Lecture 1.2 - Chemical Foundations of Life

Question 1

List the most common elements found in living organisms.

Answer 1

1. carbon
2. oxygen
3. hydrogen
4. nitrogen
5. sulfur
6. phosphorus

Question 2

Explain why carbon is a key element for life.

Answer 2

this element is a key to life because it:

1. can use its 4 valence (outer) electrons to form 4 covalent bonds w/ with hydrogen, oxygen, phosphorus, nitrogen, and even other carbon atoms.
2. form chains, rings, and other complex structures by forming single bonds, double bonds, or triple bonds with another atom

Question 3

electronegativity

Answer 3

the ability of an atom to attract an atom towards itself from an atom to which it is bonded

Question 4

hydrogen bond

Answer 4

a bond formed between hydrogen and another element such as phosphorus, sulfur, oxygen, and nitrogen.

Question 5

hydrophilic

Answer 5

polar compounds that readily dissolve in water

Question 6

nonpolar

Answer 6

used describe bonds that have:

1. electronegativity difference is less than 0.5
2. electrons are shared equally

Question 7

single bond

Answer 7

a bond with the capacity for rotation in whichch one electron is shared between 2 atoms

Question 8

valence electrons

Answer 8

electrons located in outer most shell of an atom

Question 9

water

Answer 9

a polar, bent molecule capable of forming hydrogen bonds

Question 10

Determine how many covalent bonds a given atom can form based on the number of valence electrons it has

Answer 10

The number of bonds that an atom can form can often be predicted from the number of electrons needed to reach an octet (eight valence electrons)

Question 11

Explain how and why atoms interact to form molecules.

Answer 11

n/a

Question 12

Explain how the properties of water relate to the structure of water and why they make water important for life.

Answer 12

Water is the most important molecule for life because the chemical reactions required for life occurin water. Water is a small, bent, polar molecule that can participate in hydrogen bonding.

Question 13

Describe the four types of noncovalent interactions in both words and pictures.

Answer 13

ionic
polar
nonpolar
n/a

Question 14

acid

Answer 14

chemical species that donates protons or hydrogen ions and/or accepts electrons

Question 15

amino

Answer 15

the functional group that consists of a nitrogen atom attached by single bonds to 3 hydrogen atoms

traits:
1. charged
2. basic= a proton acceptor
3. accepts H+ in living tissues NH3+
4. enters condensation reaction by giving up H+

Question 16

cation

Answer 16

an ion that has lost one or more electrons, gaining a positive charge.

Question 17

functional group

Answer 17

Functional groups have distinct chemical and physical properties that influence the behavior of the molecule to which the group is attached

Question 18

organic molecules

Answer 18

molecules that contain carbon

Question 19

polar covalent bond

Answer 19

bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair.

Question 20

ball-and-stick model

Answer 20

this molecular model displays both the three-dimensional position of the atoms and the bonds between them.

Question 21

base

Answer 21

accepts a proton, releases a hydroxide anion when dissolved in water,

Question 22

benzene

Answer 22

an organic chemical compound with the molecular formula C6H6.

Question 23

carbonyl

draw and describe 2 forms

Answer 23

a reactive group that is the site of reactions that link aldehydes and ketones into larger, more complex organic molecules

1. aldehyde
   class of compounds: aldehydes
   ex: acetaldehyde

• polar
• C=O group is very reactive
• carbon atom is double-bonded to one oxygen and singly bonded to one hydrogen
• important in buildings molecules and in energy-releasing reactions

2. keto
   class of compounds ketones
   ex: acetone

• polar
• made of carbon double-bonded to an oxygen
• C=O group is important in carbohydrates and in energy reactions

Question 24

carboxyl

Answer 24

a functional group with a carbon atom double-bonded to an oxygen atom and singly bonded to a hydroxyl group. The molecular formula is COOH.

class of compounds: carboxylic acid 
ex: acetic acids 

characteristics:
1. charged
2. acidic; capable of being a proton donor
3. ionizes in living tissues to form COO- and H+ (or COOH)
4. enters into condensation reaction by giving up -OH

Question 25

covalent bond

Answer 25

* this bond occurs when the orbitals of 2 molecules overlap in an energetically stable manner * this type of bond involves the sharing of one or more electron pairs between atoms * can also be represented in 4 ways 1. ball-and-stick 2. molecular formula 3. structural formula 4. space-filling model

Question 26

double bond

Answer 26

a chemical bond in which two pairs of electrons are shared between two atoms.

