Biological Macromolecules

Flashcards based on Biological Macromolecules Lecture Notes

What are macromolecules?

Large molecules built from small organic molecules that are complex in structure. Most are polymers.

What is a polymer?

A large molecule built from many similar building blocks, called monomers.

Name three of the four major classes of life's organic macromolecules that are polymers.

Carbohydrates, proteins, and nucleic acids.

What are the monomer(s) and polymer of carbohydrates?

Monosaccharide-Polysaccharide.

What are the monomer(s) and polymer of Proteins?

Amino Acid - Polypeptide.

What are the monomer(s) and polymer of Nucleic acids (DNA, RNA)?

Nucleotide - Polynucleotide.

Which of the 4 major classes of biological macromolecules is not strictly a polymer?

Lipids (or Fats)

What are the components of Lipids?

Glycerol + Fatty acid

For each class of polymer, where do the monomers come from?

Proteins: Amino Acids, DNA: Nucleotides, Carbohydrates: Monosaccharides

Name an example of immense variety from a small set of monomers?

DNA sequence (4 monomers), but no two individuals have the exact same sequence.

About how many nucleotides (A,T,C,G) in an individual’s DNA?

About 3 billion

How are biological macromolecules assembled?

By a condensation reaction between the polymer and a new monomer; water is lost during this reaction (also called a dehydration reaction).

How are biological polymers disassembled?

By a hydrolysis reaction, where water is used in the reaction.

How are lipids (fats) made?

Through a dehydration reaction linking a fatty acid molecule to a glycerol molecule.

What two groups react when making lipids?

A hydroxyl group on glycerol and the carboxyl group at the end of the fatty acid.

What are the two components of a Fat Molecule?

Glycerol and Fatty Acids

What is the definition of a Fatty Acid?

A hydrocarbon chain with a carboxyl group on the terminal carbon

What is the definition of Glycerol?

A 3 carbon alcohol

What is a key property of lipids?

Hydrophobic property.

What are the two variations in Fatty Acids?

The length of the carbon chain, and the number and location of carbon-carbon double bonds.

What are the two types of Fatty Acids?

Saturated and Unsaturated Fatty Acids

What are saturated fatty acids (Saturated Fats)?

Have no carbon-carbon double bonds; have the maximum number of hydrogen atoms possible.

What do studies show about diets high in saturated fatty acids?

They lead to elevated LDL cholesterol, which correlates with coronary artery disease.

What are unsaturated fatty acids (Unsaturated Fats)?

Have one or more double bonds.

What do studies show about diets high in unsaturated fatty acids?

They lead to lowering LDL cholesterol levels.

What are the two components of a Phospholipid?

Glycerol and Fatty Acids

How do phospholipids differ from triglycerides?

Phospholipids have only two fatty acids instead of three, and have a phosphate group (and polar head group) instead of a third fatty acid.

What does it mean that phospholipids are Amphipathic?

They consists of a hydrophilic “head” and hydrophobic “tails”.

What does the amphipathic structure of phospholipids lead to?

Them naturally forming a bilayer structure in aqueous environments.

What is the most energetically favorable structure for a phospholipid bilayer in water?

A sealed sphere

List the three types of carbohydrates

Monosaccharides, disaccharides, and polysaccharides.

How are Polysaccharides formed?

By covalently linking together monosaccharide monomers through a dehydration reaction.

What type of reaction joins monosaccharides together?

A dehydration reaction involving a hydroxyl group from each monosaccharide.

What is the general formula of monosaccharides?

CxH2xOx

What type of structure do monosaccharides typically adopt in an aqueous environment?

A ring structure.

What type of reaction occurs when monosaccharides adopt a ring structure in an aqueous environment?

A reaction involving a carbonyl group and a hydroxyl group.

What are disaccharides and how are they formed?

Two monosaccharides joined by a glycosidic linkage from a dehydration (condensation) reaction.

What are the two storage polysaccharides?

Starch and Glycogen

What is starch?

A polymer consisting entirely of glucose monomers found in Plants.

What is glycogen?

A polymer of glucose monomers found in Animals. Is more highly branched.

What are the two structural polysaccharides?

Cellulose (plants) and Chitin (animals)

What is cellulose?

A structural polysaccharide that is a major component of plant cell walls. It is a polymer of b-glucose.

What type of reaction joins amino acids together?

A dehydration reaction between the carboxyl group of one amino acid and the amino group of the other amino acid.

What is the bond formed between amino acids called?

A peptide bond

What is the importance of R-groups in amino acids?

The different chemical properties of these R groups are important for the structure and function of the protein.

What determines a protein's function?

Its 3-dimensional structure (or conformation).

Define a protein's primary structure

The sequence of amino acids. The sequence is determined by the gene for that protein.

What determines a protein's secondary structure?

Folding of a portion of the polypeptide into a repeating structure or conformation (alpha helix and beta pleated sheet). Involves hydrogen bonding.

What determines a protein's tertiary structure?

Overall 3-dimensional shape of a polypeptide. Non-covalent interactions between amino acid R groups and backbone groups.

What type of interaction is the most important for determining a protein's final structure?

Hydrophobic interactions

What happens when a protein denatures?

On its own, it will refold into the same 3-D structure. Demonstrates that the sequence of the polypeptide is sufficient to determine its final structure.

What are Protein Chaperones?

They keep proteins segregated from bad influences while a protein folds.

What determines a protein's quaternary structure?

The same non-covalent interactions that control the folding of a single polypeptide, also control the interaction and binding of multiple polypeptides.

What is the function of nucleic acids?

To store and transmit hereditary information.

What is a gene?

A unit of inheritance. Sequence of nucleotides. Gene sequence programs the amino acid sequence of polypeptides.

What are the two types of nucleic acids?

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

State the Central Dogma of Biology

DNA to RNA to Protein

What does DNA do?

Stores information for the synthesis of specific proteins, directs RNA synthesis, and directs protein sequences through messenger RNA (mRNA).

What are the three parts of a nucleotide?

Phosphate group, pentose sugar, nitrogenous base.

What type of reaction links nucleotides together?

A dehydration reaction

What nitrogenous bases are found in DNA?

Cytosine, thymine, adenine, guanine.

What nitrogenous bases are found in RNA?

Cytosine, uracil, adenine, guanine.

What are the two general types of Nitrogenous bases?

Pyrimidines and Purines

What are examples of Pyrimidines?

Cytosine, thymine, uracil.

What are examples of Purines?

Adenine, guanine.

How are polynucleotides linked?

By a phosphodiester bond between the 5' carbon of one ring and the 3' carbon of the next ring in the chain.

Describe a complete DNA molecule

Formed by 2 strands of the polynucleotide binding to each other. Strands linked by hydrogen bonds between the nitrogen bases. Adenine only matches up with thymine. Guanine only with cytosine. Strands must be anti-parallel.