (1)
Between carboxyl and amine groups of amino acids (1)
To form a beta pleated sheet or alpha helix (1)

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9
Q

Describe the tertiary structure of a protein (2)

A

Describe the tertiary structure of a protein

Further folding of polypeptide into a 3D shape (1)
Due to hydrogen, ionic and disulphide bonds (1)

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10
Q

Describe the quaternary structure of a protein (1)

A

Describe the quaternary structure of a protein

Multiple polypeptides bonded together (1)

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11
Q

Explain what Is meant by a polymer (1)

A

Explain what Is meant by a polymer (1)

Repeating monomer subunits bonded together

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12
Q

Haemoglobin is a protein that has four ‘haem’ prosthetic groups. What is a prosthetic group?

A

Haemoglobin is a protein that has four ‘haem’ prosthetic groups. What is a prosthetic group?

A non-protein group that forms part of a protein

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13
Q

What is an enzyme?

A

What is an enzyme?

A protein (1)
That acts as a catalyst (1)
For a specific substrate (1)
By lowering activation energy (1)

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14
Q

Explain how the formation of an enzyme-substrate complex increases rate of reaction (2)

A

Explain how the formation of an enzyme-substrate complex increases rate of reaction

Strain is added to bonds (1)
Which lowers activation energy (1)

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15
Q

Describe the induced fit model of enzyme action (2)

A

Describe the induced fit model of enzyme action (2)

Enzyme active site changes shape to become complementary to substrate (1)
Forming an enzyme substrate complex (1)

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16
Q

Sketch a graph showing the effect of temperature on the rate of enzyme action

A

Sketch a graph showing the effect of temperature on the rate of enzyme action

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17
Q

Explain the shape of the graph showing the effect of temperature on the rate of enzyme action (5)

A

Explain the shape of the graph showing the effect of temperature on the rate of enzyme action (5)

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18
Q

Which 2 bonds of an enzyme are broken by extremes of pH? (1)

A

Which 2 bonds of an enzyme are broken by extremes of pH? (1)

Hydrogen bonds and ionic bonds

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19
Q

Identify 4 factors that affect the rate of enzyme action (4)

A

Identify 4 factors that affect the rate of enzyme action (4)

Temperature 
pH
Enzyme concentration 
Substrate concentration
Inhibitors
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20
Q

Starch +amylase ——> maltose
Sketch a graph showing the progress of this reaction over time. Identify the point at which the reaction ends and state a reason why. (3)

A

Starch +amylase ——> maltose
Sketch a graph showing the progress of this reaction over time. Identify the point at which the reaction ends and state a reason why. (3)

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21
Q

How would you calculate the rate of reaction from the graph you have just drawn? (1)

A

How would you calculate the rate of reaction from the graph you have just drawn? (1)

Mass of maltose produced / time at which line plateaus

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22
Q

Rate of reaction tangents =

A

Rate of reaction = 🔺y / 🔺x

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23
Q

Explain the advantage of lipid droplets and Michelle formation (3)

A

Explain the advantage of lipid droplets and Michelle formation (3)

Droplets increase surface areas (for enzyme action/ lipase) (1)
So faster rate of hydrolysis (1)
Micelles carry fatty acids and glycerol through (1)

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24
Q

Where are the following enzymes produced?

Carbohydrases
Proteases
Lipases

A

Where are the following enzymes produced?

Carbohydrases - salivary glands, pancreas, small intestine

Proteases - stomach, pancreas, small intestine

Lipases - pancreas

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25
Q

Enzyme: salivary amylase

Where it’s made:

Where it acts:

Substrate:

Product:

A

Enzyme: salivary amylase

Where it’s made: salivary glands

Where it acts: mouth

Substrate: starch

Product: maltose

26
Q

Enzyme: pancreatic amylase

Where it’s made:

Where it acts:

Substrate:

Product:

A

Enzyme: pancreatic amylase

Where it’s made: pancreas

Where it acts: ileum

Substrate: starch

Product: maltose

27
Q

Enzyme: maltase

Where it’s made:

Where it acts:

Substrate:

Product:

A

Enzyme: maltase

Where it’s made: lining of ileum

Where it acts: ileum

Substrate: maltose

Product: a-glucose

28
Q

Enzyme: lactase

Where it’s made:

Where it acts:

Substrate:

Product:

A

Enzyme: lactase

Where it’s made: lining of ileum

Where it acts: ileum

Substrate: lactose

Product: a-glucose and galactose

29
Q

Enzyme: sucrase

Where it’s made:

Where it acts:

Substrate:

Product:

A

Enzyme: sucrase

Where it’s made: lining of ileum

Where it acts: ileum

Substrate: sucrose

Product: a-glucose and fructose

30
Q

By which two processes do glucose and amino acids exit the ileum and enter the blood?

