Human Biology Sylvia S. Mader Michael Windelspecht Chapter 2 Chemistry of Life Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required

Human BiologySylvia S. Mader

Michael Windelspecht

Chapter 2 Chemistry of

LifeLecture Outline

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Points to ponder

• How are living things organized from atoms to molecules?

• What is pH and how is it important to living organisms?• What are the four macromolecules found in living

organisms?• What are the structure (subunits) and function of these 4

macromolecules?• How are proteins organized and how is their shape

important to their function?• How are DNA similar and how are they different?

Building blocks from large to small• Matter is anything that has weight and takes up

space

• Elements are the basic building blocks of matter that cannot be broken down by chemical means

• Atoms are the smallest units of an element that retain the element’s physical and chemical properties. These bond together to form molecules.

2.1 From atoms to molecules

Atoms• Atom symbol • Atomic mass• Atomic number



I

1

H

2

V

3 4 5

B

6

C

7

N

8

O

9

F

P S

K

atomic number

atomic symbol atomic mass

1.008

Li Ne

He

4.003

VIII

II III IV VI VII

10

Be

20.1819.0016.0014.0112.016.941 9.012 10.81

11 18

Na

22.99

19

39.10

24.31

Mg

12

Ar

39.95

1716151413

Al Si Cl

35.4532.0730.9728.0926.98

20 31 32 33 34 35 36

83.60

Kr

79.90

Br

78.96

Se

74.92

As

72.59

Ge

69.72

Ga

40.08

Ca

Subatomic particles of atoms• Neutrons have a neutral charge

• Protons are positively charged

• Neutrons and protons make up the nucleus

• Electrons are negatively charged and orbit around the nucleus



0

1

1

1p

hydrogenH

Subatomic Particles

Atomic MassChargeParticle

Proton

Neutron

Electron 0.00055

+1

-1

6p6n

8p8n

7p7n

oxygenO

carbonC

nitrogenN

Isotopes

• Isotopes are atoms that have the same atomic number but a different atomic mass because the number of neutrons differ

• Radioactive isotopes are useful in dating old objects, imaging body organs and tissues through x-rays and killing cancer cells

• Radiation can be harmful by damaging cells and DNA and/or causing cancer



a.

b.

larynx

thyroid gland

trachea

missingportionoforgan

a: © Biomed Commun./Custom Medical Stock Photo; b(patient): Courtesy National Institutes of Health; (brain scan):

© Mazzlota et al./Photo Researchers, Inc.

Molecules:

• Are made of atoms that are bonded together

• Can be made of the same atom or different atoms


Ionic bonds:• Atoms in this type of bond donate or take on electrons• Results in a stable outer shell• Occurs between particles that are charged (ions)



+

Cl

–

Na

sodium atom (Na) chlorine atom (Cl)

Na Cl

sodium ion (Na+)

sodium chloride (NaCl)

chloride ion (Cl–)

b.

Na+ Cl-

a.b: (crystals, shaker)

Covalent bonds:• Atoms in this type of bond share electrons

• Results in a stable outer shell



+

+

b. When two oxygen atoms covalently bond, oxygen gas results.

8p8n

8p8n

8p8n

8p8n

1p

1p

8p8n

1p

1p

oxygenO

2 hydrogen2H

a. When an oxygen and two hydrogen atoms covalently bond, water results.

waterH2O

oxygenO2

oxygen gasO2

oxygenO2

8p8n

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What are the properties of water?• Liquid at room temperature

• Liquid water does not change temperature quickly

• High heat of vaporization

• Frozen water is less dense than liquid water

• Molecules of water cling together

• A solvent for polar molecules

2.2 Water and living things

What bond holds water molecules together?

• Hydrogen bonds occur between a hydrogen in a covalent bond anda negatively charged atom

• These are relatively weak bonds


HH

Hydrogen bonding between water molecules

O

hydrogenbond

+

+

-


Acids and bases

• Acids are substances that dissociate and release hydrogen atoms

• Bases are substances that take up hydrogen atoms or release hydroxyl ions


What is the pH scale?

