biochemistry honors

Why is an understanding of chemistry important to someone studying biology?

All cells (and thus organisms) are composed of chemicals

All life processes involve a variety of chemical reactions

Reveals the complexity and elegance of life

What we will focus on in this presentation:

•Matter and Atoms

•Compounds

•Molecules

•Chemical Bonds

•Chemical Reactions

•The Unique Properties of Water

•Ions and Living Cells

•pH

Matter is anything that has mass and takes up space…

Made up of….

Atoms are the basic building blocks of matter

Our current model of atoms was first described by John Dalton in his work “The Atomic Theory”

Living Things Are Made of Matter

Compounds are substances which contain 2 or more different elements chemically combined in a fixed ratio

Atoms Elements and Compunds

Molecules are substances which contain 2 or more atoms, and are the most basic unit of a substance

Molecules can contain atoms of the same element or different elements

Molecules

Which of the following are molecules only and which are molecules and compounds?

CO2

O2

H2

H2SO4

HCl

N2

H2O

Molecule and Compound

Molecule

Molecule

Molecule and Compound

Molecule and Compound

Molecule

Molecule and Compound

Elements are substances made up of 1 kind of atom!

6 different elements make up 97% of the compounds that are found in living things

There are more than 100 known elements today

ProtonsProtons + charge, nucleus+ charge, nucleus

NeutronsNeutrons 0 charge, nucleus0 charge, nucleus

ElectronsElectrons - charge, orbit in the electron charge- charge, orbit in the electron charge

The # of protons in an atom determines its identity!The # of protons in an atom determines its identity!

One element differs from another by the number of protons in its nucleus

An element’s atomic number equals its number of protons

Element Number of Protons

Hydrogen

Carbon

8

7

1

6

Oxygen

Nitrogen

Sometimes atoms of the same element differ in their number of neutrons

Isotopes

Useful in biological research if radioisotopes

Review of Atoms Molecules and Compounds

Use the web resources listed below to help you study the topics covered so far:

http://csep10.phys.utk.edu/krogh_instructorCD/biology/ch2/animations/mod02_1.swf

http://www.phschool.com/science/biology_place/biocoach/biokit/chnops.html

http://www.chemthink.com

The Point of Reactions and Bonding is….The Point of Reactions and Bonding is….

Why Bonds FormWhy Bonds Form

Types of BondsTypes of Bonds

Reactions and EquationsReactions and Equations

Why Do Chemical Bonds Form??

Atoms are most stable when their outermost energy level is filled with electrons

To accomplish this stable state, atoms may share or transfer electrons among their nuclei and form bonds!

A Bohr Model can be used to determine the number of electrons in the outer shell of any atom!

Types of BondsTypes of Bonds

Chemical Bonds Form When Atoms Share or Transfer Electrons

Ionic Bonds Covalent Bonds

Forms when an electron (or electrons) is transferred from one atom to another

Forms when an electron (or electrons) is shared between atoms

Type of bond formed is dependent on the electronegativity of atoms involved

Ionic Bonds

Sodium wants to lose an electron to become most stableSodium wants to lose an electron to become most stable

Draw a Bohr Model of Sodium (Na) and Chlorine (Cl)

How does each atom become most stable with a full outer shell of electrons?

Chlorine wants to gain an electron to become most stableChlorine wants to gain an electron to become most stable

The strong attraction The strong attraction between the positive between the positive sodium ion and the sodium ion and the negative chloride ion negative chloride ion creates an ionic bondcreates an ionic bond

NaCl is common table salt

Covalent Bonds

A hydrogen atom wants to share its electron. For example, it A hydrogen atom wants to share its electron. For example, it can share its electron with another hydrogen atom or two can share its electron with another hydrogen atom or two hydrogen atoms can share their electrons with an oxygen atom hydrogen atoms can share their electrons with an oxygen atom which wants to share a total of two electrons.which wants to share a total of two electrons.

Shared Pair of Electrons

Covalent Bonds

If the electrons of a bond are shared equally a non-polar bond is formed

If the electrons of a bond are not shared equally a polar bond is formed

Polar Covalent Non-Polar Covalent

A chemical reaction involves the making or breaking of chemical bonds (ionic or covalent)

Chemical reactions are necessary for life:

• To establish stable atomic structuresTo establish stable atomic structures

• To form new molecules that cells needTo form new molecules that cells need

•To manage cellular energy (energy release, usage, and storage)To manage cellular energy (energy release, usage, and storage)

Chemical equations describe a chemical reaction

Chemical equations provide the following information:

• The different elements involved in the reaction

• The number of atoms involved in the reaction

• The reactants and products of the reaction

Reading a chemical reaction…..

Carbon dioxide and water react (in the presence of sunlight and chlorophyll) to produce carbohydrate (glucose) and oxygen

Other information from the equation….

# of molecules of reactants and products:

6 CO2

6 H2O

1 C6H12O6

6 O2

Other information from the equation….

The number of each kind of atom on each side of the equation

Reactants

C

O

H

Products

C

O

H

6

18

12

6

18

12

Review of Chemical Bonds and Reactions

Use the web resources listed below to help you study the topics covered so far:

http://csep10.phys.utk.edu/krogh_instructorCD/biology/ch2/animations/mod02_2.swf

http://www2.nl.edu/jste/bonds.htm

http://www.phschool.com/science/biology_place/biocoach/biokit/valence.html

http://www.chemthink.com

The Structure of WaterTwo hydrogen atoms are each joined to an oxygen atom by a single covalent bond

The weak attraction between the hydrogen atom of one molecule and a slightly negative atom within another molecule

The tendency of molecules of the same kind to stick to one another is called cohesion.

The type of attraction that occurs between unlike molecules is called adhesion.

Temperature Moderation

Because of hydrogen bonding, water has a better ability to resist temperature change than most other substances

•Oceans and large lakes moderate the temperatures of nearby land areas

•Water also moderates temperature through evaporation, such as when you sweat

Low Density of Ice

Review of Chemical Bonds and Reactions

Use the web resources listed below to help you study the topics covered so far:

http://csep10.phys.utk.edu/krogh_instructorCD/biology/ch3/animations/mod03_1.swf

http://www.phschool.com/science/biology_place/biocoach/biokit/polarity.html

http://programs.northlandcollege.edu/biology/Biology1111/animations/hydrogenbonds.html

When NaCl dissolves in water the ionic bonds are broken. The positive sodium ion is attracted to the slightly negative part of the water molecule and the negative chloride ion is attracted to the positive part of the water molecule.

When a covalent compound such as water is converted to ions, there are H+ and OH- ions in solution

The presence and abundance of these ions is critical to the functioning of the cell in terms of its biochemistry

The level of H+ and OH- ions in solution is measured by the….

pH Scale

A pH of 7 indicates an equal number of H+ and OH- ions in solution

A pH less than 7 indicates a solution with excess H+ ions = acid

A pH greater than 7 indicates a solution with excess OH- ions = base

The functioning of living cells can be affected by a change in pH

Because the very reactions of life cause pH changes, there is a need for cells to be able to regulate the pH of the intracellular fluid

Review of Chemical Bonds and Reactions

Use the web resources listed below to help you study the topics covered so far:

http://programs.northlandcollege.edu/biology/Biology1111/animations/dissolve.html

http://www.johnkyrk.com/pH.html

http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/buffer12.swf