2.2 Biological Molecules

?
  • Created by: elbungay1
  • Created on: 16-04-19 12:17
What is a condensation reaction?
Reaction that occurs when two molecules are joined together by the removal of water
1 of 50
What is a hydrolysis reaction?
Reaction that occurs when a molecule is split into two smaller molecules with the addition of water
2 of 50
What are the elements, monomer and polymers of Carbohydrates
Contain C, H and O. Have monomers of monosaccharides (e.g. glucose) and have polymers of Polysaccharides (e.g. starch)
3 of 50
What are the elements, monomers and polymers of Proteins
Contain C, H, O, N and S. Have monomers of Amino acids and polymers of Polypeptides and Proteins
4 of 50
What are the elements, monomers and polymers of Nucleic Acids
Contain C, H, O, N and P. Have monomers of Nucleotides and polymers of DNA and RNA.
5 of 50
What is a hydrogen bond?
A weak interaction that occurs wherever molecules contain a slightly negative charged atom bonded to a slightly positively charged hydrogen atom.
6 of 50
Properties of Water: What are the benefits of water being liquid at room temperature?
Provides habitats for living things in rivers, lakes and seas. Form major components of tissues in organisms. Provide a reaction medium for chemical reaction. Provide an effective transport medium e.g. in blood
7 of 50
Properties of Water: How is ice less dense than water and how does it benefit living organisms?
When frozen, the hydrogen bonding arranges ice into an open lattice which is less dense than water. Benefits include providing aquatic organisms a stable environment in the winter, insulates bodies of water and reduces heat loss
8 of 50
Properties of Water: How is water a good solvent?
It is polar and negative oxygen atoms surround positive parts of solutes and hydrogen surround the negative. This means ionic or charged molecules can be separated and be kept apart. As its a good solvent molecules can move and react in cytoplasm
9 of 50
Properties of Water: What is cohesion and surface tension
Cohesion occurs when stronger hydrogen bonds form at surface of water and water molecules cannot form any bonds upwards so sideways bonds are strengthened. Gives surface of water ability to resist force. Allowing columns of water pulled up xylem
10 of 50
Properties of Water: What is high specific heat capacity?
Due to hydrogen bonds are slightly stronger than other intermolecular forces, more heat energy is required to heat water by 1 degree. High specific heat capacity is beneficial as living things need stable environments for enzyme-controlled reactions.
11 of 50
Properties of Water: What is high latent heat of Vaporisation?
Due to hydrogen bonds and molecules are tightly packed, a relatively large amount of energy is needed for water molecules to evaporate. Keeps organisms cool as mammals are cooled when sweat evaporates
12 of 50
Properties of Water: in what ways does water act as a reactant?
Water is a reactant in photosynthesis and in hydrolysis reactions such as digestion of starch, proteins and lipids.
13 of 50
What are the uses of Carbohydrates?
They act as a source of energy (glucose), as a store of energy (starch and glycogen) and as structural units (cellulose in plants and chitin in insects)
14 of 50
Give an example of a reducing sugar and a non-reducing sugar
Maltose and Lactose are reducing sugars. Sucrose is a non-reducing sugar
15 of 50
Why are polysaccharides good energy stores?
Compact so then don't take up much space, glucose easily snipped off by hydrolytic enzymes. Branches provide a larger surface area for hydrolytic enzymes. Less soluble so they don't affect water potential of the cell and don't disrupt functions
16 of 50
Describe the structure of Amylose (starch)
Long chain of α-glucose bonded by 1-4 glycosidic bonds. Unbranched and coils into spiral shape with hydrogen bonds, keeping hydroxyl group inside spiral making it less soluble
17 of 50
Describe the structure of Amylopectin (starch)
Branched chain of α-glucose with 1-4 and 1-6 glycosidic bonds. and coils into spiral with hydrogen bonds. Branches allow more lytic enzymes to bind simultaneously and spiral decrease solubility
18 of 50
Describe the structure of Glycogen (animals)
Branched chain of α-glucose with 1-4 and 1-6 glycosidic bonds, doesn't coil as readily but has more branches so more compact and easier to remove monomer units
19 of 50
Describe the structure of Cellulose
Tough, insoluble and fibrous. Long chains of β-glucose, each inverted 180°, 1-4 glycosidic bonds, Hydrogen bonds within molecules prevets spirals, between molecules provides strength. Form micro and macro fibrils
20 of 50
In what ways is cellulose a good material for plant cell walls
Micro and macrofibrils have very high tensile strength due to strong glycosidic and hydrogen bonds. Microfibrils run in every direction, crossing for extra strength. Difficult to digest so less easy to break
21 of 50
What features help the plant cell wall to do its job?
Provide strength as plants dont have cytoskeleton. Space between microfibrils for water and ions to pass through, high tensile strength prevents bursting when turgid protecting delicate cell membrane
22 of 50
What are other structures formed by structural polysaccharides?
Bacterial Cell Walls are made out of Peptidoglycan. Exoskeletons in insects and crustaceans are made out of chitin
23 of 50
What are Lipids?
Group of molecules that are soluble in alcohol rather than water, include triglycerides, phospholipids, glycolipids and cholesterol. Examples of macromolecules.
24 of 50
What are triglycerides?
Made of glycerol and three fatty acids joined by a condensation reaction. Glycerol is a three -OH alcohol and fatty acids are long chain hydrocarbons with a carboxylic acid on the end
25 of 50
What is the effect of unsaturation in fatty acids?
Means fewer hydrogen atoms are avaliable for respiration, unsaturation produces kinks in the chain and the kinks pushes moleucles apart, making them more fluid and have a lower melting point
26 of 50
What is the function of Triglycerides?
Energy store: broken down in respiration to produce ATP, produces more ATP than sugar (more H). Energy Store: insoluble so don't affect ψ. Insulation for heat and nerves. Buoyancy as less dense than water. Protection, shock absorber for organs.
