Notes, abstracts, papers, exams and problems of Biology

Lipids

Functions of Lipids

• Energy Storage: Lipids serve as the primary energy reserve in the body.
• Structural Components: Lipid bilayers form the plasma membrane and other cell organelles.
• Protection: Lipids cushion vital organs, like the kidneys, and protect body surfaces (e.g., waxes on hair and fruit).
• Biocatalysis: While not all lipids are biocatalysts themselves, some play a role in biocatalyst synthesis.
• Transport: Lipids are emulsified and transported from the intestine to either storage in adipose tissue or sites of utilization.

Amino Acids

Amino acids are small organic compounds characterized by a carboxyl group and an amino group. They are solid, crystalline, water-soluble, have high melting points, and exhibit optical activity. Primary amino... Continue reading "Lipids, Amino Acids, and Proteins: Structure, Function, and Properties" »

1. Health and Disease

When all organs and body systems function correctly, we consider ourselves healthy. If any part of the body is impaired and cannot perform its function properly, it causes disease. When a person becomes ill, characteristic symptoms of the disease appear, often accompanied by some deterioration. Key factors in maintaining health include:

• A proactive approach to health.
• Adopting healthy habits and lifestyles.
• Personal characteristics such as age or hereditary factors.
• An effective health system.

2. Disease Categories

Diseases can be categorized in various ways:

• Infectious: Caused by microorganisms that enter the body and can be transmitted from person to person.
• Non-infectious: Not caused by microorganisms and therefore not transmitted

Airway

Includes a conduction pipeline connecting it with the exterior lungs, which are:

• The nasal cavities: Two open cavities covered by nasal mucous. They communicate with the exterior through the nostrils and with the pharynx through the choanae (posterior openings).
• The pharynx: It is a common respiratory tract through the digestive tube and the epiglottis. The epiglottis is located above the larynx and prevents food from entering during swallowing, thus avoiding choking.
• Larynx: Communicates with the trachea and contains some folds (vocal cords) that vibrate and emit sounds.
• The bronchial tree: It consists of two bronchi that penetrate the lungs and branch into increasingly smaller bronchioles. The cells of the walls secrete mucus and have cilia,

Chromatin

Chromatin consists of strands of DNA at different degrees of condensation associated with proteins and scattered throughout the nucleoplasm. When the cell is going to divide, the chromatin filaments are organized and condensed to form thicker structures called chromosomes.

Genes

A gene is a unit of hereditary material. It is a fragment of nucleic acid that carries genetic information for a character, a protein, or a polypeptide chain. It corresponds to what Mendel called a hereditary factor.

Centriole

In animal cells, centrosomes present two small cylinders and consist of protein tubules.

Mitotic Spindle

The mitotic spindle forms when the nuclear membrane and nucleolus disappear.

Karyotype

A karyotype is a set of chromosomes from one species.... Continue reading "Cell Biology: Chromatin, Genes, Karyotype, and Cell Types" »

Changes achieved through the development, acquisition, or loss of organs are maintained and transmitted to offspring, which preserves and increases these traits through successive generations. This concept is known as the inheritance of acquired characteristics. However, analysis of these proposals has not demonstrated any inherent tendency or impulse towards complexity in living things. In light of developments in genetics, the inheritance of acquired characteristics is not supported.

Natural Selection: Darwin and Wallace

Darwinian theory posits that in a changing world, organisms also change over time. Some features disappear, and new ones emerge. This process of change is gradual and continuous. Organisms with similarities are related and... Continue reading "Evolutionary Theories: Darwinism, Neo-Darwinism, and Hominid Origins" »

The Digestive System: Functions and Anatomy

The digestive system is responsible for several key functions:

• Food intake: Consuming food.
• Nutrient preparation: Breaking down nutrients through mechanical and chemical digestion.
• Absorption: Absorbing nutrients into surrounding tissues.
• Elimination: Eliminating undigested waste.

Components of the Digestive System

The digestive system consists of the following organs:

• Mouth
• Pharynx
• Esophagus
• Stomach
• Intestines:
  • Duodenum
  • Jejunum
  • Ileum
  • Large Intestine (Cecum, Appendix, Ascending Colon, Transverse Colon, Descending Colon, Sigmoid Colon, Rectum, Anal Canal, Anus)

The entire system is lined with the peritoneum, a serous membrane.

Accessory Glands

Several accessory glands aid in digestion:

• Minor and major salivary glands

Unit 5: Cell Nutrition

All living beings need food used as follows:

• For growth: it provides the substances needed for making new cells and tissues.
• As a source of energy: required for the chemical reactions which take place in living organisms to keep them alive.
• For replacement: of worn and damaged tissues, for example, red blood cells that break down each day and to replace the skin which is worn away and to repair wounds.

Nutrition can be defined as obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Several systems are involved in cell nutrition: this process is carried out by organ systems which working together allow cells to obtain matter and energy.

• Digestive

Health and Disease: A Comprehensive Overview

Health Encompasses: Sickness absence and well-being in physical, mental, emotional, social, spiritual, sexual, and environmental aspects.

Risk Factors for Health

• Food rich in fat and/or sugar
• Tobacco and/or drug use
• Lack of hygiene
• Stress

International Sanitary Conference (Paris, 1851)

Accomplishments:

• Development of public health policies with laws governing food handling and potable water.
• Creation of the National Institute of Health.
• Methods for preventative health planning, including vaccination and infection control.
• Improved diagnostic techniques.
• Drug development.
• Promotion of better nutritional habits for a healthy life.

Infectious Diseases

Infectious diseases are caused by microorganisms and are transmitted... Continue reading "Health and Disease: Factors, Prevention, and Immunity" »

Asexual Reproduction in Cormophytes

Asexual reproduction in cormophytes involves specific vegetative organs such as stolons, rhizomes, tubers, and bulbs.

• Runners: These are side branches emerging from the base of the stems with horizontal growth. Roots emit buds, giving rise to new independent individuals.
• Rhizomes: Underground stems that grow horizontally in the soil and accumulate reserve substances. Ground stems can emerge from buds, eventually taking root and separating from the main rhizome.
• Tubers: Very enlarged underground stems that store food. They can be separated from the main plant to form separate plants.
• Bulbs: Underground stems that are more or less spherical, with fleshy, layered storage. Smaller bulbs are often formed with buds

Endocrine System

The endocrine system is formed by cells and glands that secrete specific hormones. These hormones are effective messengers that regulate various bodily functions through feedback mechanisms.

Endocrine Glands

Pituitary Gland

Anterior Lobe

• GH (Somatotropin)
• ACTH (Adrenocorticotropin)
• TSH (Thyroid Stimulating Hormone)
• PRL (Prolactin)
• FSH (Follicle-Stimulating Hormone)
• LH (Luteinizing Hormone)

Posterior Lobe

• Vasopressin (ADH - Antidiuretic Hormone)
• Oxytocin

Hypothalamus

The hypothalamus controls the neurohypophysis through nerve fibers and releases or inhibits pituitary factors.

Adrenal Glands

Cortex

• Glucocorticoids: Regulate carbohydrate and protein metabolism and inhibit the immune response.
  • Cortisol
  • Corticosterone
• Mineralocorticoids: Regulate Na-