BIOL 150 Lecture 4 (1-26)

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Questions and Answers

What defines a functional group in organic chemistry?

It is a class of hydrocarbons characterized by their solubility.

It is a separate molecule that interacts with hydrocarbons.

It is a group of atoms responsible for the molecule's specific properties. (correct)

It is a group of atoms that determines the molecule's size.

Which functional group is represented by the structure -COOH?

Carboxyl group (correct)

Hydroxyl group

Amino group

Carbonyl group

What is the primary characteristic of a hydroxyl group?

It contains an -OH configuration. (correct)

It consists of a sulfur atom and a hydrogen atom.

It is involved in double bonding with oxygen.

It is found only in carbohydrates.

Which statement about the methyl group is accurate?

It contributes to the properties of fatty acid chains. Signup and view all the answers

What role does 'R' play in the representation of organic compounds?

It denotes the rest of the hydrocarbon chain. Signup and view all the answers

Which of the following groups is not a major functional group found in biological molecules?

Alkyl group Signup and view all the answers

Which functional group is described as containing a nitrogen atom attached to two hydrogen atoms?

Amino group Signup and view all the answers

Which functional group can be identified by the structure C=O?

Carbonyl group Signup and view all the answers

What are polysaccharides primarily composed of?

Monosaccharides Signup and view all the answers

Which polysaccharide serves as the main form of stored carbohydrate in the body?

Glycogen Signup and view all the answers

Which of the following is true about cellulose?

It is the most abundant organic compound on Earth. Signup and view all the answers

Chitin is primarily found in which of the following?

The cuticles of arthropods Signup and view all the answers

What structural feature distinguishes chitin from cellulose?

Chitin includes (–NH-CO-CH3) groups. Signup and view all the answers

Which polysaccharide is known for being an ideal storage molecule for energy?

Glycogen Signup and view all the answers

What percentage of total organic carbon on Earth does cellulose comprise?

Approximately 33% Signup and view all the answers

What characteristic is true for polysaccharides in general?

They fold into compact shapes. Signup and view all the answers

What is another name for the sulfhydryl group?

Thiol group Signup and view all the answers

Which class of organic molecules is characterized by the formula (CH2O)n?

Carbohydrates Signup and view all the answers

What type of reaction is characterized by the loss of a water molecule when two substances are joined?

Condensation reaction Signup and view all the answers

What distinguishes aldoses from ketoses in monosaccharides?

Aldoses have a carbonyl group at the end of the chain Signup and view all the answers

Which of the following is a primary role of the phosphate group in nucleotides?

Providing a source of energy for cellular processes Signup and view all the answers

Why can't humans digest cellulose?

Humans lack the necessary glycoside hydrolases Signup and view all the answers

What type of carbohydrate consists of two monosaccharides?

Disaccharide Signup and view all the answers

What are the basic building blocks of nucleic acids?

Nucleotides Signup and view all the answers

Study Notes

Overview of Organic Chemistry

Organic chemistry studies carbon-containing compounds, focusing on their structures, synthesis, and reactions.
Organic molecules, primarily hydrocarbons, feature carbon atoms bonded to hydrogen and other elements.

Functional Groups

Functional groups are specific atom arrangements that grant molecules characteristic properties.
Major functional groups in biological molecules include:
- Hydroxyl (-OH)
- Methyl (-CH3)
- Carboxyl (-COOH)
- Carbonyl (C=O)
- Amino (-NH2)
- Phosphate (-PO4)

Methyl Group

The methyl group is the smallest hydrocarbon functional group (-CH3).
Methylation plays a role in regulating gene expression, protein function, and RNA metabolism.

Hydroxyl Group

The hydroxyl group (-OH) is present in alcohols, phenols, and carboxylic acids.
Common in biological molecules, found in carbohydrates, amino acids, and nucleic acids.
Ethanol (EtOH) is an example of a molecule containing a hydroxyl group.

Carbonyl Group

The carbonyl group features a carbon atom double-bonded to an oxygen atom (C=O).
Exists in two varieties: at the end (aldehyde) or in the middle (ketone) of a carbon chain.

Carboxyl Group

The carboxyl group (-COOH) consists of a carbon atom double-bonded to an oxygen atom and bonded to a hydroxyl group.
Present in carboxylic acids and amino acids.

Amino Group

The amino group (-NH2) consists of nitrogen bonded to two hydrogen atoms.
Found in all amines and amino acids, it provides bonding opportunities due to the presence of a lone electron.

Sulfhydryl Group

Comprises a sulfur atom bonded to a hydrogen atom (-SH).
Known as a thiol group, this functional group is important in biological systems.

Polysaccharides

Complex carbohydrates made of monosaccharide chains linked by glycosidic bonds.
Ideal for energy storage, large and insoluble, and fold into compact shapes.

Types of Polysaccharides

Glycogen: A branched polysaccharide stored in animals’ liver and muscles; it serves as the main carbohydrate reservoir for glucose.
Cellulose: The most abundant organic compound, crucial for plant structure; it is fully permeable to water and solutes.
Chitin: An unbranched polysaccharide found in arthropod cuticles and fungal cell walls, similar to cellulose.

Phosphate Group

Part of nucleotides (-PO4); critical for energy transfer in cells (ATP).
Regulates protein function depending on its presence or absence.

Monomers and Polymers

Oligomers consist of fewer than 50 monomers linked together.
Condensation reactions join substances with the loss of a water molecule.
Hydrolysis reactions involve water being added, resulting in decomposition.

Classes of Organic Molecules

Four major classes include:
- Carbohydrates
- Proteins
- Lipids
- Nucleic Acids

Carbohydrates

Composed of carbon and water in the ratio of one carbon to one water molecule (CH2O)n, often referred to as saccharides.
Types include:
- Monosaccharides (e.g., glucose, fructose): Single sugar molecules.
- Disaccharides (e.g., lactose, sucrose): Formed from two monosaccharides.
- Polysaccharides: Composed of multiple sugars, which can be similar or diverse.

Families of Carbohydrates

Aldoses: Have a carbonyl at the end of the carbon chain.
Ketoses: Have a carbonyl within the chain, commonly as 2-ketoses.

Starch vs Cellulose

Starch is digestible due to alpha glycosidic linkages.
Cellulose has beta glycosidic linkages, making it indigestible for humans due to a lack of suitable enzymes.

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