2.2 Flashcards
(75 cards)
1
Q
What is a hydrogen bond?
A
- Weak interaction
- Slightly negatively charged atom bonded to slightly positive charged atom
- Weaker then covalent bond
- stabilise biological molecules
2
Q
What is a condensation reaction?
A
Two molecules joined together with the removal of water.
3
Q
How are disaccharides broken down?
A
- Hydrolysis reaction (addition of water)
- Hydroxyl and Hydrogen group produced
4
Q
What elements are carbohydrates made up of and what are their monomer and polymer state?
A
- C, H, O
- Monomer = Monosaccharide
- Polymer = Polysaccharide
5
Q
What elements are proteins made up of and what are their monomer and polymer state?
A
- C, H, O, N, S
- Monomer = Amino acid
- Polymer = Polypeptide, Protein
6
Q
What elements are Nucleic acid made up of and what are their monomer and polymer state?
A
- C, H, O, N, P
- Monomer = Nucleotides
- Polymer = DNA & RNA
7
Q
Why is it important that water is liquid?
A
- Provides a reaction medium for chemical reactions
- Forms habitats for living organisms (seas, lakes, rivers)
- Forms major component of tissue
- Transport medium in blood and vascular tissue.
8
Q
Why is Density an important property of water?
A
- Aquatic organisms have a stable environment during winter
- Bodies of water insulated against extreme cold, as layer of ice reduces heat loss.
9
Q
How does Ice form?
A
Water due to its polar nature when reaching around 4 degrees celsius align themselves into a structure less dense than water.
10
Q
Why is Solvency an important property of water and how does structure allow this?
A
- Molecules and ions can move and react with each other in water
- Molecules and ions can be transported around in living things while dissolved in water.
Structure:
- Polar nature attracts negative and positive parts of solute
- Allows separation of molecules leading to dissolving and forming new molecules
11
Q
Why is Cohesion and surface tension an important property of water and how does structure allow this?
A
- Columns of water in plant vascular tissue pulled up xylem tissue together.
- Insects like pond skaters can walk on water
Structure:
- Hydrogen bonds pull water molecules together allowing resistance to force
12
Q
Why is HSHC an important property of water and how does structure allow this?
A
- Stable temperature allows for stable environment
- Stable temperature for enzyme controlled reaction
Structure:
- Strong hydrogen bond
- Does not allow temperature to change quickly
13
Q
Why is High latent heat of vaporisation an important property of water and how does structure allow this?
A
- Mammals are cooled when sweat evaporates
- Plants cooled when water evaporate from mesophyll cell
Structure:
- Strong hydrogen bond
- Large energy needed to evaporate water molecules
14
Q
Why is water being a reactant important as a property?
A
Reactant used in photosynthesis and in hydrolysis reactions
15
Q
What is a glycosidic bond?
A
A bond formed between two monomers as a result of a condensation reaction
16
Q
Describe molecular structure of water?
A
- Polar
- Oxygen slightly negative
- Hydrogen slightly positive
- Protons in oxygen exerting a stringer force of attraction for the shared electrons
- Two hydrogen atoms covalently bonded to an oxygen atom
17
Q
Alpha glucose + Alpha glucose
A
Maltose
18
Q
Alpha glucose + Fructose
A
Sucrose
19
Q
B-galactose + A-glucose
A
Lactose
20
Q
B-glucose + B-glucose
A
Cellobiose
21
Q
How is disaccharide bond formed?
A
- Condensation reaction forms glycosidic bond
- Hydroxyl group line up and water molecule is removed
- Oxygen acts up as link between two monosaccharide units
22
Q
What is role of alpha glucose in body?
A
- Energy source
- Component of starch and glycogen
23
Q
What is role of Ribose in body?
A
- Component of RNA, ATP & NAD
24
Q
What is role of deoxyribose in body?
A
- Component of DNA
25
What is role of beta glucose in body?
- Energy source
| - Component of cellulose, structural support to cell wall
26
Why are polysaccharides good energy stores?
- Starch and glucose are compact meaning they do not take up lots of space.
- Polysaccharides are held in chains, allowing for glucose molecules to be 'snipped off' through a hydrolysis reaction catalysed by an enzyme.
- Some are branched (amylose) and some aren't (amylopectin, glycogen). Branched is more compact and allows for more than one glucose molecule to be 'snipped off' via hydrolysis reaction at the same time.
- 1-4 bonds are broken via Amylase
- 1-6 bonds are broken via Glycosidase.
- Polysaccharides are not soluble in water. This is done by the hiding of regions where hydrogen bond with water can occur inside the structure.
27
Describe the structure of Amylose (plants).
Bonds:
- Alpha glucose chain
- Glycosidic bond between carbon 1 and 4
Structure:
- Hydroxyl group on Carbon 2 hidden inside structure making it less soluble.
