Biologcal Molecules - Carbohydrates

Question 1

Carbohydrates are made up of what three elements?

Answer 1

Carbon
Hydrogen
Oxygen

Question 2

What is carbohydrate structure based on?

Answer 2

Units, monomers, which can join together to form diners & polymers

Question 3

What is the monomer (single unit) of carbohydrates?

Answer 3

The monosaccharide

Question 4

Monomer =
Dimer =
Polysaccharide =

Answer 4

Monosaccharide
Disaccharide
Polymer

Question 5

Explain sugars within carbohydrates

Answer 5

They are monosaccharides and disaccharides
Their characteristics is tasting sweet and being soluble in water

Question 6

What are complex carbohydrates within carbohydrates?

Answer 6

Polysaccharides
Their characteristics are being not sweet tasting and being insoluble in water

Question 7

Give examples of monosaccharides

Answer 7

A glucose, B glucose, fructose, Ribose & deoxyribose

(Only need to fully know about A glucose and Ribose)

Question 8

Why is glucose the most important carbohydrate in our bodies?

Answer 8

Because it is used by the cells as a respiratory substrate.
This means it is gradually broken down, inside cells, to release energy

Question 9

Why is glucose an example of a hexose sugar?

Answer 9

Because it has 6 carbon atoms

Question 10

What are the two isomers of glucose?

Answer 10

Alpha glucose and Beta glucose
(Fructose is also an isomer of glucose)

Question 11

What’s an isomer?

Answer 11

Two molecules with the same molecular formula but differ structurally

Question 12

what are the structural rules to remember or monosaccharides?

Answer 12

• 6 carbon atoms
• at carbon atom 1, hydrogen is Above for Alpha (whereas Beta hydrogen is Below)
• Fructose is still a hexose even though it is not a “hexagon” based shape because it has 6 carbon atoms

Question 13

Why are glucose molecules polar & soluble in water ?

Answer 13

Due to the hydrogen bonds that form between the hydroxyl groups and water molecules.

The solubility in water is important because it means glucose is dissolved in the cytosol of the cell

Question 14

What are Penrose sugars & give examples

Answer 14

Sugars with 5 carbons

Very important ones are ribose and deoxyribose

Question 15

Go draw the Alpha glucose structure

Answer 15

(Answer in biology book online)

Question 16

Go draw the structure of ribose

Answer 16

(Answer in the biology book)

Question 17

where is ribose found?

Answer 17

In the RNA (ribonucleic acid)

Question 18

What are the differences between ribose and deoxyribose?

Answer 18

• when compared with deoxyribose it can be seen that there is a difference at carbon 2
• deoxyribose has a hydrogen atom instead of a hydroxyl group at C2 - it has one less oxygen atom
• compared to ribose it it deoxygenated - hence the term deoxyribose
• deoxyribose is the sugar found in DNA : (deoxyribonucleic acid)

Question 19

Give examples of hexose and the amount of carbon atoms

Answer 19

6 CARBON ATOMS

Alpha glucose
Beta glucose
Fructose
Galactose

Question 20

Give examples of pentose + amount of carbon atoms

Answer 20

• ribose
• deoxyribose

Question 21

Give examples of triode and the amount of carbon atoms

Answer 21

• triose phosphate
• glycerine 3 phosphate

Question 22

Why is glucose a monosaccharide?

Answer 22

As it cannot be broken down further by hydrolysis

Question 23

Monomers and monosaccharides can be joined to form what?

Answer 23

Diners & Disaccharides

Question 24

Explain a condensation reaction?

Answer 24

• in order for the two monosaccharides to join together this way, a bond has to form
• this bond is achieved when the hydroxyl group at carbon 1 of one monosaccharide and the hydroxyl group of carbon atom 4 of the other monosaccharide react together
• between them, the two hydroxyl groups donate to hydrogen atoms, and one oxygen atom, the atoms combine together to make H2O water

Question 25

What does the 1-4 glycosidic bond mean?

Answer 25

It refers to the number of the carbon atom within the molecules between which the bond is formed So carbon one of one glucose is joined to carbon four of the other glucose

Question 26

What happens in a condensation reaction?

Answer 26

Glycosidic (covalent) bond is formed Water is eliminated (released)

Question 27

What happens in the hydrolysis reaction?

Answer 27

- glycosidic (covalent) bond broken - water used up

Question 28

What are the disaccharides made of?

Answer 28

MALTOSE : a glucose + a glucose SUCROSE : a glucose + fructose LACTOSE : a glucose + galactose

Question 29

What’s sucrose?

Answer 29

A disaccharide which is made from monosaccharides which are different to one another is sucrose

Question 30

What are polysaccharides?

Answer 30

We have already seen that monosaccharides can undergo condensation reactions to become disaccharides Further condensation reactions with more monosaccharides will build up a carbohydrate, polymer or polysaccharide Important polysaccharides are : starch, glycogen, and cellulose 

Question 31

What is starch and what are the two types?

Answer 31

Starch is a polymer of glucose molecule made by plants The two types of glucose polymers within starch are amylose and amylopectin Many alpha glucose molecules can be joined by Glycosidic bonds to form two slightly different polysaccharides known collectively as starch .

