Biological Molecules Flashcards
1
Q
What makes water a polar molecule? (structure)
A
- One oxygen Atom (O) join with two Hydrogen atoms (H2) by shared electrons.
- Shared hydrogen electrons are pulled towards the oxygen atom meaning the other side of each hydrogen atom is left with a slight positive charge.
- The unshared negative electrons on the oxygen atom give it a slight negative charge.
- This makes water a polar molecule.
2
Q
Properties of Water (5)
A
- High specific heat capacity.
- High latent hear of evaporation.
- Cohesive.
- Good solvent.
- Less dense when solid.
3
Q
High specific heat capacity
A
- Hydrogen bonds between water molecules can absorb a lot of energy.
- Meaning it takes a lot of energy too heat up (high specific heat capacity).
- Means water doesn’t experience rapid temperature changes, making it a good habitat.
4
Q
High Latent Heat Of Evaporation.
A
- It takes a lot of energy (heat) to break the hydrogen bonds between water molecules.
- This means a lot of energy is used up when water evaporates.
- Means water is a good coolant. (This is why some mammals sweat).
5
Q
Cohesive
A
- Water is very cohesive (meaning they stick together) because they’re polar.
- Makes it easier for water to flow.
- Means water is good for transporting substances and helps water transport up plant stems in the transpiration stream.
6
Q
Good Solvent
A
- Water’s polarity will mean ions dissolve in water.
- Important ions can dissolve in the water in blood and then be transported around the body.
7
Q
Less dense when solid.
A
- Water molecules are held further apart in ice (less dense).
- Therefore, ice floats.
- Means ice forms an insulating layer on top of water in cold temperatures.
- This means water below doesn’t freeze so organism that live in water like fish don’t freeze and can still move around.
8
Q
What is a Monomer?
A
Monomers are small units which are the components of larger molecules. E.g monosaccharides such as glucose and Amino Acids.
9
Q
What is a Polymer?
A
Polymers are molecules made from monomers joined together. E.G Amino Acids join together form a polypeptide chain.
10
Q
A condensation reaction
A
A condensation reaction is a reaction which joins monomers by chemical bonds and it involves the loss of a water molecule.
11
Q
What are the 3 Main carbohydrates?
A
- Monosaccharides (sugar).
- Disaccharid (sugar).
- Polysaccharides
12
Q
Carbohydrate def
A
- Contains only oxygen carbon and Hydrogen.
- Stores energy in plants and animals.
- Cellulose cell wall dependant on structural role of some carbohydrates.
13
Q
Glucose+Glucose=
A
Maltose
14
Q
Glucose+Fructose=
A
Sucrose
15
Q
Glucose+Galactose=
A
Lactose
16
Q
Disaccharides def
A
- Molecule consisting of 2 monosaccharides joined by a glyosidic bonds by a condensation reaction.
17
Q
Monosaccharides def
A
- A molecule consisting of a single sugar.
18
Q
Polysaccharide def
A
- A polymer made from many sugar monomers (monosaccharides).
19
Q
What is a Monomer
A
- Single Molecule.
20
Q
How is cellulose adapted to their function in plant cells?
A
- Long Chains which are Linked to form fibrils. This Provide strength to cell wall.
21
Q
Starch function
A
- Main energy storage in plants.
- Mixture of two polysaccharides, Amylose and Amylopectin.
22
Q
Starch adaptations.
A
- Amylose,Compact so it’s good for storage because you can fit more into a small space.
- Amylopectin,Branches allow enzymes that break down the molecule to reach the glycolic bonds easily.
23
Q
Glycogen.
A
- Main energy storage material in animals.
24
Q
Glycogen adaptations
A
- Many side branches means stored glucose can be released easily.
- Compact molecule which is good for storage.
25
Cellulose
- The major component of cell walls in plants.
26
Triglyceride structure.
- one molecule of glycerol and three fatty acids (tails) attached to it.
- Tails are hydrophobic.
- Contain ester bonds. (Broken in hydrolysis reactions)
27
Esterification.
- The process by which triglycerides are synthesised.
28
Difference between Saturated and Unsaturated fatty acids.
- Saturated=No double bonds between carbon atoms.
| - Unsaturated=At least one double bond between carbon atoms. (Causes the chain to kink)
29
Similarity and difference between a phospholipid and triglyceride.
```
Similarity= They are both macromolecules.
Difference= One of the fatty acids(hydrophobic) in a phospholipid is replaced by a phosphate group (hydrophilic).
```
30
Triglyceride properties.
- Long hydrocarbon tails of the fatty acids contain lot of chemical energy, means a load of energy is released when broken down.
- Insoluble, Don’t cause water to enter the cell by osmosis, which would make them swell.
31
Phospholipid proporties
- Hydrophilic heads and hydrophobic tails, meaning they form a double layer with their heads facing out towards the water.
- Centre of the Bilayer is hydrophobic so the membrane acts as a barrier to water soluble substances.
32
Cholesterol properties.
- Small size and flattened shape, allows it to fit between the phospholipid’s in the membrane.
- They bind to phospholipids tails, causing them to pack more close together,making the membrane more rigid.
33
What are the three ‘main’ lipids?
- Cholesterol.
- Phospholipids.
- Triglycerides.
34
What are the monomers in a protein?
-Amino Acids.
