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A-Level Biology > Module 1: Biological Molecules > Flashcards

Module 1: Biological Molecules Flashcards

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1
Q

What are biological molecules?

A

Molevules made and used by living organisms e.g. carbohydrates, proteins, lipids, DNA, ATP, water, inorganic ions

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2
Q

Function of carbohydrates?

A 
Energy source (glucose in respiration) 
Energy store (starch in plants, glycogen in animals)
Structure (cellulose in plant cell walls)
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3
Q

Monomers of carbohydrates

A

Monosaccharides

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4
Q

Examples of monosaccharides

A

Glucose (alpha and beta)
Galactose
Fructose

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5
Q

Formula for monosaccharides

A

C6H12O6 (isomers= same formula different arrangement)

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6
Q

Difference between alpha and beta glucose

A

On carbon 1 alpha has OH on bottom but beta has OH on top

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7
Q

How do you join monosaccharides?

A

Condensation reaction between 2 OH groups, removes water

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8
Q

Bond in carbohydrates?

A

1-4 glycosidic

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9
Q

Examples of disaccharides

A

Maltose (GG)
Lactose (GGL)
Sucrose (GF)

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10
Q

Formula for disaccharides

A

C12H22O11

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11
Q

How are polymers separated?

A

Hydrolysis reactions (removes water but requires a catalyst)

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12
Q

What is a polysaccharide?

A

Many monosaccharides joined by condensation reactions/glycosidic bonds

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13
Q

Examples of polysaccharides

A

Starch (alpha, energy store in plants)
Glycogen (alpha, energy store in animals)
Cellulose (beta, structure in plants)

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14
Q

Structure of starch

A

Amylose (long straight coiled chain of alpha glucose)

Amylopectin (strsight chain with side branches with 1-6 glycosidic bonds)

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15
Q

Structure of glycogen

A

Straight chain of alpha glucose (1-4 glycosidic) with side branches (1-6 glycosidic)

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16
Q

Properties of starch and glycogen as energy stores

A

Insoluble: doesn’t affect water potential, doesn’t diffuse out of cells
Coiled/branched: compact
Branched/chained: easily hydrolysed

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17
Q

Structure of cellulose

A

Beta glucose in straight chains (alternative rotated 180 degrees)
Cellulose chains cross linked by hydrogen bonds to form microfibrils
Microfibrils join to form macrofibrils
Strong material

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18
Q

Test for starch

A

Iodine

Turns blue black

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19
Q

Test for reducing sugar

A

Heat in a water bath with benedicts

Turns brick red

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20
Q

Test for non-reducing sugars

A

Heat in bath with benedicts-no change
Add dilute HCL (hydrolyses glycosidic bond)
Add Sodium hydrogencarbonate (neutralise)
Heat in bath with benedicts
Turns brick red

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21
Q

Two types of proteins

A

Globular

Fibrous

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22
Q

Globular proteins

A

Soluble proteins with a specific 3D (tertiary shape)

Enzymes, antibodies, haemoglobin, hormones

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23
Q

Fibrous proteins

A

Strong
Insoluble
Inflexible
Collagen/keratin

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24
Q

Monomers for proteins

A

Amino acids

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25
Q

Structure of an amino acid

A 
Central carbon
Carboxyl to the right
Amine to the left
Hydrogen above
R below
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26
Q

How do different amino acids differ

A

Have different R groups

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27
Q

How are amino acids joined together

A

Condensation reactions
Between carboxyl group and amine group
Peptide bond between carbon and nitrogen

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28
Q

Primary structure

A

Sequence of amino acids, polypeptide chain held by peptide bonds

29
Q

Secondary structure

A

Polypeptide chain coils to form alpha helix or beta pleated sheets held by hydrogen bonds

30
Q

Tertiary structure

A

Secondary structure further folds to form 3d tertiary structure held by hydrogen/ionic bonds and disulfide bridges

31
Q

Quaternary structure

A

More than one polypeptide chain

May contain prosthetic group

32
Q

Example of quaternary structures

A

Collagen
Antibodies
Haemoglobin

33
Q

Structure of collagen

A

Strong material to make tendons/ligaments/connective tissues
Primary structure made up of glycine
Secondary forms tight coil with little branching due to glycine
Tertiary coils again
Quaternary has 3 tertiary wrapped around like rope

34
Q

Test for protein

A

Biuret

Turns purple/lilac

35
Q

What is an enzyme?

A

Biological catalyst that speeds up the rate of reaction without being used up, lowers activation energy
Specific tertiary structure

36
Q

What makes an enzyme specific?