- Also allows hydrogen bonds to form maintaining coil structure.
- Spiral shape
28
Describe the structure of Amylopectin (plants).
Bonds:
- Glycosidic bond between 1 and 4
- Branches due to glycosidic bond between carbon 1 and 6
Structure:
- Coils into spiral shape
29
Describe structure of glycogen (animals).
Bonds:
- Glycosidic bonds between Carbon 1 and 4, 1 and 6.
Structure:
- 1-4 bond smaller causing less coil
- More branches -> more compact and easier to remove units of monomer.
30
What are lipids?
A group of substances soluble in alcohol instead of water.
31
What is a phospholipid?
A glycerol molecule, two fatty acids and a phosphate group.
32
What is glycerol?
- Alcohol
- Three Carbon atoms
- Three -OH groups
33
Structure of unsaturated fats.
- Double C=C
| - Kinks push molecules slightly apart decreasing melting point
34
What is an ester bond and how is formed?
- Condensation reaction
| - Between -COOH group of fatty acid and -OH group of glycerol
35
What are the functions of triglyceride
- Energy store as not soluble in water. Releases more energy than 1g of glucose due to more hydrogen atoms.
- Energy Source as ester bonds can be broken to produce ATP and glycerol and fatty acids can be broken down into water and carbon dioxide.
- Buoyancy as fat less dense then water so animals can stay afloat
- Protection as it covers delicate organs to act as shock absorber
- Insulation in 'blubber' of whales, nerve cells as electrical insulator.
36
What is phospholipid molecule made up of?
- Hydrophilic phosphate head
| - Hydrophobic fatty acid tail
37
How does a phospholipid molecule react in water?
- Phospholipid molecule can form micelles with hydrophobic tails facing inside the micelle and hydrophilic head facing outwards towards the water.
38
What can pass through the phospholipid bilayer?
- Small, non-polar molecules
| - Oxygen & AMP; carbon dioxide.
39
What is cholesterol and its role in membranes?
- Steroid alcohol
- 4 Carbon rings/isoprene units
- Sits in the middle of bilayer controlling fluidity
- Produced in liver
- In plants its called stigma-sterol (double carbon bond at 22/23)
40
What is a peptide bond?
The bond formed when two amino acids join together through a condensation reaction.
41
Describe the structure of an amino acid.
It has an amino group (-NH2), a carboxyl group (-COOH) and an R group.
42
Define primary structure.
It is the sequence of amino acids in a molecule.
43
Define secondary structure.
The coiling or folding of amino acid chain through hydrogen bonding between chains. Either beta-pleated or alpha helix.
44
Define the tertiary structure.
The overall 3D shape of the protein as a result of hydrogen, ionic bonding, disulphide bridges and hydrophobic interactions.
45
Define quaternary structure.
Protein structure which consists of more than one polypeptide chain.
46
Where do hydrogen bonds form in proteins?
Between carboxyl and amino group.
47
Where do ionic bonds form in proteins?
When carboxyl and amino group ionise they from NH3+ and COO- which form ionic bonds between each other.
48
Where do disulfide bridges form in proteins?
When R groups consist of cystine which contains sulfur bonds with each any R group.
49
How do hydrophobic interaction occur in proteins?
Hydrophobic parts of the R group associate together in the centre of protein where as hydrophilic parts are on the edge. This interactions twists the amino acid chain.
50
Describe a fibrous protein.
- Thin, long
- Mechanically strong
- Metabolically inactive
- Insoluble in water
- Regular repetitive sequences of amino acids allow formation of fibres (Keratin, elastin, collagen)
51
Describe a globular protein.
- Spherical shape
- Soluble in water
- Metabolically active
- Hydrophobic R groups turn inwards and Hydrophilic groups on outside.
- Haemoglobin
52
What role does Collagen play in the body?
- Lines the artery wall to stop it from bursting due to high pressure of blood pumped from the heart
- Makes up tendons which connect muscle and bone
- Makes up bones but reinforced with Calcium Phosphate
- Connective tissue
53
What role does Keratin play in the body and how is it structured?
- Keratin has lots of cystine in R group therefore many disulfide bridges formed. This alongside hydrogen bonds makes it very strong.
- Mechanical strength
- Waterproof
- Impermeable to infectious diseases
54
What are the reducing sugars?
- Maltose
| - Lactose
55
What are the non reducing sugars?
- Sucrose
56
Describe structure of cell wall?
- Micro and macro fibril have high tensile strength due to glycosidic and hydrogen bonds
- Macro fibril's runs in all directions criss-crossing wall providing extra strength
57
Describe function of cell wall in relation to structure.
- Plants do not have rigid skeleton, each cell needs strength to support structure.
