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

Human Cell Structure

Cell Components

Human cells consist of three main structures:

• Plasma Membrane: The outer membrane protecting the cell, regulating nutrient intake and waste removal.
• Cytoplasm: A water-based solution containing dissolved substances and protein fibers forming the cytoskeleton. Organelles within the cytoplasm include ribosomes, mitochondria, endoplasmic reticulum, Golgi apparatus, vacuoles, and lysosomes.
• Nucleus: The spherical control center containing:
  • Nuclear Membrane: Separates the nucleus from the cytoplasm.
  • Nucleoplasm: The watery solution inside the nucleus.
  • Chromatin: Genetic material (DNA) responsible for cell control, organized into chromosomes.
  • Nucleolus: Composed of RNA and proteins, responsible for ribosome organization.

DNA: The Molecule of Life

DNA (Deoxyribonucleic Acid) is the biomolecule responsible for carrying genetic information. A core component of chromosomes and found within the nuclei of eukaryotic cells, DNA belongs to the nucleic acid family. DNA is formed from nucleotides, each composed of a monosaccharide, a phosphoric acid, and a nucleobase. DNA consists of four types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). DNA comprises two chains of nucleotides coiled together, forming the double helix. Adenine pairs with thymine, and cytosine pairs with guanine. The sequence refers to the order in which nucleotides are arranged. DNA duplication or replication is the process where a cell makes an exact copy of its DNA to share... Continue reading "Fundamentals of DNA, Genetic Concepts, and Biotechnology" »

Cells: Fundamental Units of Life

Cells are the basic structural and functional units that constitute living things. Based on their distinct structure, cells are classified as prokaryotic (e.g., bacteria) and eukaryotic (found in other living organisms). Eukaryotic cells are generally larger and more complex than prokaryotic cells. The most significant difference is the presence of a nucleus in eukaryotic cells, indicating a more evolved structure.

Essential Cellular Functions

Cells perform three primary functions:

• Nutrition: The process of obtaining materials for growth and energy to perform various cellular activities.
• Interaction (Relationship): The ability of cells to perceive and respond to environmental stimuli, allowing for adaptation.
• Reproduction:

The Origin of the Oceans

When edges diverge from the same continent, rift valleys form.

If the gap in these valleys continues to widen and connects to an ocean, it floods, creating a new ocean.

The ocean floor will have a dorsal ridge where the lithosphere is created, producing intense volcanism.

Borders with Lateral Movement

Edges with lateral movements separate plates that slide laterally with respect to each other. These are broken, called transform faults, which are usually interspersed along the different edges, allowing the accommodation of plate fragments that move at different speeds.

As these borders neither create nor destroy lithosphere, they are called passive. They are highly unstable areas, with frequent and strong earthquakes.

Endosymbiosis

Adaptation to Parasitism

Normally, endoparasites are animals that have undergone major structural changes regarding their architectural pattern, such as the disappearance of unnecessary structures. Locking mechanisms are another common characteristic in parasitic animals. Reproduction and life cycle are significantly affected in animal parasites. Populations often maintain very low levels, so finding a partner can be a problem. The appearance of hermaphroditism ensures reproduction despite the cost of producing two reproductive systems. The production of a high number of eggs compensates for the low probability of one completing the life cycle. The cyst is one of the more developed structures in these animals. Finally, to complete the life cycle,... Continue reading "Parasitism, Coral Reefs, Oligochaeta, and Biological Concepts" »

The Vital Role of Blood in Circulation

Blood is a red liquid that circulates through the blood vessels. It transports nutrients and oxygen to cells and collects carbon dioxide and other wastes.

Blood Composition: Plasma and Cells

Blood is made up of plasma and blood cells.

Blood Plasma Explained

Blood plasma is a yellowish liquid that carries nutrients, hormones, enzymes, and waste products from cells.

Types of Blood Cells

• Red blood cells (RBCs or erythrocytes): These contain hemoglobin, which binds oxygen in the lungs and transports it through the bloodstream to the capillaries, where it is released to reach all cells.
• White blood cells (leukocytes): These defend us from infectious agents like bacteria, viruses, and various parasites that enter through

Cerebral Palsy (CP): An Overview

The M-Bo makes noise due to: air inflow, low oil, or worn parts.

The M-Bo warming indicates: very high pressure, high speed, or poor refrigeration.

The B does not flow due to: base oil, clogged filter, or pump failure.

• Leaks at the pump or motor worn parts
• Leaks in the body
• Bad tightness

The M-Bo does not revolve due to: little flow, internal leakage, improper loading, or unsuitable engine.

Breaking parts can occur due to: pressure excess, stiffness due to lack of fluid, or abrasives not retained.

If the M rotates slower than the flow that arrives, it may be due to: leaks, low pressure input, or high temperature.

Wear excesses of B and M can be caused by: abrasives, excess or no viscosity, or high pressure.

For the v/v regulatory pressure:

• Regulator does

Anthropometry: Measuring the Human Body

Anthropometry is a branch of anthropology focused on the measurement of different human body parts. It provides crucial data for understanding human variation, growth, and development.

Human Body Types: Sheldon's Classification

William Sheldon classified human body types based on the predominance of three fundamental components, known as somatotypes:

• Endomorph: Characterized by a predominance of curves and significant visceral development.
• Mesomorph: Defined by the dominance of muscle and bone, indicating a robust and athletic build.
• Ectomorph: Marked by weak muscular and visceral development, typically featuring long and slender limbs.

Growth and Development of Body Systems

Nervous System Growth

The nervous system... Continue reading "Anthropometry and Human Development: Body Types and Growth" »

Bacterial Characteristics & Cell Shapes

Bacteria are prokaryotic cellular organisms. Their structure is very simple and lacks a nucleus. Most bacteria, with the exception of mycoplasmas, have a cell wall that is more or less rigid, but with a very diverse structure and chemical composition, different from those of plants. Based on cell shape:

• Cocci are small, spherical cells. They group together in pairs (diplococci), in irregular groups or clusters (staphylococci), in rows (streptococci), and in packets (sarcinae).
• Bacilli are short, cylindrical, rod-shaped cells. They may occur as pairs or chains.
• Vibrio are comma-shaped cells.
• Spirilla are rigid, spiral-shaped cells. Spirochetes are long, thin, spiral-shaped cells, which are more flexible