lecture 3 - biological macromolecules.handout
TRANSCRIPT
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Biological ScienceBiological Science(Nat(Nat--SciSci II)II)
Biological macromoleculesBiological macromolecules
• Living organisms assemble large molecules – macromolecules – that are more complex than molecules found in nonliving matter.– Same chemical laws apply.
– Four categories of biological macromolecules:• Nucleic acids
• Proteins
• Carbohydrates
• Lipids
• Recall the four major categories of
biological macromolecules:
– Carbohydrates
– Lipids
– Proteins
– Nucleic acids
Biological macromoleculesBiological macromolecules CarbohydratesCarbohydrates
• Carbohydrates are compounds of carbon
(C), hydrogen (H) and oxygen (O).
– Usually found 1C:2H:1O.
– Usually grouped as H-C-OH.
• Function as structural elements and as a source of chemical energy (ex. glucose).
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Examples of
Carbohydrates
CarbohydratesCarbohydrates
• Plants use water (H2O) and carbon dioxide
(CO2) along with solar energy to manufacture carbohydrates in the process of photosynthesis.
– 6CO2 + 6H2O light C6H12O6 + 6O2
– Life depends on this reaction – it is the
starting point for the formation of food.
CarbohydratesCarbohydrates
• Three classes of carbohydrates:
– Monosaccharides – simple sugars
– Disaccharides – double sugars
– Polysaccharides – complex sugars
MonosaccharidesMonosaccharides
• Monosaccharides –
Single carbon chain
4-6 carbons.
– Glucose C6H12O6
• Can be straight chain or
a ring.
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MonosaccharidesMonosaccharides
• Some common monosaccharides:
DisaccharidesDisaccharides
• Disaccharides –
Two simple sugars
bonded together.
– Sucrose = glucose + fructose
– Lactose =
glucose + galactose
PolysaccharidesPolysaccharides
• Polysaccharides – Many simple sugars bonded together in long chains.– Starch is the common polymer in which sugar
is usually stored in plants.
– Glycogen is an important polymer for storing sugar in animals.• Found in liver and muscle cells – can be converted
to glucose when needed.
– Cellulose is the main structural carbohydrate in plants.
LipidsLipids
• Lipids are fatty substances.
– Nonpolar – insoluble in water
– Fatty acids – smallest unit
– Neutral fats
– Phospholipids
– Steroids
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Examples of Lipids
Neutral FatsNeutral Fats
• Neutral fats are the major fuel of animals.
– Triglycerides – glycerol and 3 fatty acids
Neutral FatsNeutral Fats
• Saturated fatty acids occur when every
carbon holds two hydrogen atoms.
• Unsaturated fatty acids have two or more
carbon atoms joined by double bonds.
Neutral FatsNeutral Fats
• Neutral fats are the major fuel of animals.
– Triglycerides – glycerol and 3 fatty acids
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• Saturated fats can be
found in foods from animal
products and processed foods like dairy products,
cheese, ice creams, and
fatty meats.
Neutral FatsNeutral Fats
• Unsaturated fats
can be found in foods like olives, nuts, canola oils, fish, sunflower
and soy beans.
PhospholipidsPhospholipids
• Phospholipids are important components of cell membranes.
• They resemble triglycerides, except one fatty acid is replaced by phosphoric acid and an organic base.
• The phosphate group is charged (polar).
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SteroidsSteroids
• Steroids are complex
alcohols with fatlike
properties.
– Cholesterol
– Vitamin D
– Adrenocortical hormones
– Sex hormones
ProteinsProteins
• Proteins are large complex molecules
composed of amino acids.
– Amino acids linked by peptide bonds.
– Two amino acids joined – dipeptide
– Many amino acids – polypeptide chain
ProteinsProteins
• There are 20 different types of amino
acids.
ProteinsProteins
• Proteins serve many functions.
– Structural framework
– Enzymes that serve as catalysts
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Examples of
Proteins
Nucleic AcidsNucleic Acids
• Nucleic acids are complex molecules with
particular sequences of nitrogenous bases that
encode genetic information.
– The only molecules that can replicate themselves –with help from enzymes.
– Deoxyribonucleic acid (DNA)
– Ribonucleic acid (RNA)
• The repeated units, called nucleotides, each contain a sugar, a nitrogenous base, and a
phosphate group.
A nucleotide is made of:A nucleotide is made of: DNA structure: Double HelixDNA structure: Double Helix
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Genetic ProgramGenetic Program
• Genetic information is coded in DNA.
• DNA is a long chain of nucleotides – a sugar phosphate + nitrogenous base (A,
C, G, & T).
– The sequence of nucleotides codes for the order of amino acids in the protein specified.
• The genetic code
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Genetic ProgramGenetic Program
• RNA - is a single stranded chain of
neuclotides – a sugar phosphate + nitrogenous base (A, C, G, & U).
• RNA is trabscribed from DNA, and translated to protein by translation or protein synthesis.
– The sequence of nucleotides codes for the
order of amino acids in the protein specified.
• The genetic code
Genetic ProgramGenetic Program
• The genetic code is universal
among living organisms from bacteria through humans.– Supports the
concept of a single origin of life.