Chapter 2: Basic Cellular Chemical Processes

Question 1

Discuss the (3) components of atoms and their charge.

Answer 1

Protons: Positive (+) charge
Neutrons: Neutral charge
Electrons: Negative (-) charge

Nucleus contains protons and neutrons.
Electrons are found in orbitals/shells outside nucleus.
- first shell contains 2
- second shell contains 8

Question 2

Define atomic mass and atomic number.

Answer 2

Atomic Mass: sum of protons and neutrons in an atom

Atomic Number: number of protons in an atom

Question 3

Define valence electrons.

Answer 3

Electrons found in the outer most shell

They participate in chemical rxns and form bonds

Question 4

Define isotopes.

Answer 4

Different forms of the same atom.

Atomic # same, atomic mass is different b/c different number of neutrons

Question 5

Discuss covalent bonds.

Answer 5

• Occur when atoms share valence electrons
  2 types: nonpolar and polar
• Nonpolar covalent bonds means e- are shared equally (no + or - poles)
• Strongest bond
• Polar colavent bonds means e- are shared UNEQUALLY
• 2nd strongest bond

Question 6

Discuss ionic bonds.

Answer 6

• Occurs when valence electrons are transferred from one atom to another
• Forms charged atoms
• Weakest type of bond
• Cation (+ charge) and Anion (- charge)
• Hydrophilic/Hydrophobic (hydration spheres concept)

Question 7

Discuss Hydrogen bonds.

Answer 7

• Hydrogen forms polar bond with another atom and takes on slight + charge making it attracted to nearby - charged atoms.
• IE: Hydrogen bonds form between adjacent H20’s and create surface tension

Question 8

Discuss Acids, Bases, and pH.

Answer 8

Acid: proton donor (release H+ in soln)
Base: proton acceptor (accepts H+ in soln)

pH: symbol of H+ concentration in soln

• Scale of 0 to 14
• Acid: pH less than 7
• Base: pH greater than 7
• Pure H20 has neutral pH: 7

Question 9

Discuss buffers and the bicarbonate buffer system in blood.

Answer 9

• Buffers: molecules that slow changes in pH by either combining with or releasing H+’s

Bicardbonate buffer system in blood:
H20 + CO2 H2CO3 H+ + HCO3-

Rxn can go in either direction depending on amt of H+

Question 10

Discuss blood pH.

Answer 10

Normal Range: 7.35 - 7.45
- Maintained by buffering run

If blood pH drops below 7.35 = Acidosis
If blood pH rises above 7.45 = Alkalosis

Question 11

Discuss organic molecules.

Answer 11

Organic molecules are those that contain Carbon!

• Carbon: 4 valence e-
• Bonds covalently to fill outer shell to 8 e-

Question 12

Discuss carbohydrates and the 3 types.

Answer 12

Organic molecules containing Carbon, Hydrogen, and Oxygen in ratio 1:2:1 -> C(n)H(2n)O(n)

1. Monosaccharides (simple sugars)
   - i.e. glucose, fructose
2. Disaccharides (2 monosacchrides joined)
   - i.e. Sucrose = glucose + fructose
3. Polysaccharides (many monosaccharides joined)
   - i.e. starch and glycogen which are storage molecules for glucose

Question 13

Discuss dehydration synthesis.

Answer 13

• Splitting water of 2 monosacchrides

- An H+ and OH- are removed producing water and the remaining parts of the monosaccharide bond together

Question 14

Discuss hydrolysis.

Answer 14

• Reverse of dehydration synthesis
• H20 is split into H+ and OH- and each is added to a monosarccharide
• So you’re putting water back in and getting 2 molecules back

Question 15

Discuss lipids.

Answer 15

• Insoluable in water
• can be saturated (bad for heart) of unsaturated (good for heart)
• Phospholipids 2 parts:
  1. Phosphate part: round head, polar/hydrophilic (water loving)
  2. Lipid part: tails, nonpolar/hydrophobic (hates water)

Question 16

Discuss proteins.

Answer 16

• Proteins are long chains of amino acids
• 20 types of amino acids
• amino acids links by peptide bonds
• Short chains of amino acids are “peptides”

Protein structure described in 4 levels:

1. Primary structure
   - sequence of amino acids
2. Secondary structure
   - weak Hydrogen bonding
   - forms alpha helix shape (more common) or beta pleated sheet shape
3. Tertiary structure
   - 3D structure forms to stabilize the weak H bonds
   - not very stable; easy to break apart
4. Quaternary structure
   - put a bunch of 3D shapes together and they bond covalently

Question 17

Discuss nucleic acids.

Answer 17

• made of long chains of nucleotides
• DNA and RNA
• DNA
• contains genetic coding
• 2 strands of DNA twist to form double helix
• deoxyribose sugar covalently bonded to 1 of 4 base pairs:
  1. Guanine (G)
  2. Adenine (A)
  3. Cytosine (C)
  4. Thymine (T)

Law of complimentary base pairings:

• A and T attach to each other via Hydrogen bond
• G and C attach to each other via Hydrogen bond

RNA
- single-stranded
- Messanger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
(all come together to make a protein)

• ribose sugar bonded to 1 of 4 base pairs:
  1. Guanine (G)
  2. Adenine (A)
  3. Cytosine (C)
  4. Uracil (U)
• A and U attach to each other
• G and C attach to each other