27 of 50
What is the structure of Phospholipids?
Same structure as a triglyceride but one fatty acid is replaced by a phosphate group. Phosphate group added by a condensation reaction between OH group of glycerol and phosphoric acid H3PO4
28 of 50
What is the behaviour of Phospholipids in water?
Fatty acids are non-polar and so are repelled by water. Phosphate group has negative charge so is polar. The 'head' is hydrophilic and the 'tail' is hydrophobic. In water they form micelles, tiny balls with tails tucked inside and heads pointing out
29 of 50
Describe the structure of the phospholipid bilayer
Membranes mostly consist of a bilayer where individual phospholipids are free to move but won't expose fatty acids to water giving membrane stability. Membrane is selectively permeable, only possible for small non-polar molecules to move through
30 of 50
What is Cholesterol?
A steroid alcohol that is hydrophobic so can sit in middle of bilayer. It regulates fluidity of the membrane, preventing it from getting too fluid or too stiff
31 of 50
What are the functions of Proteins?
They form structural component of animals (e.g. muscle). Tendency to adopt specific shapes so important as enzymes, antibodies and hormones. Act as carriers and pores for active transport or diffusion across the membrane.
32 of 50
What is a peptide bond?
Covalent bonds between amino acids. Involves a condensation reaction and breaking the bond involves hydrolysis
33 of 50
What is the primary structure of a Protein?
The sequence of amino acids bonded by peptide bonds in the protein, Function of the protein determined by primary structure as it will affect secondary, tertiary and quaternary structure.
34 of 50
What is the secondary structure of a Protein?
When primary structure coil into α-helixes or β-pleated sheets. These are formed by hydrogen bonds between -NH group of one amino acid and the -CO group of another. Strong structures at optimal temperature and pH
35 of 50
What is the tertiary structure of a protein?
Very precise shape which is firmly held in place by ionic bonds and disulfide bridges. Tertiary structure decides whether protein is fibrous or globular
36 of 50
What is the quaternary structure of a protein?
When multiple polypeptide chains are arranged to make a complete protein molecule, may be held together by a variety of bonds.
37 of 50
Describe the effect of hydrophobic and hydrophilic interactions on proteins
Hydrophobic parts of the R groups tend to associate together in the centre of the polypeptide to avoid water. This causes twisting of the amino acid chain, affecting the shape of the protein
38 of 50
Describe the structure of a Fibrous protein
Have regular, repetitive sequences of amino acids and are usually insoluble in water, enable them to form fibres which tend to have a structural function.
39 of 50
Describe some functions of Fibrous proteins
Collagen: prevenst arteries bursting and form tendons. Keratin: forms strong body structures (finger nails, horns) which are waterproof and prevent pathogens entering. Elastin: Allows skin, Alveoli and blood vessels to stretch and recoil
40 of 50
Describe the structure of Globular Proteins
Hydrophobic R groups coil inside molecule, rolls up into nearly spherical shape. Hydrophilic groups on the outside means it is soluble in water. Often have very specific shapes making them takes roles like enzymes, hormones (insulin) and haemoglobin
41 of 50
Describe some structures/functions of Globular proteins
Haemoglobin: 4 polypeptides (2 α-globin and 2 β-globin), space on outside for prosthetic haem group. Carry molecules in blood. Insulin: 2 polypep increases rate of uptake/use of glucose. Pepsin: digests proteins in stomach, has very few basic R group
42 of 50
How would you test for Starch?
Add iodine solution to test a sample. If starch is present there will be a colour change of yellow-brown to blue-black.
43 of 50
What is a reducing sugar and how do you test for it?
Good reducing agents, all monosaccharides and some disaccharides. React with Benedict's solution and colour change is blue to green to yellow to orange-red. When benedicts in excess, intensity of red colour proportional to concentration
44 of 50
How do you test with non-reducing sugars (e.g. Sucrose)?
Test for reducing sugars to see if there are any, boil sample with HCL to hydrolyse sucrose to glucose. Cool and neutralise with sodium hydrogencarbonate. Test for reducing again, Positive result (green/yellow/orange/red) indicates sucrose
45 of 50
How would you test for Lipids?
Emulsion test. Sample mixed with ethanol and all lipids will dissolve in it. Filter and pour solution into water. White emulsion indicates presence of Lipids.
46 of 50
How would you test for proteins?
Use biuret test. If protein is preset the colour changes from light blue to lilac.
47 of 50
Describe a Quantitative test for reducing sugars?
If there are more sugars present, amount of precipitate will increase and copper ions will decrease. Use colorimetry. Calibrate with water in cuvette. As its red light, higher the conc of precpitate the higher the % tranmission as red light reflected
48 of 50
What is a Calibration Curve?
Graph of % transmission against Glucose concentration. Created by using known concentrations of glucose in colorimeter to draw curve. Used to predict concentration of unknown solution by its % transmission.
49 of 50
What is Chromatography?
Technique to separate biological molecules. Consists of stationary phase (TLC plate) and Mobile phase (water for polar molecules and ethanol for non polar). UV light, Idodine and Ninhydrin used to view dyes
50 of 50

Other cards in this set

Card 2

Front

What is a hydrolysis reaction?

Back

Reaction that occurs when a molecule is split into two smaller molecules with the addition of water

Card 3

Front

What are the elements, monomer and polymers of Carbohydrates

Back

Preview of the front of card 3

Card 4

Front

What are the elements, monomers and polymers of Proteins

Back

Preview of the front of card 4

Card 5

Front

What are the elements, monomers and polymers of Nucleic Acids

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biological molecules, organic chemistry and biochemistry resources »