- Space between macro fibrils for water and mineral ions to pass (permeability)
- High tensile strength prevents plant cells from bursting when turgid and helps support structure
- Macro fibril can be reinforced with suberin or cutin to waterproof and strengthen
58
Describe structure of cellulose.
- Hydrogen and hydroxyl group inverted in b-glucose causes every other beta glucose to be rotated 180
This and 1-4 glycosidic bonds stop spiralling
- Hydrogen bonds between rotated units give strength and stop spiralling
- Hydrogen bonds between hydroxyl groups sticking out on carbon 2 between chains give structural strength
59
Describe the Cell wall of bacteria?
- Peptidoglycan
| - Parallel chains cross linked by peptide chains
60
Describe exoskeleton?
- Chitin
| - Acetylamino group instead of hydroxyl group on carbon 2
61
Describe structure and function of elastin.
- Cross-linking and coiling -> strong and extensible
- Skin stretch around bones and muscles
- Skin goes back to normal shape due to elastin
- Lungs inflate and deflate
- Bladder expand to hold urine
- Blood vessel stretch and recoil to maintain pressure
62
Describe structure and function of haemoglobin.
- Two alpha-globin chain
- Two beta-globin chain
- Haem group (prosthetic group) -> iron ion
- Oxygen molecule bins to iron ion
63
Describe structure and function of insulin.
- Two polypeptide chains
- Linked by disulphide bond
- R group outside making insoluble
- A chain begins with a-helix; B chain ends with B-pleat
64
What is structure and function of pepsin.
- Digests protein
- 327 amino acid
- 43 amino acids with acidic R groups -> stable in acidic environment
- Held together by hydrogen bonds and two disulphide bonds
65
What is Ab initio protein modelling?
- Modelling of physical and electrical elements of atom in amino acid
66
How is the starch test carried out?
Sample will be in potassium iodide solution.
Iodine solution will be added to the sample containing potassium iodide.
This will will cause a colour change from yellow-brown to blue-black.
This colour change is caused by the the iodine forming a triiodide when dissolved in potassium iodide solution. The triiodide ion slips into middle of amylose helix.
67
What are the two ways you can test for reducing sugars?
- Benedicts solution
| - Test strip
68
How do you carry out test using Benedict's solution?
Sample will be suspended in Benedict's solution (alkaline copper (II) sulfate).
Mixture heated for 3 minutes at 80 degrees Celsius.
Reducing sugars will become reduced donating an electron causing Cu2+ to become Cu+.
This will from an orange-red precipitate called copper oxide (Cu2O)
The colour changed that will be observed is Blue to Green to Yellow to Orange-Red.
If excess Benedict's solution is used the intensity of the red colour of the precipitate will be proportional to the concentration of the sugar in the solution.
If not a lot of precipitate is formed then a green colour is observed. If there is a lot an orange-red colour is observed.
69
How to test reducing sugars using test strip?
Test strip is dipped into sample causing it change colour.
Colour observed is compared to calibration card provided with test strip.
Allows identification if reducing sugar present or not.
70
How to test for non-reducing sugars?
1) Test for reducing sugars to ensure none are present.
2) Take sample and boil with hydrochloric acid in order to hydrolyse sucrose into glucose and fructose
3) Cool sample and neutralise using hydrogen-carbonate solution.
4) Test for reducing sugars
Positive result will produce a green-yellow-orange-red colour.
71
How to test for lipids?
1) Mix sample with ethanol. Any lipids will not dissolve into it
2) Filter
3) Pour solution into water in clean test tube
4) Cloudy white emulsion indicates presence of lipids.
72
How to test for proteins?
1) Add biuret A (sodium hydroxide).
2) Add biuret B (copper sulfate)
3) Light blue to lilac
4) Complex formed between nitrogen atoms in peptide chain and the Cu2+ ions.
73
How to use colorimeter?
1) Centrifuge used to separate supernatant (excess Benedict's solution) and precipitate
2) Pipette takes supernatant placing it into cuvette placed into colorimeter
3) Do not touch surface of cuvette
4) Colour filter can be added to increase accuracy
5) Lots of unreacted copper sulfate, supernatant is still quite blue; percentage transmission very low, absorption is high
Little unreacted copper sulfate, supernatant is less blue, transmission percentage high; absorption is low
74
How to create a calibration curve?
1) Take series of known concentrations of reducing sugar
2) Use sample of each carry out Benedict's test
3) Colorimeter used to measure transmission of light
4) Plot graph showing Transmission of light against known concentrations
75
How do biosensors work?
1) Molecules to be measured bind to receptor on a biological layer
2) This moves through a transducer surface which produces an electronic signal
3) Electronic signal passed onto electronics (signal coordinator) which produces a signal
