2.2 Biological Molecules

Question 1

What type of molecule is water?

Answer 1

A polar molecule
It has a partially negative O atom and two partially positive H atoms

Question 2

What is meant by Universal solvent?

Answer 2

Polar and charged molecules can dissolve in water meaning water can be used as a transport medium

Question 3

What is meant by Cohesion?

Answer 3

The cohesive hydrogen bonds between molecules

Question 4

What is meant by Adhesion?

Answer 4

The ability of dissimilar molecules to stick together

Question 5

Why are cohesive forces important?

Answer 5

Surface tension between molecules allows small organisms to move along the surface
Allows columns of water to move through xylem vessels of plants and blood vessels of animals

Question 6

Why is adhesion important?

Answer 6

Allows Capillary action: Hydrogen bonds with cellulose allows water to be transported up plant stems via a transpiration stream

Question 7

What are proteins made of?

Answer 7

Amino acids

Question 8

What are amino acids?

Answer 8

Monomer units

Question 9

What is a condensation reaction?

Answer 9

When water is removed when two molecules/monomers join together

Question 10

What is a hydrolysis reaction?

Answer 10

Water is added to split molecules apart

Question 11

How is a dipeptide formed?

Answer 11

A peptide bond is formed between 2 amino acids, water is released (Condensation reaction)

Question 12

Where is a peptide bond located?

Answer 12

Between two amino acids -
the C of the first amino acid and N of the second amino acid

Question 13

What are the levels to protein structure?

Answer 13

1. Primary structure: Amino Acid sequence
2. Secondary structure: Polypeptide chain twists or folds
3. Tertiary structure: More folding to form a complex shape
4. Quaternary structure: More than one polypeptide chain joins together

Question 14

Describe the secondary structure of a protein:

Answer 14

1. Alpha Helix
2. Beta Pleated sheet
   –> weak Hydrogen bonds maintains the structure

Question 15

Describe the tertiary structure of a protein

Answer 15

Bonds between R-groups maintain structure
–> e.g. Ionic, Hydrogen, disulphide bridges

Question 16

What is the structure and function of globular proteins?

Answer 16

Compact and soluble in water

Question 17

What is the structure and function of fibrous proteins?

Answer 17

Long strands of polypeptide chains that have cross-linkages due to hydrogen bonds
These proteins have little or no tertiary structure
Insoluble
e.g. Keratin, Elastin, Collagen

Question 17

What are conjugated proteins?

Answer 17

Proteins which contain an additional prosthetic group. Prosthetic groups assist proteins, for example in their structure or bonding.
e.g. Haemoglobin

Question 18

What are the 3 types of lipids?

Answer 18

Triglycerides
Phospholipids
Steroids

Question 19

Which elements make up lipids?

Answer 19

C,H,O

Question 20

Are lipids soluble?

Answer 20

They are non-polar molecules so insoluble in water

Question 21

What is the structure of a triglyceride?

Answer 21

1 molecule of glycerol
3 fatty acid chains

Question 22

What bonds are found in a triglyceride?

Answer 22

Ester bonds

Question 23

What is the difference between saturated and unsaturated fatty acids?

Answer 23

Saturated fatty acids have single bonds between C atoms

Unsaturated fatty acids may have one or more sets of double bonds between carbon atoms

Question 24

What are the functions of triglycerides?

Answer 24

Energy source - stores more energy per gram than carbs or proteins Insulation - blubber Buoyancy Protection

Question 25

What is the structure of a phospholipid?

Answer 25

Hydrophilic phosphate head Diglyceride: Hydrophobic fatty acid tails

Question 26

What is the structure/functions of steroid alcohols?

Answer 26

4 carbon ring structure Cholesterol

Question 27

What is the function of cholesterol?

Answer 27

Binds to hydrophobic tails of phospholipids, causing them to pack more closely together Restricts the movement of phospholipids so makes the membrane less fluid - increases structure Prevents solidification at low temps and melting at high temps

Question 28

What are the 3 types of carbohydrate?

