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Biochemistry of Cells

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What you need to learn…

1.Why carbon?2.Name the 4 macromolecules3.Know the building block or monomer of each.4.Know their functions5.Know examples of each.6.Know what dehydration synthesis and hydrolysis are.7.Understand some properties of these molecules

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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 Properties

Polarity

CohesivenessAdhesivene

ss

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The Water MoleculeThe Water Molecule

PolarityPolarityA water molecule is polar because there is

an uneven distribution of electrons between the oxygen and hydrogen atoms.

(+)

(—)

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Hydrogen BondsHydrogen Bonds

Polar water molecules Polar water molecules act like magnetsact like magnets and and attract each other attract each other

Hydrogen BondsHydrogen BondsThe attraction of the Hydrogen end (+) of The attraction of the Hydrogen end (+) of

one molecule for the Oxygen end one molecule for the Oxygen end (-)(-) of of another water molecule.another water molecule.

They are the They are the strongest bondsstrongest bonds that can that can form form betweenbetween moleculesmolecules

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Hydrogen BondsHydrogen Bonds

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CohesionCohesion

The attraction between molecules of the same substance (e.g. water).

Allows some insects and spiders to walk on water.

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AdhesionAdhesion

Attraction between molecules of Attraction between molecules of different substancesdifferent substances

Responsible for Capillary forces in Responsible for Capillary forces in plantsplants

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Carbon-based MoleculesAlthough a cell is mostly water, the rest of the cell consists mostly of carbon-based molecules

Organic chemistry is the study of carbon compounds

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Carbon is a Versatile Atom

It has four electrons in an outer shell that holds eight

Carbon can share its electrons with other atoms to form up to four covalent bonds

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Carbon can use its bonds to::

Attach to other carbons

Form an endless diversity of carbon skeletons

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Shape of Organic Molecules

Each type of organic molecule has a unique

three-dimensional shape

The shape determines its function in an

organism

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Giant Molecules - PolymersLarge molecules are called polymers

Polymers are built from smaller molecules called monomersBiologists call them macromolecules

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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 Monomers

Cells link monomers by a process called 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 Organisms

There are four categories of large molecules in cells:

Carbohydrates

Lipids

Proteins

Nucleic Acids

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Monosaccharides:

Called simple sugars

Include glucose, fructose, & galactoseHave the same chemical, but different structural formulas called an isomer.C6H12O6

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Monosaccharides

Glucose is found in sports drinks

Fructose is found in fruitsHoney contains both glucose & fructoseGalactose is called “milk sugar”

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Carbohydrates

Carbohydrates include: Small sugar molecules

in soft drinksLong starch molecules in pasta and potatoes

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Rings

In 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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Disaccharides

A disaccharide is a double sugar

They’re made by joining two monosaccharides

Involves removing a water molecule (dehydration)

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Disaccharides

Common disaccharides include:

Sucrose (table sugar)

Lactose (Milk Sugar)

Maltose (Grain sugar)

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Polysaccharides

Complex 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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Sugars in Water

Simple sugars and double sugars dissolve readily in water

They are hydrophilic, or “water-loving”

WATER MOLECULE

SUGAR MOLECULE

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Lipids

Lipids are hydrophobic –”water fearing”

Includes fats, waxes, steroids, & oils

Do NOT mix with water

FAT MOLECULE

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Function of Lipids

Fats 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

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Triglyceride

Glycerol Fatty Acid Chains

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Fats in Organisms

Most 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 Organisms

Most plant oils tend to be low in saturated fatty acids & exist as liquids at room temperature (oils)

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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 steroids

Estrogen & 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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Proteins

Proteins are polymers made of monomers called amino acids

All proteins are made of 20 different amino acids linked in different orders

Proteins 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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Linking Amino Acids

Cells link amino acids together to make proteinsThe process is called dehydration synthesisPeptide bonds form to hold the amino acids together

Carboxyl

Amino Side

Group

Dehydration Synthesis

Peptide Bond

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Proteins as Enzymes

Many proteins act as biological catalysts or enzymes

Thousands of different enzymes exist in the body

Enzymes control the rate of chemical reactions by weakening bonds, thus lowering the amount of activation energy needed for the reaction

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Protein Structures

Secondary protein structures occur when protein chains coil or fold

When protein chains called polypeptides join together, the tertiary structure forms

In the watery environment of a cell, proteins become globular in their quaternary structure

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Denaturating Proteins

Changes 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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Nucleic Acids

Store hereditary information

Contain 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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Bases

Each 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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End