Biophysics Flashcards: Molecular Biophysics Amino Acids and Polypeptides

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Questions and Answers

What replaces thymine (T) in RNA alphabet?

Cytosine (C)

Guanine (G)

Uracil (U) (correct)

Adenine (A)

How many bits are needed to identify a specific amino acid?

5 bits

3 bits

4 bits (correct)

2 bits

Which of the following is a correct structure for a phospholipid?

Non-polar tail + O- X X O

Polar head group + O CH2 CH2 N (CH3)3 (correct)

Polar head group + CH CH2 O P O

Non-polar tail + CH2 CH2 NH3+ COOH

What are the names of phospholipids based on the groups choline, ethanolamine, serine, and hydrogen?

Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid Signup and view all the answers

What is the main component of the non-polar (hydrophobic) tail in a phospholipid?

(CH3)3N Signup and view all the answers

How many nucleotide bases are present in DNA?

4 Signup and view all the answers

Which of the following amino acids has the lowest isoelectric point (pI)?

Histidine Signup and view all the answers

In terms of side chain characteristics, which category does Glycine fall into?

Non-polar without hydrogen bond capability Signup and view all the answers

What is the pKa value of the side chain of Cysteine?

4.25 Signup and view all the answers

Which amino acid has the highest relative abundance among the listed amino acids?

Glycine Signup and view all the answers

Based on side chain properties, how would Lysine be classified?

Electrically charged with ionic side chain Signup and view all the answers

What is the role of a peptid bond in protein structures?

Connects two amino acids in a protein chain Signup and view all the answers

What type of weak interactions contribute to the tertiary structure of proteins?

Ionic interactions Signup and view all the answers

Which amino acid is represented by 'ala' in the polypeptide chain ala-ala-ala?

Alanine Signup and view all the answers

What is the primary structure of a protein mainly determined by?

Amino acid sequence Signup and view all the answers

Which protein secondary structure involves hydrogen bonds between N-H and C=O groups?

Alpha helix Signup and view all the answers

In proteins, which type of bonds are known for their strength and stability?

Covalent bonds Signup and view all the answers

What is the purpose of not showing side chains (R) in the figure depicting the beta sheet secondary structure?

To avoid interference in the figure Signup and view all the answers

Study Notes

Amino Acids

Lysine has a pK1' of 2.35 and a pKR of 10.53
L-glutamate has a pK1' of 2.19 and a pKR of 9.67
Amino acids can be classified into three groups based on their side chains: non-polar (incapable of hydrogen bond), polar (capable of hydrogen bond), and those with electrically charged (ionic) side chains

Protein Structure

The primary structure of a protein is its amino acid sequence
A polypeptide chain has a specific sequence of amino acids, e.g., ala-ala-ala
The secondary structure of a protein refers to the specific 3D arrangement of amino acids, such as alpha helix and beta sheet
Alpha helix is a common secondary structure in proteins, where hydrogen bonds form between N-H groups and C=O groups
Beta sheet is another common secondary structure, where side chains (R) are not shown

Tertiary Structure

Weak interactions between rings, including ionic, hydrophobic, and disulfide bonds between cysteine residues, help stabilize the tertiary structure
The tertiary structure of a protein is influenced by these weak interactions

Quaternary Structure

The quaternary structure of a protein refers to the arrangement of multiple polypeptide chains in a protein
Polypeptide chains of different characters, possibly originating from surface charges, contribute to the quaternary structure

Nucleic Acids

Nitrogen bases (nucleotides) include adenine (A), guanine (G), thymine (T), cytosine (C), and uracil (U) in RNA
The amount of information required to identify a specific amino acid is I = log2 20 = 4.32 bits

Phospholipids

Phospholipid molecules have non-polar (hydrophobic) tails and polar (hydrophilic) head groups
The head group can bind to different groups, resulting in different phospholipids, such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidic acid

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Description

Test your knowledge on amino acids and polypeptides in the field of Molecular Biophysics. Questions cover topics such as lysine, L-glutamate, primary structure, and peptide bonds.