Chapter 2: Molecules of Life

Question 1

What is the general structure of the atom?

Answer 1

Nucleus composed of protons (+) and neutrons (o) surrounded by electrons (-) in orbitals.

Atomic Number = # of protons
Atomic Mass = # of protons + # of neutrons

Question 2

What are the different bonds that can occur between molecules? (strongest to weakest)

Answer 2

Ionic Bond: the electrostatic attraction between oppositely charged ions (valence electron is transferred)

Covalent Bond: the sharing of valence electron pairs between atoms in order to fill the atom’s outer shell (can be polar or nonpolar)

Hydrogen Bond: the PARTIAL POSITIVE charge of H atoms are attracted to the PARTIAL NEGATIVE charge of O atoms

Van Der Waals Forces: the natural attraction of intermolecular forces between molecules (increases with surface area)

Question 3

Which type of bond(s) does water use and how does it affect its surroundings?

Answer 3

POLAR COVALENT BONDS (between H & O atoms)
* Water’s polarity is what causes other objects to be hydrophobic or hydrophilic

HYDROGEN BONDS (between multiple water molecules)

Question 4

What are the 4 main building blocks of life and what are they made out of? Give an example of each.

Answer 4

1) Proteins (made of amino acids)
- ex: enzymes
2) Nucleic Acids (made of nucleotides)
- ex: DNA/RNA
3) Carbohydrates (made of sugars)
- ex: glucose
4) Lipids (made of fatty acids)
- ex: plasma membranes

Question 5

What is a protein? What are the necessary components of an amino acid?

Answer 5

PROTEIN = Polypeptide Chain of Amino Acids

AMINO ACID:
- Central Carbon (C)
- Amino Group (H2N)
- Carboxyl Group (COOH)
- R Group (varies)

Question 6

Name 3 different types of Carbohydrates. Why are they different?

Answer 6

1) Glucose (an aldose)
2) Galactose (an aldose)
3) Fructose (a ketose)

Question 7

What are the three main types of lipids we discussed in class?

Answer 7

• Phospholipids
  (ex: lecithin)
• Triglycerides
  (ex: saturated, unsaturated and trans fat)
• Sterols
  (ex: cholesterol)

Question 8

How do you determine an unsaturated lipid from a saturated lipid?

Answer 8

Unsaturated: KINKY (double bond between carbons)
-> liquid at room temperature and better for body

Saturated: STRAIGHT (single bonds between carbons results in tight packing due to van der waals forces)
-> solid at room temperature and worse for body

Question 9

What is the structure of a nucleotide? Which nucleotides are purines and which are pyrimadines?

Answer 9

5-Carbon sugar bonded to a base (A, G, T, C or U) and to one or more phosphate groups that are connected in a long “backbone”

PURINES (2 rings like the G.A.s :)
G -> C
A -> T

PYRIMADINES (1 ring)
C -> G
T -> A
U -> A (in RNA)

Question 10

What type of bond connects nucleotides together?

Answer 10

Phosphodiester (COVALENT) bond

Question 11

How do you tell the difference between an RNA nucleotide and a DNA nucleotide

Answer 11

In RNA, U substitutes for T and bonds with A

Also, DNA has only -H instead of -OH on the 3’ Carbon
(“deoxy”ribonucleic acid)