Untitled Flashcards Set

Biochemistry Quiz Review

1. Relate the following terms: Atom, Molecule, Isotope, Isomer.

Molecules are made up of 2 or more atoms (the smallest complete unit of an

element) bonded together - covalently in our cases.

Isotopes are atoms that have different numbers of neutrons. When more

neutrons are added, the atoms can become unstable (radioisotope).

An isomer is a molecule that is made up of the same atoms but has a different

shape.

2. Explain the intramolecular and intermolecular bonds and forces discussed

in class.

Intramolecular bonds are within a single molecule

-

Covalent bonds occur when 2 non-metal atoms share valence electrons -

ie in water, the valence electrons of H atoms are shared with the valence

electrons of an O atom.

-

Polar covalent bonds form when theres a difference in

electronegativity of the atoms causing an unequal sharing of

electrons - ie in water the O has a higher electronegativity and a

stronger pull on the electrons; the O is more negative and the H is

more positive

-

Non-polar covalent bonds form when the electronegativity is close to

the same between atoms and there’s no uneven pull on electrons -

ie hydrocarbons, the bond between C and H has an even sharing of

electrons

Intermolecular bonds are between separate molecules

-

Hydrogen bonds form between polar molecules that have H bonded to O,

N, F, (P) ; the partially charged H from one molecule is attracted to partially

charged O, N, F in another molecule - ie in water, the H (positive charge)

from one molecule is attracted to the O (negative charge) from another

-

Hydrophobic interactions occur when non-polar molecules are in polar

solutions - the nonpolar molecules don’t stick to the water the same way

polar molecules do and instead clump together to “get away” from the polar

solvent

3. How do polar molecules differ from non-polar molecules?

Polar molecules are made up of atoms that have differences in electronegativity

causing partial charges to parts of the molecule. Non-polar molecules have an

even net charge, either due to symmetry or no difference in electronegativity.

4. What are the structural formulas and properties of the following functional

-

-

-

groups:

a. Hydroxyl

Polar, can facilitate hydrogen bonding, found in carbs, proteins, nucleic

acids, lipids

b. Carboxyl

Polar, can facilitate hydrogen bonding, found carbs, proteins, lipids

c. Phosphate

Polar, negatively charged, found in nucleic acids, lipids

5. Explain the structure and function of the 4 major macromolecules

a. Carbohydrates

Glycogen

-

Highly branched chain of glucose molecules, stored in globules

-

Many branches mean that glucose can be quickly accessed from storage -

in animals

Starch

-

Branched chains of glucose (less branched than glycogen), stored in

globules

-

Used to store sugar (energy) in plants

Cellulose

-

-

Long, linear chains of glucose

Provide structure to cell walls in plants

b. Lipids

Triglycerides

-

3 fatty acids attached to a glycerol molecule

-

Fatty acids can be saturated or unsaturated - saturated fatty acids have no

double bonds and are saturated with hydrogen, unsaturated fatty acids

have less hydrogen which causes double bonds to form between the

carbons

-

Saturated fats will form solids, unsaturated fats will form liquids

-

Triglycerides are a form of energy storage, heat insulation, impact

protection

Phospholipids

-

Phospholipids are formed when 1 fatty acid is removed from a triglyceride

and replaced with a phosphate (glycerol attached to 2 fatty acids and a

phosphate group)

-

The phosphate gives the molecule one polar end and the fatty acids give it

a non-polar end

-

The polar ends are attracted to water, and the non-polar tails are repelled,

forming a bilayer structure - cell membranes and other membrane

structures

Steroids

-

Structure made of 4 carbon rings with other things attached to give it

specific functions

-

Sends signals through the blood to parts of the body

Wax

-

-

Long carbon chain structures

Used to protect - usually exteriors

c. Proteins

-

Amino acid polymers, joined by peptide bonds

Functions:

-

Structure - cytoskeleton, microfilaments

-

Transport - hemoglobin, or carrier proteins

-

Movement - actin and myosin in muscles

-

Catalysts - enzymes like catalase

-

Signals - hormones sent through blood, or receptors on cell membranes

-

Immunity - antibodies

d. Nucleic Acids

-

Long polymers of nucleotides, made up of phosphate, sugar, nitrogenous

base

-

Sugar of one nucleotide covalently bonds to the phosphate group of

another, forming a sugar-phosphate backbone

RNA - ribonucleic acid

-

Single strand

-

Used in protein synthesis

DNA - deoxyribonucleic acid

-

Double strand held together by hydrogen bonds

-

Used to store genetic information

6. Explain the process and outcome of the following types of reactions

a. Condensation

-

One molecule loses an OH group, another molecule loses an H; a covalent

bond forms between the 2 molecules

-

Energy is required

-

Water is produced by the removes OH and H

-

-

b. Hydrolysis

A covalent bond between monomers is broken, along with a water

molecule (into H and OH)

One molecule gains an H where the covalent bond was, the other gains an

OH

-

This requires energy

7. Describe the 4 levels of protein structure.

Primary - linear structure of amino acids (the order) held together by peptide

bonds

Secondary - hydrogen bonding between R groups forming alpha helix and beta

sheet structure

Tertiary- complicated folding due to hydrophobic and hydrophilic interactions

between helices and sheets

Quaternary - combination of 2 or more tertiary structures (2 or more

polypeptides)

8. Explain how the composition and structure of a fatty acid will affect its

physical properties

Saturated - solid; unsaturated - liquid