Biological Molecules

Question 1

What is a condensation rection?

Answer 1

A reaction that joins 2 molecules together and removes a molecule of water

Question 2

what specific type of bond gives water its unusual properties?

Answer 2

Hydrogen bonds

Question 3

Why is water being a liquid at RTP usefull to living things?

Answer 3

it is a liquid at RTP so provides an aquatic habitat as well as being able to make up a majority of living tissues

Question 4

What are the 7 key properties of water?

Answer 4

Liquid at RTP: major component in tissues and provides a habitat

Density: it gets less dense as it freezes

Solvent: good slovent for many solutes found in living things (NaCl or glucose)

Cohesion and Surface Tension: Caused by hydrogen bonding and allows water to move up Xylem

High Specific Heat Capacity: Requires alot of energy to heat or cool so is good at thermoregulation in organisms and provides stable habitat

High Latent Heat: requires large amount of energy to evapourate so allows mammals to sweat to cool down

Reactant: involved in reactions such as photosynthesis and hydrolysis (digestion of starch, lipids and protiens)

Question 5

What are the three functions of Carbohydrates?

Answer 5

Energy source (Glucose)

Energy Store (Starch and Glycogen)

Structural Units (Cellulose and Chitin)

Question 6

What are Monosaccharides?

Answer 6

The simplest types of sugars, they are small molecules that are soluble in polar solvents (water)

can exist as staight chains or in cyclic form

some monosaccharides like glucose are the monomers for more complex carbohydrates like disaccharides or polysaccharides.

Question 7

Are monosaccharides reducing or non reducing sugars?

Answer 7

All monosaccharides are reducing sugars

Question 8

What are Disaccharides?

Answer 8

Disaccharides are small polar molecules, that are soluble in polar solvents

Formed when 2 monosaccharides join together in a condensation rection.

examples include maltose, sucrose, and lactose

Question 9

What is the type of bond formed when a disccharide is made

Answer 9

Glycosidic bond

Question 10

Are dissacharide reducing or non reducing?

Answer 10

Depends, some disaccharides are reducing and some are non reducing.
e.g Maltose and Lactose are reducing but Sucrose is non reducing.

Question 11

What are polysaccharides

Answer 11

They are polymers of monosaccharides, made of thousands of repeating units

Question 12

why are polysaccharides good energy stores?

Answer 12

because they can be broken down into their monosaccharide monomers (like glucose) which are often used in respiration

Question 13

What are the 2 main examples of polysaccharides as energy stores

Answer 13

Starch and Glycogen

Question 14

what are the 4 Properties of starch and glycogen that makes them good energy stores

Answer 14

Compact so don’t take up much space and can be stored as large granules

They hold glucose in long chains so can be ‘snipped off’ when needed

Branched chains (glycogen and amylopectin) are more compact meaning more can be ‘snipped off’ when lots of energy is needed at once

Polysaccharides are less soluble in water, if they were soluble then it would reduce water potential and disrupt the normal cell workings

Question 15

Name 1 example of a structural polysaccharide

Answer 15

cellulose

Question 16

Which monomer makes up Cellulose

Answer 16

Beta glucose

Question 17

Which type of reaction forms cellulose

Answer 17

Condensation

Question 18

Why don’t Beta glucose chains spiral

Answer 18

Because each monomer rotates 180 degrees so the bonds are on opposite sides forming a straight chain

Question 19

Why is cellulose so strong

Answer 19

Forms 1-4 glyosidic bonds that are very strong

Hydrogen bonds form between chains adding strength

The chains lie parallel like bricks forming microfibrils. which then further bundle to make macrofibrils.

Macrofibrils run in all directions and criss-cross.

Question 20

Where is cellulose most commonly found?

Answer 20

plant cell walls

Bacteria cell walls

Exoskeletons in insects

Question 21

Why is cellulose useful in plant cell walls

Answer 21

Plants don’t have a skeleton so each cell must be strong in order to provide structure

There are gaps between the macrofibrils so water and mineral ions are able to pass through making the cell wall fully permeable.

Question 22

What are the 3 main properties of lipids

Answer 22

Insoluble in water (non polar)

soluble in alcohol

NOT polymers, however do consist of components bound together so are called macromolecules.

Question 23

what are the 3 main types of lipids in living things

Answer 23

Triglycerides

phospholipids

steroids

Question 24

What is the structure of a Triglyceride?

Answer 24

Made up of glycerol and fatty acids

3 fatty acids

glycerol is an alcohol with 3 free -OH groups

fatty acids have a carboxyl group (-COOH) which can dissociate its hydrogen to form H+ and COO-

Question 25

How does and unsaturated fat differ from a saturated fat

Answer 25

Unsaturated fats have 1 or more C=C where as saturated fats have all single bonds.

A C=C causes a kink in the chain which prevent the molecules packing as close together. this is why all plant oils are liquid and animal fats are solid at RTP.

Question 26

What are the 5 main functions of triglycerides

Answer 26

Energy Source: Can be broken down in respiration, provide much more energy when broken down than a sugar does

Energy Store: Insoluble in water so dont affect the water potential of the cell

Insulation: good thermal insulator, Blubber in whales and penguins

Buoyancy: Fat is less dense than water so keeps aquatic animals afloat

Protection: Fat deposits round vital organs to absorb impacts and prevent damage

Question 27

Describe the structure of a phospholipid

Answer 27

Same as a triglyceride but