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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
Structure of an amino acid
``` Central carbon Carboxyl to the right Amine to the left Hydrogen above R below ```
26
How do different amino acids differ
Have different R groups
27
How are amino acids joined together
Condensation reactions Between carboxyl group and amine group Peptide bond between carbon and nitrogen
28
Primary structure
Sequence of amino acids, polypeptide chain held by peptide bonds
29
Secondary structure
Polypeptide chain coils to form alpha helix or beta pleated sheets held by hydrogen bonds
30
Tertiary structure
Secondary structure further folds to form 3d tertiary structure held by hydrogen/ionic bonds and disulfide bridges
31
Quaternary structure
More than one polypeptide chain | May contain prosthetic group
32
Example of quaternary structures
Collagen Antibodies Haemoglobin
33
Structure of collagen
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
Test for protein
Biuret | Turns purple/lilac
35
What is an enzyme?
Biological catalyst that speeds up the rate of reaction without being used up, lowers activation energy Specific tertiary structure
36
What makes an enzyme specific?
Specific active site shape Only complementary substrates can bind to active site Forms enzyme-substrate complexes
37
Lock and Key VS induced fit
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
Affect of substrate concentration on enzyme activity
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
Affect of enzyme concentration on enzyme activity
Increase EC increases chance of successful collisions, increases chance of forming ES complexes, increases rate of reaction Continues until substrates are used up
40
Affect of temperature on enzyme activity
``` 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
Affect of ph on enzyme activity
``` Change ph away from optimum Bonds in tertiary structure break Lose active site shape No longer form ES complex Enzyme denatured ```
42
Competitive inhibitors
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
Non-competitive inhibitors
Substance that binds to allosteric site on enzyme Causes active site to change shape Less ES complexes can form
44
3 types of lipids
Triglycerides (fat for energy store, insulation, organ protection) Phospholipids (membranes) Cholesterol (membrane stability, hormones)
45
Structure of a triglyceride
1 glycerol and 3 fatty acids Condensation reactions, ester bonds Bond is COOC 2 types: saturated fat and unsaturated fat
46
Saturated fat
No carbon-carbon double bonds in R group
47
Unsaturated fat
Has carbon-carbon double bonds in R group
48
Structure of phospholipid
1 glycerol, 2 fatty acids, 1 phosphate Hydrophillic heads Hydrophobic tails Phospholipid bilayers
49
What are nucleic acids?
Polymers made from nucleotides | DNA and RNA
50
What is DNA
DeoxyriboNucleic Acid Found in all organisms Carries genes (sections of DNA that code for protein)
51
DNA monomer
Nucleotides (made of phosphate, deoxyribose sugar, nitrogenous base) Adenine, Thymine, Guanine, Cytosine
52
DNA structure
Double helix 2 polynucleotides hydrogen bonds between bases Antiparallel strands Coiled
53
Bonding in base pairs
AT GC GC most common, triple bond AT have double bond
54
Properties of DNA structure
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
DNA replication
In interphase before mitosis and meiosis | Semi-conservative replicatiom
56
Semi-conservative replication process
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
Evidence for SCR?
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
What is RNA
``` RiboNucleic Acid mRNA: messenger tRNA: transfer Single stranded Phosphate, ribose sugar, nitrogenous bases AUGC ```
59
What is ATP
Adenosine Tri Phosphate | Energy carrier molecule
60
Structure of ATP
``` 1 adenosine, 3 phosphates ADP + Pi (+energy used)= ATP condensation reaction using ATP synthase Carries energy in its bonds Hydrolysis uses ATP hydrolase ```
61
Why is ATP a good source of energy
Immediate source: only need to break one weak bond | Managable source: releases small amount of energy
62
Uses of ATP
``` Protein synthesis Organelle synthesis DNA replication Cell division Active transport Metabolic reactions Movement Maintaining body temperature ```
63
Role of water in biology
Found in living organisms: cytoplasm, xylem/phloem, tissue fluid and blood Acts as habitats for living organisms
64
Properties of water
Water is dipolar Hydrogen has slight positive charge Oxygen has slight negative charge Forms hydrogen bonds
65
Role of water in habitats (sea)
High specific heat capacity due to hydrogen bonds | Freezes=ice which is less dense than water so can float to insulate water
66
Role of water as a solvent
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
Role of water hydrostatic pressure
Water pressurised can provide strong physical pushing force | Mass flow theory and turgidity in plants
68
Role of water homeostasis
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
What are inorganic ions
Salts/minerals Inorganic=no carbon Ion=charged

A-Level Biology (14 decks)

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