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BIOLOGY Module 2: Foundations In Biology > 2.1.2 Biological Molecules > Flashcards

2.1.2 Biological Molecules Flashcards

(69 cards)

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1
Q

How does hydrogen bonding occur between water molecules

A

Oxygen and hydrogen do not share electrons equally in a covalent bond, oxygen has greater share (is negative)
This means water molecules have slight positive and negative charges and are polar
The positive and negative regions attract eachother and form hydrogen bonds

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2
Q

Why is water a good solvent

A

Because its polar it can act as a medium for chemical reactions and helps transport dissolved compounds in/out of cells

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3
Q

Why is water a good transport medium

A

Cohesion means water molecules stick together when being transported through the body
Adhesion occurs between water molecules and other polar molecules and surfaces
Cohesion and adhesion result in water exhibiting capillary action which is how water can rise up a narrow tube against the force of gravity

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4
Q

How does water act as a coolant

A

Due to high specific heat capacity and high latent heat of vaporisation

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5
Q

How is water effective as a habitat

A

Habitat for pond skaters due to surface tension
Ice is more dense than water so it forms insulating layer above water, means organisms don’t freeze to death

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6
Q

What are polymers

A

Long-chain molecules made up by linking multiple individual molecules, monomers, in a repeating pattern

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7
Q

What is a condensation reaction

A

Joining of 2 molecules with formation of a chemical bond and production of a water molecule

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8
Q

Example of condensation reaction

A

Joining of 2 alpha glucose molecules, 1-4 glycosidic bond formed, forms maltose

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9
Q

What is a hydrolysis reaction

A

Addition of water to a molecule that breaks chemical bonds to form 2 smaller molecules

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10
Q

Example of a hydrolysis reaction

A

Releasing glucose for respiration, starch or glycogen undergo a hydrolysis reaction

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11
Q

What elements are present in carbohydrates

A

C H O

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12
Q

What elements are present in lipids

A

C H O

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13
Q

What elements are present in proteins

A

C H O N S

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14
Q

What elements are present in nucleic acids

A

C H O N P

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15
Q

Structure of glucose

A

C6H12O6
Hexose monosaccharide
Polar, soluble in water due to H bonds formed between water and glucose

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16
Q

Structure of alpha glucose

A

OH on carbon 1 us facing down

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17
Q

Structure of beta glucose

A

OH on carbon 2 is facing up

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18
Q

Structure of ribose

A

Pentose monosaccharide

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19
Q

Structure of sucrose

A

Glucose and fructose

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20
Q

Structure of lactose

A

Galactose and glucose

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21
Q

Structure of maltose

A

2 alpha glucose

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22
Q

Amylose structure

A

Alpha glucose molecules joined by 1-4 glycosidic bonds
Helix is formed, stabilised by H bonding
Compact and less soluble
Polysaccharide

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23
Q

Amylopectin structure

A

1-4 and 1-6 glycosidic bonds between alpha glucose molecules
Branched structure
Polysaccharide

