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Biochemistry

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Wait, Chemistry?? I thought I was in Biology

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What does Biochemistry mean?

Why do we need to understand

Biochemistry?

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Uses of Organic Molecules

Americans consume an average of 140 pounds of sugar per person per year

Cellulose, found in plant cell walls, is the most abundant organic compound on Earth

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Uses of Organic Molecules

A typical cell in your body has about 2 meters of DNA

A typical cow produces over 200 pounds of methane gas each year

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WaterAbout 60-90 percent of an organism is water

Water is used in most reactions in the bodyWater is called the universal solvent

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Water PropertiesPolarity

CohesivenessAdhesivenessSurface Tension

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Carbon-based MoleculesAlthough a cell is mostly water, the rest of the cell consists mostly of carbon-based moleculesOrganic chemistry is the study of carbon compounds

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Carbon is a Versatile AtomIt has four electrons in an outer shell that holds eightCarbon can share its electrons with other atoms to form up to four covalent bonds

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Hydrocarbons

The simplest carbon compounds …Contain only

carbon & hydrogen atoms

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Carbon can use its bonds to::

Attach to other carbons – they can be straight, unbranched or branched chains or ring structures.

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Large Hydrocarbons:Are the main

molecules in the gasoline we burn in our cars

The hydrocarbons of

fat molecules provide energy for our bodies

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Shape of Organic Molecules

Each type of organic

molecule has a unique three-dimensional

shapeThe shape determines its function in an

organism

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Functional Groups are:Groups of atoms that give

properties to the compounds to which they attach

Gained Electrons Lost Electrons

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Common Functional Groups

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Giant Molecules - PolymersLarge molecules are called polymersPolymers are built from smaller molecules called monomersBiologists call them macromolecules

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Examples of PolymersProteins

Lipids

CarbohydratesNucleic

Acids

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Most Macromolecules are Polymers

Polymers are made by stringing together many smaller molecules called monomers

Nucleic Acid

Monomer

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Linking MonomersCells link monomers by a process

called condensation or dehydration synthesis (removing a molecule of

water)

This process joins two sugar monomers to make a double

sugar

Remove H

Remove OH

H2O Forms

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Breaking Down PolymersCells break

down macromolecules by a process called hydrolysis (adding a molecule of water) Water added to split a double

sugar

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Macromolecules in OrganismsThere are four categories of large

molecules in cells:Carbohydrates

LipidsProteins

Nucleic Acids

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CarbohydratesCarbohydrates

include: Small sugar

molecules in soft drinks

Long starch molecules in pasta

and potatoes

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Monosaccharides:Called simple

sugarsInclude glucose, fructose, & galactoseHave the same chemical, but different structural formulasC6H12O6

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MonosaccharidesGlucose is found in sports drinksFructose is found in fruitsHoney contains both glucose & fructoseGalactose is called “milk sugar”

-OSE ending means SUGAR

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IsomersGlucose & fructose are isomers because they’re structures are different, but their chemical formulas are the same

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RingsIn aqueous (watery) solutions,

monosaccharides form ring structures

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Cellular Fuel

Monosaccharides are the main fuel that cells use for cellular work

ATP

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DisaccharidesA disaccharide is a double sugarThey’re made by joining two monosaccharidesInvolves removing a water molecule (condensation)Bond called a GLYCOSIDIC bond

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Disaccharides

Common disaccharides include:

Sucrose (table sugar)Lactose (Milk Sugar)Maltose (Grain sugar)

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DisaccharidesSucrose is composed of glucose + fructoseMaltose is composed of 2 glucose moleculesLactose is made of galactose + glucose GLUCOSE

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PolysaccharidesComplex carbohydrates

Composed of many sugar monomers linked togetherPolymers of monosaccharide chains

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Examples of Polysaccharides

Starch

Glycogen

Cellulose

Glucose Monomer

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StarchStarch is an example of a

polysaccharide in plants

Plant cells store starch for energy

Potatoes and grains are major sources of starch in the human diet

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GlycogenGlycogen is an

example of a polysaccharide in animalsAnimals store excess

sugar in the form of glycogenGlycogen is similar in structure to starch because BOTH are made of glucose monomers

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CelluloseCellulose is the most abundant

organic compound on EarthIt forms cable-like fibrils in the tough walls that enclose plants

It is a major component of woodIt is also known as dietary fiber

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Cellulose

SUGARS

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Dietary CelluloseMost animals cannot derive

nutrition from fiberThey have bacteria in their digestive tracts that can break down cellulose

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Sugars in WaterSimple sugars and double sugars

dissolve readily in waterThey are hydrophilic, or “water-loving”

WATER MOLECULE

SUGAR MOLECULE

-OH groups make them water soluble

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LipidsLipids are hydrophobic –”water

fearing”

Includes fats, waxes, steroids, & oils

Do NOT mix with water

FAT MOLECULE

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Function of LipidsFats store energy, help to insulate

the body, and cushion and protect organs

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Types of Fatty Acids

Unsaturated fatty acids have less than the maximum number of hydrogens bonded to the carbons (a double bond between carbons)

Saturated fatty acids have the maximum number of hydrogens bonded to the carbons (all single bonds between carbons)

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Types of Fatty Acids

Single Bonds in Carbon chain

Double bond in carbon chain

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Triglyceride

Monomer of lipids

Composed of Glycerol & 3 fatty acid chainsGlycerol forms the “backbone” of the fat Organic