Question 27

element

Answer 27

a pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei.

Question 28

hydrophobic interaction

Answer 28

describes the relations between water and hydrophobes (low water-soluble molecules). Hydrophobes are nonpolar molecules and usually have a long chain of carbons that do not interact with water molecules. The mixing of fat and water is a good example of this particular interaction

Question 29

hydroxyl

Answer 29

a functional group consisting of a hydrogen atom covalently bonded to an oxygen atom. The hydroxyl group is denoted by -OH in chemical structures and has a valence charge of -1. The hydroxyl radical is very reactive, so it quickly reacts with other chemical species. this group increase the solubility of compounds containing this group * class of compounds: alcohols * ex: ethanol characteristics: * polar * forms hydrogen bonds with water to help dissolve molecules * enables linkage to other molecules by condensation

Question 30

ionic bond

Answer 30

the force of attraction that holds together positive and negative ions. It forms when atoms of a metallic element give up electrons to atoms of a nonmetallic element.

Question 31

line-angle drawing

Answer 31

formulas imply a carbon atom at the corners and ends of lines. Each carbon atom is understood to be attached to enough hydrogen atoms to give each carbon atom four bonds.

Question 32

methyl

Answer 32

these functional groups. contribute to hydrophobic and van de Waal interactions class of compounds: alkyl ex: alaninw characteristics: * non-polar * important in interactions w/ other non-polar molecules and in energy transfer * highly stable * consisting of a central carbon atom bonded to three hydrogen atoms

Question 33

molecular formula

Answer 33

these formulas give the kind and number of atoms of each element present in the molecular compound

Question 34

molecule

Answer 34

an electrically neutral group of two or more atoms held together by chemical bonds.

Question 35

nonpolar covalent bond

Answer 35

equal sharing of the bond electrons arise when the electronegativities of the two atoms are equal.

Question 36

organic molecules

Answer 36

molecules that contain carbon

Question 37

phenyl

Answer 37

a cyclic group of atoms with the formula C6H5.

Question 38

phosphate

Answer 38

a functional group that carries 2 negative charges ``` class of compounds: organic phosphates ex: 3-phosphoglycerat ``` characteristics * phosphorus atom bonded to four oxygen atoms * has three single bonds and one double bond * charged * acidic * enters into condensations reactions by giving up -OH * when bonded to another phosphate, hydrolysis releases much energy

Question 39

polar

Answer 39

he electronegativity difference between the two elements needs to be between 0.5 to 1.6.

Question 40

salt

Answer 40

The neutral ionic compound formed by the chemical combination of acid and base, or through neutralization.

Question 41

space-filling model

Answer 41

The space-filling models are the most realistic. The size and position of an atom in a space-filling model are determined by its bonding properties

Question 42

structural formula

Answer 42

Structural formulas identify the location of chemical bonds between the atoms of a molecule. A structural formula consists of symbols for the atoms connected by short lines that represent chemical bonds—one, two, or three lines standing for single, double, or triple bonds,

Question 43

valency

Answer 43

ability of an atom or a group of chemically bonded atoms to form chemical bonds with other atoms or groups of atoms.

Question 44

van der waals interaction

Answer 44

A weak force of attraction between electrically neutral molecules that collide with or pass very close to each other.

Question 45

sulfhydryl

Answer 45

these groups are important in protein structure ``` class of compounds thiols ex: mercaptoethanol ``` characteristics 8 by giving up H, two -SH groups can react to form a disulfide bridge, thus stabilizing protein structure