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24
Q

Structure of glycogen

A

Very branched, more compact, less space needed to be stored

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25
Why are amylose, amylopectin and glycogen suited to their function
Coiling or branching makes them compact and good for storage Branching means free ends for glucose to be added/removed which speeds up process of storing and releasing glucose molecules Insoluble
26
Structure of cellulose
Alternate beta glucose molecules are turned upside down and joined together Straight chain formed
27
Cellulose in the body
Molecules form H bonds with eachother, forming microfibrils, microfibrils join to form microfibrils which combine to form fibres Fibres are strong and insoluble, used for cell walls Hard to break down into monomers, forms roughage necessary for healthy digestive system
28
Structure of triglyceride
One glycerol molecules, three fatty acids Hydroxyl groups of glycerol and fatty acids interact and 3 water molecules form, ester bond formed, esterification reaction (condensation) Macromolecule CHO
29
Structure of phospholipid
CHOP Phosphate group, glycerol, 2 fatty acids Non-polar tail, hydrophobic Charged head, hydrophilic Surfactants
30
How does unsaturation effect fatty acids
Causes molecule to kink/bend Can’t pack closely together Liquid at room temp Oils, not fats
31
Roles of lipids
Membrane formation Hormone production Electrical insulation Waterproofing Thermal insulation Cushioning Buoyancy Energy storage
32
Structure of sterols and an example
Hydroxyl group at one end, hydrophilic and hydrophobic regions Cholesterol: important in cell membranes which stabilises and regulates fluidity
33
General structure of amino acids
Amine group C H R group Carboxyl group
34
How are peptides synthesised
Amino acids join when amine and carboxyl groups join Peptide bond forms and water is produced (condensation) Dipeptide forms Many join, forms polypeptide
35
What’s primary protein structure
Sequence that amino acids are joined Directed by information in DNA Only involved peptide bonds
36
What’s secondary protein structure
H bonds, forms along long protein molecules depending on AA sequence O H N from repeating structure of amino acids interact Hydrogen bonds can form and create coil shape, alpha helix Chains can lie parallel to eachother joined by H bonds, forms beta pleated sheets
37
What’s tertiary protein structure
Folding of protein into final shape R groups brought closer together by secondary structure R groups interact - hydrophobic/hydrophilic interactions - H bonds - ionic bonds - disulfide bridges (covalent bonds between R groups w sulfur atoms)
38
What’s quaternary protein structure
Association of 2 or more individual proteins (subunits) Same as interactions in tertiary structure Enzymes have 2 identical subunits Insulin has 2 different subunits Haemoglobin four subunits, 2 pairs of identical subunits
39
How do peptides breakdown
Proteases can catalyse it Water molecules used to break peptide bond
40
Structure of globular proteins and how they form
Compact, water soluble, spherical Form when proteins fold in tertiary structure so that hydrophobic R groups are kept away from aqueous environment Hydrophilic R groups on outside
41
Function of globular proteins
Essential for regulating processes for life, chemical reactions, immunity, muscle contraction
42
Example of globular protein and how its structure relates to function
Insulin Hormone involved in regulation of blood glucose concentration Hormones transported in bloodstream, need to be soluble Need precise shapes to fit into specific receptors on cell-surface membranes
43
Conjugated protein structure
Globular proteins with prosthetic group (non-protein component) Types of prosthetic groups: lipids/carbohydrates/ haem groups Metal ions ( cofactors when essential for function)
44
2 examples of conjugated proteins and structure of them
Haemoglobin: each subunit contains prosthetic haem group, iron ions present combine reversibly with oxygen molecule Catalase: contains 4 haem prosthetic groups, iron ions present allow catalyse to speed up and interact with H2O2
45
Structure of fibrous proteins
Formed from long, insoluble molecules Only contain amino acids with hydrophobic R groups Usually repetitive sequence Strong
46
3 examples of fibrous proteins, structures and functions
Keratin: lots of cysteine, results in lots of disulfide bridges, strong inflexible and insoluble materials, present in skin hair and nails Elastin: in elastic fibres, walls of blood vessels and alveoli, provide flexibility to expand and recoil, quaternary protein Collagen: connective tissue found in skin ligaments tendons and nervous system, made up of 3 polypeptides wound together in long strong rope-like structure, flexible
47
Uses of calcium ions
Nerve impulse transmission Muscle contraction
48
Uses of sodium ions
Nerve impulse transmission Kidney function
49
Uses of potassium ions
Nerve impulse transmission Stomatal opening
50
Uses of hydrogen ions
Catalysis of reactions PH determination
51
Uses of ammonium ions
Production of nitrate ions by bacteria
52
Uses of nitrate ions
Nitrogen supply to plants for amino acid and protein formation
53
Uses of hydrogen carbonate ions
Maintenance of blood ph
54
Uses of chloride ions
Balance positive charge of sodium and potassium ions in cells
55
Uses of phosphate ions
Cell membrane formation Nucleic acid and ATP formation Bone formation
56
Uses of hydroxide ions
Catalysis of reactions Ph determination
57
Describe how to test for reducing sugars
Place sample in boiling tube Add equal volume of Benedict’s reactant Heat mixture gently in boiling water bath for 5 minute Brick red precipitate will form if the sample is a reducing sugar (qualitative test) Blue = none Green = very low Yellow = low Orange = medium Red = high
58
Examples of reducing sugars
All monosaccharides Maltose Lactose
59
What is a reducing sugar
Sugar can donate electrons or reduce another molecule or chemical
60
How to test for non-reducing sugar
Place sample in boiling tube Add equal volume of Benedict’s reagent Heat mixture gently in boiling water bath for 5 minutes Will remain blue precipitate if its a non-reducing sugar
61
Example of non-reducing sugar
Sucrose
62
How to test for starch
Add a few drops of iodine dissolved in potassium iodide solution to a sample If the solution changes colour from brown to blue-black, starch is present
63
How to use reagent strips
Test for presence of reducing sugars (glucose) Use a colour coded chart to determine concentration of sugar
64
How to test for protein
Add a few drops of sodium hydroxide solution to sample Add copper (II) sulfate solution Goes purple if protein is present Stays blue if no protein is present
65
How to test for lipids
Shake sample with ethanol for a minute Pour solution into water Solution will turn milky if lipid is present Will stay clear if no lipid is present
66
How to determine concentration of a solution
Create 5 serial dilutions with solution factor of 2 Do Benedict’s test on each solution, and a control of water Remove any precipitate by centrifuging Use colorimeter with red filter to measure absorbance of Benedict’s solution in each tube Use results to create calibration curve, plot absorbance against glucose concentration Then test unknown solution and use calibration to find concentration
67
How does chromatography work
Mobile phase: where molecules can move (solvent) Stationary phase: molecules can’t move (chromatography paper or thin layer of solid) Mobile phase moves over or through stationary phase Components in mixture spend different amounts of time in each phase Components that spend more time in mobile phase travel faster/ further
68
How to carry out paper chromatography
Draw pencil line near bottom of chromatography paper Put concentrated spot of mixture on it Add small amount of solvent to a beaker and dip bottom of paper into it As solvent spreads up paper, mixture will separate and move up at different speeds When solvent has nearly reached the top, mark where it reached and take it out
69
How to calculate Rf value
Rf = distance travelled by spot ÷ distance travelled by solvent

BIOLOGY Module 2: Foundations In Biology (6 decks)

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