PowerPoint to accompany Hole’s Human Anatomy and … · 2014-07-15 · Compound – particle...

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Chapter 02

*Lecture Outline

*See separate Image PowerPoint slides for all

figures and tables pre-inserted into

PowerPoint without notes.

2

Why study chemistry in an

Anatomy and Physiology class?

- Body functions depend on cellular functions

- Cellular functions result from chemical

changes

- Biochemistry helps to explain physiological processes

2.2: Structure of Matter

3

Matter – anything that takes up space and has mass (weight).

It is composed of elements.

Elements – composed of chemically identical atoms:

• Bulk elements – required by the body in large amounts

• Trace elements - required by the body in small amounts

• Ultratrace elements – required by the body in very

minute amounts

Atoms – smallest particle of an element

Elements and Atoms

6

• All matter is composed of elements page 60

•Elements are:

• Bulk elements—body requires in mass

• Trace elements—required in small amounts

• Ultratrace elements—vital in very small amounts

• Elements are composed of atoms of the same type

• Compounds are composed of atoms of different types

that are chemically bonded

7

Common Elements

Let's work on that a bit. When reading you will find a bunch of words on a page. Letters make up those words. In English, we only have twenty-six letters, but we can make thousands of words. In chemistry, you are working with 120 elements. When you combine them, you can make millions of molecules.

Atomic Structure

8

Atoms - composed of

subatomic particles: • Proton – carries a single

positive charge

• Neutron – carries no

electrical charge

• Electron – carries a single

negative charge

Nucleus • Central part of atom

• Composed of protons and

neutrons

• Electrons move around the

nucleus

Electron

(e–)

Lithium (Li)

Proton

(p+)

Neutron

(n0)

Nucleus

0

0 + +

0 +

0

-

-

-

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9

Atomic Number

and

Atomic Weight

Atomic Number • Number of protons in the nucleus of one atom

• Each element has a unique atomic number

• Equals the number of electrons in the atom

Atomic Weight • Approximated by the number of protons plus the number of

neutrons in one atom (since a proton and a neutron each have an

approximate atomic weight of one)

• Electrons do not contribute to the weight of the atom

Isotopes

10

Isotopes • Atoms with the same atomic numbers but with

different atomic weights

• Different numbers of neutrons

• Oxygen often forms isotopes (O16, O17, and O18)

• Radioactive isotopes are unstable, releasing energy or

pieces of themselves (atomic radiation)

For an element, the atomic weight is often considered the

average of the atomic weights of its isotopes.

2.1 From Science to Technology

11

Radioactive Isotopes Reveal Physiology

Atoms that have the same atomic

number but different atomic weights

are called isotopes of an element.

Some radioactive isotopes are used to detect and treat

disease. (see page 62)


12

Ionizing Radiation:

Unstable isotopes are called radioactive, and the

energy or atomic fragments they emit are called

atomic radiation.

Elements that have radioactive isotopes include

oxygen, iodine, iron, phosphorus, and cobalt.

Atomic radiation includes three common forms

called alpha, beta, and gamma. Gamma radiation

is a form of energy similar to X-RAY

Molecules and Compounds

13

Molecule – particle formed when two or more atoms

chemically combine

Compound – particle formed when two or more atoms of

different elements chemically combine

Molecular formulas – depict the elements present and

the number of each atom present in the molecule

14

Molecules are groups of atoms bonded

together in the same way that words are groups

of letters. An "A" will always be an "A" no

matter what word it is in. A sodium (Na) atom

will always be a sodium atom no matter what

compound it is in. While the atoms may have

different masses and organization, they are all

built with the same parts. Electrons, protons,

and neutrons make the Universe the way it is.

