Biochemistry Quiz Review

1)• Proton positive charge 1 amu nucleus• Neutron neutral charge 1 amu nucleus• Electron negative charge ~0 amu electron cloud

2) Chemical bonds allow reactive elements to give/take or share electrons in order to get a full outer shell. ALL elements are reactive EXCEPT the Noble Gases, which already have a full shell and therefore do not bond with other elements.

3)• Ionic bonds & covalent bonds both occur between atoms in a molecule.• Hydrogen bonds occur between molecules (a H from one molecule forms a weak bond with an

atom from another molecule).• Ionic bonds involve giving or taking electrons.• Covalent bonds involve sharing electrons. The sharing can be equal (non-polar, like Carbon) or

unequal (polar). Water is a polar covalent molecule.

4) Ions are formed when atoms give or take electrons. They end up with more or less electrons than protons, which is why ions are charged.

5) An electron shell is a ring around the nucleus of an atom. The first shell (period 1) can hold 2 electronsThe second shell (per 2) can hold 8 electrons.

The third shell (per 3) can also hold 8 electrons 2-8-8!

6)Mendeleev was a Russian chemist who organized the periodic table according to weight.

(skipping ahead to #8)

8) Moseley corrected Mendeleev’s problem by organizing the PT by atomic number, AKA, proton number.

7) Mendeleev was clever enough to recognize that there were holes in his PT, where other, undiscovered elements should fit in. He actually left spaces in his arrangement to accommodate for them!

9) The modern PT is arranged in groups and periods and progresses by atomic number, AKA proton number.

10) Atomic mass = protons PLUS neutrons

11) Groups are the vertical arrangementsPeriods are the horizontal arrangements

12) Groups tell you how many valence/outermost electrons are in that element. Group 1 elements 1 ve. Group 16 elements 6 ve’s. Group 18 elements 8 ve’s (excepting Helium, which has 2 to make a full shell)

13) Periods tell you how many energy levels / shells an element has in order to hold all its electrons.

14 – 15)

16) Families = groups. Families are given names like the Noble Gases, and the Alkali Earth Metals, because all the elements in a Family/Group have many similar properties in common.

Biochemistry

• H, O, N, C – 4 elements that make up 96% of all living things.• What element must be present for a molecule to be a biological

compound/organic molecule? • Carbon

• What is so special about Carbon?• It shares electrons equally with all other atoms including our weak little Hydrogen.• The bonds carbon creates are extremely stable and thus the strongest bonds and THUS THUS

molecules built with carbon can be HUMONGOUS!!! Allowing life to emerge from atoms that themselves do not have the qualities of life.

• A bond that is shared equally is a COVALENT bond.

Properties of Water

• 1. Water is composed of one oxygen and two hydrogens. • What happens when an oxygen atom or a nitrogen atom bonds with

Hydrogen?• The O or N atom will share electrons unequally with the Hydrogen. This is

called a POLAR covalent bond. • This occurs in water because the nucleus of Oxygen is so much larger than

Hydrogen’s nucleus. As the oxygen pulls the hydrogen’s one electron away the hydrogen is left hanging out mostly with his proton. T• This POLAR BOND results in a slightly charged atom.• The O is slightly NEGATIVELY charged while the H atoms are slightly

POSITIVELY charged.

The Polarity of Water results in Hydrogen Bonds• A polar bond creates a molecule with two differently charged ends.

Opposite charges stick to one anotherThus water sticks to itself. This is called Cohesion.

The small electrostatic charge that sticks two water molecules together is referred to as a Hydrogen Bond.

This is the weakest bond of the four we have discussed (Covalent, Polar Covalent, Ionic, and H bonds).

Electrons are not shared as in covalent or polar covalent bondsElectrons are not given up or taken away in this bond as in Ionic bonds.The water molecules are not changed chemically because of H bonds.

A chemical bond such as the first three (covalent, polar covalent, ionic) lowers the energy states of the atoms involved and new properties emerge from the molecule that did not previously exist in the atoms alone.

Water’s polarity creates a Universal Solvent• Water will stick to anything with a charge. Thus, any molecule with a

charge will mix with water to form a solution. (Adhesion)• IONIC bonds create one negatively charged ion and one positive ion.• These ions stick together due to weak electrostatic attraction. • The ions are not tethered together by their outer energy levels as atoms

sharing electrons are.• Thus they are easily separated in water.

• The positive ion will attract the slightly negative o atom in water.• The negative ion will attract the slightly positive H atoms in water.

• Thus water will work its way in between all the ions spreading them throughout the water. We call this dissolving.

Polarity and Shape of Water creates floating Ice.• Water lines up in a particular way because of its charges and

shapes.• When water lines up to form a solid the molecules actually

spread out farther than they are as a liquid. • Thus, Ice is less dense than water.• Thus, Ice expands.

Summary of Water’s Properties.

• Solid ICE floats on Liquid Water• Cohesion • Cohesion leads to Surface Tension

• Adhesion• Adhesion creates a Universal Solvent

Photosynthesis and Cellular Respiration

Photosynthesis Explained

• A plant or other photoautotroph takes in CO2 and H2O from its suroundings • The sun’s energy is used to rip these molecules apart so the atoms can be

rearranged• They are arranged to form One glucose molecule that will be used for fuel

to run a protein machine in the mitochondria and 6 oxygen molecules that are used to rip apart/burn up the glucose in the mitochondria• The glucose can be stored and the oxygen released to the atmosphere• The glucose and oxygen can be sent to the mitochondria to be used

during cellular respiration.

Cellular Respiration Explained

• The mitochondria gets one glucose molecule and 6 oxygen molecules.• The oxygen is used to rip apart the glucose. The energy released during this

process is used to run a protein machine (ATP synthase). This machine produces ATP energy.• ATP energy is needed for the cell to run properly.• After the glucose is ripped up and the oxygen used, the atoms are converted

back into water and carbon dioxide.• Heterotrophs – release the CO2 back into the air (we exhale it) and can use

or discard the water• Autotrophs – can use the CO2 and H20 all over again during photosynthesis

or discard it as well.