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Biology - Y12 > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

Explain why monitoring pH of mixture could show whether the milk contained lipids (2)

A
  • Hydrolysis of lipids produce fatty acids
  • Which lowers pH
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2
Q

Describe biochemical tests to confirm the precense of amylase?

A
  • Add Biuret and becomes lilac
  • Add starch, test for reducing sugar
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3
Q

When writing a null hypothesis, what is said?

A

X has no effect on Y

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4
Q

Explain why biologist chose to examine 200 cells?

A

So is a representative sample

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5
Q

Describe how a scientist could have used the temporary mounts of leaves to determine mean number of choloplasts in mesophyll cells of a leaf? (3)

A
  • Select large number of cells
  • Count all cells in field of view + count number of chloroplasts
  • Divide chloroplasts by number of cells
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6
Q

Describe how temporary mounts of plant tissue are made? (4)

A
  • Add a drop of water to slide
  • Add thin plant tissue with drop of stain
  • Macerate using mounting needle
  • Add coverslip and remove excess
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7
Q

Explain why buffer solutions are used?

A

To maintain a stble pH throughout practical so optimum RoR

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8
Q

What does a non-competitive inhibitor do? (4)

A
  • Bonds to enzyme away from active site (allosteric site)
  • Causes conformational change of shape of active site so substrate can’t bind
  • Fewer ESC form
  • RoR decreases
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9
Q

What does competitive inhibitor do? (4)

How can this be overcome?

A
  • Inhibitor has similar shape to substrate
  • They bind to enzyme + prevent substrate from binding temporarily
  • Fewer ESC form
  • RoR decreases

Increasing substrate conc.

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10
Q

What’s the tertiary structure of a protein?

A
  • Further folding determined by R group into 3D shape
  • With hydrogen, ionic + disulphide bonds
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11
Q

Structure of an amino acid?

A

https://studymind.co.uk/notes/structure-of-amino-acids/

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12
Q

Describe structure of proteins? (5)

A

1) Polymer of amino acids, which are joined by peptide bonds by condensation reaction
2) Primary - Order + sequence of amino acids
3) Secondary - Folding of polypeptide chain due to hydrogen bonding forming a alpha helix/ beta pleated sheet
4) Tertiary - 3D folding due to hydrogen, ionic + disulphide bonds
5) Quaternary - 2 or more polypeptides joined together

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13
Q

Name 6 proteins

A

Haemoglobin
Antibody
Enzymes
Actin + Myosin —–> involved in muscle contraction
Keratin
Collagen

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14
Q

How does pH affect enzyme activity? (5)

A
  • Charge on R group is altered
  • Weak hydrogen/ionic bonds break
  • Active site no longer complimentary
  • Less ESC form
  • RoR decreases + enzyme denatures
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15
Q

How does temperature affect enzyme activity?Increases/Decreases?

A

Temp increases - KE increases, more successful collisions, RoR increases because more ESC are formed

Temp decreases - KE decreases, weak hydrogen/ionic bonds break, changes tertiary structure so changes active site, no longer complimentary so less ESC are formed

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16
Q

What’s the induced fit model?

A

Active site isn’t complimentary so changes shape to bind with substrate
Lowers activation energy
Returns to original shape

17
Q

Sucrase doesn’t hydrolyse lactose - why?

A
  • Lactose has a different shape
  • So doesn’t bind to active site of sucrase
  • Active site + substrate aren’t complimentary
  • No enzyme-substrate complex forms
18
Q

How does active site of an enzyme increase the rate of reaction?

A
  • Lowers the activation energy
  • So induced fit causes active site to change shape
  • By stressing + weakening bonds to form an enzyme-substrate complex
19
Q

Why do proteins denature at:

1) High temperatures?
2) Changes in pH?

A

1) Increasing temperature, increases kinetic energy which breaks the weak hydrogen bonds in secondary + tertiary structure

2) “ “ breaks the ionic bonds between the R groups in tertiary structure

20
Q

Test for lipid?