Next slide shows the sodium-chloride bond forming common table

salt

http://www.chem4kids.com/files/elements/011_speak.html

http://www.chem4kids.com/files/atom_electron.html

http://www.chem4kids.com/files/atom_neutron.html

Bonding of Atoms

16

• Bonds form when atoms combine with other atoms

• Electrons of an atom occupy regions of space called

electron shells which circle the nucleus

• For atoms with atomic numbers of 18 or less, the following

rules apply:

• The first shell can hold up to 2 electrons

• The second shell can hold up to 8 electrons

• The third shell can hold up to 8 electrons

Bonding of Atoms

17

• Lower shells are filled first

• If the outermost shell is full, the atom is stable

Lithium (Li) Helium (He) Hydrogen (H)

+

-

-

-

0 0 +

+ -

-

-

0

0 + +

0 0

+


Ionic Bonds

18

• An attraction between a cation and an anion

Ionic Bonds

• Formed when electrons are transferred from one atom to

another atom

+ – 11p+

12n0

Chloride ion (Cl–) Sodium ion (Na+)

Sodium chloride

17p+

18n0


Na+

Cl–


Bonding of Atoms: Ions

19

Ion • An atom that gains or loses electrons to become stable

• An electrically charged atom

Cation • A positively charged ion

• Formed when an atom loses electrons

Anion • A negatively charged ion

• Formed when an atom gains

electrons

11p+

12n0

Sodium atom (Na) Chlorine atom (Cl)

17p+

18n0

Covalent Bonds

20

• Formed when atoms share electrons

• Hydrogen atoms form single bonds

• Oxygen atoms form two bonds

• Nitrogen atoms form three bonds

• Carbon atoms form four bonds

H ― H

O = O

N ≡ N

O = C = O

Hydrogen atom +

H

Hydrogen molecule

H2

Hydrogen atom

H

+ + + +

- -

-

-


Bonding of Atoms:

Structural Formula

21

• Structural formulas show how atoms bond and are arranged in

various molecules


O O O

CO2 H2O O2 H2

C

H H

O O H H

Bonding of Atoms:

Polar Molecules

22

Polar Molecules • Molecule with a slightly negative end and a slightly positive end

• Results when electrons are not shared equally in covalent bonds

• Water is an important polar molecule

Slightly negative ends

Slightly positive ends (a)

Hydrogen Bonds

23

Hydrogen Bonds • A weak attraction between the positive end of one polar

molecule and the negative end of another polar molecule

• Formed between water molecules

• Important for protein and nucleic acid structure

H

H

H

H

H

H

H H

H

H

O

O

O

O

O

Hydrogen bonds

(b)

24

When ionically bound substances are placed in

water, the ions are attracted to the positive and

negative ends of the water molecules and tend to

leave each other or dissociate. In this way, the

polarity of water dissociates the salts in the

internal environment.

The resulting solutions has electrically charged

particles (ions) so it conducts an electric current.

Substances that release ions in water are,

therefore called electrolytes.

Chemical Reactions

25

Chemical reactions occur when chemical bonds form or

break among atoms, ions, or molecules

Reactants are the starting materials of the reaction - the

atoms, ions, or molecules

Products are substances formed at the end of the chemical

reaction

NaCl Na+ + Cl-

Reactant Products

Types of Chemical Reactions

26

Synthesis Reaction – more complex chemical structure is

formed

A + B AB Decomposition Reaction – chemical bonds are broken to form

a simpler chemical structure

AB A + B

Exchange Reaction – chemical bonds are broken and new bonds

are formed

AB + CD AD + CB

Reversible Reaction – the products can change back to the

reactants

A + B n AB page 66

27

Electrolytes that dissociate to release hydrogen

ions in water are called acids. Substances that combine with hydrogen ions

are called bases. The compound sodium

hydroxide in water releases hydroxide ions

which can combine with hydrogen ions to form

water. Thus sodium hydroxide is a base.

Hydrogen ion concentration can be measured

by a shorthand we call the pH scale. This

system tracks the numbers of decimal places in

a hydrogen ion concentration.

