1.0: MOLECULES OF LIFE...Carbon backbone of 3 to 6 carbon atoms. Have a carbonyl group and multiple...
Transcript of 1.0: MOLECULES OF LIFE...Carbon backbone of 3 to 6 carbon atoms. Have a carbonyl group and multiple...
1.1 WATER1.2 CARBOHYDRATES1.3 LIPIDS1.4 PROTEINS1.5 NUCLEIC ACIDS
1.0: MOLECULES OF LIFE
BIOLOGY
At the end of this topic, students should be able to:
1.0: MOLECULES OF LIFE
• a) State the structure and properties of water molecules.
• b) Relates the properties of water and its importance.
1.1 Water
WATER MOLECULE
Water has a simple molecular structure. It is composed of
one oxygen atom and two hydrogen atoms.
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WA
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RWATER
1.1
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RWATER MOLECULE
▪ Oxygen also has two unshared pairs of electrons. Thus, oxygen
is an "electronegative“ compared with hydrogen.
▪ A hydrogen atoms
combined with the oxygen
atom by sharing of
electrons.
▪ Each hydrogen atom is covalently bonded to the oxygen via a
shared pair of electrons.
Angle of water atoms
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RPolarity of water
Polar molecule : A molecule with uneven distribution of charges in different regions of the molecules. (Campbell 9th edition)
Oxygen region
has partial negative
charge.
Hydrogen has a
partial positive
charge.
Partially negative side
of water molecule
Partially positive side
of water moleculeBall-and-Stick Model
1.1
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RBonds of water molecules
Universal solvent due to its polarity/
polar molecules
Low viscosity
High specific heat capacity
High latent heat of vaporization
High surface tension
Maximum density at 4°C
PROPERTIES OF WATER1
.1 W
AT
ER
At the end of this topic, students should be able to:
1.0: MOLECULES OF LIFE
1.2 Carbohydrates
• a) State the classes of carbohydrates such
as monosaccharides, disaccharides and polysaccharides.
• b) Illustrate the formation and breakdown of maltose.
• c) Compare the structure and function of starch, glycogen and cellulose.
1.2
C
AR
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DR
AT
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Organic compounds containing C, H and O (ratio of 1:2:1)
• Empirical formula :(CH2O)n
CARBOHYDRATES
1.2
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DR
AT
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MONOSACCHARIDES
• Characteristics:
• Small
• Sweet tasting
• Primary source of energy
• Readily soluble in water
• Reducing sugar
• Crystalline
• Simple sugar
Carbon backbone of 3 to 6 carbon atoms.
Have a carbonyl group and multiple hydroxyl groups.
ALDOSE KETOSE
CARBONYL
group is located
on the terminal
carbon in
the chain.
CARBONYL
group is located
on a carbon
That is not
on the end
of the chain.
Carbonyl group : C = OHydroxyl group : OH
All carbon atoms except
one have a hydroxyl
group attached.
1.2
C
AR
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DR
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MONOSACCHARIDES
DISACCHARIDES
1.2
C
AR
BO
HY
DR
AT
ES Formed by condensation reaction of TWO monosaccharides.
Bond linking : glycosidic bond.
• Water-soluble
• Sweet tasting
• Readily soluble in water
• Reducing sugar(maltose, lactose)
• Crystalline
Characteristics:• Disaccharides:
• Maltose
• Sucrose
• Lactose
DISACCHARIDES
1.2
C
AR
BO
HY
DR
AT
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MALTOSE - condensation1.2
C
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DR
AT
ES
DISACCHARIDES
MALTOSE - hydrolysis1.2
C
AR
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DR
AT
ES
DISACCHARIDES
POLYSACCHARIDES1.2
C
AR
BO
HY
DR
AT
ES Polymers of monosaccharides made up of condensation of
hundreds of monosaccharides
Characteristics:
- Large and complex
- Most are not soluble in water
- Not sweet tasting
- Food storage
• Polysaccharides:
• Starch
• Glycogen
• Cellulose
POLYSACCHARIDES1.2
C
AR
BO
HY
DR
AT
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STARCH
• Condensation of α-glucose subunits
• Used for energy storage in plants
• A linear unbranched polymer
•Glucose units joined by α-1,4 glycosidic bonds
• Made up of two components :
1. Amylose
2. Amylopectin
• A branched polymer
• linear chains held together by α-1,4 glycosidic bonds
• short branches: held by α-1,6 glycosidic bonds
POLYSACCHARIDES1.2
C
AR
BO
HY
DR
AT
ES
GLYCOGEN
• Condensation of α-glucose subunits
• Major storage of carbohydrate in animals
• Structure similar to amylopectin : larger & with more branches.
