Macromolecules( UPDATE) Flashcards
What are the four groups bonded to the α-carbon in amino acids?
- Carboxyl group (COOH)
- Amino group (NH2)
- Hydrogen atom (H)
- Variable side chain (R-group)
The R-group varies in size, charge, polarity, and reactivity, dictating the amino acid’s specific chemical properties.
What is a dipeptide?
A dipeptide is formed from the condensation reaction between two amino acids, linked by a peptide bond
The peptide bond is an amide bond formed between the carboxyl group of one amino acid and the amino group of another.
List the levels of protein structure.
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
What defines the primary structure of a protein?
The linear sequence of amino acids in a polypeptide chain, stabilized by peptide bonds.
What stabilizes the secondary structure of a protein?
Hydrogen bonds between the backbone amide and carbonyl groups.
Describe the structure of α-helices.
A right-handed coiled conformation where the polypeptide backbone forms a spiral structure, stabilized by hydrogen bonds.
What characterizes β-sheets?
Extended polypeptide chains arranged side-by-side, forming a pleated sheet-like structure, stabilized by hydrogen bonds.
What is tertiary protein structure?
The three-dimensional arrangement of a polypeptide chain, stabilized by various types of bonds.
What types of interactions stabilize tertiary structure?
- Hydrophobic interactions
- Hydrogen bonds
- Ionic bonds (salt bridges)
- Disulfide bonds
Define quaternary protein structure.
The arrangement of multiple polypeptide chains (subunits) into a single functional protein complex.
What is the primary function of hemoglobin?
Transportation of oxygen gas around the body to respiring cells.
How many oxygen molecules can one hemoglobin molecule carry?
Four molecules of O2.
What are the two main types of proteins?
- Globular
- Fibrous
Characteristics of globular proteins include:
- Metabolically active
- Soluble in water
- Compact, tightly-packed structure
Provide examples of globular proteins.
- Enzymes (lysozyme, amylase, trypsin)
- Transport proteins (Hemoglobin, Myoglobin, Serum albumin)
- Storage proteins (Ferritin)
- Hormones (Insulin)
- Antibodies (Immunoglobulins)
Characteristics of fibrous proteins include:
- Usually metabolically inactive
- Structural role
- Insoluble in water
Provide examples of fibrous proteins.
- Collagen
- Elastin
- Keratin
- Fibroin
- Myosin
What is the Biuret test used for?
To detect the presence of peptide bonds characteristic of proteins.
What are lipids primarily composed of?
- Carbon
- Hydrogen
- Oxygen
What are triglycerides composed of?
A glycerol molecule esterified to three fatty acid chains.
What distinguishes saturated fatty acids from unsaturated fatty acids?
Saturated fatty acids have no double bonds between carbons, while unsaturated fatty acids have one or more double bonds.
Define phospholipids.
Amphipathic lipids composed of a glycerol backbone, two fatty acid chains, and a phosphate group.
What is the structure of steroids?
Characterized by a four-ring hydrocarbon structure.
What are the functions of lipids?
- Energy storage
- Making biological membranes
- Insulation
- Protection
- Acting as hormones
- Utilization of nutrients
Phospholipids vs. Triglycerides: What is a key difference?
Phospholipids contain a phosphate group, while triglycerides do not.
