Antibodies, Viruses, and Prions: An Immunology Primer
Antibodies: Structure and Function
Antibodies are glycoproteins found in a soluble form in blood or other bodily fluids of vertebrates. They act as receptors on B lymphocytes and are employed by the immune system to identify and neutralize foreign materials. Each antibody consists of basic structural units with two large heavy chains and two light chains.
Antibodies are synthesized by a type of white blood cell called a B lymphocyte. Although the general structure of antibodies is very similar, a
Read MoreEcology: Population Regulation, Niches, and Interactions
- r-selection is selection for life history traits that maximize reproductive success at low density.
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In density-independent population regulation, birth rate and death rate do not change with population density.
- Environmental factors that occur randomly, regardless of population size.
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In density-dependent population regulation, birth rates fall and death rates increase with rising population density.
- Population density is maintained at or near carrying capacity (K).
- Density-independent factors are
Understanding Common Non-Infectious Diseases
Key Non-Infectious Diseases
Cancer
Cancer results from an abnormal proliferation of cells caused by DNA modifications. For instance, the p53 protein normally halts cell division, allowing time for DNA repair or triggering apoptosis (programmed cell death) if damage is irreparable. When this process fails, cells with damaged DNA can survive and multiply uncontrollably, forming tumors. These tumors can grow, press on organs, and spread (metastasize) through blood or lymph to other parts of the body.
Read MoreHuman Sensory Receptors: Eye and Ear Anatomy and Function
Eye Receptors: The Sense of Sight
Most of the information that reaches your brain comes through your eyes. Of all the senses, sight is the most complex and often dominates the others.
Structure of the Eye
The eyes are the sensory organs where the receptors for light are located. They are fragile and protected by the bones of the skull, housed inside the orbits. Externally, the eyelids, eyelashes, and tears protect and clean the eyes, while eyebrows help keep sweat out.
- Outer Layer: This consists of
Lipids and Proteins: Structure, Types, and Functions
Lipids: Structure and Functions
Waxes
Waxes result from the esterification of a long-chain alcohol with a fatty acid. They primarily function to prevent dehydration.
Esterification Reaction Example:
CH3-(CH2)n-CH2OH + HOOC-(CH2)m-CH3 → CH3-(CH2)n-CH2-OOC-(CH2)m-CH3 (Wax) + H2O
An example is beeswax.
Unsaponifiable Lipids
These lipids cannot be hydrolyzed by saponification.
Steroids
Steroids are lipids derived from the cyclopentanoperhydrophenanthrene structure. Their structure consists of four fused carbon
Read MoreMitochondria and Plastids: Structure and Cellular Roles
Mitochondria: Structure and Functions
Mitochondrial Structure
Mitochondrial Matrix
Contains a semi-liquid material with the consistency of a gel. It includes:
- Mitochondrial DNA molecules: In most mammalian cells, this is circular, double-stranded DNA, distinct from nuclear DNA.
- Mitochondrial RNA molecules.
- Enzymes for mitochondrial DNA replication, transcription, and translation.
- Enzymes involved in the Krebs cycle and the beta-oxidation of fatty acids.
- Ions of Calcium (Ca), Phosphorus (P), and ribonucleoproteins.