• A measure of hydrogen ion concentration

• Working scale is between 0 and 14 with 7 being neutral

• A pH below 7 is acidic and above 7 is basic

• The concentration of ions between each whole number is a factor of 10


Looking at the pH scale2.2 Water and living things

H+ OH–


acid

icb

asi

c

stomach acid, lemon juice

vinegar, cola, beer

10

23456789

H+ IonConcentration pH Value Examples

hydrochloric acid

tomatoesblack coffeeurinepure waterseawaterbaking sodaGreat Salt Lakehousehold ammonia

household bleach

sodium hydroxide

10-1

100

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

10-13

10-14

10-2

1413121110

Making and breaking down organic molecules

• Dehydration reaction – the removal of water that allows subunits to link together into larger molecules

• Hydrolysis reaction – the addition of water that breaks larger molecules into their subunits

2.3 Molecules of life

How do we build and break down organic molecules?



subunitsubunit

hydrolysisreaction

subunitsubunit

subunitsubunit

dehydrationreaction

subunitsubunit H

H2O

H2O

b.

a.

OH

OH H

What organic molecules are found in living organisms?

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids


1. What are carbohydrates?

• Made of subunits called monosaccharides

• Made of C, H and O in which the H and O atoms are in a 2:1 ratio

• Function as short and long-term energy storage

• Found as simple and complex forms

2.4 Carbohydrates

• Monosaccharide – 1 carbon ring as found in glucose

• Disaccharide – 2 carbon rings asfound in maltose

What are simple carbohydrates?2.4 Carbohydrates

O H

O H

H

H

H

H

H O

C6H12O6

O H

HO

C

C

C

CC

4

5

6

3 2

1

O HH

H

H

CH2OH

HO O

OHHO

OH

CH2OH

maltose

O O

O

C12H22O11

CH2OHCH2OH



What are complex carbohydrates?• Polysaccharides are made of many carbon rings

• Glycogen is the storage form in animals

• Starch is the storage form in plants

2.4 Carbohydrates


O

H

O

O

OH

HHOH H

starchgranule

cell wall

potato cells

nonbranched

branched

H OHHOHOH H OH H

OO

H O

OH HH

HOH OHH

HOHH H H H O CH2OH CH2OH CH2OH CH2OH

© Jeremy Burgess/SPL/Photo Researchers, Inc.

2. What are lipids?

• Molecules that do not dissolve in water

• Used as energy molecules

• Found in cell membranes

• Found as fats and oils, phospholipids and steroids

2.5 Lipids

How are fats and oils different?

• Fats• Usually animal origin• Solid at room temperature• Function as long-term energy storage, insulation from

heat loss and cushion for organs

• Oils• Usually plant origin• Liquid at room temperature

2.5 Lipids

What is the structure of fats and oils?

• A glycerol molecule and 3 fatty acid tails

2.5 Lipids


C

C

H H H H H H

C

H H H

C C C

H

C

C

H

C

H

H H H H

C

H H

C

H

C

+

C

H

H

3 fatty acidsglycerol fat molecule 3 watermolecules

dehydration reaction

OH

OH

OH

H

H

H

H

H C

C

C

H H H H

HCCCCCO

HO

HO

O

HO

O

HHH

HCCCCC

HHHHH

HHHHHH

HCCCCCC+

H

H

H

H

H H H H

HCCCCCC

HHHHHO

HHHHO

HHHHHO H

HC

C

C

O

O

O

3 H2O

H

Chydrolysis reaction

Understanding fats when reading a nutrition label

• Recommendation for total amount of fat for a 2,000 calorie diet is 65g

• Be sure to know how many servings there are

• A % DV of 5% or less is low and 20% or more is high

• Try to stay away from trans fats

• Would you eat the food on the right? Why or why not?

2.5 Lipids


Start here.

Limit thesenutrients.

Get enoughof thesenutrients.

18%

15%

10%

20%

10%

0%

4%

2%

20%

4%

Calories from Fat 110Calories 250

Amount Per Serving

Serving Size 1 cup (228g)Servings Per Container 2

%Daily Value

Iron

Calcium

Vitamin C

Vitamin A

Protein 5g

Sugars 5g

Dietary Fiber 0g

Total Carbohydrate 31g

Sodium 470mg

Cholesterol 30mg

Trans Fat 1.5g

Saturated Fat 3g

Total Fat 12g


What are steroids?