Alcohol (-OL ending)

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Triglyceride

Glycerol Fatty Acid Chains

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Fats in OrganismsMost animal fats have a high

proportion of saturated fatty acids & exist as solids at room temperature (butter, margarine, shortening)

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Fats in OrganismsMost plant oils tend to be low in

saturated fatty acids & exist as liquids at room temperature (oils)

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FatsDietary fat consists largely of the

molecule triglyceride composed of glycerol and three fatty acid chains

Glycerol

Fatty Acid Chain

Condensation links the fatty acids to Glycerol

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Lipids & Cell Membranes

• Cell membranes are made of lipids called phospholipids

• Phospholipids have a head that is polar & attract water (hydrophilic)

• Phospholipids also have 2 tails that are nonpolar and do not attract water (hydrophobic)

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SteroidsThe carbon skeleton of steroids is bent to form 4 fused ringsCholesterol is the “base steroid” from which your body produces other steroidsEstrogen & testosterone are also steroids

Cholesterol

TestosteroneEstrogen

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Synthetic Anabolic SteroidsThey are variants of testosteroneSome athletes use them to build up their muscles quicklyThey can pose serious health risks

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ProteinsProteins are polymers made of

monomers called amino acids

All proteins are made of 20 different amino acids linked in different ordersProteins are used to build cells, act as hormones & enzymes, and do much of the work in a cell

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Four Types of Proteins

Structural

Contractile

Storage

Transport

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20 Amino Acid Monomers

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Structure of Amino Acids

Amino acids have a central carbon with 4 things bonded to it:Amino group –NH2

Carboxyl group -COOH

Hydrogen -HSide group -R

Amino

group

Carboxylgroup

R group

Side groups

Leucine -hydrophobic

Serine-hydrophillic

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Linking Amino AcidsCells link amino acids together to make proteinsThe process is called condensation or dehydrationPeptide bonds form to hold the amino acids together

Carboxyl

Amino Side

Group

Dehydration Synthesis

Peptide Bond

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Proteins as EnzymesMany proteins act as biological

catalysts or enzymesThousands of different enzymes exist in the bodyEnzymes control the rate of chemical reactions by weakening bonds, thus lowering the amount of activation energy needed for the reaction

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Enzymes

Their folded conformation creates an area known as the active site.

Enzymes are globular proteins.

The nature and arrangement of amino acids in the active site make it specific for only one type of substrate.

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Enzyme + Substrate = Product

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How the Enzyme Works

Enzymes are reusable!!!Active site changes SHAPECalled INDUCED FIT

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Primary Protein StructureThe primary structure is the specific sequence of amino acids in a proteinCalled polypeptide

Amino Acid

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Protein Structures

Secondary protein structures occur when protein chains coil or foldWhen protein chains called

polypeptides join together, the tertiary structure forms because R groups interact with each otherIn the watery environment of a cell, proteins become globular in their quaternary structure

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Protein Structures or CONFORMATIONS

Hydrogen bond

Pleated sheet

Amino acid

(a) Primary structure

Hydrogen bond

Alpha helix

(b) Secondary structure

Polypeptide(single subunit)

(c) Tertiary structure

(d) Quaternary structure

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Denaturating ProteinsChanges in temperature & pH can denature (unfold) a protein so it

no longer worksCooking denatures protein in eggs

Milk protein separates into curds & whey when it denatures

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Changing Amino Acid Sequence

Substitution of one amino acid for another in hemoglobin causes

sickle-cell disease

(a) Normal red blood cell Normal hemoglobin

1 2 34 5

6 7. . . 146

(b) Sickled red blood cell Sickle-cell hemoglobin

2 314 5

6 7. . . 146

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Other Important Proteins

•Blood sugar level is controlled by a protein called insulin

•Insulin causes the liver to uptake and store excess sugar as Glycogen

•The cell membrane also contains proteins

•Receptor proteins help cells recognize other cells

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INSULIN

Cell membrane with proteins & phospholipids

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Nucleic AcidsStore hereditary informationContain information for making all the body’s proteinsTwo types exist --- DNA & RNA

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Nucleic AcidsNitrogenous base

(A,G,C, or T)

Phosphategroup

Thymine (T)

Sugar(deoxyribose)

Phosphate

BaseSugar

Nucleic acids are polymers of nucleotides

Nucleotide

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Nucleotide – Nucleic acid monomer

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BasesEach DNA nucleotide has one of the following bases:

Thymine (T) Cytosine (C)

Adenine (A) Guanine (G)

–Adenine (A)–Guanine (G)–Thymine (T)–Cytosine (C)

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Nucleotide MonomersForm long chains called DNA

Backbone

Nucleotide

Bases

DNA strand

Nucleotides are joined by sugars & phosphates on the side

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DNA

Two strands of DNA join together to form a double helix

Basepair

Double helix

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RNA – Ribonucleic AcidRibose sugar has an extra –OH or hydroxyl groupIt has the base uracil (U) instead of thymine (T)

Nitrogenous base(A,G,C, or U)

Sugar (ribose)

Phosphategroup

Uracil

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ATP – Cellular Energy

•ATP is used by cells for energy

•Adenosine triphosphate•Made of a nucleotide with 3

phosphate groups

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Summary of Key Concepts

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Nucleic Acids

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Macromolecules

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Macromolecules

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End