1.3 The Carbon Chemistry of Life

Question 1

Carbon forms the ______ of large diverse molecules

Answer 1

backbone

Question 2

Carbon atoms _____ to each other to form long chains, rings, or branched structures.

Answer 2

bind

Question 3

Molecules consisting only of carbon atoms bonded to hydrogen atoms are called
_____________.

Answer 3

hydrocarbons

Question 4

What is the smallest hydrocarbon?

Answer 4

Methane

Question 5

The chain of carbon atoms in a biochemical molecule is the carbon _______ of the
molecule.

Answer 5

skeleton

Question 6

Many carbon-containing rings can join to produce ________, such as the string of sugar molecules that make up a ________ sugar chain.

Answer 6

polymers; complex

Question 7

Double or triple bonds can form between two carbon atoms, _________ the number of remaining ___________ sites by one or two,

Answer 7

decreasing; bonding

Question 8

True or false:

There is almost no limit to the number of different hydrocarbon structures that are pos-
sible, but they are rarely used by living organisms.

Answer 8

True

Question 9

These molecules fall into four major groups, based on their _________: carbohydrates, lipids
(fats), proteins, and nucleic acids.

Answer 9

function

Question 10

Functional group definition

Answer 10

a group of atoms that affects the function of a molecule by participating in chemical reactions

Question 11

Unlike non-polar hydrocarbon chains,
functional groups are usually _______ or strongly _______.

Answer 11

ionic; polar

Question 12

Functional groups on large molecules interact with other molecules and introduce different types of _________.

Answer 12

bonding

Question 13

the chemical or physical properties of a large biological molecule are influenced by the
______ and ______ characteristics of its functional groups.

Answer 13

polar; ionic

Question 14

The forces of attraction that are created by ionic and polar groups are necessary in a chemical reaction in order to form new ______.

Answer 14

bonds

Question 15

What does ethane’s high solubility mean for a cell?

Answer 15

It means that it can be dissolved in the cell cytosol, where it can be used as a fuel,
providing energy for the cell.

Question 16

The release of H+ in water makes the carboxyl group a(n) ____.

Answer 16

acid

Question 17

Proteins are made of ______ ____

Answer 17

amino acids

Question 18

The amino group, NH2, can attract and bond to an H+ proton to become an _____ group.

Answer 18

NH3+

Question 19

True or false

An amino acid has only an acid (carboxyl) as a functional group.

Answer 19

False

An amino acid has BOTH an acid (carboxyl) and a
base (amino) as functional groups.

Question 20

Phosphate functional groups are ________

Answer 20

acidic

Question 21

Why is the overall charge of DNA negative?

Answer 21

DNA is an acid because it contains a huge number of phosphate groups along the
backbone of its structure.

These groups lose their H+ ions and become negatively charged. For this reason, the overall charge of DNA is negative.

Question 22

Dehydration Reaction

Answer 22

Removes components of a water molecule, usually during the assembly of a larger molecule from smaller subunits

Question 23

An example of a dehydration reaction occurs when individual sugar molecules combine to form a _____ molecule, which is a larger
_____________

Answer 23

starch; macromolecule

Question 24

The reverse process of dehydration is ________.

Answer 24

hydrolysis

Question 25

What happens during hydrolysis?

Answer 25

In this process, the components of a water molecule, H+ and OH-, are added to functional groups as the molecules break into smaller subunits.

Question 26

Which type of reaction allows the breakdown of starch into individual sugars?

Answer 26

Hydrolysis

Question 27

True or false:

Both the assembly and breakdown of large biological molecules depend on hydrolysis and dehydration reactions.

Answer 27

True

Question 28

During a ________ reaction, larger molecules react with water and break down into smaller subunits.

Answer 28

hydrolysis

Question 29

Explain how the electron arrangement in carbon atoms enables them to form straight and branching chains and ring structures.

Answer 29

Carbon has four unpaired valence electrons allowing it to form four covalent bonds.

Carbon can bond with one or two other carbons to form straight chains.

When carbon bonds with three or four other carbons, each secondary carbon can form a chain resulting in a branched chain.

Due to electron repulsion, the bonds form a tetrahedral structure.

The angles between the bonds allow chains of carbon to bend around and form ring structures.

Question 30

What is the primary purpose of the functional groups that are found in organic molecules?

Answer 30

Functional groups are specific groups of atoms within organic molecules that are responsible for the characteristic chemical reactions of those molecules.

The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of.

Question 31

Considering the functional groups you have studied, why do you think that compounds with similar structures often have similar uses?

Answer 31

Compounds with similar structures often have similar uses.

Their use is dependent on the properties of the compounds and the properties are dependent on structures of the compounds.

Question 32

Explain how functional groups influence solubility and the forces of attraction between molecules.

Answer 32

Functional groups help determine if a molecule is polar or non-polar.

This property determines the types of solvents and molecules that it is attracted to.

For example, polar solvents dissolve polar and ionic compounds and non-polar solvents dissolve non-polar compounds

Question 33

What role does oxygen play in most functional groups?

Answer 33

In many functional groups, oxygen helps establish the polarity of the molecule.

In some groups, oxygen acts as a reducing agent by losing electrons from compounds while in other groups, it acts as an oxidizing agent by gaining electrons to form a bond.

Question 34

Compare and contrast dehydration synthesis and hydrolysis.

Answer 34

Dehydration synthesis and hydrolysis are both processes that rearrange molecules in organic substances.

Dehydration synthesis connects smaller molecules to form larger organic compounds. Water is lost during the process.

In hydrolysis, water is added, and larger compounds are broken down into smaller units.

Question 35

When would a cell use the dehydration and hydrolysis reactions of polysaccharides?

Answer 35

Dehydration could be used to form longer and more complex polysaccharides for cell function.

Hydrolysis could be used to reduce polysaccharides into simple more easily utilized sugars.

Question 36

How will amino groups influence the solubility and or acidity of the molecule?

Answer 36

Amino groups decrease the acidity and increase the solubility of the molecule in polar solvents.

Question 37

How will carboxyl groups influence the solubility and/or acidity of the molecule?

Answer 37

Carboxyl groups increase the acidity and solubility of the molecule in polar solvents.

Question 38

How will phosphate groups influence the solubility and/or acidity of the molecule?

Answer 38

Phosphate groups increase the acidity and solubility of the molecule in polar solvents.

Question 39

How will carbonyl groups influence the solubility and/or acidity of the molecule?

Answer 39

Carbonyl groups increase the acidity of neighbouring functional groups and increase the solubility of the molecule in polar solvents.

Question 40

How will hydroxyl groups influence the solubility and/or acidity of the molecule?

Answer 40

The hydroxyl group does not influence acidity, but it does enhance water solubility.

Question 41

Carbon molecules that
only contain Carbon and
Hydrogen are called…

Answer 41

hydrocarbons

Question 42

true or false:

carbon molecules can occur only in unbranched chains

Answer 42

false

Carbon molecules can
occur in BRANCHED and
UNBRANCHED Chains

Question 43

functional group

Answer 43

a group of atoms that
affects the function of a molecule by participating in chemical reactions

Question 44

True or false:

the non-polar parts of a functional group do NOT interact in rxns

Answer 44

true

Question 45

purpose of functional groups

Answer 45

makes molecules available for cell use by making them water soluble

e.g Ethanol can be metabolised by the cell because it contains a functional group that makes it water soluble.
Ethane, even though it contains more energy, is not usable since it is not water soluble due to the lack of a functional group.

Question 46

Why are DNA molecules negative?

Answer 46

they contain phosphate groups