Introduction to Organic Molecules and Carbohydrates

Flashcards covering organic molecules, carbon bonding, functional groups, dehydration and hydrolysis reactions, macromolecules, and carbohydrate structures.

What defines an organic molecule?

An organic molecule contains carbon-to-hydrogen and/or carbon-to-carbon bonds and is abundant in living organisms.

What is the most abundant and stable form of carbon in the atmosphere on Earth?

Carbon dioxide ($CO_2$).

What molecule serves as the direct chemical energy used by cells?

Adenosine triphosphate (ATP).

What is the atomic composition of a carbon atom?

A carbon atom has 6 electrons, 6 protons, and 6 neutrons, with 4 electrons in its outer shell.

How many covalent bonds can a single carbon atom form?

Carbon can form up to 4 covalent bonds.

How many electrons do nitrogen and oxygen need to fill their outer shells, respectively?

Nitrogen needs 3 electrons (forming 3 bonds), and oxygen needs 2 electrons (forming 2 bonds).

Which carbon chemical bonds are nonpolar, and which are polar?

Carbon-to-carbon ($C-C$) and carbon-to-hydrogen ($C-H$) bonds are nonpolar, while carbon-to-oxygen ($C-O$) and carbon-to-nitrogen ($C-N$) bonds are polar covalent.

Why does glucose dissolve easily in water?

Glucose contains polar hydroxyl ($-OH$) groups that form hydrogen bonds with water molecules.

What is the chemical function of an amino group ($NH_2$)?

It acts as a weak base by taking on a hydrogen proton, which reduces the proton concentration of water.

What is the chemical function of a carboxylic acid group ($COOH$)?

It acts as a weak acid by donating a proton to water, becoming $COO^-$.

Why is a methyl group ($CH_3$) classified as hydrophobic?

It consists entirely of nonpolar carbon-to-hydrogen bonds.

What happens when methyl groups are added to DNA?

Adding methyl groups to DNA shuts down a gene from being expressed.

Why is the phosphate group on nucleic acids, ATP, and phospholipids termed inorganic?

It is termed inorganic because it contains no carbon atoms.

What chemical reaction joins monomers together into a polymer by removing a water molecule?

A dehydration or condensation reaction.

Why is polymer assembly referred to as both a dehydration and a condensation reaction?

It is called dehydration because a water molecule is removed from the monomers, and condensation because that water molecule is released into the surrounding environment.

What type of chemical reaction breaks polymers down into monomers by adding a water molecule?

A hydrolysis reaction.

How do condensation and hydrolysis reactions differ in terms of energy requirements?

Condensation is energetically unfavorable (requires energy input), whereas hydrolysis is energetically favorable (releases energy).

What are the monomer subunits for polysaccharides, proteins, and nucleic acids?

Monosaccharides are the monomers for polysaccharides, amino acids are the monomers for proteins, and nucleotides (bases) are the monomers for nucleic acids.

What ratio of hydrogen to oxygen is found in all carbohydrates?

Carbohydrates have a hydrogen-to-oxygen ratio of $2:1$, which is the same ratio as water.

In chemical structure drawings, what atom is represented by an unlabeled node or corner?

A carbon atom.

What monosaccharides make up the disaccharides sucrose and lactose?

Sucrose is composed of glucose and fructose; lactose is composed of glucose and galactose.

What is the specific name of the covalent bond that holds two sugars together?

A glycosidic bond.