C 24:The chemistry of lifeBiomolecules
Primary Organic Compounds
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
You are expected to learn the structure and functions of these organic compounds:
Polymers and Monomers
Each of these types of molecules are polymers that are assembled from single units called monomers.
Each type of biomolecule is a string of a different type of monomer.
MonomersMacromolecule
Carbohydrates
Lipids
Proteins
Nucleic acids
Monomer
Monosaccharide
Not always polymers; Hydrocarbon chains
Amino acids
Nucleotides
Proteins
Organic polymers are made up of repeating blocks called monomers.
Proteins are made up of amino acid monomers – spider webs are examples of protein polymers, and so are your muscles.
Amino acid structure
An amine +
carboxyl acid
Peptide bonds
Take ¼ sheet of paper Draw 4 consecutive amino acids across the top
evenly spaced.
Cut the paper so you have a strip with the 4 amino acids.
Curl the paper around so you have a helix – connect amino acids with peptide bonds - draw in peptide bonds.
If you do not wish to keep your protein - denature your protein and place in the recycling bin
Proteins Peptide – 2 or more amino acids bonded together
Polypeptide – 10 or more amino acids
Protein – 50 or more amino acids bonded together
Are long chains of amino acids that start to fold into 3-d shapes.
Cooking causes DENATURATION – unfolding of the protein molecule
Functions of proteins Enzymes – are catalysts for cellular
reactions.
Transport proteins – hemoglobin is an example of this – it carries oxygen to all parts of your body.
Structural proteins – collagen is an example of this – it make up skin, tendons, hair, and fingernails
Hormones – Insulin is a protein that carries signals from one part of the body to another.
Enzymes A biological
catalyst
Substrate – bind to specific sites on enzyme molecules – Like a lock= where the key fits; and a key= enzyme.
Active site – is the lock to which the enzyme binds, or the key fits.
Carbohydrates
Carbohydrates are made of carbon, hydrogen, and oxygen atoms, always in a ratio of 1:2:1; functional groups of alcohols –OH, and -C=O are common.
Carbohydrates are the key source of energy used by living things.
The building blocks of carbohydrates are sugars, such as glucose and fructose.
How do two monosaccharides
combine to make a
polysaccharide?
Mono-saccharidesare called ‘simple Sugars’.
Two monomers linked together are calledDisaccharides
Polysaccharides – 12
or more monomer units
Functions of carbohydrates
Glucose – a monosaccharide that is found in our blood : commonly referred to as “blood sugar”
Sucrose –a disaccharide commonly called table sugar. This is too big to be taken into the bloodstream and is broken down in the small intestine.
Polysaccharides – many monomers 12 or more monomer units strung together – pasta is an example of this. Starch, Glycogen and Cellulose are examples of polysaccharides.
Functional groups break!
Lipids Lipids are large, are nonpolar, are hydrophobic
(water/fear – they are insoluble in water)
Lipids ARE NOT Always POLYMERS.
Lipids are made up of Fatty acids – long-chained carboxylic acids.
Fats are either saturated – have the maximum number of hydrogens Unsaturated – have double bonds, so they could add
more hydrogens.
Types of lipids Fatty acids
Triglycerides – used in making soap, cell membranes (called phospholipids)
Waxes – contain fatty acids
Steroids – have no fatty acid chains, have cyclic rings - are used as hormones which regulate metabolic processes.
Functions of lipids
Store energy efficiently
Make up most of the structure of the cell membrane
Nucleic AcidsDNA & RNA
What are they ?
The 4th type of macromolecules
The chemical link between generationsThe source of genetic
information in chromosomes
What do they do ?
Dictate amino-acid sequence in proteins
Give information to chromosomes, which is then passed from parent to offspring
What are they made of ? Simple units (monomers) called
nucleotides, connected in long chains
Nucleotides have 3 parts:
1- A phosphate group ( P )
2- 5-Carbon sugar (pentose)
3- Nitrogen containing base
(made of C, H and N)
The P groups make the links that unite the sugars (hence a “sugar-phosphate backbone”
Two types of Nucleotides (depending on the
sugar they contain)
1- Ribonucleic acids (RNA)The pentose sugar is Ribose
(has a hydroxyl group in the 3rd carbon---OH)
2- Deoxyribonucleic acids (DNA)The pentose sugar is
Deoxyribose (has just an hydrogen in the same place--- H)
Deoxy = “minus oxygen”
DNA NucleotidesComposition (3 parts):
1- Deoxyribose sugar (no O in 3rd carbon)
2- Phosphate group
3- One of 4 types of bases (all containing nitrogen):
- Adenine
- Thymine (Only in DNA)
- Cytosine
- Guanine
RNA NucleotidesComposition ( 3 parts):
1- Ribose sugar (with O in 3rd carbon)
2- Phosphate group
3- One of 4 types of bases (all containing nitrogen):
- Adenine
- Uracyl (only in RNA)
- Cytosine
- Guanine
DNA vs RNA
DNA
1- Deoxyribose sugar
2- Bases: Adenine, Thymine, Cytosine, Guanine
3- Double-stranded helix arrangement
RNA
1- Ribose sugar
2- Bases: Adenine, Uracyl, Cytosine, Guanine
4- Single stranded
The Double Helix (DNA)Structural model:
Model proposed by Watson & Crick, 1953
Two sugar-phosphate strands, next to each other, but running in opposite directions.
Specific Hydrogen bonds occur among bases from one chain to the other:
A---T , C---G
Due to this specificity, a certain base on one strand indicates a certain base in the other.
The 2 strands intertwine, forming a double-helix that winds around a central axis
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Double Helix of DNA
Quick Check
An ending of –yne means?
An ending of –ene means?
An ending of –ane means?
Metabolism vs anabolism
METABOLISM: Changing complex molecules (nucleic acids, polysaccarides, proteins, triglycerides) into their building blocks (amino acids, fatty acids, nucleotides, monosaccharides)
ANABOLISM: The reverse: linking the building blocks (amino acids, fatty acids, nucleotides, monosaccharides) to make a complex molecule (nucleic acids, polysaccarides, proteins, triglycerides)
Slime cross linking
