Molecules Stephen Repacholi

Introduction For each of the following you should be able to: Describe the properties Know the general formulae & structure Understand the role in animals & plants Water Carbohydrates Lipids Proteins Nucleic acids

For each of the following you should be able to:

Describe the properties

Know the general formulae & structure

Understand the role in animals & plants

Water

Carbohydrates

Lipids

Proteins

Nucleic acids

Lipids Made up of C, H and O Can exist as fats, oils and waxes They are insoluble in water They are a good source of energy (38kJ/g) They are poor conductors of heat Most fats & oils are triglycerides

Made up of C, H and O

Can exist as fats, oils and waxes

They are insoluble in water

They are a good source of energy (38kJ/g)

They are poor conductors of heat

Most fats & oils are triglycerides

Triglycerides Formed by esterification… …a condensation reaction between 3 fatty acids and glycerol: Glycerol H C H C C H H H H O O O

Formed by esterification…

…a condensation reaction between 3 fatty acids and glycerol:

Fatty acids Carboxyl group (-COOH) attached to a long non-polar hydrocarbon chain (hydrophobic): H A saturated fatty acid (no double bonds) H C H H C H H C H C O O H C H H C H H C H H C H H

Carboxyl group (-COOH)

attached to a long non-polar hydrocarbon chain (hydrophobic):

H H C O O H C C C C H A polyunsaturated fatty acid C O O H C H H C H A monounsaturated fatty acid H H H C H H C H H C H H C H H C H H C H H C H H C H

Esterification Glycerol Fatty acid H C H C C H H H H O O O C O O H C H H C H H C H H C H H

Esterification Glycerol Fatty acid H C H C C H H H H O O O C O O H C H H C H H C H H C H H

Esterification H C H C C H H H H O O O C O O H Glycerol Fatty acid H C H H C H H C H H C H

Esterification H C H C C H H H H O O O C O O H Ester bond water H C H H C H H C H H C H

Esterification This happens three times to form a triglyceride: glycerol fatty acids

This happens three times to form a triglyceride:

Phospholipids One fatty acid can be replaced by a polar phosphate group: glycerol Hydrophobic fatty acids hydrophilic phosphate

One fatty acid can be replaced

by a polar phosphate group:

Functions of lipids Protection of vital organs To prevent evaporation in plants & animals To insulate the body They form the myelin sheath around some neurones As a water source (respiration of lipids) As a component of cell membranes

Protection of vital organs

To prevent evaporation in plants & animals

To insulate the body

They form the myelin sheath around some neurones

As a water source (respiration of lipids)

As a component of cell membranes

Water Water is a polar molecule It forms weak hydrogen bonds It remains a liquid over a wide temperature range Water molecules stick to one another = cohesion (surface tension) Water molecules stick to other substances = adhesion (capillarity) O H H + + -

Water is a polar molecule

It forms weak hydrogen bonds

It remains a liquid over a wide temperature range

Water molecules stick to one another = cohesion (surface tension)

Water molecules stick to other substances = adhesion (capillarity)

Water It has a high specific heat capacity – so water can maintain a reasonably constant temperature (homeostasis) It has a high latent heat of vaporisation – so animals use water to cool themselves It is less dense as a solid (ice)… … and ice is a poor conductor Water is a good solvent

It has a high specific heat capacity – so water can maintain a reasonably constant temperature (homeostasis)

It has a high latent heat of vaporisation – so animals use water to cool themselves

It is less dense as a solid (ice)…

… and ice is a poor conductor

Water is a good solvent

Carbohydrates Contain the elements Carbon Hydrogen & Oxygen There are 3 types: Monosaccharides Disaccharides Polysaccharides

Contain the elements Carbon Hydrogen & Oxygen

There are 3 types:

Monosaccharides

Disaccharides

Polysaccharides

Monosacharides (CH 2 O) n If n=3, triose (glyceraldehyde) If n=5, pentose (fructose, ribose) If n=6, hexose (glucose, galactose) Monosaccharides are used for Energy Building blocks O C C C C C C

(CH 2 O) n

If n=3, triose (glyceraldehyde)

If n=5, pentose (fructose, ribose)

If n=6, hexose (glucose, galactose)

Monosaccharides are used for

Energy

Building blocks

Isomerism They can exist as isomers:  &  glucose OH OH  

They can exist as isomers:

 &  glucose

Disaccharides Formed from two monosaccharides Joined by a glycosidic bond A condensation reaction: glucose + glucose  maltose glucose + galactose  lactose glucose + fructose  sucrose

Formed from two monosaccharides

Joined by a glycosidic bond

A condensation reaction:

glucose + glucose  maltose

glucose + galactose  lactose

glucose + fructose  sucrose

Condensation reaction OH OH O C C C C C C O C C C C C C

Condensation reaction O H OH O C C C C C C O C C C C C C

Condensation reaction O H 2 O O C C C C C C O C C C C C C

Condensation reaction O A disaccharide 1,4 glycosidic bond 4 1 O C C C C C C O C C C C C C

