Protein And Carbs

Question 1

What are carbs?

Answer 1

Molecules that only contain the elements carbon, hydrogen and oxygen.

Question 2

Examples of monosaccharides

Answer 2

Glucose, fructose and ribose.

Question 3

What happens when two monosaccharides link together?

Answer 3

They form a disaccharide, for example lactose and sucrose.

Question 4

What happens when 2 or more monosaccharides link together?

Answer 4

They form a polymer called a polysaccharide. For example glycogen, cellulose and starch.

Question 5

How many carbons is glucose composed of?

Answer 5

Six and therefore is called a heroes monosaccharide.

Question 6

Properties of glucose molecules.

Answer 6

Polar, soluble in water.

Question 7

What type of bond is a glycosidic bond?

Answer 7

Covalent.

Question 8

What happens during a condensation reaction?

Answer 8

The reaction is called a condensation reaction because a molecule is formed as one of the products of the reaction.

Question 9

What do Pentose monosaccharides contain?

Answer 9

5 carbon atoms.

Question 10

What is amylopectin made of?

Answer 10

Amylopectin is also made by 1-4 glycosidic bonds between alpha glucose molecules.

Question 11

What does glycogen form?

Answer 11

Glycogen forms more branches than amylopectin, which means it is more compact and less space is needed for it to be stored.

Question 12

Key properties of amylopectin and glycogen.

Answer 12

Insoluble, branched and compact. These properties mean they are ideally suited to the store age roles that that carry out.

Question 13

Different between reducing and non-reducing sugars?

Answer 13

Reducing sugars have the ability to be oxidised (loss of electrons), while non-reducing sugars have the ability to be reduced (gaining of electrons).

Question 14

What is glucose stored as?

Answer 14

Starch until it’s needed for respiration.

Question 15

Hydrolysis reaction in starch/glucose.

Answer 15

To release glucose for respiration, starch or glycogen undergo hydrolysis reactions, requiring the addition of water molecules. The reactions are catalysed by enzymes.

Question 16

Why can’t beta glucose molecules join together in the same way that alpha glucose molecules can?

Answer 16

The hydroxyl groups on carbon 1 and carbon 4 of the two glucose molecules are too far from each other to react.

The only way that beta glucoses molecules can join together can join together and form a polymer is if alternate beta glucose molecules are turned upside down.

Question 17

What do cellulose molecules make when forming microfibrils?

Answer 17

Hydrogen bonds.

Question 18

Properties of micro/macro fibrils.

Answer 18

Strong
insoluble
Used to make cell walls

Question 19

Reducing sugars test.

Answer 19

1. Place the sample to be tested in a boiling tube. If it is not in liquid form, grind it up or blend it in water.
2. Add an equal volume of Benedict’s reagent.
3. Heat the mixture gently in a boiling water bath for 5 minutes.

Positive result = brick red precipitate is formed.

Question 20

Non-reducing sugars test.

Answer 20

1. Place the sample to be tested in a boiling tube. If it is not in liquid form, grind it up or blend it in water.
2. Add an equal volume of Benedict’s reagent.
3. Heat the mixture gently in a boiling water bath for 5 minutes.

Non-reducing sugars don’t react with Benedict’s solution.

Solution remains blue if negative.

If sucrose is first boiled with dilute hydrochloric acid it will then give a positive result when warmed with Benedict’s solution. This is because the sucrose has been hydrolysed by the acid to glucose and fructose, both reducing sugars.

Question 21

Iodine test for starch.

Answer 21

1. Add a few drops of iodine dissolved in potassium iodide solution to the sample and mix.
2. If the solution changes colour from yellow/brown to purple/black then starch is present. If it stays the same, starch isn’t present.

Question 22

What are peptides?

Answer 22

Polymers made up of amino acids. They contain carbon, hydrogen, oxygen and nitrogen.

Question 23

Essential and non-essential amino acids.

Answer 23

All amino acids have the same basic structure. There are 20 different amino acids commonly found in cells. 5 are said to be non-essential as our body can make them from other amino acids. 9 are essential and can only be obtained from what we eat. 6 are said to be conditionally essential as they are only needed by infants and growing children.

Question 24

Synthesis of peptides.

Answer 24

Amino acids join when the amine and carboxylic acid groups connected to the central carbon atoms react.

Question 25

How are peptide bonds formed?

Answer 25

A peptide bond is formed between the amino acids and water is produced. The resulting compound is a dipeptide.

Question 26

How are polypeptides formed?

Answer 26

When many amino acids are joined together by peptide bonds. The reactions is catalysed by the enzyme peptidyl transferase present in ribosomes, the site of photosynthesis.

Question 27

Primary structure of proteins.

Answer 27

This is the sequence in which the amino acids are joined. The particular amino acids in the sequence will influence how the polypeptide folds and to give the proteins final shape.

Question 28

Secondary structure of proteins.

Answer 28

The oxygen, hydrogen, and nitrogen atoms of the basic, repeating structure of the amino acids interact. Hydrogen bonds may form within the amino acid chain, pulling it into a coil shape called an alpha helix.

Question 29

Tertiary structure of proteins.

Answer 29

This is the folding of the protein into this final shape. It often includes sections of secondary structure. The coiling or folding of sections of proteins into their secondary structures brings R-groups of different amino acids together so they are close enough to interact and further folding of these sections will occur.

Question 30

Quaternary structures of proteins.

Answer 30

The association of two or more individual proteins called subunits.

Question 31

Hydrophilic and hydrophobic interactions. Where are they based on molecules?

Answer 31

Hydrophilic groups are on the outside of the protein while hydrophobic groups are on the inside if the molecule shields from the water in the cytoplasm.

Question 32

The breakdown of peptides.

Answer 32

Protease are enzymes that catalyse the reverse reaction, turning peptides back into their constituent amino acids.

Question 33

How is water used in the breakdown of peptides.

Answer 33

A water molecule is used to break the peptide bond in a hydrolysis reaction, reforming the amine and carboxylic acid groups.

Question 34

Properties of globular proteins.

Answer 34

Compact, water soluble, and usually roughly spherical in shape.

Question 35

How are globular proteins formed?

Answer 35

They form when proteins fold into their tertiary structures in such a way that the hydrophobic R-groups on the amino acids are kept away from the aqueous environment.

Question 36

Haemoglobin structure.

Answer 36

It is a quartenary protein made from four polypeptides , 2 alpha and 2 beta subunits.

Question 37

Catalase structure.

Answer 37

A quarter ADH protein, 4 haem prosthetic groups. Contains iron II ions that allow catalase to interact with hydrogen peroxide and speed up its breakdown.

Question 38

Collagen.

Answer 38

A fibrous protein.
Connective tissues found in skin, tendons, ligaments and the nervous system.
Rope-like structure.
Flexible.

Question 39

How is elastin made?

Answer 39

By linking many soluble tropoelastin protein molecules to make a very large, insoluble, and stable, cross-linked structure.

Question 40

Tropoelastin molecules.

Answer 40

Are able to stretch and recoil without breaking, acting like small springs. They contain alternate hydrophobic and lysine-rich areas.

Question 41

Collagen structure.

Answer 41

Collagen molecules gave three polypeptide chains wound around each other in a triple helix structure to form a tough, rope-like protein.