Question 32

What are the features of amylose?

Answer 32

- linear chains - coil up into a helix - helix maintained by hydrogen bonds - joined by 1-4 glycosidic bonds (no branches)

Question 33

What are the features of amylopectin?

Answer 33

Joined together by 1-4 glycosidic bonds with some branching achieved by 1-6 glycosidic bonds

Question 34

What is glycogen?

Answer 34

Is a polymer of glucose molecules made by animals It was joined by a 1-4 glycosidic bonds with frequent branching achieved by a 1-6 glycosidic bonds It is very similar to amylopectin in structure

Question 35

Glycogen is stored in liver / muscle cells Why do we store it as glycogen instead of glucose?

Answer 35

- it is insoluble, so it does not affect water potential of cells (doesn’t affect osmosis) - It is compact, so a lot of glucose can be stored in a small place - It is a branched molecule, so there’s a lot of “ends” where glucose can be quickly released when needed

Question 36

What is needed to convert glucose to glycogen and vice versa?

Answer 36

GLUCOSE TO GLYCOGEN: Insulin is needed GLYCOGEN TO GLUCOSE: Glucagon is needed Glucose is a soluble monosaccharide found in the blood Glycogen is insoluble and found in the liver & muscle cells

Question 37

What is glucose? And how do the levels in the blood work?

Answer 37

- glucose is used as a respiratory substrate it is broken down during respiration to release energy - our diet supplies the respiratory substrate we require to stay alive. During digestion, the carbohydrate components of a diet, a broken down into simple sugars, including glucose. - Some of those glucose will be used up immediately within respiring cells. There must always be enough glucose in the blood sustain the respiring cells. (Particularly brain cells.) - However, too much glucose in blood is harmful to brain cells, the retinas, and the glomerulus (filtering unit within the kidney) so it is important to keep the levels of glucose in the blood within a range of narrow parameters - When blood glucose levels are high, for example, after carbohydrate rich meal, glucose is taken it out of the blood and converted into glycogen When blood glucose levels are low, for example, after a timer fasting like sleep or after a long period of exercise, glycogen is broken down into glucose, which is then released into the bloodstream

Question 38

What is cellulose?

Answer 38

Selling those is made up of beta glucose molecules. This has implications on the orientation of the glucose molecules within the polysaccharide chain.

Question 39

Explain the structure of beta glucose on the polysaccharide chain

Answer 39

When beta glucose molecules which are orientated in the same way, I’m not place together. It is not possible to make a Glycosidic bond. This is because the two hydroxyl groups are not increase proximity with one another. But when alternate beta glucose molecules are flipped over by 180°, then the two hydroxyl groups are brought together. Every other one is flipped over. This allows condensation reactions to occur from Glycosidic bonds. These are 1-4 glycosidic bonds

Question 40

Explain how fibrils are made

Answer 40

Cellulose molecules do not coil. They live straight because the glucose monomers contains so many hydroxyl groups lots of hydrogen bonds form between neighbouring cellulose molecules. This produces bundles of 60 to 70 cellulose molecules, laying side-by-side all held together by thousands of hydrogen bonds These bundles are called fibrils (Hydrogen bonds form in cross bridges between cellulose molecules)

Question 41

How are fibres made?

Answer 41

The cellulose molecules bundle together to make fibrils, these are maintained by hydrogen bonds The fibrils bundle together to make fibres more hydrogen bonding maintains these. You can see the fibres in micrographs of cellulose cell walls.

Question 42

Why are cellulose fibres so strong?

Answer 42

They are very strong because of all the hydrogen bonds The cellulose fibres are embedded in pectins to form the cell wall (Proteins that act as a glue) I live in criss-crossing, layers for extra strength from busting on water moves into it by osmosis - it has to be able to stand turgor pressure

Question 43

How are the cellulose fibres fully permeable?

Answer 43

There are gaps between the cellulose fibres, which account for it being fully permeable

Question 44

Why is cellulose difficult to digest?

Answer 44

Cellulose is difficult to digest because mamusia do not make the enzyme cellulase- this is the enzyme which is required to break beta 1-4 glycosidic bonds because 1-4 glycosidic bonds don’t fit through the amylase enzyme

Question 45

FOR AMYLOSE GIVE: The monosaccharide from which it is formed Types of glycosidic bonds Overall shape Solubility Function Hydrogen bonding within or between molecules

Answer 45

Alpha glucose A 1-4 Helix Insoluble Energy store in plants Hydrogen bonds between sugar units in the chain

Question 46

FOR CELLULOSE GIVE: The monosaccharide from which it is formed Types of glycosidic bonds Overall shape Solubility Function Hydrogen bonding within or between molecules

Answer 46

- Beta glucose - B 1-4 - straight chain - insoluble - forms cell walls - hydrogen bonds between sugar units in different chains

Question 47

FOR GLYCOGEN GIVE: The monosaccharide from which it is formed Types of glycosidic bonds Overall shape Solubility Function Hydrogen bonding within or between molecules

Answer 47

- a glucose - a 1-4 with a 1-6 at branches - branched and slightly coiled - insoluble - an energy store in animal cells - some hydrogen bonds between sugar units in the chain