POLYSACCHARIDES1.2
C
AR
BO
HY
DR
AT
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CELLULOSE
• Condensation of β-glucose subunits
• Structural polysaccharides in plant cell walls
• linked by β -1,4 glycosidic bonds
• Composed of long unbranched chains
• Many hydrogen bonds are formed between hydroxyl groups on parallel
chains ( between C atoms 3 and 6).
• a) State the types of lipid: triglycerides (fat and oil),
1.0: MOLECULES OF LIFE
At the end of this topic, students should be able to:
• b) Describe the structure of fatty acids and glycerol.
1.3 Lipids
phospholipids and steroids.
• b) Explain the formation and breakdown of triglycerides.
LIPIDS1.3
L
IPID
SCharacteristics:
• Insoluble in water
• Have little or no affinity for water (hydrophobic behavior)
• Soluble in organic solvent such as ether, acetone, chloroform and hot alcohol
• Can store large amount of energy:
The ratio of energy storing C-H bonds in fats is more than twice that carbohydrates / more C and H.
• General formula : CnH2nO2
• Proportion of oxygen is lower than in carbohydrates.
• Lipids are organic compounds.
• Not polymer
LIPIDS
• - TRIGLYCERIDESi.e Fat and oil
• - PHOSPHOLIPIDS
i.e Lecithin
• - STEROID• i.e Cholesterol
Testosteron
TYPE OF LIPIDS
1.3
L
IPID
S
LIPIDS1.3
L
IPID
S
• Glycerol is a three-carbon alcohol that contains three
hydroxyl group (-OH)
• a fatty acid is a long, unbranched hydrocarbon chain with
carboxyl group (-COOH) at one end.
TRIGLYCERIDES:
STRUCTURE OF FATTY ACIDS AND GLYCEROL
Formation/Breakdown of Triglycerides
condensation
hydrolysis
1.3
L
IPID
S
1.0: MOLECULES OF LIFE
• b) State how amino acids are grouped.
At the end of this topic, students should be able to:
• a) Describe the basic structure of amino acid
1.4 Protein
• c) Describe primary, secondary, tertiary and quaternary level of proteins and the type of bonds involved
1.0: MOLECULES OF LIFE
• e) Explain the formation and breakdown of dipeptide
At the end of this topic, students should be able to:
• d) Describe the effect of pH and temperature on the structure of protein.
1.4 Protein
• f) Classify proteins according to structure and composition
PROTEINS1.4
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Molecule made up of one/more polypeptides, each folded and coiled into specific 3D structure.
Constructed from amino acids.
The bond between amino acidsis called peptide bond.
• Each polypeptide has a unique linear sequence of amino acids.
PROTEINS1.4
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(R group)
a variable group
• Amino acid containing
• a carboxyl group,
• a hydrogen atom
• a side chain
Protein Monomer : Amino acid
• an amino group
– that are specific to each amino acid.
How amino acids are grouped?
Nonpolar
amino acid
Polar
amino acid
Acidic
amino acid
Basic
amino acid
The 20 amino acids
are grouped
according to the
properties of their
side chains (R
groups)1.4
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PROTEINS
Proteins Structure
• The sequence of amino acids determines aprotein’s three-dimensional structure.
4 levels of protein structure
Primary
(1 ͦ )
Secondary
(2 ͦ )
Tertiary
(3 ͦ )
Quaternary
(4 ͦ )
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PROTEINS
Proteins Structure: Primary (1 ͦ )
• sequence of amino acids determined by genetic code carried in DNA molecules in the nucleus.
• Eg: InsulinAmino acidsubunits
+H3NAmino end
25
20
15
10
5
1
Primary Structure
1.4
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Proteins Structure: Secondary (2 ͦ )
• Polypeptide chains are coiled (-helix ) and folded (β-pleated sheet) .