Polysaccharides Polymers formed from many monosaccharides Three important examples: Starch Glycogen Cellulose

Polymers formed from many monosaccharides

Three important examples:

Starch

Glycogen

Cellulose

Starch Insoluble store of glucose in plants formed from two glucose polymers: Amylose  -glucose 1,4 glycosidic bonds Spiral structure Amylopectin  -glucose 1,4 and some 1,6 glycosidic bonds Branched structure

Amylose

 -glucose

1,4 glycosidic bonds

Spiral structure

Amylopectin

 -glucose

1,4 and some 1,6 glycosidic bonds

Branched structure

Glycogen Insoluble compact store of glucose in animals  -glucose units 1,4 and 1,6 glycosidic bonds Branched structure

Insoluble compact store of glucose in animals

 -glucose units

1,4 and 1,6 glycosidic bonds

Branched structure

Cellulose Structural polysaccharide in plants  -glucose 1,4 glycosidic bonds H-bonds link adjacent chains O O O O O

Structural polysaccharide in plants

 -glucose

1,4 glycosidic bonds

H-bonds link adjacent chains

Proteins Made from C H O N & sometimes S Long chains of amino acids Properties determined by the aa sequence Amino acids ~20 aa Glycine R=H Alanine R=CH 3 amine carboxyl H C H N C H H O O R

Made from C H O N & sometimes S

Long chains of amino acids

Properties determined by the aa sequence

~20 aa

Glycine R=H

Alanine R=CH 3

Peptide bonding H C H N C H H O O R H C H N C H H O O R

Peptide bonding H C H N C H H O O R H C H N C H H O O R

Peptide bonding H C H N C H H O O R H C H N C H H O O R

Peptide bonding C H N C H H O R H C H N C H O O R water Peptide bond A condensation reaction H O H

Peptide bonding H C H N C H O O R A dipeptide C H N C H H O R

Primary structure The sequence of aa is know as the primary structure The aa chain is a polypeptide Secondary structure H-bonding forms between the –COOH and the -NH 2 of adjacent aa This results in the chains folding:

The sequence of aa is know as the primary structure

The aa chain is a polypeptide

H-bonding forms between the –COOH and the -NH 2 of adjacent aa

This results in the chains folding:

Secondary structure  -helix  -pleated sheet

Tertiary structure Bonding between R-groups gives rise to a 3D shape H-bonds =O HN- Ionic bonds –NH 3 - COO- Disulphide bridge --CH 2 S - SCH 2 - affected by temp & pH affected by pH affected by reducing agents

Bonding between R-groups gives rise to a 3D shape

H-bonds =O HN-

Ionic bonds –NH 3 - COO-

Disulphide bridge

--CH 2 S - SCH 2 -

Quaternary structure Some proteins have more than one polypeptide chain Each chain is held together in a precise structure eg Haemoglobin

Some proteins have more than one polypeptide chain

Each chain is held together in a precise structure

eg Haemoglobin

Types of proteins Fibrous proteins e.g. collagen Insoluble structural Globular proteins e.g.enzymes Soluble 3D shape

Fibrous proteins

e.g. collagen

Insoluble

structural

Globular proteins

e.g.enzymes

Soluble

3D shape

Functions of proteins Enzymes – Transport – Movement – Cell recognition – Channels – Structure – Hormones – Protection – Amylase Haemoglobin Actin & myosin Antigens Membrane proteins Collagen & keratin Insulin Antibodies

Enzymes –

Transport –

Movement –

Cell recognition –

Channels –

Structure –

Hormones –

Protection –

Amylase

Haemoglobin

Actin & myosin

Antigens

Membrane proteins

Collagen & keratin

Insulin

Antibodies

Nucleic acids DNA & RNA Made up of nucleotides: phosphate pentose sugar base

DNA & RNA

Made up of nucleotides:

Nucleotides 2 types of base: Pyrimidines - Cytosine C Thymine T Purines Adenine A Guanine G

2 types of base:

Pyrimidines -

Cytosine C

Thymine T

Purines

Adenine A

Guanine G

Complimentary base pairing Adenine will only bind with Thymine Cytosine will only bind with Guanine T C G A

Adenine will only bind with Thymine

Cytosine will only bind with Guanine

DNA structure nucleotide Condensation polymerisation of the deoxyribose nucleotides

Replication During cell division the DNA must replicate The DNA double helix unwinds The exposed bases bind to free floating nucleotides in the nucleoplasm DNA polymerase binds the complimentary nucleotides Replication is semiconservative

During cell division the DNA must replicate

The DNA double helix unwinds

The exposed bases bind to free floating nucleotides in the nucleoplasm

DNA polymerase binds the complimentary nucleotides

Replication is

semiconservative

The genetic code The sequence of nucleotide bases forms a code Each ‘code word’ has three letter – a triplet code Each codon codes for a specific amino acid e.g: GGG = proline CGG = glycine ATG = tyrosine ACT = stop (no amino acid)

The sequence of nucleotide bases forms a code

Each ‘code word’ has three letter – a triplet code

Each codon codes for a specific amino acid e.g:

