Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OCR A Level Biology > Module 2.2 Biological Molecules > Flashcards

Module 2.2 Biological Molecules Flashcards

1
Q

Water

Properties of water

A

High specific heat capacity: water acts as a buffer for temperature, so it’s acts of a habit for fish

Ice: the hydrogen bonds are frozen in place ice insulated water, acts as a habitat,

Latent heat of vaporisation: heat energy evaporated from skin for cooling mechanism like sweating

Solvent: good solvent, can be used to transport substances (blood plasma, xylem vessels)

Cohesive properties: water molecules stick together, causes surface tension acts of surface of water to act as habiats (pond skaters)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Carbohydrates

What elements are carbohydrates made up of?
give the properties of monosaccharides?
Give examples of monosaccharides

A

All carbohydrates contain carbon hydrogen and oxygen
Glucose is a hexose sugar
Soluble because of hydroxyl groups, small
Examples: Galactose, glucose, fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a disaccaride

A

Two monosaccharides joined together by a 1,4 glycosidic bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of reaction produces disaccharides

A

Condensation reaction

Produces water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Carbohydrates

Give examples of disaccharides

A

Sucrose: glucose and fructose
Maltose: glucose and glucose
Lactose: glucose and galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Carbohydrates

What is the structure of amylose

A

Structure of amoylose

  • polymer of alpha glucose
  • joined by (1,4 glycosidic bonds)
  • twists into a compact helix
  • unbranched
  • forms hydrogen molecules with glucose molecules along the chain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Carbohydrates

What is the structure of amylopectin

A

Structure

  • polymer of alpha glucose
  • has a branch every 25/30 glucose molecules
  • forms a 1,6 glycosidic bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Carbohydrates

How does the structure of starch relate to its function

A
  • compact- store a large amount of gocuose molecules for its size
  • insoluble: so does not change water potential of cells
  • amylopectin has many ends so it’s easier for enzymes to break starch down

70% amylose and 30% amylopectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the structure of glycogen

A

Structure

  • polymer of alpha glucose
  • many branches
  • has 1,4 glycosidic bonds and 1,6 bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the structure of glycogen relate to its function

A

Properties

  • large: so it can’t diffuse into cells
  • insoluble: so it can’t change water potential of cell
  • many branches: enzymes can break down glycogen quicker as animals have a higher metabolic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Carbohydrates

What is the structure of cellulose

A

Structure

  • polymer of beta glucose
  • every other carbon ring is rotated 180
  • forms 1,4 glycosidic bonds
  • unbranched
  • forms a straight chain, which allows hydrogen bonds to form between chains
  • huge numbers means cellulose strong
  • forms microfibrils which forms macro-fibrils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the function of cellulose relate to its function?

A
  • strong due to high tensile strength provided through hydrogen bonds
  • prevents cell from bursting
  • impermeable to water, still doesn’t burst when contents of cell is pushing against it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the general structure of amino acids

A

Amino acids contains carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
-contains an amine group and a carboxyl group
Amino acids can have different r groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the difference between a polypeptide and protein

A

Polypeptide: a large number of amino acids joined together

-protein: polypeptide folded into a shape that can carry out a function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the levels of protein structure

A

Primary structure- a sequence of amino acids joined by a peptide bond. Helps determine final 3D shape. This is determined by DNA sequence

Secondary structure: hydrogen bonds form causing an alpha helix and beta pleated sheet

Tertiary structure: overall 3D shape of chain, folding depends on the Interactions of r groups (Hydrogne bonding, ionic bonding, hydrophilic and phobic interactions, disulphides bridges)

Quaternary structure: polypeptides interact with other polypeptide chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the features of globular proteins

A

-spherical
-soluble in water: due to r groups that are attracted to water on their surface
Hydrophobic amino acids in centre of protein

