Orientation to Bio & Chem

By the end of this class you should understand:

• The organization of the fields of science• Characteristics common to all living things• The organization of living things, and humans

in particular• The nature of atoms, bonds, and polarity• The four major macromolecules found in

living things including humans

Biology is an Integrated Science

• To understand biology well, one must also understand:– Chemistry– Physics– Math– Statistics

Science!

Source: xkcd.com

Organization of Living Things

• All living things are highly organized into levels of organization

• More complex organisms are organized into more levels– Some living things are only one cell– Some living things do not have organs

Smallest “unit” of life?

• A cell is the smallest thing that is alive– It is made of things

that are not alive– It meets all the

criteria of being alive

• Huge variety of cells

Consider a car• A car is made of many parts• Each part is made of

materials• Only the complete car will

drive around• Cells are alive but made of

nonliving things just as cars can drive but are made of parts that cannot

Characteristics of Life

• Maintain homeostasis (WTF is that?)• Acquire energy and raw materials• Excrete waste products• Respond to environment• Grow and reproduce• Made of macromolecules (WTF are those?)

WTF are these?

• Homeostasis: the process of maintaining a constant internal temperature despite changes in external environment– Example: body temperature

• Macromolecules: large molecules made mostly with carbon. Refers to nucleic acids, proteins, sugars, and fats.

Macromolecules

• To discuss macromolecules, we will have to explore some chemistry

• Everything you’ll need to know about chemistry will fit on these few slides– I promise!

The Basics

• All matter is made of atoms• Every atom has a nucleus with at least one

proton and usually some neutrons– Protons exert a + charge around them– Neutrons have no charge

• These + charges attract electrons which each have a – charge– Electrons are way smaller so they zoom around

really fast and can’t hold still

Chemistry is Electron Behavior

• The number of protons determines what element it is– Where it goes on the periodic table of the elements

• The reason this matters is because there are fixed slots the electrons fit into, and electrons “want” to fill the slots if possible

• Atoms will sometimes donate or receive electrons– Ionic bonds

• Other atoms will share electrons to fill the slots– Covalent bonds

Why Does This Matter??• Sometimes covalent bonds are uneven– Electron spends more time on one end than the other– Anyone who’s shared custody of children knows

sharing is often uneven!

• This means the atom with more than 50% time is slightly negative and the atom with less than 50% is slightly positive– This is a polar bond and may make the molecule a

polar molecule

Example of Polar Molecule:

• Water!• Water dissolves salt (ionic

bonds) because the positive and negative atoms mix with the positive and negative charges in the water

• This means water (and other polar chemicals) are slightly “sticky”

Three questions:

• Why is water “sticky” when you can slip on it?

• What is a very sticky liquid?

• What is a very not-sticky liquid?

Best Answers:

1) All liquids are slippery to some degree– Also note: ice is only slippery if it has a layer of

water on the outside

2) Honey, syrup, molasses: all have sugar in them!

3) Oil, grease: all have lipids which are nonpolar!

Sugar (Carbohydrates)

• Sugars are carbon molecules with lots of oxygen and hydrogen, so they are also polar molecules

• They mix well with water and form many more + - attachments– This is why honey is so sticky!

Starch• Starches are made of many individual sugar rings

bonded together• Some starches (white bread, white rice, etc) can be

digested quickly• Others (brown rice, whole wheat bread etc) are

digested more slowly– This is why brown carbs are better for you!

Lipids (Fats & Oils)

• Lipids are made with carbon and hydrogen– Carbon and hydrogen form a

nonpolar bond

• Since electron sharing is even, no + and – charges form

• This means they do not mix with water– Hydrophobic

Consider the Following:

• Since oils are not sticky (no polar bonds) they don’t stick to glass like water does

• Since oil and water don’t mix, how do you get oil off your hands?– Soap! Soaps are chemicals with

hydrophobic and hydrophilic parts so they can make oil and water mix

Nucleic Acids and Amino Acids

• DNA and RNA• Stores/handles

information• Usually made of a

nitrogenous base attached to a sugar with 1 or more phosphate groups– The phosphate groups

store energy

• Strung together to make proteins

• Proteins perform almost all jobs in human body– Messengers– Structural fibers– Enzymes– Transportation

• Made using information in DNA

See you next week!

• DNA and Proteins will be discussed in week 3