CHAPTER 2 OBJECTIVE EXERCISE

CHAPTER 2 OBJECTIVE EXERCISE

1. Define the terms chemistry, matter, atom, and element.

*Chemistry*	the study of matter.
*Matter*	anything that occupies space and has mass; (i.e. solids, liquids, gases)
*Atom*	the smallest particle of an element;
*Element*	a basic chemical substance composed of atoms

2. Give the chemical symbol for the naturally occurring elements in humans.

3. List the six major elements considered bulk elements of the human body

O, C, H, N, Ca, P

4. Name the three subatomic particles, and distinguish between them in terms of charge, weight, and location of each. Sketch a diagram to illustrate their relationship.

SUBATOMIC

PARTICLE

CHARGE

LOCATION

MASS (WEIGHT)

PROTON

POSITIVE

NUCLEUS

1 amu

NEUTRON

ZERO (NEUTRAL)

NUCLEUS

1 amu

ELECTRON

NEGATIVE

SHELLS OR ORBITALS AROUND NUCLEUS

5. Distinguish between the atomic number and atomic weight of an atom of an element.

Atomic number

The Atomic Number (A#) of an atom represents the number of protons in its nucleus.

a. A# of H = 1

b. A# of He = 2

c. A# of O = 8.

Atomic weight

The Atomic Weight (AW) of an atom is nearly equal to the number of protons plus the number of neutrons in its nucleus.

6. Discuss how isotopes of atoms of a particular element differ.

Isotopes of atoms differ in their AW's (i.e. same # of protons, different # of neutrons).

7. Given the atomic number of an atom, you should be able to determine the following: Use Mg with A# = 12, and N with A# =7.

a. the number of protons; Mg = 12; N = 7

b. the number of electrons; Mg = 12; N = 7

c. the electron configuration of the atom; See your notes

Mg N

d. the number of valence electrons; Mg = 2; N= 5

e. how that atom will react.

Mg will share 2 pairs of electrons with another atom and

N will share 3 pairs of electrons with another atom and

8. Explain how atoms react with one another (i.e. interactions between what subatomic particles?

Through their valence electrons

9. Distinguish between ionic, covalent, and hydrogen bonds, and give an example of a molecule (or macromolecule) that demonstrates each.

TYPE OF BOND

DEFINITION

DESCRIPTION

EXAMPLE

IONIC

when atoms lose or gain electrons becoming ions, and then oppositely charged ions are attracted to one another

bond is broken by water

salts, NaCl

COVALENT

when 1 or more pair(s) of electrons is/are shared equally by atoms

Very strong bond

the bonds holding together a molecule of CO₂

(POLAR)

when 1 or more pair(s) of electrons is/are shared unequally by atoms

Strong bond

the bonds holding together a molecule of H₂O

HYDROGEN

when a (slightly positive) hydrogen atom that is already covalently bonded to a molecule is attracted to a slightly negative atom.

Very weak bond; in molecules whose purpose is to easily break and then come back together

reactions between water molecules (i.e. ice to water to gas);

DNA chains

10. Name the three types of chemical reactions.

SYNTHESIS

DEGRADATION

EXCHANGE

11. Compare and contrast the major divisions (types of chemical reactions) of metabolism, in terms of a general descriptive sentence, additional descriptive terms, how energy is involved, whether bonds are formed or broken, and how water is involved. Also write a chemical reaction for each and give an example important in human metabolism.

Chemical Reaction Comparison Table (outline page 10)

SYNTHESIS REACTIONS

DEGRADATION RXN'S

GENERAL DESCRIPTION

Synthesis involves the building of a large molecule (polymer) from smaller building blocks (monomer).

Degradation involves the breakdown of a polymer into individual monomers.

DESCRIPTIVE TERMS

building

constructive

anabolic

breakdown

digestive

decomposition

catabolic

BOND FORMATION OR

BREAKING?

Bonds are formed.

Bonds are broken.

IS ENERGY REQUIRED

OR RELEASED?

Energy is required to form the bond.

Energy is released when the bond is broken.

HOW IS WATER

INVOLVED?

NAME THAT TERM.

Water is released when he bond is formed.

Dehydration

Water is required to break the bond.

Hydrolysis

EXAMPLE

Building a protein from individual amino acids;

Building a triglyceride from glycerol and 3 fatty acids, etc

Breaking a protein into individual amino acids;

Breaking starch down into monosaccharides, etc.

12. Distinguish between organic and inorganic compounds.

organic compounds.

inorganic compounds

contain the atoms carbon (and hydrogen);

are small molecules (monomers or building blocks) are covalently bonded together to form large polymers or macromolecules;

Water is usually involved in the formation and breakage of bonds between monomers;

a. Dehydration Synthesis = removal of water to form a covalent bond between monomers;

b. Hydrolysis = using water to break bonds between monomers.

The four major classes found in cells include:

a. carbohydrates

b. lipids

c. proteins

d. nucleic acids

are small compounds that do not contain the atoms C and H; Examples include oxygen, carbon dioxide (CO₂) water, salts, acids & bases. See table 2.6, page 62.

13. List five inorganic substances of importance to humans.

oxygen, carbon dioxide (CO₂) water, salts, acids & bases.

14. Discuss the unique structure of a water molecule and name the bonds that hold liquid water together.

Water is a polar molecule that demonstrates hydrogen bonding and therefore it possesses very unique characteristics. See Fig 2.8, page 58.

15. List and discuss the characteristics of water.

a. Water is an excellent solvent (universal?)

b. Water participates in many chemical reactions (in our cells and fluids)

c. Water is an excellent temperature buffer.

absorbs and releases heat very slowly

d. Water provides an excellent cooling mechanism.

