Exam 1 Study Questions

Question 1

Name the three parts of an atom and what charge is associated with each. Which part is responsible for the formation of chemical bonds?

Answer 1

Proton - positive
Neutron - neutral
Electron - negative
- Electrons in the valence shell

Question 2

Concerning Hydrogen bonds, Covalent Bonds, and Ionic Bonds.
Which is the strongest? The weakest?
What is the difference between the three? (Compare and contrast each)

Answer 2

Covalent Bond: Strongest- pairs of electrons are shared between atoms
Ionic Bond: when differences in electronegativity are so great that atoms strip electrons form their bonding partners
- resulting in ions (two oppositely charged atoms that are attracted to each other)
Hydrogen Bond: the attraction between partial (+) charge of a Hydrogen atoms and (-) charge of another atom

Question 3

What does it mean if a element is highly electrognegative?

Answer 3

The more electronegative an atom, the stronger it pulls electrons towards itself

Question 4

What are the attractions between water molecules called?

Answer 4

hydrogen bond

Question 5

What is the difference between a hydrophobic molecule and hydrophilic molecule?

Answer 5

A hydrophilic molecule has an affinity for water (ionic or polar substances). A hydrophobic molecule repels water because it is nonionic or non polar

Question 6

Why is water such an important molecule for life?

Answer 6

water’s role as a solvent helps cells transport and use substances like oxygen or nutrients

Question 7

What is a polar molecule?

Answer 7

A molecule where one atom is more electronegative and doesn’t not equally share electrons; causes partial positive and partial negative

Question 8

How are hydrogen bonds formed?

Answer 8

they form between molecules with oxygen and nitrogen

Question 9

What are the six common side chains we discussed in class?

Answer 9

1. Hydroxyl
2. carboxyl
3. amino
4. sulfhydryl
5. Phosphate
6. carbonyl

Question 10

What types of bonds are formed between sugar subunits?

Answer 10

glycosidic bonds

Question 11

What is the difference between glycogen and starch?

Answer 11

glycogen is very branched while starch is not very branched.

Question 12

What is the difference between saturated and unsaturated fatty acids?

Answer 12

unsaturated fats have less hydrogens resulting in a bent carbon chain with a double bond. saturated fats have a carbon chain that is fully saturated with hydrogens

Question 13

How do saturated fats affect membranes?

Answer 13

saturated fatty acid makes the model membrane more rigid,

Question 14

What dictates the overall properties of fats?

Answer 14

tail length and degree of saturation alter the properties of fats

Question 15

What does it mean that phospholipids are amphipathic?

Answer 15

it means that they have both a hydrophilic and a hydrophobic region

Question 16

What bonds are formed between amino acids?

Answer 16

peptide bonds

Question 17

Name the four functional classes of amino acids, on what basis are they separated?

Answer 17

1. Acidic side chains
2. Basic side chains
3. Uncharged polar side chains
4. non polar side chains

Question 18

Be able to recognize purines vs pyrimidines and know which nucleotides are in each group

Answer 18

Purines (two rings): adenine, guanine
Pyrimidines (one ring): cytosine, uracil, thymine

Question 19

What bonds are found between nucleotides? Where are these bonds formed?

Answer 19

Phosphodiester bond; formed between the 5’ and 5’ carbon atoms of adjacent sugar rings

Question 20

What makes ATP so energetic?

Answer 20

it carries chemical energy in its easily hydrolyzed phosphoanhydride bonds

Question 21

What is the purpose of an enzyme? How do they help reactions proceed?

Answer 21

enzymes catalyze reactions by binding to particular substrates in a way that lowers the activation energy required for making and breaking specific covalent bonds

Question 22

Compare and Contrast catabolism and anabolism. Which consist of energetically favorable reactions and which of energetically unfavorable reactions?

Answer 22

Catabolism (energetically favorable): food molecules are broken down into building blocks for biosynthesis, chemical bonds from food are mainly lost as heat but some of the energy is converted into useful forms of energy
Anabolism (energetically unfavorable): building blocks are synthesized into the many molecules that form the cell and is powered by the useful forms of energy from catabolism.

Question 23

What does it mean for a molecule to be oxidized? Reduced?

Answer 23

Oxidized: loses electrons
Reduced: gains electrons

Question 24

Is the ∆G of a reaction (-) or (+) for a energetically favorable reaction?

Answer 24

negative

Question 25

What is equilibrium and how does this affect the ∆G of two molecules that react with each other?

Answer 25

• There are no net changes in the concentration ratio of Y to X
• the delta G=0 for both reactions

Question 26

Know the role of ATP and the possible outcomes of its hydrolysis.

Answer 26

• Transfers energy from the breakdown of molecules in food to cell processes.
• During ATP hydrolysis, the terminal phosphate is frequently transferred to another molecule/ is able to form hydrogen bonds with water

Question 27

Compare and contrast a condensation/dehydration reaction vs a hydrolysis reaction.

Answer 27

Condensation: macromolecules are synthesized in unfavorable condensation reaction; water is formed
Hydrolysis: uses water to break bonds/ break down molecules into smaller parts and release energy; energetically favorable