A coiled shape of the -helix is held in place by hydrogen bonds between amino groups and the carboxyl groups of the amino acids.
• Hold protein in a parallel arrangement (β-pleated sheet) with hydrogen bond.
• E.g.: silk protein of a spider’s web.
• E.g. : keratin in hair, nails,
horn and feathers1.4
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Proteins Structure: Tertiary
• Structure is maintained by :
–Hydrogen bond
–Ionic bond
–Disulfide bridge
–Hydrophobic interactions
–van der Waals interactions
Polypeptidebackbone
Hydrophobicinteractions andvan der Waalsinteractions
Disulfide bridge
Ionic bond
Hydrogenbond
• Involves interactions (attractions & repulsions) between R groups of the amino acids
1.4
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Proteins Structure: Quaternary
• Two or more polypeptide chains
form one functional macromolecule.
• Combination two or more tertiary
units.
• Stabilized with the same
interactions found in
tertiary structure.
1.4
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Factors Affecting Protein Structure
Temperature
• Heat increases the kinetic energy of the protein
chain.
• Excessive motion can break relatively weak
hydrogen bonds, electrostatic interactions (ionic
bond) and hydrophobic interactions.
• Protein chain is free to rearrange after disrupting.
• E.g : Fried egg
1.4
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pH
• Extreme of pH can cause protein to denature.
• Change the charges of acidic and basic functional
groups of proteins.
• Those functional groups will lose & gain a proton.
• Break hydrogen bonds between acidic and basic R
groups & disrupt ionic bonds.
Factors Affecting Protein Structure
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The Formation and Breakdown of Dipeptide 1.4
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Fibrous protein Globular protein Conjugated protein
Collagen
α-keratin
Elastin
Enzymes
AntibodiesHormones
Hemoglobin
PROTEIN CLASSIFICATION BASED ON THEIR STRUCTURE
1.4
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INS
At the end of this topic, students should be able to:
1.0: MOLECULES OF LIFE
• a) State the structure of nucleotide as the basic composition of
nucleic acid (DNA and RNA)
1.5 Nucleic Acids
• b) Illustrate the structure of DNA based on Watson and Crick model.
• c) State the types of RNA
• d) Compare DNA and RNA
• Macromolecules (large molecules) made up of chains of individual units called nucleotides.
• Each nucleotide is made up of pentose sugar, phosphate group and nitrogenous bases.
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NUCLEIC ACIDS1.5
N
UC
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IC A
CID
SNUCLEIC ACIDS
Components of NucleotideNUCLEIC ACIDS
1.5
N
UC
LE
IC A
CID
S
Formation of Phosphodiester bond between phosphate group at C5
& Hydroxyl group (OH) at C3 next monomer.
NUCLEIC ACIDS1.5
N
UC
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IC A
CID
S
43
Watson and Crick’s DNA Model
A
T
A
A
TTG
G
CC
G
C
A DNA molecule is linkage
of nucleotides forms long
chains called
polynucleotides.
Chemically, one strand
runs 5’ to 3’ upward while
the other runs in the
opposite direction of 5’ to
3’ downward.
and coiled (clockwise
spiral) into a double helix.
NUCLEIC ACIDS1.5
N
UC
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IC A
CID
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RNA Structure
• A single-stranded polymer of
nucleotides
NUCLEIC ACIDS1.5
N
UC
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IC A
CID
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Differences of DNA and RNANUCLEIC ACIDS
1.5
N
UC
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CID
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Differences of DNA and RNANUCLEIC ACIDS
1.5
N
UC
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CID
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DNA RNA
Mostly two polynucleotide chains //
double-stranded
Mostly single polynucleotide chain // most
single-stranded
Double helix No double helix
Deoxyribose as pentose sugar Ribose as pentose sugar
Organic bases: A, T, C, G
* Base thymine (T)
Organic bases: A, U, C, G
* Base Uracil (U)
Manufactured in nucleus Manufactured in nucleus but found
throughout the cell
Chemically very stable// long live Chemically much less stable// temporary
Larger molecular size/ mass Smaller molecular size/ mass
Only one basic form Many/ 3 basic forms : mRNA, rRNA and
tRNA
Susceptible to UV damage Relatively resistance to UV damage