Chapter 3 (a) - Proteins, Carbohydrates, and Lipids

Question 1

Living organisms consist mostly of ______-_____ compounds.

Answer 1

• carbon-based Proteins
• DNA
• carbohydrates
• molecules that distinguish living matter are all composed of carbon compounds.

Question 2

Organic chemistry

Answer 2

the study of compounds that contain carbon.

Question 3

Most organic compounds contain ________ atoms in addition to carbon atoms.

Answer 3

hydrogen

Question 4

Vitalism

Answer 4

the idea that organic compounds arise only in organisms, was disproved when chemists synthesized these compounds. Stanley Miller’s classic experiment demonstrated the abiotic synthesis of organic compounds.

Question 5

Mechanism

Answer 5

the view that all natural phenomena are governed by physical and chemical laws

Question 6

With four valence electrons, carbon can form ____ covalent bonds with a variety of atoms.

Answer 6

four. Carbon is unparalleled in its ability to form large, complex, and diverse molecules.

Question 7

In molecules with multiple carbons, each carbon bonded to four other atoms has a ____________ shape.

Answer 7

tetrahedral However, when two carbon atoms are joined by a double bond, the atoms joined to the carbons are in the same plane as the carbons.

Question 8

Carbon chains

Answer 8

form the skeletons of most organic molecules. Carbon chains vary in length and shape. They can vary by:

• Length
• Branching
• Double bond position
• Presense of rings

Question 9

Hydrocarbons

Answer 9

organic molecules consisting of only carbon and hydrogen. Many organic molecules, such as fats, have hydrocarbon components. Hydrocarbons can undergo reactions that release a large amount of energy.

Question 10

Isomers

Answer 10

compounds with the same molecular formula but different structures and properties.

Question 11

Structural isomers

Answer 11

Isomers that have different covalent arrangements of their atoms.

Question 12

Cis-trans isomers (Geometric Isomers)

Answer 12

Isomers that have the same covalent bonds but differ in spatial arrangements. (On different sides than before)

• Cis isomer: The two Xs
  are on the same side.
• Trans isomer: The two Xs
  are on opposite sides.

Question 13

Enantiomers

Answer 13

are isomers that are mirror images of each other. Usually only one isomer is biologically active. Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules.

Question 14

Functional groups

Answer 14

the components of organic molecules that are most commonly involved in chemical reactions. The number and arrangement of functional groups give each molecule its unique properties.

Question 15

The seven functional groups that are most important in the chemistry of life:

Answer 15

• Hydroxyl group
• Carbonyl group
• Carboxyl group
• Amino group
• Sulfhydryl group
• Phosphate group
• Methyl group

Question 16

Hydroxyl

Answer 16

• Name of Compound: Alcohols (names usually end in -ol)
• Functional Properties:
  
  • Is polar as a result of the electrons spending more time near the electronegative oxygen atom.
  • Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars

Question 17

Carbonyl

Answer 17

• Name of Compound:
  
  • Ketones if the carbonyl group is within a carbon skeleton.
  • Aldehydes if the carbonyl group is at the end of the carbon skeleton.
• Functional properties:
  
  • A keytone and an aldehyde may be structural isomers with different properties, as in the case for acetone and propanal.
  • Keytone and aldehyde groups are also found in sugars, giving rise to two major groups of sugars: ketoses (containing ketone groups) and aldoses (containing aldehyde groups)

Question 18

Carboxyl

Answer 18

• Name of compound: Carboxlic acids, or organic acids
• Functional properties:
  
  • Acts as an acid; can donate an H+ because the covalent bond between oxygen and hydrogen is so polar.
  • Found in cells in the ionized form with a charge of 1- and called a carboxylate ion.

Question 19

Amino

Answer 19

• Name of compound: Amines
• Functional properties:
  
  • Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms).
  • Found in cells in the ionized from with a charge of 1+

Question 20

Sulfhydryl

Answer 20

• Name of compound: Thiols
• Functional properties:
  
  • Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure.
  • Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair.

Question 21

Phosphate

Answer 21

• Name of compound: Organic phosphates
• Functional properties:
  
  • Contributes negative charge to the molecules of which it is a part (2- when at the end of a molecule and 1- when located internally in a chain of phosphates.
  • Molecules containing phosphate groups have the potential to react with water, releasing energy.

Question 22

Methyl

Answer 22

• Name of compound: Methylated compounds
• Functional properties:
  
  • Addition of a methyl group to DNA, or to molecules bound to DNA, affects the expression of genes
  • Arrangement of methyl groups in male and female sex hormones affects their shape and function

Question 23

adenosine triphosphate (ATP)

Answer 23

• A phosphate molecule that is the the primary energy-transferring molecule in the cell
• consists of an organic molecule called adenosine attached to a string of three phosphate groups