43 Questions
Which elements are basic constituents of proteins?
Oxygen, Hydrogen, Carbon
What type of bond links amino acids in proteins?
Peptide bond
Proteins retain their biological activity within a limited range of which factors?
pH and temperature
Which atom is found in the general structure of an amino acid and is labeled as the central α-carbon?
Carbon
Which group forms part of the amino acid structure and is responsible for its acidic properties?
Carboxyl group
Which amino acid is classified as aliphatic?
Alanine
How many amino acids are included in the aliphatic group mentioned?
Five
Which code represents Lysine?
Lys, K
Which type of side chain do amino acids in the aliphatic group possess?
Hydrocarbon side chains
Which of the following is a basic amino acid?
Arginine
How are amino acids differentiated from each other?
By their side chain
What type of chemical bond links the amino acids in peptides?
Peptide bond
Which of the following hormones stimulates uterine contraction?
Oxitocin
How much protein is destroyed daily during the continuous renewal process in the body?
200 to 300 grams
Which classification of proteins can be categorized based on their biological function?
Enzymes and antibodies
What property of proteins is affected by pH levels?
Solubility
What is the role of glutathione in the cell?
Participates in Redox reactions
Which amino acid is essential?
Histidine
Which amino acid has an acidic side chain?
Aspartic acid
At what pH does an amino acid have no net charge?
Isoelectric point
Which amino acid is not essential?
Cystine
What is the characteristic of amino acids that allows them to act as both acids and bases?
Amphoteric nature
Which of the following amino acids are paired with their corresponding amides?
Aspartic acid and Asparagine
What type of bonds are involved in the quaternary structure of proteins?
Ionic bonds
Which type of protein structure determines the sequence of amino acids?
Primary
What is lost during the denaturation of a protein?
Its secondary, tertiary, and quaternary structures
Which of the following is a physical agent that can cause protein denaturation?
Radiations
Which of the following proteins have a quaternary structure?
Collagen, hemoglobin, keratin
What structural level is described by the spatial arrangement of amino acids?
Secondary
What effect does denaturation have on the physicochemical properties of proteins?
It causes structural changes and loss of function
Which is not a type of secondary structure of a protein?
Pledged sheet
What happens to the solubility of proteins when exposed to high concentrations of salts?
It decreases.
Which type of proteins include lipoproteins, glycoproteins, and metalloproteins?
Conjugated proteins
Primary structure in proteins refers to the:
sequence and identity of amino acids.
Which type of interaction stabilizes the secondary structure of proteins?
Hydrogen bonds.
What effect does a low concentration of salts have on protein solubility?
Increases solubility.
Which is an example of a protein with secondary structure being alpha-helix?
Miosin in muscles
What is the normal recommended protein intake per day based on body weight?
1.5 g per kg
Which function is associated with hemoglobin and myoglobin?
Transport
What property allows proteins to maintain internal pH and osmotic balance?
Homeostatic
Which of the following is NOT a property of proteins?
Polarization
Which molecule is considered the 'building blocks' of proteins?
Amino acids
What type of bond is formed between two amino acids?
Peptide bond
Study Notes
Proteins
- Biopolymers (macromolecules) composed of oxygen, hydrogen, carbon, sulfur, phosphorus, iodine, iron, and magnesium.
- Preserve biological activity only within a relatively limited pH and temperature range.
Amino Acids
- Building blocks of proteins
- General formula: atomic hydrogen, alpha carbon, amino group, carboxyl group, and side chain
- Classified based on their side chain:
- Aliphatic (non-polar)
- Basic (polar)
- Acidic (polar)
- Essential amino acids: cannot be synthesized by the human body and must be obtained through the diet
- Phenylalanine
- Histidine
- Tryptophan
- Threonine
- Methionine
- Valine
- Lysine
- Leucine
- Isoleucine
- Non-essential amino acids: can be synthesized by the human body
- Alanine
- Aspartic acid
- Glutamic acid
- Cysteine
- Serine
- Arginine
- Tyrosine
Peptides
- Linear chains of amino acids linked by amide bonds
- Examples:
- Oxytocin: hormone that stimulates uterine contraction
- Glucagon: hormone that has actions opposite to insulin
- Antibiotics
- Glutathione: participates in cellular redox reactions
Protein Structure
- Primary structure: sequence of amino acids in a protein
- Secondary structure: spatial arrangement of amino acids in a protein (α-helix and β-pleated sheet)
- Tertiary structure: 3D arrangement of the secondary structure
- Quaternary structure: union of multiple polypeptide chains to form a complex protein
- Denaturation: loss of native protein structure leading to loss of biological activity
Protein Functions
- Structural: provide framework and support for cells and tissues
- Enzymatic: catalyze chemical reactions
- Hormonal: regulate various physiological processes
- Defensive: create antibodies and regulate factors against foreign agents or infections
- Transport: transport molecules and ions across cell membranes
- Homeostatic: maintain pH and osmotic balance
Protein Properties
- Acidity/basicity: isoelectric point
- Solubility: affected by pH, salts, and non-polar solvents
- Specificity
- Polarizability
- Flexibility
- Ability to form cross-links
- Solubility
- Acid-base properties (isoelectric point)
This quiz covers the classification of amino acids based on their side chain, including aliphatic amino acids. Learn about the different types of amino acids and their characteristics.
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