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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.