A

By which two processes do glucose and amino acids exit the ileum and enter the blood?

Diffusion and active transport

31
Q

What are transport proteins?

A

What are transport proteins?

Carrier and channel proteins

32
Q

Cells lining the ileum of mammals absorb the monosaccharide glucose by co transport with sodium ions. Explain how.

A

Cells lining the ileum of mammals absorb the monosaccharide glucose by co transport with sodium ions. Explain how.

Sodium ions are actively transported from the ileum cell to the blood (1)
Which maintains the diffusion gradient for sodium ions to enter the cells from the gut (1)
Glucose enters the blood by fascilitated diffusion with sodium ions (1)

33
Q

Mammals have some cells that produce extra cellular proteases
They also have cells with membrane bound dipeptidases

Describe the action of these membrane-bound dipeptidases and explain their importance

A

Mammals have some cells that produce extra cellular proteases
They also have cells with membrane bound dipeptidases

Describe the action of these membrane-bound dipeptidases and explain their importance

Hydrolyse peptide bonds to release amino acids (1)
So amino acids can cross the cell membrane (1)

34
Q

Some proteases are secreted as extracellular enzymes by bacteria

Suggest and explain one advantage to a bacterium of secreting an extracellular protease in its natural environment (2)

A

Some proteases are secreted as extracellular enzymes by bacteria

Suggest and explain one advantage to a bacterium of secreting an extracellular protease in its natural environment (2)

To digest protein (1)
So they can absorb amino acids for growth (1)

35
Q

Explain the shape of a curve at 50 c and 60 c

A

Explain the shape of a curve at 50 c and 60 c

Both denatured by high temperature (1)
Denaturation higher at 60 c because there’s higher kinetic energy (1)
Breaks H/ionic bonds between amino acids/ R groups
So there’s a change in active site shape (1)
So fewer e-s complexes form as substrate doesn’t fit in active site of enzyme (1)

36
Q

The addition of a respiratory inhibitor stops the absorption of amino acids. Explain why.

A

The addition of a respiratory inhibitor stops the absorption of amino acids. Explain why.

No ATP produced (1)
So sodium ions don’t move into or out of the cell (1)
Which means no diffusion gradient for sodium to move into cell with amino acid (1)

37
Q

Why is the combined actions of endopeptidases and exopeptidases are more effective than exopeptidases on their own? (2)

A

Why is the combined actions of endopeptidases and exopeptidases are more effective than exopeptidases on their own? (2)

Endopeptidases hydrolysed internal peptide bonds and exopeptidases hyrolyse bonds at ends, which increases surface area

38
Q

Enzymes required in the hydrolysis of proteins

A

Enzymes required in the hydrolysis of proteins

Dipeptidases
Endopeptidases
Exopeptidases

39
Q

Explain how cells lining the ileum absorb the monosaccharide glucose by co-transport with sodium ions (3)

A

Explain how cells lining the ileum absorb the monosaccharide glucose by co-transport with sodium ions (3)

Sodium ions are actively transported from ileum cell to blood (1)
Which maintains the diffusion gradient for sodium to enter the cells from the gut (1)
Glucose can then enter the blood by fascilitated diffusion with sodium ions (1)

40
Q

Biuret test for proteins results

Blue -

Purple -

A

Biuret test for proteins results

Blue - negative

Purple - positive

41
Q

Biuret test

1) .
2) .

A

Biuret test

1) . The solution needs to be alkane so add a few drops of sodium hydroxide solution
2) . Then you add some copper sulfate solution

42
Q

Suggest why the scientist tested de-ionised water to see if it contained protein?

A

Suggest why the scientist tested de-ionised water to see if it contained protein?

As a control

43
Q

The scientist measured the pH of each liquid after the test. The pH of the cows milk was below 7, so the scientist marked the test result as void.
Suggest why.

A

The scientist measured the pH of each liquid after the test. The pH of the cows milk was below 7, so the scientist marked the test result as void.
Suggest why.

