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A Level Biology: 2.1.2 Biological Molecules > 2.1.2c Carbohydrates > Flashcards

2.1.2c Carbohydrates Flashcards

1
Q

Element composition of Carbohydrates

A

Carbon, Hydrogen, Oxygen

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2
Q

Element composition of Lipids

A

Carbon, Hydrogen, Oxygen

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3
Q

Element composition of Proteins

A

Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur

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4
Q

Element composition of Nucleic acids (DNA & RNA)

A

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus

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5
Q

What are monomers

A

Small units which are the components of larger molecules.

Eg. Monosaccharides sa glucose, amino acids & nucleotides

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6
Q

What are polymers

A

Molecules made from many monomers joined together

Eg. starch, cellulose

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7
Q

Process of monomers into polymers

A

Polymerization

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8
Q

What is a condensation reaction

A

A reaction in which 2 molecules join together by a chemical bond with the release of a water molecule.

Eg. when 2 glucose molecules bond tg

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9
Q

What is a hydrolysis reaction

A

Hydrolysis is the opposite of a condensation reaction & is when water is added to break a chemical bond between 2 molecules

Eg. Carbohydrates can be broken down into their constituent monosaccharides by hydrolysis

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10
Q

See showbie slide 5 to see diagrams of condensation & hydrolysis reactions

A
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11
Q

What is the basic monomer in carbohydrates

A

Sugar, otherwise known as a saccharide

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12
Q

What would a single monomer be called

A

Monosaccharides

mono = 1
O (hexagon)

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13
Q

What would a pair of monomers be called

A

Disaccharide

When combined in pairs, monosaccharides form disaccharides through a condensation reaction. The 2 monosaccharides are held tg by glycosidic bond

di = 2
O-O

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14
Q

What would a large chain of monomers be called

A

Polysaccharide - macromolecules consisting of more than 2 sugars (monosaccharides) - often a long chain polymer, joined by glycosidic bonds.

Polysaccharides are NOT SUGARS

poly = many
O-O-O-O-O-O

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15
Q

How do monosaccharides form disaccharides

A

2 monosaccharides can join tg by a glycosidic bond in a condensation reaction to form a disaccharide. In this process, a molecule of water is produced

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16
Q

How are polymers & disaccharides broken down into monomers

A

Hydrolysis reaction (breaking chemical bond using a water molecule)

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17
Q

What are the bonds in carbohydrates

A

Glycosidic bonds

18
Q

2 Monosaccharides you need to know

A

GLUCOSE (hexose monosaccharide) *6 carbon atoms in each molecule

RIBOSE (pentose monosaccharide) *5 carbons

see slide 10 to see their diagrams

19
Q

Different forms of glucose

A

There are 2 forms (isomers) of the monosaccharide glucose. These are a-glucose (alpha) and B-glucose (beta). They have the same chemical formula, but their structures are slightly different

20
Q

See slide 11-13 for diagrams of alpha and beta glucose

A
21
Q

What are isomers

A

Molecules with the same molecular formula as eachother, but with the atoms connected in a different way

Eg. alpha and beta glucose

22
Q

3 Disaccharides you need to know

A

MALTOSE - a disaccharide formed by condensation of 2 glucose molecules

SUCROSE - a disaccharide formed by condensation of glucose & fructose

LACTOSE - a disaccharide formed by condensation of glucose & galactose

23
Q

3 Polysaccharides you need to know

A

GLYCOGEN - formed by the condensation of alpha glucose molecules

STARCH - formed by the condensation of alpha glucose molecules

CELLULOSE - formed by the condensation of beta glucose molecules

24
Q

Different chains in polysaccharides

A

Macromolecules that are formed by many monosaccharides joined by glycosidic bonds in a condensation reaction to form chains

These chains may be:
- branched or unbranched
- folded (making the molecule compact which is ideal for storage eg. starch & glycogen)
- straight (making the molecules suitable to construct cellular structures eg. cellulose) or coiled

25
Q

What is the polysaccharide, Glycogen

A
  • The main energy storage molecule in animals
  • A multi-branched alpha glucose polymer
26
Q

What is Glycogen joined by

A
  • Main chains are joined tg by 1,4 glycosidic bonds
  • Branches are linked tg by 1,6 glycosidic bonds
27
Q

Structure of Glycogen

A
  • It has a large no. of side branches meaning that energy can be released quickly as enzymes can act simultaneously on these branches
28
Q

Where is Glycogen stored

A
  • In the muscles and in the liver
  • In times of high energy usage, these organs hydrolyse the glycogen stored & break it down into glucose molecules which can be used in respiration
29
Q

Size of Glycogen

A
  • It is a relatively large but compact molecule thus maximising the amount of energy it can store.
  • Makes it optimal for an energy storage molecule
30
Q

Is Glycogen insoluble

A

Yes, being soluble means it will not affect the water potential of cells & cannot diffuse out of cells

31
Q

see showbie slide 19 for diagram of Glycogen

A
32
Q

What is the polysaccharide, Starch

A
  • Starch is a mixture of 2 polysaccharides called amylose and amylopectin
  • Both amylose and amylopectin are long-chain a-glucose polymers.
33
Q

Main use of Starch

A

Starch is the main form of carbohydrate used for energy storage in plants

34
Q

Where is Starch stored

A

Starch grains are stored in chloroplasts & are insoluble in water so they dont affect water potential up & down the xylem - important for water & nutrient transport in the plant

35
Q

Starch is constructed from 2 different polysaccharides: AMYLOSE

A
  • (10-30% of starch)
  • long, unbranched, helix-shaped chain with 1,4 glycosidic bonds between a-glucsoe molecules.
  • The helix shape enables it to be more compact & thus its more resistant to digestion
36
Q

Starch is constructed from 2 different polysaccharides: AMYLOPECTIN

A
  • (70-90% of starch)
  • shorter, branched chains
  • 1,4 glycosidic bonds between a-glucose molecules but also 1,6 glycosidic bonds form between glucose molecules creating a branched molecule
37
Q

What is the polysaccharide, Cellulose

A
  • Cellulose is a polysaccharide found in plants
  • Unbranched, linear chains of B-glucose molecules which are joined by glycosidic bonds in a condensation reaction.
  • It is a polymer of abt 10,000 B-glucose molecules in a long unbranched chain called a microfibril
38
Q

Structure of Cellulose

A
  • It consists of long chains of B-glucose, so in order to form the 1,4 glycosidic bonds consecutive B-glucose molecules must be rotated 180 to eachother
  • High stability due to structure
39
Q

What are microfibrils

A

Strong threads which are made of long cellulose chains running parallel to one another that are joined tg by hydrogen bonds forming strong cross linkages

40
Q

Function of Cellulose

A

Important in stopping the cell wall from bursting under osmotic pressure. This is bc it exerts inward pressure that stops the influx of water. This means that cells stay turgid & rigid, helping to maximise the SA of plants for photosynthesis

41
Q

See slide 39 for diagrams of cellulose, amylose & amylopectin, and glycogen

A

A Level Biology: 2.1.2 Biological Molecules (13 decks)

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