Acids, Bases, and Salts

28

Electrolytes – substances that release ions in water

Acids – electrolytes that dissociate to release hydrogen ions

in water HCl H+ + Cl-

Bases – substances that release ions that can combine with

hydrogen ions

NaOH Na+ + OH-

Salts – electrolytes formed by the reaction between an acid

and a base

NaCl Na+ + Cl-

HCl + NaOH H2O + NaCl

29

Acids, Bases, and Salts


Ions in

solution

Na+

Cl–

Na+

Cl–

Salt crystal

Acid and Base Concentration

30

pH scale - indicates the concentration of hydrogen ions in

solution

Neutral – pH 7;

indicates equal

concentrations of H+

and OH- (hydroxide)

Acidic – pH less than

7; indicates a greater

concentration of H+

Basic or alkaline – pH greater than 7;

indicates a greater concentration of OH-

OH – concentration increases H + concentration increases

Acidic

H + Relative

Amounts

of H+ (red)

and OH–

(blue)

Basic

OH–

2.0

gastric

juice 6.0

corn

7.0

Distilled

water

8.0

Egg

white

10.5

milk of

magnesia

11.5

Household

ammonia

pH 0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 14

Basic (alkaline) Neutral Acidic

3.0

apple

juice

4.2

tomato

juice

5.3

cabbage

6.6

cow’s

milk

7.4

Human

blood

8.4

Sodium

biocarbonate


Changes in pH and Buffers

31

Blood pH • Normal blood pH is 7.35 – 7.45 which is venous and

which arterial ?????????????

• Alkalosis occurs when blood pH rises to 7.5 – 7.8

• Acidosis occurs when blood pH drops to 7.0 – 7.3

• Homeostatic mechanisms help regulate pH

• Buffers are chemicals which act to resist pH changes

2.3: Chemical Constituents

of Cells

32

Organic vs. Inorganic Molecules

Organic molecules

• Contain C and H (carbon and hydrogen)

• Usually larger than inorganic molecules

• Dissolve in water and organic liquids

• Carbohydrates, proteins, lipids, and nucleic acids

Inorganic molecules

• Generally do not contain C and H

• Usually smaller than organic molecules

• Usually dissociate in water, forming ions

• Water, oxygen, carbon dioxide, and inorganic salts

Inorganic Substances

33

Water

• Most abundant compound in living material

• Two-thirds of the weight of an adult human

• Major component of all body fluids

• Medium for most metabolic reactions

• Important role in transporting chemicals in the body

• Absorbs and transports heat

Oxygen (O2)

• Used by organelles to release energy from nutrients in

order to drive cell’s metabolic activities

• Necessary for survival

Inorganic Substances

34

Carbon dioxide (CO2)

• Waste product released during metabolic reactions

• Must be removed from the body

Inorganic salts

• Abundant in body fluids

• Sources of necessary ions (Na+, Cl-, K+, Ca+2, etc.)

• Play important roles in metabolism

Organic Substances

Carbohydrates

35

• Provide energy to cells

• Supply materials to build cell structures

• Water-soluble

• Contain C, H, and O

• Ratio of H to O close to 2:1 (C6H12O6)

• Monosaccharides – glucose, fructose

• Disaccharides – sucrose, lactose

• Polysaccharides – glycogen, cellulose

Organic Substances

Carbohydrates

36

(a) Some glucose molecules

(C6H12O6) have a straight

chain of carbon atoms.

C

C

C

C

C

C

H

O

H

O

O

O

H H

O H

H

H

H

H O

H

H

H

H

C

H

O

O H

H

O

H

O H

H

H H

C

O

H

C

C C

O C

H

(b) More commonly, glucose

molecules form a ring structure.

O

(c) This shape symbolizes

the ring structure of a

glucose molecule.




