Proteins

Proteins

Recap (Nutrients and Water)

Biological Molecules

Nutrients

Energy Raw materials

Carbohydrates

Proteins Fats

Repair/Growth

Water

Functions

Carbohydrates

maltose

monosaccharides

disaccharides

polysaccharides

glucose

galactose

lactose

fructose sucrose

starch

Straight and branched chains of glucose molecules

Condensation reaction

Hydrolysis

+ glucoseEnergy store

+ glucose

+ glucose

are grouped into

examples examples

examples

function

structure

Notes

Some notes are in the PPT, some are not. Do listen out for the clues

in my lesson!

“Proteins Proteins Proteins”

Why study proteins?

See it for yourself

African child Singapore child

Kwashiorkor

• In poor countries, when children do not have sufficient intake of proteins, they developed “big tummy”, which is the accumulation of water outside the blood capillaries.

Active research area

HIV researchPakinson’s disease

Elements in Proteins

Carbohydrates• Carbohydrates are a

group of organic biomolecules made up of the elements carbon, hydrogen and oxygen.

Proteins• Proteins are a group of

organic biomolecules made up of the elements carbon, hydrogen and oxygen and …

• Nitrogen and some sulphur.

Other differences?

Structural Differences!

General chemical structure for the Basic unit of carbohydrates

maltose

C6H12O6 + C6H12O6 C12H22O11 + H20

glucose + glucose maltose + water

OH

+ +

glycosidic bondCondensationreaction

OH O

General chemical structure for the Basic unit of proteins

—N—H

HC—OH

||O

R

|—C— |

H

Basic unit of protein is called Amino Acid (aa)

Basic unit comparison

Carbohydrates Proteins

Amino acidsStructure:central carbon amino groupacidic group (Carboxyl) R group (side chain)

variable group gives unique

chemical properties to the amino acid

—N—H

HC—OH

||O

R

|—C— |

H

What is the “R” group?1. It is the variable

groups that give rise to different Amino Acids in our body

2. There are 20 natural occurring AAs

With different “R” groups, you can come out with different AAs

—N—H

HC—OH

||O

R

|—C— |

H

Alanine

Joining different AAs together[Condensation]

Hydrolysis

Condensation and Hydrolysis Game !

2 groups • 1&2 vs 3&4

Objectives •Form the given polypeptides and hydrolyse it in the time given•Time limit is 5 mins

Instructions •Move the tables to the side, with the pail at the center•Paste the AAs sticker on your shirt

Example

Gly – Arg – Val

1st Polypeptide

Gly – Arg – Val- Ala- Ser – Thr – Cys- Met - His

2nd Polypeptide

Ser– Met- His- Gly– Thr - Ala– Cys- Arg -Val

What are the functions of proteins?

Other functions of food? Other than providing energy?

Growth

Regeneration By providing the necessary raw

material

“Proteins Proteins Proteins”

How does the lobster protein got transformed

into your muscle protein?

Eat the lobster

Digestion

Proteins

Polypeptide

Amino Acids

Digestion is a series of hydrolytic process

Proteins are first hydrolysed into short polypeptides which are in turn hydrolysed to amino acids.

Amino Acids

Polypeptide

Proteins

To different kinds of tissues and cells

Muscles

EnzymesAntibodies

Main functions of proteins

• Synthesis of new protoplasm, for growth and repair of worn-out body cells.• Synthesis of enzymes, hormones,

antibodies and other biological molecules.

Going a bit further

• What if the sequence in a protein is arranged wrongly?

•Gly – Arg – Val changed to Val– Arg –Gly

• What will happen?• Let’s watch a video

Mad Cow Disease

Q1. What is the basic unit of protein?

A. GlucoseB. MaltoseC. Amino AcidsD. Water

Q2. How many natural occuring amino acids are there?

A. 19B. 20C. 21D. 22

Q3. Proteins are only found in the cells of animals

A. TrueB. False

Q4. Condensation only happens in protein synthesis

A. TrueB. False

Q5. What is the name of the bond between two adjacent Amino acids?

A. Ionic BondB. Hydrogen BondC. Covalent BondD. Peptide Bond

HW• Find out the test for proteins. • Biuret test. • Write down the exact steps in conducting the

biuret test and find pictures on the internet that describe the test.

• Put it in a word document.• Send to [email protected] by

Wednesday. Go through on thurs!

Construct a protein mind map

• Construct a protein mind map based on today’s lesson.

• Take reference from the mind maps constructed by the teachers in water and carbohydrates

• Hand in by this thurs, 12th March.