Amino Acids: Structure and Properties

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Questions and Answers

What is the primary factor that determines the chemical and physical properties of amino acids?

The ionizable nature of the –NH2 and –COOH groups

The number of amino and carboxyl groups

The R group (correct)

The aromatic nature of the molecule

Which of the following amino acids is classified as basic?

Glutamic acid

Glycine

Valine

Lysine (correct)

What is the characteristic of amino acids that changes their structure in solutions of different pH?

The presence of a carboxyl group

The presence of a hydroxy methyl group

The ionizable nature of the –NH2 and –COOH groups (correct)

The presence of a methyl group

What is the general characteristic of lipids?

They are generally water insoluble Signup and view all the answers

What is the difference between a fat and an oil?

The melting point of the lipid Signup and view all the answers

What is the characteristic of phospholipids?

They have a phosphorylated organic compound Signup and view all the answers

What is the general characteristic of fatty acids?

They have a carboxyl group attached to an R group Signup and view all the answers

What is the characteristic of triglycerides?

They have three fatty acids esterified with glycerol Signup and view all the answers

What is the term used to describe biomolecules such as amino acids, sugars, and others?

Metabolites Signup and view all the answers

Which of the following is an example of a primary metabolite?

Amino acids Signup and view all the answers

What is the main difference between primary and secondary metabolites?

Primary metabolites have identifiable functions, while secondary metabolites do not Signup and view all the answers

Which of the following is an example of a secondary metabolite?

Morphine Signup and view all the answers

What is the term used to describe biomolecules such as alkaloids, flavonoids, and rubber?

Secondary metabolites Signup and view all the answers

Why are secondary metabolites important to human welfare?

They can be used as drugs, spices, and scents Signup and view all the answers

What is the characteristic common to all compounds found in the acid-soluble pool?

They are not specified in the content Signup and view all the answers

What is the term used to describe biomolecules such as cellulose, rubber, and gums?

Polymeric substances Signup and view all the answers

Which of the following is NOT an example of a secondary metabolite?

Amino acids Signup and view all the answers

What is the main difference between primary metabolites and biomacromolecules?

Primary metabolites are small molecules, while biomacromolecules are large molecules Signup and view all the answers

Study Notes

Amino Acids

The R group in amino acids can be a hydrogen (glycine), a methyl group (alanine), hydroxy methyl (serine), etc.
Chemical and physical properties of amino acids are determined by the amino, carboxyl, and R functional groups.
Amino acids can be classified into acidic (e.g., glutamic acid), basic (lysine), and neutral (valine) based on the number of amino and carboxyl groups.
Aromatic amino acids include tyrosine, phenylalanine, and tryptophan.
Amino acids have ionizable –NH2 and –COOH groups, which change structure in solutions of different pH.

Lipids

Lipids are generally water insoluble.
Fatty acids have a carboxyl group attached to an R group, which can be a methyl, ethyl, or higher number of –CH2 groups.
Fatty acids can be saturated (without double bond) or unsaturated (with one or more C=C double bonds).
Examples of fatty acids include palmitic acid (16 carbons) and arachidonic acid (20 carbons).
Glycerol is a trihydroxy propane and a simple lipid.
Lipids can be classified into monoglycerides, diglycerides, and triglycerides based on the number of fatty acids esterified with glycerol.
Fats and oils are classified based on melting point, with oils having a lower melting point (e.g., gingelly oil).

Phospholipids

Phospholipids have phosphorus and a phosphorylated organic compound.
They are found in cell membranes and are examples of lipids with more complex structures.
Lecithin is a type of phospholipid.

Nucleic Acids

Nitrogen bases include adenine, guanine, cytosine, uracil, and thymine.
Nucleosides are formed when nitrogen bases are attached to a sugar.
Nucleotides are formed when a phosphate group is also esterified to the sugar.
Examples of nucleosides include adenosine, guanosine, thymidine, uridine, and cytidine.
Examples of nucleotides include adenylic acid, thymidylic acid, guanylic acid, uridylic acid, and cytidylic acid.
Nucleic acids like DNA and RNA consist of nucleotides and function as genetic material.

Carbonic Anhydrase

CO2 reacts with H2O to form H2CO3, a slow reaction that produces about 200 molecules of H2CO3 per hour.
With the presence of carbonic anhydrase, the reaction rate increases dramatically, forming about 600,000 molecules of H2CO3 per second.
The enzyme accelerates the reaction rate by about 10 million times.

Metabolic Pathways

A multistep chemical reaction, where each step is catalysed by the same enzyme complex or different enzymes, is called a metabolic pathway.
The reaction of glucose becoming pyruvic acid is a metabolic pathway that involves ten different enzyme-catalysed reactions.

Stability and Energy

Stability is related to the energy status of a molecule or structure.
The energy level difference between the substrate (S) and product (P) determines if the reaction is exothermic or endothermic.
Activation energy is the difference in average energy content of the substrate from the transition state.
Enzymes bring down the energy barrier, making the transition of S to P more easy.

Enzyme Action

Each enzyme has a substrate binding site, forming a highly reactive enzyme-substrate complex (ES).
The ES complex is short-lived and dissociates into the product(s) and the unchanged enzyme.
The formation of the ES complex is essential for catalysis.

Biomolecules

Biomolecules are thousands of organic compounds, including amino acids, sugars, etc.
Primary metabolites are found in animal tissues and include categories of compounds shown in Figure 9.1.
Secondary metabolites are found in plant, fungal, and microbial cells, and include compounds such as alkaloids, flavonoids, rubber, essential oils, antibiotics, and colored pigments.

Secondary Metabolites

Examples of secondary metabolites include pigments, alkaloids, terpenoids, essential oils, toxins, lectins, drugs, and polymeric substances.
Secondary metabolites may have ecological importance or be useful to human welfare.
The role or functions of all secondary metabolites in host organisms are not yet fully understood.

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Description

Learn about the structure and properties of amino acids, including their functional groups and classification into acidic, basic, and neutral categories.