Enzyme Structure, Classification, and Regulation
Enzyme Structure and Function
Enzyme activity depends on the integrity of its structure. Maintaining primary, secondary, tertiary, and quaternary structures ensures that the enzyme retains its functionality.
Cofactors and Coenzymes
Some enzymes require the participation of other chemicals:
- When one or more metal ions, such as iron, magnesium, or zinc, are involved, they are designated as cofactors.
- If the chemical components are more complex organic molecules, they are called coenzymes.
- When the coenzyme
Immunology Key Concepts: Pathways, Organs, and Selection
1. Cytosolic vs. Endocytic Antigen Processing
| Characteristic | Cytosolic Pathway | Endocytic Pathway |
|---|---|---|
| Antigen origin | Intracellular (viruses, cytosolic proteins) | Extracellular (bacteria, ingested pathogens) |
| MHC involved | Class I | Class II |
| Activated cell type | CD8+ (cytotoxic T cells) | CD4+ (helper T cells) |
| Antigen processing | In the proteasome | In endosomes and lysosomes |
| Peptide transport | TAP (Transporter associated with processing) | From endosomes to MHC molecules in vesicles |
| Polymorphic zones | α1 and α2 | α1 and β1 |
2. Primary
Read MoreBacterial Genetics: Competency, Plasmids, PCR, and Electrophoresis
Bacterial Genetics
Explain Competency
- The physical state of a bacterial cell which allows nucleotide bases in primers to anneal to the complementary base present in a DNA template.
Describe the Transformation Experiment
- The uptake of free-floating DNA from the environment by bacterial cells.
Characteristics of a Plasmid: pGLO Example
- Plasmids carry full-length genes and, therefore, can introduce new genotypes into bacterial cells, which can cause new phenotypes.
Function of Buffers in Plasmid DNA Isolation
- An
Plasma Membrane: Structure, Functions & Signaling
Plasma Membrane
Every cell (eukaryotic or prokaryotic) has a plasma membrane that allows:
- To maintain the composition of the cell
- To regulate the passage of material into and out of the cell
In eukaryotes, there are other membranes in several organelles. All of them have a common structure: a lipid bilayer with proteins and carbohydrates. Thickness: 7 to 10 nm.
Membrane Composition
Chemically, the cell membrane is composed of three components, namely:
- Lipids (3 types:
- Phospholipids
- Glycolipids
- Cholesterol
- Proteins
- Carbohydrates
1.
Read MoreCereal Grains: Structure, Composition, and Dough Making
Grasses: Cereals are cultivated grasses, members of the monocotyledonous family Poaceae. Do not confuse them with pulses, which are legumes. The fruit (grain) develops after pollination. Pseudo-cereals include quinoa and amaranth.
Grain Structure
Embryo: 2 to 10% of the grain. It consists of the embryonic axis (EA) and scutellum (S). The EA contains primordial roots and shoots with leaf initials. The S is a secretory and absorptive organ that connects with the endosperm and releases hormones and enzymes
Read MoreCell Membrane Transport and Biological Molecules
Cell Membrane and Transport
The cell membrane, composed of a phospholipid bilayer, is selectively permeable, allowing certain molecules to pass while restricting others. Small non-polar molecules (O₂, CO₂) and small uncharged polar molecules (H₂O, glycerol) can pass freely, while ions (Na⁺, K⁺, Cl⁻) and large polar molecules (glucose, amino acids) require transport proteins. Membrane proteins serve various functions: structural support (desmosomes), enzymatic activity, signal transduction
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