It requires a lot of heat to change water from a liquid to a gas (i.e. high heat of vaporization). If water does change forms and evaporate, it leaves a cool surface behind.

e. Water serves as a lubricant

o mucus

o internal organs

o joints.

16. List the major electrolytes released by inorganic salts when placed in water (and in general, explain how these electrolytes are needed for metabolic reactions). Na⁺, K⁺, Cl^-, Ca⁺, PO₄^-; HCO₃^-, etc.

17. Describe what happens to an acid and base when they are placed in water, and discuss the significance of these products in the human body. They dissociate or ionize . Acids release hydrogen ions. Bases release hydroxyl ions.

18. Illustrate the pH scale, denoting acid, neutral, and basic (alkaline) pH values. Also denote the relationship between [H⁺] to [OH^-] at each of the above pH's, and show approximately where on that scale the following substances would fall: acetic acid, distilled water, blood and ammonia.

0 ---------------------------7---------------------------14

acidic neutral basic

[H⁺] > [OH^-] [H⁺] = [OH^-] [H⁺] < [OH^-]

20. Name the value of physiological pH. 7.4

21. Define the term buffer, and explain how the carbonic acid buffering system works in humans.

A buffer prevents abrupt pH changes.

Example = the carbonic acid (H₂CO₃) buffering system.

when pH is rising equation goes to the right

H₂CO₃ « HCO₃^-+ H⁺

when pH is falling equation goes to the left

carbonic acid bicarbonate ion hydrogen ion

(H+ donor) (H+ acceptor)

22. List the four major organic substances needed for human survival, name the building blocks that compose each, and give a general function for each.

ORGANIC MOLECULE SUMMARY TABLE (outline page 18)

Organic Molecule

Carbohydrates (sugars)

Lipids (Fats)

Proteins

Nucleic

Acids

Composed of what atoms?

C, H, 0

C, H, O

C, H, O, N, S

C, H, O, N, P

Building Blocks (monomers)

Monosaccharide or hexoses

Triglycerides: glycerol and 3 fatty acids

amino acids

nucleotides: pentose sugar, phosphate, nitrogen base

Specific types & functions of monomers

glucose, fructose, galactose.

energy

TG: energy

Phospholipid: cell membrane component

Steroid: cell membrane component and chemical messenger (i.e. cholesterol)

20 different amino acids

N/A

Specific types and functions of polymers

Disaccharides:

sucrose, lactose, maltose; energy

_____________

Polysaccharides

Starch (plant);

Glycogen (animal); energy storage.

N/A

proteins (>100 amino acids);

Many functions:

ENZYMES,

antibodies, structure, transport, chemical messengers,

storage

DNA: deoxy-ribonucleic acid; genetic material; RNA:

ribonucleic acid; aids DNA in protein synthesis.

Other

Information

Saturated (only single bonds between C’s in FA chain) vs. Unsaturated (at least 1 double bond in FA chain)

DNA controls cellular activity by instructing our cells what proteins to make (i.e. Enzymes through protein synthesis).

23. Name the three types of atoms that compose sugars and lipids. C, H, O

24. Name three monosaccharides and three disaccharides.

Monosaccharides	Disaccharides
glucose, fructose, galactose.	sucrose, lactose, maltose;

25. Name two polysaccharides, indicate whether each is a plant or animal carbohydrate, and name the tissue where the animal carbohydrate is stored.

Animal glycogen	Plant starch
Energy store	structure

26. Distinguish between the three types of lipids, in terms of structure and function.

riglyceride	phospholipid	steroid
energy	cell membranes	Chemical messengers (hormones),cell membranes

27. Compare and contrast saturated and unsaturated fats.

saturated fats	Unsaturated fats
Single bonds between carbons in hydrocarbon chain; solid at RT; animal fats	At least one double bond between carbons in hydrocarbon chain; liquid at RT; plant oils

28. Name the bond that is formed when two amino acids are joined. peptide

29. Describe the levels of structural organization of a protein and explain the significance of a protein's conformation on its overall function.

Primary (1^o) = sequence of amino acids;

Secondary (2^o) = twisting of amino acid chain; due to hydrogen bonding;

Tertiary (3^o) = folding of the amino acid chain; due to ionic bonds, disulfide bridges, and hydrophobic interactions;

Quaternary (4^o) = interactions between different amino acid chains

A protein must be in its Quaternary structure to be functional.

30. Define the term denaturation and explain what conditions may cause a protein to become denatured.

Denaturation is the loss of 3-dimensional conformation (shape) of a protein. This results in loss of function.

extreme pH values; At what pH do our enzymes work best?

extreme temperature values; At what temperature do our enzymes work best?

harsh chemicals (disrupt bonding);

high salt concentrations; At what osmotic pressure do our enzymes work best

31. List and discuss the many functions of proteins (Which is the most important?).

a. structure

o keratin in hair, nails and skin

b. transport

o hemoglobin

c. chemical messengers

o hormones

o neurotransmitters

d. movement

o actin and myosin in muscle

c. defense

o antibodies

e. catalysts

o ENZYMES = most important

32. Discuss the structure of a nucleotide.

Pentose sugar

Phosphate group

Nitrogen base

33. Name the type of chemical bond that holds the chains of a DNA molecule together. hydrogen

34. List three differences between DNA and RNA.

DNA	RNA
Sugar = deoxyribose	Sugar = ribose
Bases include A, T, G, C	Bases include A, U, G, C
Double stranded	Single stranded

35. Name the two types of nucleic acids, describe the structure of each, and give a general function for each molecule.

DNA	RNA
Directs protein synthesis	Assists in protein synthesis