• A lipid

• Structure is four fused carbon rings

• Examples are cholesterol and sex hormones

2.5 Lipids


OHCH3

a. Cholesterol

b. Testosterone c. Estrogen

CH3

CH3

CH3

CH3

HO

HO

OH

O

CH3

H3C

H3C

b: © Warren Toda/epa/Corbis; c: © Tony Marsh/Reuters/Corbis

3. What are proteins?

• Made of subunits called amino acids

• Important for diverse functions in the body including hormones, enzymes, antibodies and transport

• Can denature, change in shape, that causes loss of function

2.6 Proteins

What do amino acids look like?2.6 Proteins


C

O

C C

C C

C C

H O

C

O

C C

O

cysteine (cys)(polar)

aspartic acid (asp)(ionized, polar)

tryptophan (trp)(nonpolar)

valine (val)(nonpolar)

lysine (lys)(ionized, polar)

glutamic acid (glu)(ionized, polar)

N+H3

CH2

CH2

CH2

H3N+

O

O–

H

CH2

CH2

COO–CH2

CH

H3C

H3N+

H

C C

O

O–

H3N+

H O

O–

H3N+

H

C

CH2

NH CH2H3N+

SH

HH3N+

CH2

O–

O–

O–

–O


What are the four levels of protein organization?

• Primary – the linear order of amino acids• Secondary – localized folding into pleated

sheets and helices• Tertiary – the 3-D shape of the entire protein in

space• Quaternary – combination of more than one

polypeptide• All proteins have primary, secondary and tertiary

structure, while only a few have quaternary structure

2.6 Proteins

What do the levels of organization look like?

2.6 Proteins


C NR

C

R

C N

C

R

C

N

C

R

N

C

R

N R

N

C

N R

hydrogen bondSecondary Structure:Alpha helix or a pleated sheet

hydrogen bond

(beta) sheet=pleated sheet (alpha) helix

Tertiary Structure:final shape of polypeptide disulfide bond

Quaternary Structure:two or more associatedpolypeptides

CH

CH

CHCH

CH

CHCH

CH

peptide bond

H3N+

Primary Structure:sequence of amino acids

amino acid

COO–

4. What are nucleic acids?

• Made of nucleotide subunits

• Function in the cell to make proteins

• Includes RNA and DNA

2.7 Nucleic acids

What are the 3 parts of a nucleotide?

2.7 Nucleic acids


nitrogen-containingbase

sugar

Nucleotide

phosphate P C

5'

4'

3'

1'

2'

S

O

What are the five bases found in nucleotides?

• Adenine (A) and guanine (G) are double-ringed purines• Cytosine (C), thymine (T) and uracil (U) are single-ringed

pyrimidines• In DNA A pairs with T and G pairs with C

2.7 Nucleic acids


C

O

U

ON

N

NO

a. DNA structure with base pairs: A with T and G with C b. RNA structure with bases G, U, A, C

Uracil (U)(RNA only)

bases

backbone

Hydrogen bond

Cytosine (C)Guanine (G)

A

T

CA

G

G

C

T

Adenine (A) Thymine (T)(DNA only)

P

S

P

S

P

S

S

P

G

U

A

CN

N

H N

H

O

H

H

H

N

N

N

H

H

N

N

N

NC

NO

H N

CH3

HN CH

CH

O

NH

C

Summary of DNA and RNA structural differences?

• DNA– Sugar is deoxyribose– Bases include A, T, C

and G– Double stranded

• RNA– Sugar is ribose– Bases include A, U, C

and G– Single stranded

2.7 Nucleic acids

Summary of the macromoleculesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

S

C

O

P

OHH

H

H

HO OH

HO

C

H

H H H

C

H

C

H

C

H

H

C

H

H

RC

O

H O

C O HH

H

C O HH

C O HH

H

H

C

R

Long-termenergystorage;membranecomponents

Immediateenergyand storedenergy;structuralmolecules

Carbohydrates

Lipids

Proteins

Nucleic acidsStorage ofgeneticinformation

Support,metabolic,transport,regulation,motion

Fatty acid

Glycerol

Monosaccharides,disaccharides,polysaccharides

Fats, oils,phospholipids,steroids

Structural,enzymatic,carrier,hormonal,contractile

DNA, RNA

Organicmolecules

Examples Monomers Functions

Nucleotide

basephosphate

aminogroup

acidgroupCOOH

Glucose

Amino acid

group

H2N

CH2OH

OH

Documents

Human Biology Sylvia S. Mader Michael Windelspecht Chapter 2 Chemistry of Life Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required