A
  • Add ethanol
  • Shake
  • Add water
  • Shake
  • If present then white emulsion
21
Q

Structure of phospholipid?

A

https://studymind.co.uk/notes/phospholipids-introduction/

22
Q

Formula for fatty acids?
Difference between saturated + unsaturated?

A

https://www.thoughtco.com/fatty-acid-definition-608747

Saturated - No double bond

23
Q

Function of lipids? (2)

A

Conduct heat slowly - good insulator
Stored around organs to protect

24
Q

Where are these found?

  • Triglyceride
  • Phospholipid
A

Food (storage molecule)
Helps to form cell membrane

25
Q

Diagram of galactose?

A

https://byjus.com/galactose-formula/

26
Q

1) Glucose + Fructose =
2) Glucose + Galactose =
3) Glucose + Glucose =

A
  • Sucrose
  • Lactose
  • Maltose
27
Q

Diagram of Alpha + Beta Glucose?

A

https://www.aqa.org.uk/subjects/science/as-and-a-level/biology-7401-7402/subject-content/biological-molecules/carbohydrates

28
Q

What is a monomer?

A

Small indentical/similar molecules which can be condensed to make larger molecules called polymers

29
Q

How is the structure of cellulose related to its role in plant cell wall? (4)

A
  • Long, unbranched chains of beta glucose
  • Joined by many weak hydrogen bonds
  • Forms microfibrils
  • To provide strength + structure to cell wall
30
Q

Describe how you would produce a calibration curve for an unknown conc. of a reducing sugar?

A
  • Make up several known concentration of named sugar
  • Carry out Benedict’s test
  • Use colorimeter to measure colour intensity of each solution + plot on calibration curve
  • Use graph
31
Q

Describe how a student would show that non-reducing sugars were present in a solution?

A
  • Complete Benedict’s test - not present
  • Add acid to solution
  • Heat until boil in water bath
  • Neutralise with alkali
  • Add Benedict’s solution
  • Heat at 95 degrees
  • If present then - red, yellow, green precipitate
32
Q

Properties of glycogen? (5)

A
  • Shorter chains - so more rapidly hydrolysed into glucose for respiration
  • More highly branched
  • Large surface area
  • Insoluble - doesn’t affect water potential
  • Large - doesn’t diffuse out of cell
33
Q

Properties of amylose? So…(4)

A
  • Carbon 1:4 glycosidic bonds - so long + straight chain of alpha glucose which coil into helix
  • structure is compact - good for storage
  • Insoluble - doesn’t affect water potential
  • Large - doesn’t diffuse out of cells
34
Q

Diagram of fructose?

A

https://www.geeksforgeeks.org/fructose/

35
Q

What is a polymer?

A

Large molecules made from joining 3 or more identical/similar monomers together

36
Q

Compare + contrast the structure + properties of triglycerides + phospholipids? (6)

A

Both contain:
- Ester bonds
- Glycerol
- C, H + O but phospholipids contain P
- Fatty acids on both maybe saturated or unsaturated
- Both insoluble in water

  • Tri. have 3 fatty acids whereas Phos. have 2 with phosphate group
  • Tri. are hydrophobic whereas Phos. have hydrophilic + hydrophobic regions
37
Q

Describe how ATP is formed from its component molecules? (3)

A
  • Adenine, ribose/pentose, 3 phosphates
  • Condensation (reaction);
  • ATP synthase;
38
Q

Describe how ATP is resynthesised? (3)

A
  • From ADP and phosphate
  • By ATPsynthase
  • During respiration/photosynthesis
39
Q

Why does the denature of an enzyme occur faster at higher temperatures? (3)

A
  • More kinetic energy (so more successful collisions)
  • Breaks hydrogen + ionic bonds
  • Changes shape of active site/fewer ESC form

Biology - Y12 (12 decks)

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