17
Q

Proteins

Haemoglobin

A
  • made up of 4 polypeptide subunits
  • two alpha and two subunits
  • contains prosthetic group haem
  • so it’s a conjugated protein
  • when oxygen attaches to haemoglobin changes quaternary structure making it easier for other oxygen molecules to bind onto haemoglobin
18
Q

Proteins

Insulin

A
  • two polypeptide chains
  • linked by disulphides bonds
  • globular protein
  • hormone
  • shape of insulin molecule means that it complimentary to target cells
19
Q

Proteins

Enzymes

A
  • only react with specific substrates

- the active site is complimentary to the substrate

20
Q

Proteins

What is the general structure of fibrous proteins

A
  • play a structural role
  • form linear chains
  • insoluble in water due to hydrophobic r groups
21
Q

Proteins

Collagen

A
  • found in tendons
  • strong molecule due to structure
  • forms a triple helix
  • joined together by cross links, these form microfibrils
  • the molecule is staggered so there are no weak spots
  • third amino acid is glycine which alleos collagen to wrap tightly making it strong
22
Q

Keratin

A

Found in hair nails
Strong
Long stranded
Contains cysteine which forms disulphides brides increases strength of kertain molecules

23
Q

Elastin

A
  • Found in artery walls and skin
  • long strands which are cross linked
  • hydrophobic strands associate
  • when stretched they remain attached to crosslinks
  • making molecule stretchy
24
Q

Lipids

What is the functions of lipids

A
  • source of energy
  • store energy
  • cushioning around organs
  • waterproofing
  • electrical insulation around neurone
  • thermal insulation
  • can make vitamins and steroid hormones
  • buoyancy
25
Q

Triglycerides

A

Formed from 1 molecule of glycerol and 3 fatty acids
The fatty acids can be unsaturated (has a double bond)
Or saturated (no double bond)
-form an ester bond
-called estérification
-form through condensation reaction
-non polar
-large number of carbon carbon bonds means lost of energy can be released

26
Q

What is the structure of a phospholipid

A

Structure
Glycerol molecule bonded to a phosphate and two fatty acids
Part hydrophilic and part hydrophobic
Can form a phospholipid bilayer

27
Q

Cholesterol

A
  • hydroxyl group is hydrophilic
  • rest is hydrophobic
  • insert it’s self in membranes
  • controls fluidity
  • starting point for steroid hormones like oestrogen, can pass through cell membranes
  • vitamin D
  • used in liver for bile
28
Q

Tests for biological molecules

Starch

A

Process

  • grind up food
  • add water
  • filter out water

Test for starch

  • add 1 cm3 of iodine and potassium iodide
  • positive result should turn blue black
29
Q

Tests for biological molecules

Proteins

A

Process

  • grind up food
  • add water
  • filter out water

Using filtrate
Add 3cm3 of NAOH and mix
Then add 10 drops of copper two sulfate
Detects for peptide bonds

30
Q

Tests for biological molecules

Lipids

A

Food should not be filtered as lipids could stick to filter paper

Add 3cm3 of food soutien
Add 3cm3 of ethanol and water
If lipids of present a white cloudy emulation will form

Should not do this near a naked flame

31
Q

Tests for biological molecules

Reducing and non reducing sugars

A

A reducing sugar can donate electrons to another molecule

Reducing sugars

  • grind up food
  • add water
  • filter out water
  • add 3cm3 of filtrate and Bénédicts to a test tube
  • positive test from blue to yellow, orange, red

Benedicts test is semi quantitive, gives is an idea of amount of sugar, people can perceive colours differently

Non reducing sugars
-we need to break glycosidic bond of sucrose
-get unknown solution and add 3cm3 of HCL, then place in boiling tube for 5 minutes (hydrolyses glycosidic bonds)
-then add 3cm3 add NAOH
-check if solution is alkaline
Then do the Benedicts tests

32
Q

What are the other ways of testing for biological molecules that aren’t food tests

A
  • Colorimeter

- bio sensor

OCR A Level Biology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions