C1 Biological Molecules

Question 1

Condensation reaction

Answer 1

A reaction in which water molecules are formed when monomers are joined together

Question 2

Hydrolysis

Answer 2

(Inverse of condensation reaction) - Adding water to a polymer to split it

Question 3

Polymer

Answer 3

Large molecules made by bonding single repeating units

Question 4

Monomer

Answer 4

Repeating unit that joins to form polymers

Question 5

Disacchardies

Answer 5

Formed when monosaccharides join via a condensation reaction with glycosidic bonds in between

Question 6

Glycosidic Bonds

Answer 6

Bonds between monosaccharides in a di/polysaccharide

Question 7

Types of Monosaccharides

Answer 7

Fructose, Galactose, Glucose

Question 8

Types of Disaccharides

Answer 8

Sucrose, Lactose, Maltose

Question 9

Glucose + Fructose

Answer 9

Sucrose

Question 10

Galactose + Glucose

Answer 10

Lactose

Question 11

Glucose + Glucose

Answer 11

Maltose

Question 12

Reducing sugar

Answer 12

Sugars that acts as a reducing agent in chemical reactions (donate electrons to other molecules)

Question 13

Non - reducing sugar

Answer 13

Does not donate electrons

Question 14

Test for REDUCING sugar

Answer 14

Benedict’s;
1. Benedict’s solution in a tube with water
2. Grind the solution with mortar and pestle and distilled water
3. Put the sample in a test tube
4. Heat with a water bath
5. If positive, the solution with turn BRICK RED (from blue)

Question 15

Test for NON-REDUCING sugars

Answer 15

If negative for reducing sugars:
1. Add dilute HCl
2. Add sodium carbonate to neutralise
3. Add Benedict’s solution & gently heat

Question 16

Polysaccharides

Answer 16

A molecule made up of more than 2 monosaccharides

Question 17

Types of Polysaccharides

Answer 17

Starch, Glycogen, Cellulose

Question 18

Properties of Starch

Answer 18

1. Insoluble; doesn’t affect water potential (water isn’t drawn into the cell via osmosis
2. Large; doesn’t diffuse out of cells
3. Compact; can fit large amounts into small spaces
4. Breaks down into alpha glucose when hydrolysed; stored in small spaces & transported to be ready for use in respiration
5. Branched form (many ends); each can have an enzyme attached to the end to be acted on rapidly to release glucose - (1,4) & (1,6) bonds; more branches

Question 19

Properties of Glycogen

Answer 19

• Insoluble; doesn’t affect water potential (water isn’t drawn into the cell via osmosis
• Large; doesn’t diffuse out of cells
• Compact; can fit large amounts into small spaces
• MORE branched than starch; more enzymes > more rapid release of glucose for respiration (animals have higher metabolic rates than plants (starch))
• (1,4) & (1,6) bonds; more branches

Question 20

Properties of Cellulose

Answer 20

• made of BETA glucose; forms long straight unbranched chains
• chain run parallel + CROSSLINK via H BONDS; making the structure stronger
• molecules are grouped to form MICROFIBRES which then group to form FIBRES; which adds to the strength of the polymer

Question 21

Triglyceride

Answer 21

3 fatty acids with ester bonds between glycerol (hence glyceride)

Question 22

Saturated

Answer 22

Fatty acid with no carbon-carbon double bond; bonded to max number of hydrogen atoms (monounsaturated if 1 double bond)

Question 23

Unsaturated

Answer 23

Fatty acid with carbon-carbon double bond; bonded to max number of hydrogen atoms (polyunsaturated if multiple double bond)

Question 24

Phospholipid

Answer 24

Similar to triglyceride
- 2 fatty acids instead of 3; one replaced by a phosphate molecule

Question 25

Phospholipid structure

Answer 25

-Have 2 parts: -Hydrophilic 'head' > attracted to water -Hydrophobic tail > orients away from water -2 ends are POLAR (behave differently) -when placed in water, they orient themselves so that the hydrophilic head is closer to the water

Question 26

Roles of lipids

Answer 26

1. Cell membrane - flexibility of membrane 2. Source of Energy - releases more than 2x the energy the same mass of carbohydrates do when oxidised 3. Waterproofing - insoluble in water = waterproofing eg: plants w/ waxy cuticles, mammals w/ oily secretion from sebaceous glands in the skin 4. Insulation - slow conductors of heat; help retain heat when stored beneath body surface 5. Protection - fat is stored around the delicate organs

Question 27

Polypeptide

Answer 27

molecule made up of MORE THAN 2 amino acids

Question 28

Peptide bond

Answer 28

Bond betweeen the 2 amino acids

Question 29

Primary Structure

Answer 29

Peptide bonds between amino acids

Question 30

Secondary Structure

Answer 30

- Alpha = helix - Beta = pleated sheet; with H bonds between amino group H+ and Carboxyl group H

Question 31

Tertiary Structure

Answer 31

-H bonds -Disulfide bridges, and ionic bonds between R groups(makes it into a globular protein)

Question 32

Quaternary Structure

Answer 32

Consists of many different polypeptides

Question 33

Activation energy

Answer 33

The minimum amount of energy required for a reaction to take place

Question 34

Active site

Answer 34

The area of the enzyme where the reaction with the substrate takes place

Question 35

Substrate

Answer 35

The chemical reactant that enzymes bind to

Question 36

Induced Fit Model

Answer 36

The idea that the active site of the enzyme changes shape slightly due to bonds distorting as the substrate binds to it to better fit the shape of the active site

Question 37

Competitive Inhibitors

Answer 37

Compete with the substrate for the active site > binds to the active site to prevent the substrate

Question 38

Non-competitive Inhibitors

Answer 38

Binds to a different site on the enzyme, changing the shape of the enzyme preventing the enzyme from binding to the substrate effectively

Question 39

Factors affecting enzyme activity

Answer 39

-Temperature; when the temp gets too high, H bonds & others begin to break in the enzyme, therefore enzyme (and its active site with it) changes shape (DENATURATION) -pH; changes the charge on the amino acid that makes up the active site, causes the bonds maintaining the tertiary structure to break, changing the shape of the active site -Enzyme concentration

Question 40

LOW enzyme concentration

Answer 40

Too few enzymes to allow substrates to be broken down

Question 41

What will the rate of reaction be like with an INTERMEDIATE enzyme concentration?

Answer 41

DOUBLES as there are enough enzymes for the substrates

Question 42

Inorganic ions

Answer 42

Sodium, Phosphate, Hydrogen, Iron

Question 43

Sodium ions

Answer 43

Involved in nerve impulse transmission, the control of cell osmotic pressure and the absorption of molecules such as glucose into the cell. Actively transported outside of a cell across the plasma membrane using ATP. As it is now at a higher concentration gradient outside of the cell, it diffuses back in via a channel protein, along with a glucose molecule against the concentration gradient. Ensures that all available glucose produced during digestion is utilised.

Question 44

Phosphate Ions

Answer 44

Phosphorus is chemically bonded to other atoms, in this case, 3 oxygen atoms. Forms the phosphodiester backbone of DNA and RNA. In ATP 3 phosphate ions are linked to ribose and Adenine. These bonds are unstable and, therefore only require a small amount of activation energy which releases a lot of energy.

Question 45

Hydrogen ions

Answer 45

Responsible for the pH of a cell. This is a critical role as a significant change would result in the denaturation of enzymes in the cytoplasm. In reality, the pH fluctuations are only slight, which would more likely affect the activity of the enzyme. Hydrogen results in a buffering effect of haemoglobin. During the transport of carbon dioxide, it forms hydrogen carbonate in the blood.

Question 46

Iron ions

Answer 46

Involved in the transport of oxygen. They form the prosthetic group, haem. There are 4 haem groups per haemoglobin molecule which can reversibly bind molecules of oxygen each.