Biological molecules

Question 1

What are monomers?

Answer 1

Monomers are the smaller units from which larger molecules are made

Question 2

what are polymers?

Answer 2

Polymers are multiple repeating units of monomers

Question 3

what is a condensation reaction?

Answer 3

the joining of two monomers with the formation of a covelant bond involving the elimination of a molecule of water

Question 4

what is a hydrolysis reaction?

Answer 4

the breaking of a covenant bond between two monomers using a molecule water

Question 5

what are disaccharides and how are they formed?

Answer 5

Two monosaccharides joined together with a glycosidic bond, formed by a condensation reaction therefore releasing a molecule of water

Question 6

What is the special bond that is formed during the condensation reaction between two monosaccharides?

Answer 6

A glycosidic bond

Question 7

what are monosaccharides and give 3 examples?

Answer 7

monomers form which larger molecules form carbohydrates: glucose, galactose and fructose

Question 8

what are disaccharides and how are they formed?

Answer 8

two monosaccharides joined together with a glycosidic bond, formed by a condensation reaction, therefore releasing a molecule of water

Question 9

list 3 disaccharides and the monomers from which they are formed

Answer 9

Maltose = glucose ×2
Lactose = glucose + galactose
Sucrose = glucose + fructose

Question 10

What are polysaccharides and how are they formed

Answer 10

Many monosaccharides joined together with glycosidic bonds formed by a condensation reaction

Question 11

describe the structure of starch

Answer 11

-Made of alpha glucose
Amylose= is lo g and unbranded and forms a coiled shape
Amylopectin= is long and branched due to the 1-6 glycosidic bonds

Question 12

what is the properties of starch?

Answer 12

Amylose- the coiling makes it compact and acts as storage in smaller places
Amylopectin- branches increase the surface are for enzymes to hydrolyse glycosidic bonds allowing glucose to be releases quickly

Question 13

what are the uses for starch?

Answer 13

.plants use starch to store excess glucose as it is too large to leave cells and it is insoluble
.starch can be hydrolysed to release glucose for respiration

Question 14

describe the structure to glycogen

Answer 14

Made of alpha glucose
-is long and branched with side branches with 1-6 glycosidic bonds

Question 15

what are the properties of glycogen?

Answer 15

losts of branches increase the surface area for enzymes to hydrolyse glycosidic bonds allowing a faster release of glucose. It also is a compact molecule and so allows for storage

Question 16

what is the use for glycogen?

Answer 16

Animals store excess glucose as glycogen in muscles and in the liver and is therefore an energy store as it can be hydrolysed to release glucose quickly when needed for respiration

Question 17

describe the structure of cellulose

Answer 17

Made from beta glucose
-long unbranded straight chains with 1-4 glycosidic bonds and the chains are linked together by hydrogen bonds between the glucose molecules which form microfibrills

Question 18

what are the properties of cellulose

Answer 18

the hydrogen bonds between the cellulose chains make the microfibrills strong and flexible allowing them to provide support

Question 19

what are the uses of cellulose?

Answer 19

provides structural support in the cell walls of plants allowing them to become turgid

Question 20

what can polysaccharides be formed from?

Answer 20

glucose monomers that ate joined by 1-4 or 1-6 glycosidic bonds

Question 21

describe the test for reducing sugars

Answer 21

reducing sugars= monosaccharides, maltose and Lactose

1, add benedicts solution to sample
2, heat in a water bath
3, positive result = green, yellow, orange, red precipitate

Question 22

describe the test for non reducing sugars

Answer 22

non reducing sugars = sucrose

1, do benedicts test an stays blue
2, heat in water bath with acid
3, neutralise with an alkaline
4, heat in water bath with benedicts solution
5, positive= green, yellow, orange, red precipitate

Question 23

suggest the method to measure the quantity of sugar in a solution

Answer 23

carry out the benedicts test then filter and dry the precipitate then find the mass

Question 24

What is the structure of both α-glucose and β glucose?

Answer 24

They both have 6 carbon atoms, α-glucose has its OH group attached at the bottom right and β glucose has its OH group attached at the top right.

Question 25

What is the test for reducing sugars?

Answer 25

• Add test sample to Benedict’s Reagent.
• Heat it gently
• If solution turns brick red, then a reducing sugar is present.
• If the solution stays blue, then no reducing sugar is present.

Question 26

What is the test for non-reducing sugars?

Answer 26

After the test for reducing sugars, you should:

• Add dilute hydrochloric acid to the test sample (hydrolyse the polysaccharides/disaccharides into its constituent monosaccharides)
• Then add sodium hydrogencarbonate to neutralise the acid. (Benedict’s reagent does not work in acidic conditions)
• Add the sample to Benedict’s reagent and then heat the sample.
  -If the solution turns brick red then a non-reducing sure is present. If the solution stays blue then there isn’t a non-reducing or reducing sugar present.

Question 27

describe the structure of a fatty acid (RCOOH)

Answer 27

variable R group- hydrocarbon chain (saturated or unsaturated)
COOH- carboxyll group

Question 28

describe how a triglyceride is formed

Answer 28

a condensation reaction between 1 glycerol molecule and 3 fatty acids which removes 3 molecules of water forming 3 ester bonds

Question 29

explain of the properties of triglycerides link to their function

Answer 29

-high ratio of C-H bonds to carbon atoms in hydrocarbon chain so they are used in respirationas they release more energy
-hydrophobic / non-polar fatty acids so they are insoluble in water so they have no effect on water potential of cell or can be used as waterproofing

Question 30

describe the formation of a phospholipid

Answer 30

A condensation reaction reaction between a glycerol molecule, a phosphate group and 2 fatty acids forming an ester bond between the glycerol molecule and 2 fatty acid chains

Question 31

describe how the properties of phospholipids relate to their function

Answer 31

they form a bilayer in the cell membrane allowing for diffusion of lipid soluble or very small substances and restrict the movement of larger molecules and water soluble substances

-phosphate heads are hydrophilic and so attract water
-fatty acid tails are hydrophobic so repell the water

Question 32

describe the test for lipids

Answer 32

1, add ethanol, shake then add water
2, positive test is a milky emulsion

Question 33

What is a saturated fatty acid?

Answer 33

They dont contain any double bonds between their carbon atoms

Question 34

What are lipids?

Answer 34

they are not polymers, they contain hydrogen and carbon atoms. Lipids are a source of energy that help to insulate organisms and act as waterproofing

Question 35

What is an unsaturated fatty acid?

Answer 35

THey contaain a carbon-carbon double bond, meaning they contain fewer hydrogen atoms

Question 36

What bond is formed in triglycerides?

Answer 36

ester bond formed between each of the three OH groupson the glycerol and OH group on each fatty acid chain

Question 37

what bond is formed in phospholipids?

Answer 37

ester bond between two OH groups n the glycerol and OH group of each fatty acid chain.

Question 38

Describe the role of micelles in the absorption of fats into the cells lining the ileum.

Answer 38

Micelles include bile salts and fatty acids which make the fatty acids soluble in water
For lipids to carry fatty acids to the lining of the ileum, maintaining a higher concentration of fatty acids to the lining of the ileum for the fatty acids to be absorbed by diffusion

Question 39

Expalin the arrangement of phospholipids in a cell surface membrane.

Answer 39

It forms a bilayer, with hyrophillic phosphate heads that are attracted to water, hydrophobic tails that face way from the water