Notes, abstracts, papers, exams and problems of Biology

Carnitine: An Essential Nutrient

Carnitine is a nutrient synthesized in the liver, kidneys, and brain from two essential amino acids: lysine and methionine. Carnitine is responsible for transporting fatty acids into the mitochondria, cellular organelles responsible for energy production.

Some individuals need carnitine supplements to maintain normal metabolism, which indicates that carnitine should be considered an essential nutrient.

Carnitine Deficiency

Carnitine deficiency is classified into two major groups: systemic deficiency (rare) and myopathic (more common). The systemic form affects the whole body, while the myopathic form affects only muscle tissue.

Causes of Carnitine Deficiency

Known causes of carnitine deficiency include:

• Deficiency

Population, Community, and Ecosystem

A population is a group of individuals of the same species living in a specific area. A community is a set of populations inhabiting the same area. The biotope is the physical environment occupied by a community, characterized by specific environmental conditions. An ecosystem encompasses both the community (biocenosis) and the biotope, including the interactions of organisms with each other and their environment.

Habitat and Optimal Conditions

A habitat is the specific environment where an organism finds the necessary conditions for life. Optimal conditions, regarding a given environmental factor, are the values at which a species thrives, reproduces effectively, and experiences high offspring survival.... Continue reading "Understanding Ecosystems: Species, Niches, and Interactions" »

In the early 1990s, research on the human being began with the Human Genome Project. In April 2003, the entire nucleotide sequence of the human genome was completed. Today, we know that:

• Our haploid genome (all 23 different chromosomes that we possess) contains 3,000 million pairs of nitrogenous bases, which equates to about 30,000 genes.
• 99.9% of these genes are the same in all people: the differences between us do not represent more than 0.1% of the genome.
• 90% of the genome has no known coding function, which does not mean it has no function, such as gene regulation or various biological controls. It is thought that some of this DNA may correspond to genetic remains of our ancestors.

Applications of the Human Genome Project

The practical applications... Continue reading "Decoding the Human Genome: Applications and Biotechnology" »

Biotic Relationships

Biotic relationships are the interactions among living organisms in an environment. There are two main types of biotic relationships:

Interspecific Relationships

Interspecific relationships occur between organisms of different species. These include:

• Mutualism: A relationship where both species benefit. Example: Bees pollinating flowers.
• Commensalism: A relationship where one species benefits, and the other is unaffected. Example: Beetles feeding on mammal excrement.
• Inquilinism: A specific type of commensalism where one organism uses another for housing.
• Parasitism: A relationship where one species (the parasite) benefits at the expense of the other (the host). Example: Cochineals feeding on cacti.
• Predation: A relationship where

Non-Infectious Diseases

In addition to diseases caused by microorganisms, other diseases are caused by different reasons:

a) Diseases Affecting the Functioning of the Equipment

These include circulatory diseases, which affect the respiratory tract (such as asthma or bronchitis), and those that affect bones or joints (osteoarthritis and osteoporosis).

b) Cancer

This occurs when certain cells, for reasons not yet fully clarified, undergo a metamorphosis that makes them divide rapidly and uncontrollably. As a result, it creates a mass of abnormal cells, called a tumor, which causes the destruction of nearby tissue.

c) Deficiency Diseases

These are caused by a poor diet lacking in certain nutrients. Examples include vitamin deficiency or anemia.

d) Traumatic

1. Nutrients, Material, and Energy Source

Nutrients are the raw materials from which cells produce their own components. They replace lost components, facilitate growth, and produce new cells. Nutrients are the fuel for cells.

Other nutrients that reach the cells are used as fuel for cellular respiration. Glucose is the nutrient most used by cells as fuel. During cellular respiration, the following events occur:

• Oxygen consumption
• Release of energy usable by cells
• Production of carbon dioxide and water

Lipids and proteins can also be used as fuel to provide nutrients for energy. Cells use this energy to perform their functions.

Our body needs energy-containing nutrients to function; this energy is called chemical energy. Cellular respiration releases... Continue reading "Cellular Nutrition: Fueling Life, Energy, and Health" »

Plant Metabolism: Vital Processes

Like all living organisms, plants perform essential functions to facilitate growth, development, and reproduction.

The primary metabolic processes include:

• Absorption
• Circulation
• Respiration
• Transpiration

Absorption: Nutrient Uptake

Plants acquire nutrients not only from the soil but also from the air, primarily through their leaves, absorbing oxygen and carbon dioxide.

Water and dissolved minerals enter the roots via diffusion. Plants then convert these substances into organic molecules, such as:

• Glucose
• Fructose
• Starch
• Proteins
• Lipids (fats)

This conversion of minerals into organic compounds is unique to plants, certain bacteria, and microscopic algae. Consequently, wildlife, fungi, and protozoa rely on plants as their... Continue reading "Plant Metabolism: Absorption, Circulation, and Respiration" »

Parasite Life Cycles

Direct (Monoxenic) Cycles

Direct cycles are those that do not require the presence of an intermediate host.

Indirect (Heteroxenic) Cycles

Indirect cycles require an intermediate host to complete their cycle.

Key Features of Parasites

Resistance to the Outside

To cope with climatic factors and chemical agents, eggs, cysts, or larvae are protected with coverings that make them resistant to protein.

Pathogenicity

Pathogenicity is associated with morbidity and mortality.

Auto-infection

Auto-infection is the way for the parasite to remain longer in the host.

It can be:

• Autoexoinfection, which is outside for a very short time
• Autoendoinfection, which multiplies within the host

Recontamination is done on the inside.

Prepatent Period

The prepatent... Continue reading "Understanding Parasite Life Cycles and Survival Strategies" »

Polymers

A polymer is a macromolecule composed of long chains of repeating molecular units known as monomers. Polymers are typically organic compounds formed by joining monomers containing carbon, hydrogen, and other elements. The properties of a polymer depend on its monomers and its spatial structure, which can be a linear chain, a ring, or other more complex configurations.

Types of Polymers

• Natural Polymers: Found in nature and formed by living organisms. Examples include proteins and cellulose.
• Artificial Polymers: Derived from chemically modified natural polymers. Celluloid was the first artificial polymer. Other examples include cellulose nitrate, rayon, and vulcanized rubber.
• Synthetic Polymers: Designed and synthesized by humans. Examples