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

Occupational Hazards

Hearing Loss

Occupational hearing loss, or deafness, is the functional deficit that occurs when an individual experiences a partial or complete loss of hearing. This is determined by the hearing threshold, which is the weakest sound stimulus that a particular ear can perceive. While the terms "deafness" and "hearing loss" are often used interchangeably, they are distinct conditions.

Pneumoconiosis

Pneumoconiosis encompasses a group of lung diseases caused by inhaling and accumulating inorganic dust particles, and the subsequent reaction within lung tissue. Disease development depends on the dose of inhaled and retained particles, the particles' biological activity, the induced tissue reaction, and individual sensitivity.

Drug

Mitosis: Cell Division for Growth

1. Interphase: DNA and centrosomes have been duplicated.
2. Prophase: The nuclear membrane disappears, chromosomes condense and become visible, and the spindle apparatus begins to form from proteins.
3. Metaphase: The centrioles are at opposite poles of the cell. The spindle fibers align the chromosomes at the cell's equator (metaphase plate).
4. Anaphase: The spindle fibers pull the sister chromatids of each chromosome toward opposite centrosomes.
5. Telophase: The chromatids decondense back into chromatin. New nuclear membranes form around the chromatin, and the spindle breaks down.
6. Cytokinesis: The cytoplasm is divided, forming two new, genetically identical daughter cells.

Meiosis: Producing Gametes

Interphase: DNA and centrosomes... Continue reading "Mitosis vs Meiosis: Understanding Cell Division Processes" »

What is Animal Cloning?

Cloning is the process by which we obtain an identical copy, or clone, from the genetic point of view of any living entity, such as a cell or an organism.

How Do You Clone an Animal?

The first time that clone cells were obtained from an adult animal was in 1996. As a result, the sheep Dolly was born, the first mammal cloned in history. The technique used is called nuclear transfer.

Stages of Animal Cloning

1. A differentiated cell is taken from the individual that is to be cloned. These cells contain the entire genome of the organism, with the difference that it is a specialized cell that has lost the ability to reproduce.
2. An egg is taken from a female donor.
3. The egg nucleus is removed.
4. The nucleus of the differentiated cell is

Sensory Perception and Bodily Responses

Sensory Perception

Sensory perception is the process of obtaining information through our senses: sight, hearing, balance, smell, taste, and touch. Receptors also exist that capture the internal conditions within the body.

Bodily Responses

Our body's responses are executed by the locomotor system (formed by bones and muscles) and the endocrine system (which functions through hormones), responsible for movement and regulation.

The Sense of Sight (Vision)

Key components of the eye include:

• Cornea: A transparent layer that covers the front of the eye.
• Iris: A layer that can dilate or shrink, regulating the passage of light through an opening called the pupil.
• Sclera: The layer that gives shape to the eyeball.
• Conjunctiva:

Key Ecological Concepts

Ecology is the science that studies the relationships between living beings, and also between them and their surrounding environment.

• Population: A group of individuals of the same species living together in a given area.
• Community: A group of populations living together in a specific area.
• Biotope: The physical environment or habitat occupied by a community.
• Ecosystem: The combination of the community and the biotope in which they live, including the ways in which individuals interact with one another and with their surrounding environment to reproduce and form a stable system.

Environmental Factors

The environment is influenced by various factors:

• Biotic factors: Factors that result from the presence and activities of other

Polymerase Chain Reaction (PCR)

Continuous replication is a fragment of DNA containing a gene or genes of our interest. In this way, we obtain a large number of copies that make it possible to study without worrying about the amount of the sample.

At first, it was a cumbersome technique. Due to the different temperatures used during the process, some of them very high, we were forced to replace the polymerase at each change in temperature. This problem was solved by the DNA polymerase of a thermophilic bacterium: Thermus aquaticus (Taq polymerase).

The method is deceptively simple and involves replication in a medium rich in triphosphate nucleotides, the DNA strand of interest, to which we add small pieces of RNA and Taq polymerase.

A cyclic temperature

Human Digestive and Circulatory Systems

Nutrition is the process by which a living being obtains the matter and energy needed to sustain life.

Components of Digestive Function:

• Taste: Involves eating food, breaking it down, and transporting it.
• Reduce: Food is broken down into simple molecules that cells can use.
• Absorb: Simple molecules are absorbed and passed into the bloodstream for circulation to all body tissues.
• Remove: Undigestible remains are eliminated.

Digestive Tract Components:

The Pharynx

A short part of the digestive tract, also part of the respiratory system, extending from the oral cavity to the top of the esophagus.

The Esophagus

The conduit between the pharynx and the stomach.

The Stomach

An enlarged, bag-shaped part of the digestive tube,... Continue reading "Human Digestive and Circulatory Systems: Functions and Components" »

The Digestive Process

There are three phases in food processing: digestion, absorption, and the expulsion of waste. The movement of food through the digestive tract is known as peristaltic movements. These consist of the narrowing of the tube through the contraction of the muscles of the walls. The muscles contract successively.

Digestion

Types of Digestion

• Mechanical digestion consists of cutting, crushing, moving, and diluting foods.
• Chemical digestion is done through the action of various substances, which attack the foods and bring about chemical changes.

Stages of Food Digestion

• Digestion in the mouth is a result of mastication and salivation. Mastication cuts and crushes the food. Saliva is a liquid produced by the salivary glands in the mouth.

Mechanisms of Defense: The Immune System

The immune system consists of a set of organs, cells, and molecules dispersed throughout the body that is responsible for its defense. This defense system operates through internal and external defenses.

External Defenses

They consist of physical and chemical barriers and are the first line of defense to prevent the entry of pathogens. These barriers are mainly the skin and mucous membranes.

Internal Defenses

In the interior of the body, we can distinguish two types of defenses:

• Nonspecific Defenses

  Are so called because they do not depend on the nature of the pathogen. The most important are the inflammatory reaction and the nonspecific cellular defense:

  • Inflammatory reaction. It is a local reaction involving

Stress and the Nervous System

In alarming situations, the nervous and hormonal systems trigger a series of processes that provoke reactions such as increased heart rate, elevated blood pressure, and heightened tension. This tension typically subsides when the alarming situation ends. However, if the situation persists, it can lead to anxiety, distress, depression, and insomnia.

To reduce these effects, consider the following:

• Adequate sleep
• Regular exercise
• Balanced diet
• Avoid consumption of tranquilizers, drugs, and sleep aids

Hormonal Coordination: The Endocrine System

The endocrine system is a set of glands formed by specialized cells that secrete hormones. Glands are classified as:

• Endocrine: Release hormones into the bloodstream.
• Exocrine: Discharge