Notes, summaries, assignments, exams, and problems for Biology

Vertebrates vs. Invertebrates

Vertebrates: are generally larger than invertebrates and possess a bony or cartilaginous internal skeleton. This skeleton includes a spine composed of bones or cartilages called vertebrae.

Invertebrates: lack a spine and internal skeleton. They exhibit either radial or bilateral symmetry, undergo metamorphosis to reach adulthood, and their bodies are formed by true tissues.

Mammals: Key Characteristics

Mammals are characterized by:

• The presence of hair on their bodies.
• The ability to regulate their body heat (homeothermy), making them warm-blooded animals.
• Internal fertilization and viviparous reproduction (live birth).
• Pulmonary respiration.
• Double-loop blood circulation with a heart divided into four chambers.
• A skeleton

Types of Digestion

Digestion is the process by which complex molecules are broken down into simpler ones. There are two methods of digestion:

• Intracellular Digestion: This takes place inside cells. Each cell functions as a complete digestive system:
  • Food capture (pseudopodia, cilia, or flagella)
  • Food inclusion (endocytosis)
  • Food digestion (lysosomes)
  • Expulsion of undigested material (exocytosis)
  Typical of sponges.
• Extracellular Digestion: This is performed inside the digestive systems consisting of one tract and specialized glands. The nutrients pass into the bloodstream and are distributed to reach all cells. Typical of most animals.

Some animals combine both types of assimilation:

• The food comes in the form of large fragments.
• The inner wall of the

Protein Definition

A protein consists of amino acids linked together. Each amino acid has a central carbon atom attached to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable radical group (side chain).

Protein Classification

Proteins can be classified based on their composition:

• Holoprotein: Composed solely of amino acids.
• Heteroprotein: Composed of amino acids along with other non-amino acid molecules (prosthetic groups).

Amino Acids

Amino acids are organic compounds characterized by having both a carboxyl group (-COOH) and an amino group (-NH2). They are typically solid, crystalline substances with high melting points, soluble in water, and possess optical activity. Their chemical behavior is amphoteric, meaning they... Continue reading "Protein Essentials: Structure, Properties, and Functions" »

Non-Infectious Diseases

Cardiovascular Diseases

Cardiovascular diseases affect the heart and blood vessels, and their incidence is higher in adults and the elderly.

• Atherosclerosis: An enlargement of the walls of the arteries due to the deposition of cholesterol, platelets, and fibrous tissue. The arteries can become calcified and hardened, resulting in a loss of elasticity.
• Thrombus: A blood clot that occurs in an artery or vein, leading to its obstruction (thrombosis). When the clot forms in a vein, it can be released and easily move to another place (embolism).
• Aneurysm: A weakening of the arterial wall, which promotes dilation of the artery. This can rupture and form a hemorrhage.
• Stroke: Interruption of blood supply to the brain.
• Coronary Artery

Emerging and Reemerging Diseases

Emerging diseases are caused by previously unknown germs. These germs may have been hidden or have mutated. An example is Ebola.

Reemerging diseases are those that reappeared after a period of decline. Examples include cholera, tuberculosis, dengue, and malaria.

Outbreaks and Spread

An epidemic outbreak is the rapid spread of an infectious disease affecting many people in a limited area and time.

A pandemic is an epidemic affecting many parts of the world.

Key Concepts

A syndrome refers to the complex and variable damage caused by infectious agents.

A reservoir is an animal that harbors infectious agents transmissible to humans, such as rodents.

A vector is an animal that transmits germs to a healthy person, such as... Continue reading "Infectious Diseases: Emergence, Spread, and Immunity" »

Essential Health Concepts

Public health encompasses the activities and services aimed at promoting, protecting, and restoring the health of populations.

The Immune System

The immune system is a complex network of organs, cells, and molecules that defends the body against infectious agents and abnormal cells, including cancerous cells.

Diagnosis

Diagnosis is the process of identifying a disease and determining its primary cause.

Chemotherapy

Chemotherapy involves the use of chemical drugs to combat disease.

Disinfectants and Antiseptics

• Disinfectants: Substances used to destroy microorganisms on objects.
• Antiseptics: Substances used to eliminate microorganisms that colonize tissues, such as skin.

Antibiotics

Antibiotics are chemicals that destroy or inhibit... Continue reading "Essential Health Concepts: Public Health, Immunity, and Treatments" »

Mendel's Experiments with Pea Plants

Mendelian genetics refers to the laws of inheritance discovered by Gregor Mendel through his work with pea plants. He studied specific characters, including:

• Seed color (Yellow vs. Green)
• Seed surface (Smooth vs. Wrinkled - implied, though not explicitly stated in the original text)

In his first cross, Mendel bred purebred yellow-seeded plants with purebred green-seeded plants. The resulting first filial generation (F1) consisted of 100% plants with yellow seeds.

Conclusions from Initial Crosses

• Each individual carries two hereditary factors (now called alleles) for each character, one inherited from each parent.
• In an individual carrying alleles for both yellow and green seeds, the yellow allele dominates over

1. Inorganic Chemical Compounds in Cellular Reactions

Electrolytes are inorganic chemical compounds necessary for cellular reactions.

2. Collecting Tube Reabsorption

Chloride reabsorption in the collecting tube: 1%

3. Urinary Potassium Excretion

Urinary excretion of potassium: 15%

4. Medullary Osmotic Gradient

The countercurrent multiplier mechanism in the loop of Henle creates the medullary osmotic gradient.

5. Urine Acidification

Urine acidification occurs in the collecting tube.

6. Hormonal Control of Blood Pressure

Renin converts angiotensin I in the hormonal control of blood pressure.

7. Glomerular Filtration

Capillary hydrostatic and colloid osmotic pressures determine glomerular filtration volume.

8. Smooth Muscle in Digestive Tract

Longitudinal and... Continue reading "Renal and Digestive Physiology: Cellular Processes and Regulation" »

DNA Replication: A Detailed Explanation

DNA replication is a fundamental process in all living organisms. It ensures the accurate duplication of the genome before cell division. This process involves several key steps and enzymes.

1. Unwinding the DNA Helix

The first step involves unwinding and opening the DNA helix. This process, also known as DNA despiralization, separates the two DNA strands. Specific enzymes, including helicases, attach to the DNA strands and unwind them. Topoisomerases prevent the formation of knots during this unwinding process.

Replication begins at specific points of origin. In prokaryotes, there is typically one point of origin, while eukaryotes have multiple origins due to their larger DNA content. Helicases break the... Continue reading "Understanding DNA Replication: A Comprehensive Look" »