Biological Molecules

Question 1

What bonds are formed in a condensation reaction

Answer 1

Glycosidic bond

Question 2

Sucrose

Answer 2

Glucose + fructose

Question 3

Lactose

Answer 3

Glucose + galactose

Question 4

Maltose

Answer 4

Glucose + glucose

Question 5

Test for non reducing sugars

Answer 5

Add dilute HCl and heat in water bath then neutralise with sodium hydrogen carbonate

Question 6

Reducing sugars test

Answer 6

Add Benedicts reagent to sample and heat in water bath

If positive coloured ppt forms

Question 7

What polysaccharides of alpha glucose make starch

Answer 7

Amylose and Amylopectin

Question 8

Amylose structure and benefit

Answer 8

Long unbranched chain of a-glucose
Angles if glycosidic bonds give coiled structures like cylinder making it compact making it good for storage as fit more in one space

Question 9

Amylopectin structure and benefit

Answer 9

Long branched chain of a-glucose
Side branches allow enzymes that break down molecule to reach glycosidic bonds easily meaning glucose can be released quickly

Question 10

Starch adaption to function

Answer 10

Insoluble in water and doesn’t affect water potentiometer so doesn’t cause water to enter cells by osmosis making it sweep
Good for storage

Question 11

Glycogen

Answer 11

Has more branches than amylopectin for faster release of glucose which important for animals and very compact for good storage

Question 12

Cellulose structure and benefit

Answer 12

Made of long unbranched chains of beta glucose, when beta glucose molecules bond they form straight cellulose chains
Cellulose chains linked by hydrogen bonds to form strong fibres called microfibrils. These provide structural support for cells

Question 13

Structure of triglyceride

Answer 13

One molecule of glycerol with 3 fatty acids attached to it

Type of lipid

Question 14

Fatty acid structure

Answer 14

Have long tails made of hydrocarbons
Tails aye hydrophobic making it insoluble in water
All fatty acids have same basic structure but hydrocarbon tail varies

Question 15

Phospholipid structure

Answer 15

One molecule of glycerol with 2 fatty acids and a phosphate group which is hydrophilic

Question 16

Triglyceride adaptation to function

Answer 16

Used as energy storage molecules, Long hydrocarbon tails of fatty acids contain chemical energy which is released when broken down, contain twice as much energy per gram as carbs
Insoluble so don’t affect water potential, insoluble droplets clump together facing inwards sheilding glycerol hews from water

Question 17

Phospholipid adaptation to function

Answer 17

Make up bilateral of cell membranes what comes in and out
Heads are hydrophilic and tails hydrophobic so form double layer with heads facing out towards water on either side
Centre of bilayer is hydrophobic so water soluble substances can’t pass through so acting as barrier to those substances

Question 18

Primary structure of proteins

Answer 18

Sequence of amino acids in the polypeptide chain

Amino acids joined by polymerisation

Question 19

Secondary structure

Answer 19

Doesn’t remain flat and straight
Hydrogen bonds form between amino acids in chain making it coil into alpha helix or fold into a beta pleated sheet
Twist into 3D structure

Question 20

Tertiary structure of proteins

Answer 20

More bonds form including hydrogen and ionic bonds.
Ionic bonds between anime group and carboxyl
Disulfide bridges form between two molecules of amino acid cysteine. Sulfur atoms bond together. Forms final 3D structure for proteins made from single polypeptide chain

Question 21

Quaternary structure of proteins

Answer 21

Way multiple chains assembled together.

For proteins made from more than one polypeptide chain it is the final 3D structure

Question 22

Carbohydrates

Answer 22

Made from monosaccharides and is polymers

Question 23

Polymers

Answer 23

Complex molecules composed of long chains of monomers joined together ( monomers are small basic molecular units)

Question 24

Iodine test

Answer 24

Add iodine dissolved in potassium iodide solution to test sample
If starch present go from browny orange to dark blue/black

Question 25

Emulsion test

Answer 25

Shake test substance with ethanol for a minute so it dissolves, then pour solution in water
Lipid will show up as milk emulsion

Question 26

Biuret Test

Answer 26

Add drops of sodium hydroxide solution to make solution alkaline then add copper (11) sulfate solution
Turns purple then present if not remain blue

Question 27

Triglyceride

Answer 27

Release energy when broken down
Insoluble non polar
Clump together to protect hydrophobic tail

Question 28

Bonds between amino acids

Answer 28

Peptide

Question 29

Induced fit theory

Answer 29

Active site changes so as substrate binds resulting in tight fit where active site is complementary
Puts strain on substrate bonds lowering activation energy