Proteins And Amino Acids Flashcards
What are amino acids?
Amino acids are nutritional elements needed by the body, forming basic structural units of peptides and proteins.
What functions do amino acids serve in the body?
They are involved in the synthesis of body protein, non-protein nitrogen-containing compounds, and provide 12 to 20% of total daily body energy needs.
How are amino acids synthesized?
Many amino acids are derived from the diet, while others are synthesized in the body through metabolic processes.
What is the chemical structure of amino acids?
Amino acids have an amino group and a carboxyl group, with their behavior changing based on pH levels.
What happens to amino acids at neutral pH?
At neutral pH, amino acids exist as zwitterions with zero net charge.
What is the charge of amino acids at low pH?
At low pH, amino acids have a net positive charge, with both amino and carboxyl groups protonated.
What is the charge of amino acids at high pH?
At high pH, amino acids have a net negative charge, with both amino and carboxyl groups deprotonated.
What is the significance of the R group in amino acids?
The R group confers high variability in structure and physical properties, influencing hydrophobicity and solubility.
What are the classifications of amino acids based on the carbon atom?
Amino acids can be classified as α-amino acids, β-amino acids, and γ-amino acids based on the position of the amino group.
What are proteinogenic amino acids?
Proteinogenic amino acids include essential and non-essential amino acids.
What are some examples of essential amino acids?
Essential amino acids include histidine, leucine, isoleucine, lysine, methionine, valine, phenylalanine, threonine, and tryptophan.
What are some examples of non-essential amino acids?
Non-essential amino acids include alanine, cysteine, glycine, proline, serine, tyrosine, aspartate/asparagine, and glutamate/glutamine.
What is the simplest amino acid?
Glycine is the simplest amino acid and acts as an inhibitory neurotransmitter.
What is the most abundant amino acid?
Glutamine is the most abundant amino acid, comprising 61% of skeletal muscle.
What are branched-chain amino acids (BCAA)?
Branched-chain amino acids include leucine, isoleucine, and valine, which are important for skeletal muscle.
What is the isoelectric point of an amino acid?
The isoelectric point (pI) is the pH at which an amino acid bears no net charge.
How is the genetic code related to amino acids?
The genetic code consists of codons that correspond to specific amino acids, defining how DNA is translated into proteins.
Who first described the concept of codons?
The concept of codons was first described by Francis Crick and his colleagues in 1961.
What did Nirenberg and Matthaei discover about the genetic code?
They showed that the RNA sequence UUU specifically coded for the amino acid phenylalanine.
What percentage of body mass do proteins constitute in an adult?
15% of body mass.
What is the role of proteins as biological catalysts?
Proteins act as enzymes.
What is the transport and storage function of proteins?
Haemoglobin is responsible for transport and storage.
How do proteins contribute to defense in the body?
Proteins function as antibodies.
What role do proteins play in regulation and homeostasis?
Proteins act as hormones.
What are some structural components made of proteins?
Muscle (actin and myosin), hair, nails, and skin.
What is the primary structure of proteins?
The sequence of amino acids on a peptide chain.
What does the primary structure of proteins include?
It includes the determination of the number of amino acids in a peptide chain.
How is the primary structure of proteins typically written?
From the amino end to the carboxyl end (N – C).
What are the classifications of peptide bonds in a primary structure?
Peptides: fewer than 50 amino acids; Dipeptides: 2 amino acids; Tripeptides: 3 amino acids; Polypeptides: more than 10 amino acids; Proteins: more than 50 amino acids.
What is the secondary structure of proteins?
Folding of the polypeptide chain into specific coiled structures held together by hydrogen bonds.
What are the types of secondary structures in proteins?
- Alpha Helix 2. Beta pleated sheet 3. Loop or coiled conformation 4. Super secondary motif.
What is the shape of an alpha helix?
A clockwise rodlike spiral shape.
How is the alpha helix formed?
By intrachain hydrogen bonding between C=O group of each amino acid and NH2 group present 4 residues ahead.
What are the properties of proteins with an alpha helix structure?
They have great strength and elasticity and can be easily stretched due to tight coiling.
What characterizes a beta pleated sheet?
5 to 10 amino acids line up side by side, forming a structure that is fully expanded and inelastic.
What is the loop or coil conformation in proteins?
Present mainly in globular proteins, connecting two alpha helices or beta sheets.
What are super secondary motifs?
Structures formed when two beta pleated sheets are connected by an alpha helix.
What does the tertiary structure of proteins refer to?
The overall conformation of a polypeptide.
What is the shape of myoglobin when fully extended?
Its length is 20 times its width.
What does the quaternary structure of proteins involve?
Proteins with more than one peptide chain subunit.
What is an example of a protein with a quaternary structure?
Hemoglobin.
What are globular proteins?
Spherical or oval-shaped proteins, subdivided into albumin and globulins.
What are fibrous proteins?
Long threadlike fibers that are usually insoluble in water, constituting structural proteins.
What are examples of fibrous proteins?
Collagen, elastin, keratin.
How are proteins classified based on function?
- Structural proteins 2. Transport proteins 3. Regulatory proteins 4. Catalytic proteins 5. Contractile proteins 6. Protective proteins 7. Storage proteins.
What are some clinical correlates related to proteins?
Nutrition, antioxidants, hormones and enzymes, genetic disorders, laboratory tests.
What are disorders of protein misfolding called?
Proteopathies.
What are some examples of diseases related to protein misfolding?
Creutzfeldt–Jakob disease, Alzheimer’s disease, Parkinson’s disease, amyloidosis, Gaucher’s disease.
