Chapter 3: The Compounds of Cells

Hydrocarbons

Organic molecules consisting only of carbon and hydrogen (e.g., methane). Hydrophobic.

Organic Compounds

Contain carbon (and usually H). Carbon's ability to form 4 covalent bonds allows for immense molecular diversity.

Enzymes

Protein catalysts that speed up chemical reactions in cells

It speeds up chemical reactions in organisms without being consumed in the process

Denaturation

The loss of a protein's specific 3-dimensional shape (its native structure) due to changes in physical/chemical conditions (e.g., pH, temperature).

A denatured protein is biologically inactive.

What property of carbon allows it to form diverse molecules?

Carbon has 4 valence electrons,

allowing it to form 4 covalent bonds and create varied carbon skeletons (chains, branches, rings).

What are the six functional groups and their basic properties?

• Hydroxyl (-OH): polar

• Carbonyl (>C=O): polar

• Carboxyl (-COOH): acidic

• Amino (-NH₂): basic

• Phosphate (-OPO₃²⁻): acidic, energy-rich

• Methyl (-CH₃): nonpolar

How do functional groups affect molecular properties?

They participate in chemical reactions in characteristic ways and determine how molecules behave.

What is a monomer

are building blocks

What is a polymer?

are chains of monomers.

How do you break/create them?

DEHYDRATION SYNTHESIS links monomers; HYDROLYSIS breaks polymers.

What are the three categories of carbohydrates with examples?

• Monosaccharides: glucose, fructose (single sugars)

• Disaccharides: sucrose, lactose (double sugars)

• Polysaccharides: starch, glycogen, cellulose (many sugars)

starch

Plant energy storage (unbranched glucose chains).

Glycogen

Animal energy storage (highly branched glucose chains; more compact).

Cellulose

Plant cell wall structure (different bonding than starch; humans cannot digest it).

What is a saturated fat?

no double bonds, solid at room temp (butter)

What is a unsaturated fat

C=C double bonds, liquid (olive oil)

What is trans-fats

artificial trans double bonds, solid, unhealthy

What are the three main types of lipids

Fats

Phospholipids

Steriods

What is a the function of a fat?

long term energy storage

What is a the function of a Phospholipid

cell membranes (amphipathic)

What is a the function of a steroid

cholesterol, hormones (4 fused rings)

How are polypeptides formed

Amino acids linked by peptide bonds via dehydration synthesis to form long chains.

what determines protein function?

The AMINO ACID SEQUENCE determines 3D structure which determines function.

DNA vs. RNA

DNA is double-stranded and contains deoxyribose, while RNA is single-stranded and contains ribose.

DNA stores genetic information, whereas RNA is involved in protein synthesis.

DNA

double-stranded, deoxyribose, A-T/C-G, stores information

RNA

single-stranded, ribose, A-U/C-G, involved in protein synthesis

What is complementary base pairing in DNA?

A pairs with T (2 hydrogen bonds), C pairs with G (3 hydrogen bonds)

What is a mutation and how does it affect protein function?

Any change in the nucleotide sequence of DNA. It can alter the amino acid sequence, changing the protein's 3D structure and function (e.g., SARS-CoV-2 spike protein variants).

What macromolecule CANNOT be a polymer

Lipids

What is a phospholipid made of

Made from 1 glycerol + 2 fatty acids + 1 phosphate group.

What is a steroid made from

Lipids with a carbon skeleton of 4 fused rings.

What is a fat made from

Made from 1 glycerol + 3 fatty acids