Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Molecular Structure of Immunoglobulins

Immunoglobulins are high molecular weight globular proteins consisting of four polypeptide chains: two heavy (H) and two light (L) chains. These chains are joined by disulfide bonds—one between the L and H chains, and two between the H chains. These molecules are glycoproteins containing glucidic protein chains.

Types of Light and Heavy Chains

There are two types of light (L) chains (λ and κ) and five types of heavy (H) chains (α, δ, ε, γ, μ). This results in five distinct immunoglobulin isotypes: IgA, IgD, IgE, IgG, and IgM.

Characteristics of Immunoglobulin Isotypes

Immunoglobulin G (IgG): This is the most abundant isotype, representing 80% of total immunoglobulins. It rapidly binds to macrophages...

Diseases Caused by Microorganisms

Diseases caused by microorganisms are a significant public health concern. These tiny organisms, including bacteria, viruses, protozoa, and fungi, can cause a wide range of illnesses.

Common Examples of Infectious Diseases

• Malaria
• Diarrheal Diseases
• Tuberculosis (TB)
• AIDS
• Influenza (Flu)
• SARS, Measles, Poliomyelitis
• Ebola and Marburg Hemorrhagic Fevers

Malaria

Cause and Transmission

Malaria is caused by Plasmodium protozoa, which infect erythrocytes (red blood cells).

It is transmitted by Anopheles mosquitoes, which act as vectors.

Prevention and Treatment

Prevention includes antimalaria drugs and avoiding mosquito bites.

Mosquito control methods like crop spraying with insecticide are also used.

Distribution

Malaria is prevalent...

Muscle Tissue Structure and Function

Large cylindrical cells are called fibers. These cells contain a large number of mitochondria due to high energy expenditure, are multinucleated, and possess a specialized membrane (sarcolemma) and cytoplasm (sarcoplasm). Electron microscopy reveals repeating structures called sarcomeres, which contain ordered protein fibrils forming distinct bands.

Muscle Contraction Mechanics

When a muscle contracts, fibers slide past one another, decreasing the sarcomere length and causing the H-band to almost completely disappear.

Types of Muscle Tissue

• Skeletal Muscle: Characterized by rapid, voluntary contraction. These fibers are elongated and composed of myofibril proteins (actin and myosin).
• Cardiac Muscle: Features rapid,

Defining Health and Quality of Life

Health is a state of complete physical, mental, and social well-being, not only as the absence of disease. Disease is defined as impaired health or a transient loss of physical, psychological, or social well-being.

Quality of life refers to the happiness and comfort level; it is the satisfaction that allows one to act and feel their life positively. This depends on their physical and mental level of autonomy and social relationships with their environment.

Classifications and Origins of Diseases

Genetic and Congenital Conditions

• Genetic diseases: These are alterations in the genome where the genetic defect is the direct cause of the disease. Examples include Hemophilia, Down syndrome, and some forms of diabetes.

Excretion Organs in Invertebrates

In primitive animals, excretion occurs externally by diffusion across the body surface.

Protonephridia

Found in flatworms, these are highly branched tubes whose inner ends terminate in a cell with flagella, known as a flame cell, while the outer end is an excretory pore. Flame cells are located among intercellular liquids. Waste substances pass through diffusion to the cells and from there to the tubules, where the liquid is expelled, aided by the movement of the flagella.

Metanephridia

Found in annelids and molluscs, this system consists of a long tube with one internal funnel-shaped end called nephrostomes, which possess cilia. The motion of these cilia drives the liquid towards the inside of the tube. Along the...

RNA Maturation: Post-Transcriptional Processing

After transcription, RNA molecules often undergo modifications before they become fully functional. This process is called post-transcriptional maturation.

Prokaryotic RNA Processing

In prokaryotic organisms, messenger RNA (mRNA) can often be translated directly as it is being transcribed. However, when the DNA encoding transfer RNA (tRNA) and ribosomal RNA (rRNA) is transcribed, it forms a long precursor RNA molecule containing multiple copies of tRNA or rRNA sequences. This long primary transcript is then cut into smaller, functional fragments by specialized enzymes to yield the final tRNA and rRNA molecules.

Eukaryotic RNA Processing and Splicing

In eukaryotic organisms, most protein-encoding genes...

The Evolving Concept of the Gene

The concept of the gene has varied throughout history as knowledge of its function and structure has increased. Initially, the term was applied to hereditary factors studied by Mendel.

Later in the twentieth century, the gene was localized to the chromosome (the chromosomal theory of inheritance of the early twentieth century).

In the 1940s, in accordance with the one gene–one enzyme principle, it was considered that the gene is a region of the genome that directs the synthesis of a single enzyme. This theory was proposed by Beadle and Tatum, whose experiments using the fungus Neurospora demonstrated this relationship. Following this work, a gene was defined as a piece of DNA that encodes a polypeptide chain....

Homopolysaccharides: Structure and Function

Homopolysaccharides are the most abundant type of polysaccharide, consisting of only one type of monosaccharide. Their primary function is to provide support, protection, or energy storage.

Structural Homopolysaccharides

These polysaccharides are integral parts of the cell structure, providing support and protection. They are found in the cell walls of fungi and the shell structure of arthropods, often serving as linking molecules.

Cellulose

• Cellulose is a linear polymer composed of D-glucose molecules linked by $\beta$-D(1→4) bonds.
• Among the glucose molecules of the same chain, it forms intrachain hydrogen bonds.
• The linear chains are arranged in parallel and held together by interchain hydrogen bonds.

ATP: The Cellular Energy Currency

ATP acts as an intermediary between reactions that release energy and those that consume it. It is formed by the union of an energy-rich molecule and a phosphate group. ATP is synthesized in the inner mitochondrial membrane through the process of oxidative phosphorylation.

Aerobic Respiration

This is the process by which molecules are oxidized for energy, using oxygen as the final electron acceptor.

Catalysts and Enzymes

Catalyst

A substance that facilitates a chemical reaction in tiny quantities. It is not consumed, does not provide energy, and functions by lowering the activation energy.

Enzymes

Biological catalysts that regulate the speed of chemical reactions within organisms.

Enzymatic Digestion

Enzymes form an...