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

Milk and Dairy

Provides protein, vitamins, and calcium. Recommended serving: 250 mL of milk and 80g of dairy products.

Meat, Fish, and Eggs

Excellent sources of protein, vitamins, and iron. Recommended serving: 100g of meat and 150g of fish.

Legumes and Potatoes

Offer carbohydrates and protein. Recommended serving: 80g of pulses and 180g of potatoes.

Vegetables

Rich in vitamins, minerals, and fiber. Recommended serving: 125g.

Fruits

Packed with vitamins, fiber, minerals, and carbohydrates. Recommended serving: 125g.

Cereals and Grains

Provide carbohydrates. Recommended serving: 80g of pasta or rice, 50g of bread.

Fats, Oils, and Butter

Sources of lipids.

Carbohydrates

Nutrients that provide energy. Simple sugars, like glucose, are the primary source of cellular... Continue reading "Nutrition Essentials: Building a Balanced Diet" »

Cell Membrane Differentiations: Junctions

Some areas of the cell membrane may have specific adaptations, such as invaginations (e.g., microvilli) to increase surface area, or structures that form unions between cells. These junctions are essential for stabilizing tissues and providing mechanical adhesion. They are particularly prevalent in tissues under heavy strain, like epithelial tissues or heart muscle, where their primary function is to provide mechanical strength to the union. These junctions are classified into:

Adherens Junctions (Bands of Adhesion)

• These junctions are formed by transmembrane proteins that bind cells together.
• On the intracellular side, these proteins are associated with actin filaments, which are part of the cytoskeleton.

Active Transport Across Cell Membranes

Active transport enables certain types of proteins within the cell membrane to move substances. This process consumes energy, typically provided by ATP molecules, allowing transport against a concentration gradient.

The Sodium-Potassium Pump

The sodium-potassium pump is a transmembrane protein that actively transports sodium ions (Na+) out of the cell and potassium ions (K+) into the cell. This counter-gradient transport exhibits ATPase activity, meaning it breaks down ATP to power the movement. For every three Na+ ions pumped out, two K+ ions are pumped in, consuming one ATP molecule. This action generates potential differences across the membrane, contributing to the membrane potential. This potential is... Continue reading "Cellular Membrane Transport and Nerve Signal Transmission" »

English Vowels

Short Vowels

• /ɪ/ (as in: sit): Front, unrounded, between close and half-close.
• /ɛ/ (as in: dead): Front, unrounded, between half-close and half-open.
• /æ/ (as in: cat): Front, unrounded, between half-open and open.
• /ʌ/ (as in: does): Between front and central, unrounded, half-open.
• /ɒ/ (as in: dog): Back, rounded, between half-open and open.
• /ʊ/ (as in: good): Between back and central, rounded, near-close.

Long Vowels

• /i:/ (as in: sweet): Unrounded, almost fully closed.
• /ɜ:/ (as in: bird): Central, unrounded, between half-close and half-open.
• /ɑ:/ (as in: fast): Almost fully back, unrounded, fully open.
• /ɔ:/ (as in: hawk): Back, rounded, between half-close and half-open.
• /u:/ (as in: shoe): Almost fully back, rounded, almost fully

The Organization of the Human Body

Cellular and Tissue Hierarchy

A Cell is the basic structural and functional unit of living things.

• All human cells originate from a single initial cell called the Zygote.
• Although we originate from one cell, we develop several types of specialized cells.
• A group of specialized cells results in a Tissue.

From Tissue to Organism

A Tissue is a set of cells of the same type performing a specific function.

• The combination of various tissues forms an Organ.
• A combination of organs results in an Organ System or Apparatus.

We use the term System when there is only one predominant tissue type (e.g., Nervous System).

The union of all systems and apparatuses results in a Multicellular Organism.

Specific Roles of Human Tissues

Tissues... Continue reading "Human Body Structure and Function: Cells, Tissues, and Organ Systems" »

The Biosphere

The biosphere is the set of all living things on Earth.

Understanding Ecosystems

An ecosystem consists of interconnected components:

• Biotic Components: Living things that inhabit a particular place and interrelate.
• Abiotic Components: All the physical environmental conditions or non-living elements within the dwelling of living beings.

Relations Between Components: Living organisms in a specific location are adapted to certain conditions of their physical environment and, in turn, modify it.

Ecological Relationships

There are relationships between individuals of the same species and between different species, such as predation, parasitism, symbiosis, and commensalism.

Photosynthesis

Photosynthesis is the process of converting light energy... Continue reading "Understanding Earth's Living Systems" »

Kinds of Amino Acids

Amino acids can be classified into several categories:

• Nonpolar:
  • Aliphatic
  • Aromatic
• Polar Uncharged
• Charged:
  • Acidic (Anionic)
  • Basic (Cationic)

Proteins: Building Blocks of Life

Proteins are biopolymers formed by molecular chains of 20 different amino acids, each with its own characteristics.

Protein Structures

Primary Structure

The primary structure is characterized by the specific composition of amino acids and their sequential order within the polypeptide chain.

Secondary Structure

The secondary structure refers to the folding of the primary structure due to the formation of hydrogen bonds between the -C=O group of one peptide bond and the -NH group of another. This results in the side chains (R groups) adopting specific spatial arrangements... Continue reading "Amino Acids and Protein Structures: A Comprehensive Look" »

Ecosystems: Definition and Characteristics

An ecosystem is a system formed by the interaction between a community and a biocenosis, or physical environmental factors. An ecosystem model for the subject is closed but open to energy, being capable of regulating itself and remaining in dynamic equilibrium over time.

Population Dynamics

A population is comprised of a set of individuals of the same species living in a particular location. There are some factors that prevent a population from reaching its full biotic potential. These can be external or internal to the population:

• External Factors: These may be biotic (predators, parasites, or diseases caused by other agencies competing for a given resource) and abiotic (climate change, food shortages,

• In the pyramids of numbers, the lengths of the steps are proportional to the number of individuals of all species in each trophic level per unit area or volume.

  Biomass in the lengths of the steps are proportional to the dry weight of all individuals in each trophic level per unit area or volume.

  These pyramids best describe the trophic relationships of the ecosystem as they indicate the amount of organic matter that can be eaten at each trophic level, but do not express the amount transferred from one level to another.

  Energy in the lengths of the steps are proportional to the energy produced per unit time of all individuals in each trophic level per unit volume or surface.

  These pyramids provide a better overall picture of trophic relationships