The liquid needs to be alkaline for the solution to work

44
Q

The scientist measured the pH of each liquid after the test. The pH of the cows milk was below 7, so the scientist marked the test result as void.
Suggest what mistake the scientist might have made during the experiment?

A

The scientist measured the pH of each liquid after the test. The pH of the cows milk was below 7, so the scientist marked the test result as void.
Suggest what mistake the scientist might have made during the experiment?

Didn’t add any/ enough sodium hydroxide solution

45
Q

What’s a polypeptide?

A

What’s a polypeptide?

Chain of more than 2 amino acids

46
Q

Name three bonds that form between amino acids in a polypeptide chain to form the tertiary structure.

A

Name three bonds that form between amino acids in a polypeptide chain to form the tertiary structure.

Hydrogen and ionic bonds and disulphide bridges

47
Q

Explain how the shape of structural proteins make them specialised for their function?

A

Explain how the shape of structural proteins make them specialised for their function?

Structural proteins are made of long polypeptide chains lying parallel to each other with cross links between them that make them physically strong

48
Q

What is an extracellular enzyme?

A

What is an extracellular enzyme?

An enzyme that acts outside cells

49
Q

Explain in terms of activation energy why an enzyme enabled reactions to happen at lower temperature than they could without an enzyme

A

Explain in terms of activation energy why an enzyme enabled reactions to happen at lower temperature than they could without an enzyme

Activation energy is needed to start a reaction (1)
The activation energy is often provided as heat (1)
With the presence of an enzyme, the ectivation energy required is lowered. So not as much heat is needed (1)

so the reaction can take place at lower temperatures than it could do without an enzyme(1)

50
Q

What’s the difference between the lock and key model and the induced fit model?

A

What’s the difference between the lock and key model and the induced fit model?

In the lock and key model, the active site has a fixed shape that’s complementary to the substrate,

But in the induced fit model the active site has to change the shape slightly to allow the substrate to bind tightly

51
Q

What determines the shape of enzymes active site

A

What determines the shape of enzymes active site

The Enzymes tertiary structure

52
Q

Why will an enzyme only bind with one substrate

A

Why will an enzyme only bind with one substrate

An enzyme can only bind with the substrate that has a complimentary shape to its active site

53
Q

What’s “saturation” point?

A

What’s “saturation” point?

The point which all active sites are occupied by substrate molecules

54
Q

Where do the following molecules bind to an enzyme

A). non-competitive inhibitor

B). competitive inhibitor

A

Where do the following molecules bind to an enzyme

A). non-competitive inhibitor (Away from the active site)

B). competitive inhibitor (At the active site)

55
Q

Explain how non-competitive inhibition prevents enzyme activity

A

Explain how non-competitive inhibition prevents enzyme activity

A non-competitive inhibitor molecule binds to the enzyme away from the active site.

its present alters the shape of the active site meaning that substrate molecules can no longer find here.

this prevents enzyme activity.

56
Q

Sucrase is membrane-bound disaccharidase where in the body would you find sucrase

A

Sucrase is membrane-bound disaccharidase where in the body would you find sucrase

On the cell membranes of epithelial cells lining the ileum

57
Q

Explain the role of sucrase in the body

A

Explain the role of C crease in the body

Sucrase catalyses the hydrolysis of sucrase into glucose and fructose.

These smaller molecules/monosaccharides can then be absorbed across the ileum epithelium into the bloodstream

58
Q

What type of enzymes are needed to break down lipids

A

Type of enzymes are needed to break down lipids?

Lipases

59
Q

Describe how micelles are formed in digestion

A

Describe how micelles are formed in digestion

Once lipids have been broken down by lipase, the monoglycerides and fatty acids stick with the bile salts to form micelles

60
Q

Describe the action of exopeptidases

A

Describe the action of exopeptidases

Exopeptidases act to hydrolyse peptide bonds at the end of protein molecules.

they remove single amino acids from proteins

61
Q

Explain how monoglyceride and fatty acids are absorbed across the ileum epithelium.

A

Explain how monoglyceride and fatty acids are absorbed across the ileum epithelium.

The micelles break up, releasing the monoglycerides and fatty acids, which diffuse directly across the membrane because they are lipid soluble

62
Q

How are sodium ions involved in the transport of amino acids

A

How are sodium ions involved in the transport of amino acids

Sodium ions are actively transported out of the epithelial cells into the ileum itself

they then diffuse back into the cells through sodium-dependent transporter proteins in the epithelial cells membranes, carrying amino acids with them

Biology A Level (13 decks)

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