Amino Acids and Protein Structure

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Questions and Answers

Which of the following amino acids is considered highly hydrophilic?

Arginine (correct)

Leucine

Phenylalanine

Isoleucine

What characteristic differentiates the N-terminal from the C-terminal of a peptide?

The C-terminal has a side chain.

The C-terminal is the first amino acid in the sequence.

The N-terminal contains a carboxyl group.

The N-terminal has an amino group. (correct)

Which of the following statements about peptide bonds is incorrect?

Peptide bonds result in the formation of a polypeptide chain.

Peptide bonds connect amino acids in proteins.

Peptide bonds can be broken by hydrogen bonding. (correct)

Peptide bonds are formed by dehydration reactions.

Which property of amino acids is influenced by the functional groups in their side chains?

Solubility in water Signup and view all the answers

Which of the following statements about the molecular weight of amino acids is accurate?

Tryptophan is heavier than Glycine in terms of molecular weight. Signup and view all the answers

Which characteristic distinguishes α-amino acids from other types of amino acids?

They are found in proteins. Signup and view all the answers

How many different combinations can be made with 3 amino acids?

8,000 Signup and view all the answers

Which of the following is true about the stereoisomers of amino acids?

Chiral amino acids have four different substituents. Signup and view all the answers

Which class of biomolecules is NOT categorized with amino acids?

Steroids Signup and view all the answers

What role do proteins serve in biological systems?

They can act as enzymes and antibodies. Signup and view all the answers

What is the significance of the R group in the structure of amino acids?

It determines the identity and characteristics of the amino acid. Signup and view all the answers

Which statement about amino acids is incorrect?

Only β-amino acids are used in protein synthesis. Signup and view all the answers

What type of amino acid is GABA?

γ-amino acid Signup and view all the answers

Which of the following characteristics is true about amino acids in the nonpolar, aliphatic group?

They do not contain a benzene ring. Signup and view all the answers

How does electronegativity influence bond polarity in amino acids?

A larger difference in electronegativity increases bond polarity. Signup and view all the answers

What does it mean when a compound is described as hydrophobic?

It repels water molecules. Signup and view all the answers

Which factor differentiates glutamate from glutamic acid?

Glutamate is the ionized form of glutamic acid. Signup and view all the answers

Which of the following correctly describes the role of water in relation to charged compounds?

Charged compounds are soluble in water due to its polarity. Signup and view all the answers

Which statement about glycine is true?

Glycine is the only amino acid that does not have an isomer. Signup and view all the answers

How can aromatic compounds in amino acids be identified?

They contain a benzene ring or derivatives. Signup and view all the answers

What is a characteristic feature of polar, uncharged amino acids?

They are soluble in water due to the presence of polar bonds. Signup and view all the answers

Study Notes

Amino Acids

Amino acids are the building blocks of proteins
Proteins are composed of 20 different amino acids
Each amino acid contains a central carbon atom (α-carbon) bonded to four groups:
- An amino group (NH₂)
- A carboxyl group (COOH)
- A hydrogen atom (H)
- A variable side chain (R group), which differentiates the 20 amino acids
Proteins are typically 50-2,000 amino acids long
Possible combinations of 20 amino acids in a protein are massive: 20^2 = 400, 20^3 =8,000, 20^100 ≈ 10¹³⁰, 20¹⁰⁰⁰ ≈ ?
Proteins have diverse functions including hormones, antibodies, muscle fibers, oxygen transport, ion channels, and enzymes
The α-carbon is tetrahedral with bond angles of 109.5°
Amino acids in proteins are L-amino acids
Amino acids have both positive and negative charges (e.g., H₃N⁺ - C - COO^-)
Proteins contain various amino acids having different R-groups, defining different classes
Classification of amino acids bases on their R groups:
- Nonpolar, aliphatic
- Aromatic
- Polar, uncharged
- Positively charged
- Negatively charged
Abbreviations are used to represent amino acids (e.g., Ala for alanine)
Peptide bonds link amino acids to create polypeptide chains
The ends of a peptide chain are different (amino-terminal and carboxyl-terminal ends).
Peptides are smaller than proteins and are made from amino acids, using peptide bonds
Size of peptides and proteins varies, as shown by examples such as cytochrome c(12,400 MW, 104 residues) and titin (2,993,000 MW, 26,926 residues).
Amino acids are important for the structure and function of biomolecules

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Description

This quiz delves into the fundamental concepts of amino acids and their role as the building blocks of proteins. You will explore the structure of amino acids, the diversity of protein functions, and the significance of the α-carbon and R groups. Perfect for biology students looking to deepen their understanding of protein biochemistry.