Answer 28

Monosaccharides Disaccharides Polysaccharides

Question 29

What is the general formula for monosaccharides?

Answer 29

Cx H2x Ox

Question 30

What are the features of glucose?

Answer 30

Polar and soluble in water Energy source

Question 31

What is the difference between alpha and beta glucose?

Answer 31

Alpha: C1 has the H on the top and OH on the bottom Beta: C1 has OH on the top and H on the bottom

Question 32

What bond is formed between glucose molecules?

Answer 32

1,4-glycosidic bonds

Question 33

Which monomers make up maltose?

Answer 33

Glucose + Glucose

Question 34

Which monomers make up sucrose?

Answer 34

Glucose + Fructose

Question 35

Which monomers make up lactose?

Answer 35

Glucose + Galactose

Question 36

What is starch made from?

Answer 36

Amylose and amylopectin

Question 37

What are key features of starch?

Answer 37

1,4 and 1,6 glycosidic bonds Highly branched Insoluble so doesnt affect water potential Storage molecule in plants

Question 38

What is the structure of amylose?

Answer 38

Long straight chain molecules 1,4-glycosidic bonds between alpha glucose molecules

Question 39

What is the structure of amylopectin?

Answer 39

Branched 1,4 and 1,6 glycosidic bonds

Question 40

What is the structure of cellulose?

Answer 40

Made of beta glucose every other glucose molecule is flipped 180 to allow OH on C1 and C4 to be next to each other No branching Parallel strands form hydrogen bonds Used in plants to form the cell wall

Question 41

What is the structure of Glycogen?

Answer 41

Alpha glucose Branched chain storage in animals More dense than starch Insoluble Lots of 1,4 and 1,6 glycosidic bonds

Question 42

What is the test for starch?

Answer 42

Addition of iodine. Iodine turns blue-black when in contact with starch

Question 43

What is the test for proteins?

Answer 43

Biurets test

Question 44

What is the test for lipids?

Answer 44

Emulsion test

Question 45

What is the test for reducing sugars / non-reducing sugars?

Answer 45

Benedict's solution Blue copper 2+ ions are reduced to red copper 1+ ions in the presence of a reducing sugar e.g. glucose Copper 1+ ions are insoluble and form a red precipitate

Question 46

What is the difference between hexose and pentose sugars and give examples of each

Answer 46

Hexose: Glucose - 6 C Pentose: Ribose - 5 C

Question 47

What is the charge on a calcium ion and where is it used?

Answer 47

Cu2+ Transmission of impulses Stimulation of muscle contraction Regulates protein channels

Question 48

What is the charge on an iron ion and where is it used?

Answer 48

Fe2+ or Fe3+ Binds to oxygen in haemoglobin Transfers electrons during photosynthesis/respiration

Question 49

What is the charge on a sodium ion and where is it used?

Answer 49

Na2+ Transport of glucose and amino acids Transmission of nerve impulses

Question 50

What is the charge on a potassium ion and where is it used?

Answer 50

K+ Nerve transmission

Question 51

What is the charge on an ammonium ion and where is it used?

Answer 51

NH4 + The intermediate ion that forms during the deamination of proteins in the liver and kidneys

Question 52

What is the charge on a nitrate ion and where is it used?

Answer 52

NO3 - Provides an essential source of nitrogen for protein synthesis

Question 53

What is the charge on a hydrogencarbonate ion and where is it used?

Answer 53

HCO3 - Transport of carbon dioxide in the blood

Question 54

What is the charge on a chloride ion and where is it used?

Answer 54

Cl- Chloride-shift, maintaining the charge and pH balance in the blood

Question 55

What is the charge on a phosphate ion and where is it used?

Answer 55

PO4 3- Stores energy in ATP

Question 56

What is the charge on a hydroxide ion and where is it used?

Answer 56

OH- Bonding between molecules