Biological Moleculer: Chemical Compenent

8/7/2019 Biological Moleculer: Chemical Compenent

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Cemist component Biological molecules are made by the

relatively simple process of joiningtogether many small repeating subunits


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Organic Molecules

Composed primarily of H, C, O, & N.

Look at the common functional groups.


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General characteristics

the term carbohydrate is derived from thefrench: hydrate de carbone

compounds composed ofC, H, and O (CH2O)n when n = 5 then C5H10O5 not all carbohydrates have this empirical

formula: deoxysugars, aminosugars

carbohydrates are the most abundantcompounds found in nature (cellulose: 100billion tons annually)


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General characteristics

Most carbohydrates are found naturally inbound form rather than as simple sugars

Polysaccharides (starch, cellulose, inulin, gums) Glycoproteins and proteoglycans (hormones, blood group

substances, antibodies)

Glycolipids (cerebrosides, gangliosides)

Glycosides

Mucopolysaccharides (hyaluronic acid)

Nucleic acids


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Monosaccharides - simple sugars with multiple OH

groups. Based on number of carbons (3, 4, 5, 6), amonosaccharide is a triose, tetrose, pentose or hexose.

Disaccharides - 2 monosaccharides covalently linked.

Oligosaccharides - a few monosaccharides covalently

linked.

Polysaccharides - polymers consisting of chains ofmonosaccharide or disaccharide units.

I(CH2O)n orH-C-OH

I

Carbohydrates (glycans) have the

following basic composition:


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Monosaccharides

Aldoses (e.g., glucose)have an aldehyde group atone end.

Ketoses (e.g., fructose)have a keto group,usually atC2.

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose


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Sugar Nomenclature

For sugars with morethan one chiral center,D or L refers to theasymmetric C farthestfrom the aldehyde orketo group.

Most naturallyoccurring sugars are Disomers.

O H O H

C C

H C OH HO C H

HO C H H C OH

H C OH

H C OH

CH2OH CH2OH

D-glucose L-glucose


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Fructose forms either

a 6-member pyranose ring, by reaction of the C2keto group with the OH on C6, or

a 5-member furanose ring, by reaction of the C2

keto group with the OH on C5.

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

H

OHH

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) E-D-fructofuranose


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Cyclization of glucose produces a new asymmetric center atC1. The 2 stereoisomers are called anomers, E & F.

Haworth projections represent the cyclic sugars as havingessentially planar rings, with the OH at the anomeric C1:

E (OH below the ring)

F (OH above the ring).

H O

OH

H

OHH

OH

CH2OH

H

E-D-glucose

OH

H HO

OH

H

OHH

OH

CH2OH

H

H

OH

F-D-glucose

23

4

5

6

1 1

6

5

4

3 2


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Carbohydrates

Organic moleculesthat contain carbon,hydrogen and

oxygen. CnH2n0n.

Monosaccharides =

simple sugars. Structural isomers:

Glucose, fructose,

galactose.


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Disaccharide:

2 monosaccharides joined covalently.

Sucrose (glucose and fructose), lactose (glucose and

galactose), maltose (2 glucose). Polysaccharide:

Numerous monosaccharides joined covalently.

Starch (thousands of glucose joined), glycogen

(repeating glucose joined that are highly branched)..


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Organic molecules are built by dehydrationsynthesis:

C6H12O6 + C6H12O6 C12H22O11 + H2O


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Organic Molecules are broken down byhydrolysis

C12H22O11 + H2O C6H12O6 + C6H12O6


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Lipids

Insoluble in water because of nonpolarmolecules Triglycerides = 3 fatty acids + glycerol

Saturated = joined by only single bonds

Unsaturated = joined by at least one double bond

Hydrolysis oftriglycerides in adipose tissuereleases free fatty acids.

Free fatty acids can be converted in the liverto ketone bodies.

Excess ketone bodies can lower blood pH..


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Phospholipids = phosphate + fatty acid

phosphate end is polar = hydrophilic

fatty acid end is nonpolar = hydrophobic Steroids = aromatic rings = three 6-carbon

rings joined to a 5-carbon ring

Steroid hormones are cholesterol derivitaves..