A

Specific active site shape
Only complementary substrates can bind to active site
Forms enzyme-substrate complexes

37
Q

Lock and Key VS induced fit

A

LK: active site is rigid, only exactly complementary substrates can bind to form ES complexes
IF: active site changes shape, substrate binds, forms ES complex

38
Q

Affect of substrate concentration on enzyme activity

A

Increase SC increases chances of successful collisions, increases chances of ES complexes forming, increases rate of reaction
Continues until all enzymes active sites are saturated

39
Q

Affect of enzyme concentration on enzyme activity

A

Increase EC increases chance of successful collisions, increases chance of forming ES complexes, increases rate of reaction
Continues until substrates are used up

40
Q

Affect of temperature on enzyme activity

A 
Temp increases
Kinetic energy increases
Molecules move faster 
Increased chance of successful collisions
Increased chance of forming ES complex 
Increased rate
Until optimum 
Hydrogen and ionic bonds in tertiary structure break
Lose active site shape
Substrate no longer complementary 
No ES complexes
Enzyme denatured
41
Q

Affect of ph on enzyme activity

A 
Change ph away from optimum 
Bonds in tertiary structure break
Lose active site shape 
No longer form ES complex
Enzyme denatured
42
Q

Competitive inhibitors

A

Substance with similar shape to substrate and complementary shale to active site of enzyme, binds to active site and blocks it, prevents ES complexes from forming

43
Q

Non-competitive inhibitors

A

Substance that binds to allosteric site on enzyme
Causes active site to change shape
Less ES complexes can form

44
Q

3 types of lipids

A

Triglycerides (fat for energy store, insulation, organ protection)
Phospholipids (membranes)
Cholesterol (membrane stability, hormones)

45
Q

Structure of a triglyceride

A

1 glycerol and 3 fatty acids
Condensation reactions, ester bonds
Bond is COOC
2 types: saturated fat and unsaturated fat

46
Q

Saturated fat

A

No carbon-carbon double bonds in R group

47
Q

Unsaturated fat

A

Has carbon-carbon double bonds in R group

48
Q

Structure of phospholipid

A

1 glycerol, 2 fatty acids, 1 phosphate
Hydrophillic heads
Hydrophobic tails
Phospholipid bilayers

49
Q

What are nucleic acids?

A

Polymers made from nucleotides

DNA and RNA

50
Q

What is DNA

A

DeoxyriboNucleic Acid
Found in all organisms
Carries genes (sections of DNA that code for protein)

51
Q

DNA monomer

A

Nucleotides (made of phosphate, deoxyribose sugar, nitrogenous base)
Adenine, Thymine, Guanine, Cytosine

52
Q

DNA structure

A

Double helix
2 polynucleotides hydrogen bonds between bases
Antiparallel strands
Coiled

53
Q

Bonding in base pairs

A

AT
GC
GC most common, triple bond
AT have double bond

54
Q

Properties of DNA structure

A

Double stranded: more stable, act as templates in semi-conservative replication
Coil into helix: more compact
Sugar-phosphate backbone: protects bases
hydrogen bonds between bases: weak so strands can separate
Complementary base pairing: so identical copies can be made in replication

55
Q

DNA replication

A

In interphase before mitosis and meiosis

Semi-conservative replicatiom

56
Q

Semi-conservative replication process

A

DNA helicase breaks hydrogen bonds between complementary bases
Double strand separates leaving two template strands
Free complementary nucleotides bind to exposed bases on template strands
DNA polymerase catalyses reformation of sugar-phosphate backbone

57
Q

Evidence for SCR?

A

Replicating bacterial DNA in nitrogen isotopes 15N and 14N
Nitrogen found in bases of DNA
15N will have heavy density but 14N will be light
15N replicated in environment of 14N, produces DNA with half 15N and half 14N, DNA has medium density

58
Q

What is RNA

A 
RiboNucleic Acid
mRNA: messenger
tRNA: transfer
Single stranded
Phosphate, ribose sugar, nitrogenous bases AUGC
59
Q

What is ATP

A

Adenosine Tri Phosphate

Energy carrier molecule

60
Q

Structure of ATP

A 
1 adenosine, 3 phosphates
ADP + Pi (+energy used)= ATP
condensation reaction using ATP synthase
Carries energy in its bonds
Hydrolysis uses ATP hydrolase
61
Q

Why is ATP a good source of energy

A

Immediate source: only need to break one weak bond

Managable source: releases small amount of energy

62
Q

Uses of ATP

A 
Protein synthesis
Organelle synthesis
DNA replication 
Cell division 
Active transport
Metabolic reactions
Movement
Maintaining body temperature
63
Q

Role of water in biology

A

Found in living organisms: cytoplasm, xylem/phloem, tissue fluid and blood
Acts as habitats for living organisms

64
Q

Properties of water

A

Water is dipolar
Hydrogen has slight positive charge
Oxygen has slight negative charge
Forms hydrogen bonds

65
Q

Role of water in habitats (sea)

A

High specific heat capacity due to hydrogen bonds

Freezes=ice which is less dense than water so can float to insulate water

66
Q

Role of water as a solvent

A

Water molecules are dipolar so can separate solutes based on their charge
Hydrogen mixes with negative and oxygen mixes with positive so solute dissolves
Useful in cytoplasm and diffusion

67
Q

Role of water hydrostatic pressure

A

Water pressurised can provide strong physical pushing force

Mass flow theory and turgidity in plants

68
Q

Role of water homeostasis

A

Control body temperature by sweating
Sweat made of hydrogen bonds so has a stable structure and requires large amount of heat to evaporate
Called latent heat of vaporisation

69
Q

What are inorganic ions

A

Salts/minerals
Inorganic=no carbon
Ion=charged

A-Level Biology (14 decks)

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