GGG = proline

CGG = glycine

ATG = tyrosine

ACT = stop (no amino acid)

Protein synthesis The DNA codes for proteins A copy of DNA (mRNA) is made in the nucleus (transcription) The mRNA is used to make a protein (translation) in the cytoplasm

The DNA codes for proteins

A copy of DNA (mRNA) is made in the nucleus (transcription)

The mRNA is used to make a protein (translation) in the cytoplasm

Transcription The DNA polymerase unwinds the DNA Free nucleotides join onto complimentary bases RNA polymerase links adjacent nucleotides The completed mRNA moves out of the nucleus

The DNA polymerase unwinds the DNA

Free nucleotides join onto complimentary bases

RNA polymerase links adjacent nucleotides

The completed mRNA moves out of the nucleus

Transcription

Amino acid activation transferRNA: tRNA binds onto a specific amino acid

transferRNA:

tRNA binds onto a specific amino acid

Translation mRNA binds to a ribosome tRNA carries an amino acid to the ribosome

mRNA binds to a ribosome

tRNA carries an amino acid to the ribosome

Translation A second tRNA brings another aa The two aa’s bind The process repeats

A second tRNA brings another aa

The two aa’s bind

The process repeats

Translation A polypeptide chain forms Eventually a stop codon is reached

A polypeptide chain forms

Eventually a stop codon is reached

The Human Genome Project A multinational project aimed at sequencing the entire human genome Visit the Human Genome Web site: www.ornl.gov/hgmis/project/about.html www.sanger.ac.uk

A multinational project aimed at sequencing the entire human genome

Visit the Human Genome Web site:

www.ornl.gov/hgmis/project/about.html

www.sanger.ac.uk

Acknowledgements Animated cell models used by kind permission of The Virtual Cell website: Feel free to use this presentation for educational non-profit making purposes.

Animated cell models used by kind permission of The Virtual Cell website:

Feel free to use this presentation for educational non-profit making purposes.

Quiz 1. Which of the following is not an important property of water Its polar nature Its low specific heat capacity Its high latent heat of vaporisation Its low density in solid form

1. Which of the following is not an important property of water

Its polar nature

Its low specific heat capacity

Its high latent heat of vaporisation

Its low density in solid form

Quiz 2. The general formula for a monosaccharide is: (CH 2 O) n (CHO) n C(H 2 O) n C n H 2 O n

2. The general formula for a monosaccharide is:

(CH 2 O) n

(CHO) n

C(H 2 O) n

C n H 2 O n

Quiz 3. Sucrose is made up of glucose + fructose glucose + galactose glucose + glucose galactose + fructose

3. Sucrose is made up of

glucose + fructose

glucose + galactose

glucose + glucose

galactose + fructose

Quiz 4. Amylopectin is made up of:  - 1,4 glycosidic bonds  - 1,4 &  -1,4 glycosidic bonds  - 1,4 & 1,6 glycosidic bonds  - 1,4 & 1,6 glycosidic bonds

4. Amylopectin is made up of:

 - 1,4 glycosidic bonds

 - 1,4 &  -1,4 glycosidic bonds

 - 1,4 & 1,6 glycosidic bonds

 - 1,4 & 1,6 glycosidic bonds

Quiz 5. Formation of a triglyceride does NOT involve: A condensation reaction Esterification Polymerisation A reaction between 3 fatty acids & glycerol

5. Formation of a triglyceride does NOT involve:

A condensation reaction

Esterification

Polymerisation

A reaction between 3 fatty acids & glycerol

Quiz 6. The general formula of a saturated fatty acid is: C n H 2n O 2 C n (H 2 O) n (CH 2 O) n (CH 2 ) n O

6. The general formula of a saturated fatty acid is:

C n H 2n O 2

C n (H 2 O) n

(CH 2 O) n

(CH 2 ) n O

Quiz 7. Which of the following is not responsible for a proteins tertiary structure ionic bonding covalent bonding hydrogen bonding disulphide bonding

7. Which of the following is not responsible for a proteins tertiary structure

ionic bonding

covalent bonding

hydrogen bonding

disulphide bonding

Quiz 8. Which of these is not an amino acid: alanine cysteine glycine cytosine

8. Which of these is not an amino acid:

alanine

cysteine

glycine

cytosine

Quiz 9. Which process involves tRNA: transciption translation DNA replication gene mutation

9. Which process involves tRNA:

transciption

translation

DNA replication

gene mutation

Quiz 10. The formation of RNA does not involve: ribose sugar thymine removal of water phosphate

10. The formation of RNA does not involve:

ribose sugar

thymine

removal of water

phosphate

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Answers That’s right – water has a high specific heat capacity Click here to go to the next question

That’s right – water has a high specific heat capacity

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Answers That’s right, cytosine is an organic base Click here to go to the next question

That’s right, cytosine is an organic base

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Answers That’s right, in RNA thymine is replaced with uracil Click here to go back to the start Press escape to exit

That’s right, in RNA thymine is replaced with uracil

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