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Proteins

Large molecules composed of long chainsof amino acids.

20 different amino acids can be used in

constructing a given protein. Each amino acid contains an amino group

(NH2) at one end and carboxyl group (COOH)at the other end.

Differences between amino acids are dueto differences in functional groups (R).

Amino acids are joined by peptide bonds..


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Protein Structure Levels

Primary structure is the sequence of theamino acids in the protein.

Secondary structure is produced byweak hydrogen bonds betweenhydrogen of one amino acid and the

and oxygen of a different amino acidnearby.

E-helix or F-sheet..


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The backbone of the nucleic acid isformed by the sugar and phosphatepairs.

The rungs are formed by pairednitrogenous bases.

Nitrogenous bases complementary pair

A + T (U) C + G..


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Overview: Types f B ndsOverview: Types f B nds There are 2 b nd types:ionic and covalent

In ionic bonding one atom has a stronger

attraction forelectrons than theother, and

steals an electron from a second atom

In covalent bonding the attraction forelectronsissimilar for two atoms. They

share theirelectrons toobtain an octet

MgO (ionic), CaCl2 (ionic), SO2(covalent),

PbCl2(ionic), CCl4 (covalent), CH4(covalent)


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Bonding is accomplished by interactionsbetween two atoms valence e-.

Ife- are shared between two atoms thatforms a covalent bond.

Single bonds = one shared pair

Double bonds = two shared pairs

Triple bonds = three shared pairs Ife- are transferred from one atom (ion)

to another that forms an ionic bond.

Hydrogen bonds are special (polar)

covalent bonds that are very importantto physiology.

Covalent Animation

Ionic Animation..


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Covalent bondingCovalent bonding

CCl4 - Covalent

C

Cl

ClCl

Cl

HCl - Covalent

H Cl

MgF2 - Ionic

[ F 2[Mg]2+

H2O - Covalent

H O H

NH3 - Covalent

H N H

H

NaCl - Ionic

[ Cl [Na] +

OH - Covalent

O H

H2 - Covalent

H H

For more lessons, visitwww.chalkbored.com


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MultipleMultiplebondsbonds

Build modelsofmolecules, O3 as challenge(cant build it orionic)

HCl - Covalent

H Cl H Cl

CO2 - Covalent

C OO

Na2O - Ionic

[ O ]2[Na]2+

H N H

H

H N H

H

OO

OO

O2 - Covalent

OO C

II

II

I2 - Covalent

[ O ]32[Al]2

3+

Al2O3 - Ionic

NH3 - Covalent

OO O

O OO

O3 - Covalent

H C H

H

H

H C H

H

H


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Bonds formed between the hydrogen

end (+ charged) of a polar moleculeand the end of any other polarmolecule or highly electronegative atom(e.g. P, N, O) are called hydrogenbonds.

These hydrogen bonds are veryimportant because they alter the

physical and chemical properties ofmany molecules (especially water)..


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Water

.

Life o earthevolvedin water,andall life still depends

on water.

At least 80% ofthe mass ofliving organisms is waterandalmostall chemical reactions oflifetakeplacein

aqueous solution.


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02_12_polar covalent.jpg


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Cohesion

The bonding of a high percentage of molecules toneighboring molecules

Helps pull water up through the microscopic vessels ofplants

Waterconducting cells

100 mFigure3.3


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CohesionSurface tension (related to cohesion) is

measure of how hard it is to break thesurface of a liquid

Figure3.4


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A universal solvent Is polar

Can dissolves salts


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Water as a solvent

The different regions of the polar watermolecule can interact with ionic

compounds called solutes and dissolvethem

Negative

oxygen regions

of polarwatermolecules

are attracted tosodium

cations(Na+).

+

+

+

+Cl

Na+

Positivehydrogen regions

ofwatermolecules

cling tochloride anions(Cl).

++

+

+

Na+

Cl

Figure3.6


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Biological Moleculer: Chemical Compenent

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