Unit 12Biochemistry

Carbohydrates

Tro's Introductory Chemistry, Chapter 19 3

Carbohydrates

• carbon, hydrogen & oxygen

• also known as sugars, starches, cellulose, dextrins & gums

• Produced through photosynthesis by plants

• Identified by the number of carbon atoms

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Types of Carbohydrates The types of carbohydrates are

• monosaccharides, the simplest carbohydrates

• disaccharides, which consist of two monosaccharides

• polysaccharides, which contain many monosaccharides

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Monosaccharides Monosaccharides are carbohydrates with

• three to six carbon atoms

• a carbonyl group (aldehyde or ketone)

• several hydroxyl groups

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Some Important Monosaccharides

Glucose (C6H12O6) is

• an aldohexose

• found in fruits, vegetables, corn syrup, and honey

• found in disaccharides

• the monosaccharide in polymers of starch, cellulose, and glycogen

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Blood Glucose LevelIn the human body,

• glucose has a normal blood level of 70 to 90 mg/dL

• a glucose tolerance test measures blood glucose for several hours after ingesting glucose

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Some Important Monosaccharides

Fructose is

• a ketohexose with the formula C6H12O6

• the sweetest monosaccharide

• found in fruit juices and honey

• converted to glucose in the body

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Cyclic Structure for Glucose

STEP 1 Turn the open-chain structure

clockwise 90°.

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Cyclic Structure for Glucose (continued)

STEP 2 Fold the carbon chain into a hexagon and bond the O on carbon 5 to the carbonyl group.

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Cyclic Structure for Glucose (continued)

STEP 3 Draw the new –OH on C1 down to give the form or up to give the form.

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Solution

Lipids

Tro's Introductory Chemistry, Chapter 19 14

Lipids• chemicals of the cell that are insoluble in water,

but soluble in nonpolar solvents• fatty acids, fats, oils, phospholipids, glycolipids,

some vitamins, steroids and waxes• structural components of cell membrane

because they don’t dissolve in water

• long-term energy storage• insulation

Tro's Introductory Chemistry, Chapter 19 15

Fatty Acids• carboxylic acid (head) with a very long

hydrocarbon side-chain (tail)• saturated fatty acids contain no C=C double bonds

in the hydrocarbon side-chain• unsaturated fatty acids have C=C double bonds

monounsaturated have 1 C=C polyunsaturated have more than 1 C=C

CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 C

O

OH

HeadTail

Tro's Introductory Chemistry, Chapter 19 16

Fats & Oils: Triglycerides• fats are solid at room temperature,

oils are liquids• trigylcerides are triesters of

glycerol with fatty acids the bonds that join glycerol to the

fatty acids are called ester linkages• triglycerides differ in

Length of the fatty acid side-chains (12 to 20 C)

Glycerol

CH2

CH2

CH2

OH

OH

OH

CH2

CH2

CH2

O

O

O

C

C

C

O

O

O

CH2

CH2

CH2

CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2

CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2

CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2

CH3

CH3

CH3

ester linkage

Tro's Introductory Chemistry, Chapter 19 17

Steroids• characterized by 4 linked carbon

rings• mostly hydrocarbon-like

dissolve in animal fat• mostly have hormonal effects• serum cholesterol levels linked to

heart disease and strokelevels depend on diet, exercise,

emotional stress, genetics, etc.• cholesterol synthesized in the liver

from saturated fats

Proteins

Tro's Introductory Chemistry, Chapter 19 19

Amino Acids• main difference between amino acids is the side

chainR group

• some R groups are polar, others are nonpolar• some polar R groups are acidic, others are basic• some R groups contain O, others N and others S• some R groups are rings, other are chains • the differences in the R groups give the amino

acids their different properties

Tro's Introductory Chemistry, Chapter 19 20

Types of Proteins

• tertiary structure determines the type of protein• globular

folds into a fairly compact, spherical shapewater solublemobile

• fibrous long coils aligned in stacks like pipeswater insolubleprovide strength to tissues

Common Functions of Proteins

• Structure – bone, skin, cartilage, tendons, nails, hair

• Movement – muscles

• Protection – antibodies, blood clotting

• Catalysis – emzymes

• Transport – oxygen (hemoglobin)

• Energy – extract energy from food

Tro's Introductory Chemistry, Chapter 19 21

Nucleic Acids

Tro's Introductory Chemistry, Chapter 19 23

Nucleic Acids• carry genetic information• Every cell has a complete copy• RNA molar mass = 20K to 40K amu

i.e BIG polymers

Tro's Introductory Chemistry, Chapter 19 24

DNA• deoxyribonucleic acid• sugar is deoxyribose• one of the following amine

basesadenine (A)guanine (G)cytosine (C) thymine (T)

• 2 DNA strands wound together in double helix