Lecture 3

Question 1

What atoms make up more than 99% of the cell mass

Answer 1

C, N, O, H

Question 2

What is the atomic number

Answer 2

number of protons or # of electrons

Question 3

How to calculate atomic weight

Answer 3

number of protons + # neutrons

Question 4

What is an isotope

Answer 4

same number of protons different number of neutrons

Question 5

What’s the difference between an element and an atom?

Answer 5

• element is a substance that can’t be broken down to any other chemical form; made up of a single type of atom
• atom is the smallest part of and element that still retains its distinctive chemical properties

Question 6

what is composed of elements

Answer 6

a periodic table

Question 7

Whats the difference between a molecule and a compound

Answer 7

• a molecule has two or more atoms join together chemically
• a compound is a molecule that contains at least 2 different elements

Question 8

What determines how atoms interact

Answer 8

outermost electron because unfilled electron shells are less stable that a filled one therefore an atom with an unfilled electron shell will interact with another atom to complete their outermost cell

Question 9

What is a covalent bond

Answer 9

• strong bonds being formed by the sharing of electrons between adjacent atoms
• the shared electrons complete the outer shell of both atoms

Question 10

What is bond length

Answer 10

when attractive forces (+ and -) and repulsive forces (+ and +) are in balance

Question 11

Compare single vs. double bonds

Answer 11

• single bonds: free rotation around the bond axis when a single pair of electrons is shared
• double bonds: no free rotation around the bond axis when two pairs of electrons are shared

Question 12

What is bond strength/ dissociation energy

Answer 12

the amount of energy required to break a chemical bond

Question 13

what is electronegativity and what is its implication on covalent bonds

Answer 13

• generally, a single covalent bond between two atoms results in an unequal sharing of electrons due to the difference in electronegativity resulting in polar covalent bonds
• electronegativity is the indication of an atoms ability to attract an electron

Question 14

What is a dipole moment

Answer 14

• it measures the polarity of a bond or molecule
• it is a vector quantity and is the sum of the magnitude and direction of each individual bond dipole

Question 15

what are non-Covalent interaction and give examples

Answer 15

• bond that does not involve sharing electrons
• individually weak, but cumulatively very strong
• examples: charge-charge electrostatic interactions, hydrogen bonds, Van Der Waals

Question 16

What feature of non covalent bonds are important to the dynamic nature of the cell?

Answer 16

• non covalent interactions are weak enough that they are continually being formed and reformed at room temperature

Question 17

ionic bonds

Answer 17

• result from a gain or loss of electron
• generally from atoms with only 1 or 2 electrons in their outer shell
• two atoms held together with electrostatic interactions

Question 18

Hydrogen bond

Answer 18

• an interaction between a covalently bonded hydrogen atom on a donor group and a pair of non bonded electrons on a acceptor group

Question 19

what is a donor group and hydrogen acceptors

Answer 19

• donor group is a hydrogen attached to an electronegative atom (usually N or O)
• hydrogen acceptors are electronegative atoms (usually N or O)

Question 20

acid

Answer 20

substances that release protons when dissolved in water

Question 21

base

Answer 21

substance that accepts protons when dissolved in water

Question 22

What is sugars general formula

Answer 22

(CH2O)n

Question 23

What are sugars

Answer 23

• they are called carbohydrates because of their composition
• the simplest sugars are called monosaccharides
• monosaccharides can be joined together through glycosidic bonds to form disaccharides ( 2 monomers together), oligosaccharides (2-10 monomers) and polysaccharides (>10 monomers)

Question 24

What are sugars used for

Answer 24

• energy source (ex. glucose or can be stored as glycogen)
• can be used for structure (ex. cellulose that forms cell wall)
• slime, mucus
• modification of lipids and proteins
• involved in information storage of our DNA

Question 25

what does TAG stand for

Answer 25

Triacyglycerols

Question 26

What are fatty Acids (FA)

Answer 26

- hydrocarbon chain that contribute to the makeup of fats and membrane lipids - FAs from TAG which serve as an energy source - Fas form membrane lipids which contribute to membrane structure and function

Question 27

how are amino acids joined together

Answer 27

with peptide bonds

Question 28

what are polypeptides

Answer 28

they are long chains of amino acids

Question 29

What are amino acids

Answer 29

- they are the subunits of proteins - they have the same basic structure with a variable side chain (R)

Question 30

How do amino acids form the final 3D structure of a protein

Answer 30

- they fold by using covalent and non covalent interactions

Question 31

What are nucleotides

Answer 31

- they are the subunits of DNA and RNA - base + sugar + phosphate (AMP)

Question 32

what is a nucleoside

Answer 32

base + sugar (adenosine)

Question 33

what does RNA and DNA stand for

Answer 33

- RNA (ribonucleic acid) - DNA (deoxyribonucleic acid)

Question 34

What are the functions of nucleotide functions

Answer 34

- short term carriers of chemical energy (ATP) - storage and retrieval of biological information (DNA, RNA)

Question 35

Macromolecules are the most ______. of the organic molecules in a living cell

Answer 35

abundant

Question 36

How are macromolecules made

Answer 36

from monomers (the subunits: sugar, amino acids, nucleotides)

Question 37

What is native state

Answer 37

- in general all molecules of a given protein or RNA species adopt the same 3D conformation despite the countless folding possibilities - in general dictated by non covalent bonds (electrostatic interactions, van Der Waal interactions, hydrogen bonds, hydrophobic interactions)

Question 38

What effect do non covalent interactions have on macromolecules

Answer 38

- non covalent interactions allow macromolecule to act as building blocks to form much larger structures