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

True or False Statements:

Characteristics of the Genetic Code

• Universality: The specificity of the genetic code has been conserved from very early stages of evolution.
• Degenerate: A particular codon always codes for the same amino acid.
• Specificity: Each codon corresponds to a single amino acid.
• Nonoverlapping and Commaless: The code is read from a fixed starting point as a continuous sequence of bases, taken 3 at a time.

Amino Acid Calculation:

The shortest gene discovered in human chromosome 19 consists of 1000 nucleotides, 666 nucleotides of which are introns. What is the maximum number of... Continue reading "Genetics: Transcription, Translation, and Genetic Code Principles" »

Microbial Resistance Levels

Understanding the varying levels of microbial resistance is crucial for effective control strategies.

Categories of Microbial Resistance

• Highest Resistance: Prions and bacterial endospores.
• Moderate Resistance: Protozoan cysts, some fungal spores, and some non-enveloped viruses.
• Least Resistance: Bacterial vegetative cells, other fungal spores and hyphae, enveloped viruses, yeast, and trophozoites.

Terminology of Microbial Control

Precise terminology is essential when discussing methods for controlling microbial growth and survival.

Sterilization

The process of destroying all forms of microbial life, including endospores, on an object or in a material.

Absolute Sterilization

Sterilization is an absolute process; there are no... Continue reading "Microbial Resistance & Control: Key Concepts" »

Cell Membrane Dynamics

Plasma membrane phospholipids are labeled with a fluorescent tag and then the phospholipids in one area are bleached with a laser beam to eliminate the fluorescent signal. What would one observe after the cell is incubated for a few minutes? The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules. Cellular membranes are mosaic and fluid. Glycosylated proteins and lipids within the plasma membrane are important for cell recognition and protection.

Passive Diffusion

Passive diffusion is a spontaneous process. Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for... Continue reading "Cell Membrane Dynamics and Transport Mechanisms" »

Still the Eye

Homeostasis

Thermoregulation

Zika is a mosquito-borne disease transmitted by the same mosquito that carries the dengue virus. There have also been cases of transmission through sexual intercourse.

Transmission

Most people get Zika from a mosquito bite. Mosquitoes become infected when they feed on the blood of a person already infected with the virus, and when they bite others, they can transmit the virus. Other forms of transmission include:

• A pregnant woman can pass the Zika virus to her fetus during pregnancy or at the time of birth.
• Zika can also be transmitted through sexual intercourse and blood transfusion.

Symptoms

Zika can cause incomplete brain development in fetuses. Common symptoms include fever, rash, joint pain, and conjunctivitis.

Prevention

To reduce the risk of

SPERMATOZOA 

Food and Essential Nutrients

Food is our source of nutrients. Nutrients are biomolecules our body needs to sustain vital functions. They are the chemical components of food, the building blocks and energy sources our cells require to live.

Basic Nutritional Requirements

• Energetic: Some nutrients are broken down in mitochondria to extract energy.
• Structural: Some nutrients are building blocks of body structures.
• Regulatory: Some nutrients are necessary in small quantities to regulate body metabolism.

Carbohydrates (Glucids)

Biomolecules present in bread, cereals, potatoes, pasta, etc. They provide energy to cells, and some of them must be consumed on a regular daily basis.

Simple and Complex Glucids

Simple Glucids (Sugars)

Sweet taste, small molecules.... Continue reading "Essential Nutrients and Their Role in Health" »

Receptors

Internal receptors perceive changes inside the body, such as a rise in blood pressure. External receptors perceive stimuli in the external environment.

Types of Receptors

• Mechanoreceptors: Perceive mechanical stimuli (pressure).
• Thermoreceptors: Perceive changes in temperature.
• Chemoreceptors: Detect chemical substances in the air, water, etc.
• Nociceptors: Perceive pain stimuli.
• Photoreceptors: Light sensitive.

Nervous System

The nervous system analyzes internal and external stimuli perceived by receptors, generating responses. It carries out this function through nerve impulses transmitted by cells called neurons. This system coordinates fast, short-lived responses (e.g., muscle contraction).

Endocrine System

The endocrine system is made up... Continue reading "Sensory Systems and Nervous Coordination" »

Sensory receptors are responsible for perceiving infortion, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces a feeling.

Biogeographical Evidence

Isolated groups evolved in different ways.

Molecular Evidence

The higher the molecular similarities, the closer their evolutionary relationship.

Coevolution

Coevolution is the process by which two species mutually influence each other during their evolution.

Lamarckism

Lamarckism is the theory of inheritance of acquired traits, explaining that animals develop the structures and organs they need in order to adapt to the environment they live in, and these new characteristics are transmitted to offspring.

Darwinism

Darwinism posits that there is competition between the individuals of a species, known as the struggle for existence. Individuals whose characteristics help their survival are favored over those who are poorly adapted... Continue reading "Understanding Evolutionary Processes and Species Development" »