Chapter 3: Carbon and the Molecular Diversity of Life — Flashcards

A comprehensive set of Question-and-Answer flashcards covering key concepts from Carbon and the Molecular Diversity of Life, including macromolecules, carbohydrates, lipids, proteins, nucleic acids, and genomics.

What unique bonding capability does carbon have that enables the diversity of organic molecules?

Carbon can form up to four covalent bonds with other atoms (valence 4), allowing a vast diversity of molecular structures. The four most common partners in organic molecules are carbon, hydrogen, nitrogen, and oxygen.

What are the four major classes of macromolecules studied in this chapter?

Carbohydrates, lipids, proteins, and nucleic acids.

What is a hydrocarbon and why are hydrocarbons hydrophobic?

A hydrocarbon is an organic molecule consisting only of carbon and hydrogen. They are hydrophobic because most of their bonds are nonpolar C–H bonds, making them poorly soluble in water.

What is the difference between isotopes and isomers?

Isotopes are different atomic forms of the same element. Isomers have the same number of atoms of the same elements but different structures, leading to different properties.

What is a functional group?

A chemical group that affects molecular function by being directly involved in chemical reactions.

Name the seven functional groups that are important in biology.

Hydroxyl, Carbonyl, Carboxyl, Amino, Sulfhydryl, Phosphate, Methyl.

Which functional group can act as a base and is often involved in amino group chemistry?

Amino group (-NH2).

Which functional group is key for ATP and energy transfer?

Phosphate group.

What is ATP’s relevance in biology?

ATP releases energy when its terminal phosphate bond is hydrolyzed, providing energy for cellular work.

What happens in a dehydration synthesis reaction?

Two monomers covalently bond with the loss of a water molecule, forming a polymer.

What is a polymer and what is a monomer?

A polymer is a long chain formed from many similar or identical building blocks (monomers) linked by covalent bonds.

What are the four main classes of macromolecules in biology?

Carbohydrates, lipids, proteins, and nucleic acids.

What occurs when two monomers join to form a polymer, and what is this type of reaction called?

Two monomers join with a dehydration synthesis reaction to form a polymer.

What is the term for the breakdown of polymers into monomers using water?

Hydrolysis.

What do ‘hydro-’ and ‘-lysis’ mean in their root words?

Hydro- means water; lysis means break.

What are monosaccharides and what are their general building blocks for carbohydrates?

Monosaccharides are the simple sugar monomers that make up carbohydrates.

What is the formula for hexose sugars?

C6H12O6.

Name the three common monosaccharides.

Glucose, Fructose, and Galactose.

All sugars contain the same functional group; what is it?

Carbonyl group.

Monosaccharides are classified by what structural property?

The number of carbons (e.g., triose C3, hexose C6).

Where are the other carbon atoms located in the ring form of glucose?

Five carbons are part of the ring or attached to the ring; the sixth carbon is outside the ring in the linear form or attached to the ring in the ring form.

What is a glycosidic linkage?

A covalent bond formed between two monosaccharides by a dehydration reaction.

What are the two main categories of polysaccharides and give examples for each?

Storage: starch and glycogen; Structural: cellulose and chitin.

Why can humans digest starch but not cellulose?

Humans have enzymes to hydrolyze alpha-linkages in starch, but not the beta-linkages in cellulose.

Name two organisms that can digest cellulose and how they do it.

Certain bacteria, protists, and some fungi in herbivores (e.g., cows, termites) possess enzymes that break beta linkages in cellulose.

What are the components and bonding of fats (triglycerides)?

Glycerol + three fatty acids; formed by dehydration synthesis with ester linkages.

How many water molecules are removed to form a triacylglycerol from glycerol and three fatty acids?

Three water molecules.

What distinguishes saturated and unsaturated fats?

Saturated fats have no double bonds in their fatty acids; unsaturated fats have one or more double bonds (often cis), causing kinks.

What is a trans fat and why should it be limited in the diet?

An unsaturated fat with a trans double bond; associated with increased risk of cardiovascular disease due to atherosclerosis.

What is the major function of fats in living organisms?

Energy storage.

What is a phospholipid and what is its key structural feature?

A phospholipid has glycerol, a phosphate group, and two fatty acid tails; it forms a bilayer with a hydrophilic head and hydrophobic tails.

Why are phospholipid tails hydrophobic?

They are hydrocarbon chains with nonpolar C–H bonds.

Where are the hydrophobic tails of a phospholipid bilayer located and why?

In the interior of the bilayer, away from water, to avoid contact with water.

Name two other steroids besides cholesterol.

Vertebrate sex hormones and cortisone.

What are the monomers of proteins and how many different R groups exist?

Amino acids; 20 different R groups.

List the eight major protein functions (types) with examples.

Enzymes (maltase, pepsin, sucrase); Storage (casein, ovalbumin); Contractile and motor (actin, myosin); Transport (membrane proteins, hemoglobin); Receptor (cell signaling); Hormonal (insulin); Defensive (antibodies); Structural (keratin, collagen).

What are the four levels of protein structure?

Primary, Secondary (alpha helix and beta pleated sheet), Tertiary, Quaternary.

What types of interactions drive protein folding?

Hydrophobic interactions, van der Waals forces, hydrogen bonds, disulfide bridges, and ionic bonds.

Why is hemoglobin said to have quaternary structure?

Because it consists of four polypeptide subunits (two alpha and two beta) that assemble together.

How does a single amino acid substitution cause sickle-cell disease?

Valine replaces glutamic acid in the beta chain of hemoglobin, altering protein shape and causing fibers that deform red blood cells.

What is denaturation and how can it occur?

Unraveling of a protein and loss of native shape due to changes in pH, salt concentration, temperature, solvents, chemicals, or excessive heat.

Name four diseases associated with misfolded proteins.

Cystic fibrosis, Alzheimer’s disease, Parkinson’s disease, mad cow disease.

What are nucleic acids built from, and what are their monomers?

Nucleic acids are built from nucleotides; monomers are nucleotides composed of a sugar, a nitrogenous base, and a phosphate group.

What are the DNA bases and which are purines vs pyrimidines?

DNA bases: Adenine (A), Guanine (G) are purines; Cytosine (C) and Thymine (T) are pyrimidines.

What bases are found in RNA that are not in DNA?

Uracil (U) replaces thymine in RNA.

How do ribose and deoxyribose differ?

Deoxyribose lacks an oxygen on the 2' carbon (has H instead of OH).

What forms the backbone and what forms the rungs in DNA?

Backbone: sugar and phosphate; Rungs: base pairs joined by hydrogen bonds.

What is the shape of DNA and why are the strands antiparallel?

DNA is a double helix; strands run in opposite directions (5' to 3' and 3' to 5') so they are antiparallel.

What is the term for the two strands of DNA and what assembles them?

The uprights are sugars and phosphates; the rungs are base pairs; hydrogen bonding between bases holds the strands together.

What is the complementary sequence to a given DNA strand (example: 5' TAGGCC T-3')?

3' ATCCGGA-5' (complementary base pairing with opposite orientation).

What is genomics and what is proteomics?

Genomics is the study of entire genomes; proteomics is the large-scale analysis of protein data sets from genomes, often informing personalized medicine.

How can DNA and protein sequences serve as tape measures of evolution?

Closely related species share more identical DNA and protein sequences; greater differences indicate more distant relationships.