35
What is a dipeptide?
When two Amino Acids join together.
36
What is a polypeptide?
When more than two amino acids join together.
37
Amino Acid structure.
- A Carboxyl group (-COOH) and an amine group(-NH2) attached to a carbon atom.
38
What is the difference between the structure of Amino Acids?
- The variable group they contain.
39
What bond join up Amino Acids and how is it broken/formed.
- Peptide bond.
- Formed by a condensation reaction, molecule of water released.
- Broken by a hydrolysis reaction, molecule of water added.
40
What are the 4 protein structural levels?
- Primary structure.
- Secondary structure.
- Tertiary Structure.
- Quaternary structure.
41
What is the Primary structure?
- The sequence or amino acids in a polypeptide chain.
42
What is the secondary structure?
- Hydrogen bonds form between the amino acids in the chain.
| - This makes it coil into an alpha helix or fold into a beta pleated sheet.
43
What is the tertiary structure of a protein?
- Coiled chain of Amino acids is coiled and folded further.
- More bonds form between different parts of polypeptide chain.
- Final 3D structure for protein made from 1 polypeptide chain.
44
What is the quaternary structure of proteins?
- The way polypeptide chains are assembled together. e.g Haemoglobin.
- Final 3D structure for protein made from more than 1 polypeptide chain.
45
Primary structure bonds.
- Peptide bonds between Amino Acids.
46
Secondary structure bonds .
- Hydrogen bonds.
47
Tertiary structure bonds
- Ionic bonds (Attraction between negatively and positively charged R groups)
- Disulphide bonds.
- Hydrogen bonds.
48
Quaternary structure bonds.
- Determined by the tertiary structure of the individual polypeptide chains being bonded together.
- Therefore, can be influenced by all the bonds.
49
Globular protein
- Round and compact.
- Hydrophilic R groups on the Amino Acids tend to be pushed on the outside of the molecule, this makes globular proteins soluble, so they’re easily transported in organisms.
50
Examples of globular proteins
- Haemoglobin.(Carries oxygen around the body in red blood cells).
- Insulin.(Helps regulate blood glucose levels).
- Amylase. (Catalyses the breakdown of starch in the digestive system).
51
Fibrous protein.
- Tough and rope-shaped.
- Insoluble.
- Fairly unreactive.
52
Examples of fibrous proteins.
- Collagen (Found in animal connective tissues, strong molecule, minerals can bind to increase rigidity).
- Keratin.(Found in skin, nails and hair, can be flexible or hard and tough.
- Elastin (Found in connective tissues, allows tissues to turn to its original shape after is has been stretched.
53
What is a conjugated protein?
-A protein with a non-protein group attached.
54
What are inorganic ions?
- An atom that has an electric charge.
55
What is a ion with a positive charge called?
- Cations.
56
Cations.
- Calcium (ca2+).
- Sodium (Na+).
- Potassium (K+)
- Hydrogen (H+).
- Ammonium (NH4+)
57
What are ions with a negative charge called?
- Nitrate (NO3-)
- Hydrogencarbonate (HCO3-).
- Chloride (Cl-)
- Phosphate (PO43-)
- Hydroxide (OH-)
58
Biuret test for proteins
- Add a few drops of sodium hydroxide to the solution (so it becomes an alkaline).
- Add some copper surface solution.
- Protein present=purple.
- No protein= stays blue.
59
Iodine test for starch.
- Add iodine dissolved in potassium solution to the test sample.
- Starch present=Dark blue-black.
- No starch= stays browny-orange.
60
Emulsion test for lipids.
- Shake the test substance with ethanol for about a minute, then pour the solution into water.
- Lipid present=Milky.
- No lipid= Solution remains clear.
61
Benedicts test for reducing sugars.
- Add benidicts to a sample and heat it in a water bath.
- Reducing sugars present= Coloured precipitate, Green-Yellow-Orange-Brick red. (The higher than concentration of reducing sugar present, the further the colour change.
- No reducing sugar present= Sample stays blue.
62
Benedicts test for non-reducing sugars. (E.g sucrose).
- Add dilute hydrochloric acid to the sample and heat it in a water bath.
- Neutralise the solution it’s sodium hydrogen carbonate.
- Non-reducing sugar present=Coloured precipitate.
- No Non-reducing sugar present= stays blue.
63
What is a colorimeter?
- A device that measures the strength of a coloured solution by seeing how much light passes through it.
64
Chromatography
- Draw a pencil line near the bottom of a piece of chromatography paper.
- Put a concentrated spot of the mixture of the molecule on it.
- Add a small amount of prepared solvent to a beaker and dip the bottom of the paper into it.
- Cover with a lid to stop the solvent evaporating.
- When the solvents near the top, take the paper out and marker the solvent front with pencil.
- Let the paper dry out and then analyse it.
65
Rf values.
- Distance travelled by spot/distance travelled by solvent.
66
What Is the mobile phase in chromatography?
- Where the molecules can move.
67
What is the stationary phase in chromatography?
- Where the molecules Can’t move,
68
Which chemical elements make up carbohydrates?
- C,H and O
69
Which chemical elements make up lipids?
- C, H and O
70
Which chemical elements make up proteins?
- C, H, O and S
71
Which chemical elements make up nucleic acids?
- C,H,O,N and P