Organic Substances

Carbohydrates

37

O

(a) Monosaccharide

O O

O

(b) Disaccharide

O

O

O

(c) Polysaccharide

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Organic Substances

Lipids

38

• Soluble in organic solvents; insoluble in water • Fats (triglycerides)

• Used primarily for energy; most common lipid in the body

• Contain C, H, and O but less O than carbohydrates (C57H110O6)

• Building blocks are 1 glycerol and 3 fatty acids per molecule

•Saturated fatty acids have only single carbon to carbon bonds

• Unsaturated fatty acids have one or more carbon to carbon

double bond


C

H

H

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C H C O

O

H

C

H

H

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

C C O

O

H

(b) Unsaturated fatty acid

(a) Saturated fatty acid

Organic Substances

Lipids • Fats (triglycerides)

• Saturated fats contain three saturated fatty acids

• Mostly solid and come from animals

• Unsaturated fats contain at least one unsaturated fatty acid

• Mostly liquid and come from plants


C

O

O H C C

H

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

H

C

O

O H C C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

H

C

O

O H C C

H

H H

C

H

H

C

H

H

C

H

H

C

H H

H

Glycerol

portion Fatty acid

portions

Organic Substances

Lipids

40

• Phospholipids

• Building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per

molecule

• Hydrophilic and hydrophobic

• Major component of cell membranes

C

H

C

O H

C H

H

Glycerol portion

(a) A fat molecule

O

O

Fatty acid

Fatty acid

Fatty acid

H

C

H H

H H

C

H

H

N

O

O

Fatty acid

Fatty acid

O

P O C H

O –

Phosphate portion

(b) A phospholipid molecule

(the unshaded portion may vary)

H

C H

C

H

H

O

(c) Schematic representation

of a phospholipid molecule

Water-insoluble

(hydrophobic)

“tail”

Water-soluble

(hydrophilic)

“head”




Organic Substances

Lipids

41

• Steroids • Four connected rings of carbon

• Widely distributed in the body, various functions

• Component of cell membrane

• Used to synthesize hormones

• Cholesterol

(a) General structure of a steroid

C

C

C H 2 C

H 2 C C

H

(b) Cholesterol

C

CH CH 2

CH 2

CH

CH 3

CH 2

H C

HC

H 2

H 2

CH 2 CH CH 2

CH 3

CH 3

C H 2

C H

CH 3

HO C

CH 3

CH 2

CH C

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Organic Substances

Proteins

42

• Structural material

• Energy source

• Hormones

• Receptors

• Enzymes

• Antibodies

• Protein building blocks are

amino acids

• Amino acids held

together with peptide bonds

H N

H

C

H

C

O

OH

S

C

H

H H

H N

H

C

H

C

O

OH

C

C

C

H

H

C H

C H

H

C H

C H

H N

H

C

H

C

O

OH

R

Four Levels of Protein Structure

(b)

( N

O

C

C

H

N

C

H

N

O

C

C

H

R

R

ng

Amino acids

The primary and secondary levels of protein

structure and are vital to the function

A.--primary—oblong shape represents an

amino acid molecule.

B. secondary—polypeptide chain of a protein

molecule is either pleated or twisted to form a

coil. Dotted lines represent hydrogen bonds.

C. tertiary—the pleated and coiled

polypeptide chain of a protein molecule folds

into a unique three-dimensional structure.

D. quaternary—two or more polypeptide

chains may be connected to form a single

protein molecule.

Organic Substances

Nucleic Acids

44

• Encode amino acid sequences of proteins

• Building blocks are nucleotides

• DNA (deoxyribonucleic acid) – double polynucleotide

• RNA (ribonucleic acid) – single polynucleotide

S

P B


Organic Substances

Nucleic Acids

45 S

P

S

P

S

P

S

P

S

P

S

P

B

B

B

B

B

B

S

S

S

S

S

S

P

P

P

P

P

P

B

B

B

B

B

B

(b)

S

P

S

P

S

P

S

P

S

P

S

P

B

B

B

B

B

B

(a)




46

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