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

Understanding and Managing Stress

Concept of Stress

Stress, an uneasy experience of pressure, can stem from various sources: yourself, others, and the environment. Modern life's fast pace creates numerous pressures, leading to frequent stressful situations. Effective stress management starts with understanding its sources and how to address them.

Self-Inflicted Stress

Sometimes, we create our own stress. This isn't always negative. Eustress, or positive stress, can produce beneficial results. Its counterpart, distress, is the negative dimension of stress.

Environmentally Caused Stress

External factors can also induce stress. Imagine your crops are ready for harvest, but continuous rain creates worry and helplessness. This stress originates from... Continue reading "Stress Management Techniques" »

The Human Heart: Chambers, Vessels, and Blood Flow

Heart Action: Blood Collection, Pumping, and Valve Function

The right atrium collects blood from the superior and inferior vena cava, and the left atrium collects blood from the pulmonary veins. This blood then flows into the right and left ventricles, which pump the blood into the arteries. The direction of blood flow is controlled by the atrioventricular valves and semilunar valves. When the atria contract, the blood flows through the open atrioventricular valves into the ventricles. At this stage, the semilunar valves are closed, so the ventricles fill with blood. The ventricles then contract, which causes a rise in pressure. This rise in pressure first causes the atrioventricular valves to... Continue reading "Human Circulatory and Immune System Fundamentals" »

Parts of Eukaryotic Cells:

• Animal: cytoskeleton, cilia and flagella, proteasomes, ribosomes, nucleus, centrioles, vacuoles, golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes.
• Plant: ribosomes, cell wall, cytoskeleton, proteasomes, plastids, vacuoles, golgi apparatus, nucleus, endoplasmic reticulum, mitochondria.

Cell Cycle:

All changes that a cell undergoes from its formation until its division into two new cells.

Phases:

• Interphase: The longest phase, cells do not divide. Before the end of this phase, cells duplicate their DNA.
• Mphase: This short phase, the cell reproduces by cellular division. Two new cells are formed. This can occur in 2 processes:

Mitosis:

The process in which the cell nucleus duplicates with the same genetic material.... Continue reading "Parts of Eukaryotic Cells and the Cell Cycle" »

Extracellular is inactive DNA or RNA surrounded by proteinIntracellular – active inside a host cell/ viral reproductionprotein capsid - Viral nucleic acid presentcapsomere- protects genetic materialretroviruses: ss RNA hepadnaviruses: dsRNA enveloped”- membrane lipid bilayer (host)& proteins (virus)naked-+ viral DNA complex viruses- icosahedral head/ helical tail/ Tail fibers attach to host cellviral replication: the virion attaches host specific/ proteins interact w/ receptors on surface/ if receptor not present= can’t infect. 2. Phages often complex3.active/intracell/ production of new virions/ viral mRNA is required SS DNA ->DS DNA -> mRNA / DS DNA= mRNA (w/polymerase) RNA polymerase” to make mRNA from viral RNA/ SS RNA

Key Concepts in Enzymes, Cellular Respiration, and Genetics

1. Free Energy Curve

In a catalyzed reaction, the enzyme lowers the activation energy required for the reaction, making it proceed more quickly. The free energy curve for the catalyzed reaction is shifted to the left compared to the uncatalyzed reaction.

2. Components in a Chemical Reaction

• Reactants: A and B
• Products: C and D (catalyzed)

3. Factors Affecting Enzyme Function

• Temperature: Enzymes have an optimal temperature; deviation can denature them.
• pH: Enzymes function best within a specific pH range.
• Substrate Concentration: Up to a point, increasing substrate concentration increases enzyme activity.

4. Definition of an Enzyme

Enzymes are biological catalysts that accelerate chemical reactions... Continue reading "Enzymes, Cellular Respiration, and Genetics: Key Concepts" »

Barrera especifica: Acciones que realiza el sist. inmunitario que se pone en funcionamiento cuando el organismo no ha podido evitar la invacion del agente patogeno. hace que la persona adquiera inmunidad. FAGOSITOS.
Barrera inespecifica: son iguales para todos los agentes patogenos y actuan de forma indiscriminada frente a cualquiera de ellos.
1º barrera: evita entrada de germenes. estructural-piel-mucosas-lagrimas-saliva-jugos gastricos-secreciones acidas.
es inespecifica----> intenta que ninguna noxa ingrese, no deja memoria inmune.
2º barrera o respuesta inflamatoria: impide que las noxas que ingresan causen infeccion.(inflamacion-dolor-rubor-color)
Sangre->globulos blancos o leucocitos= fagocitan cualquier noxa.
             ... Continue reading "Barrera." »

Principles of Inheritance and Genetics

Basic Genetic Terminology

Diploid Organisms: Organisms possessing two sets of chromosomes and two alleles (forms) of each gene.

• Homozygous: Having two identical alleles for a trait (e.g., C^RC^R).
• Heterozygous: Having two different alleles for a trait (e.g., C^RC^r).

Mutation: A change in the amount or the chemical structure of DNA.

• Chromosomal Mutation: A difference in the number or structure of chromosomes.
• Gene Mutation: Changes within a gene (e.g., substitution, deletion, addition).

Phenotype: The observable characteristics (e.g., tall).

Genotype: The genetic makeup (e.g., Tt).

Gamete: A haploid reproductive cell (e.g., T & t).

Patterns of Inheritance

Codominance: Both alleles are expressed in the heterozygote.... Continue reading "Core Concepts of Genetics, DNA Technology, and Profiling Methods" »

Cellular Immunity

Cellular immunity involves two main types of lymphocytes: T lymphocytes and B lymphocytes. It also involves non-T, non-B cells. This system effectively destroys:

• Foreign cells
• Tumor cells
• Virus-infected cells
• Cells infected by intracellular pathogens

T Lymphocytes

T4 Lymphocytes

T_H Lymphocytes: These cells stimulate other T cells and B lymphocytes.

T_D Lymphocytes: These cells increase the number and activity of macrophages.

T8 Lymphocytes

T_C Lymphocytes: These cells destroy target cells.

T_S Lymphocytes: These cells regulate and suppress excessive or inappropriate immune responses. They deactivate lymphocytes once antigenic agents are controlled.

A phagocyte captures a foreign element, digests it, and presents it as an antigen-presenting... Continue reading "Understanding Cellular and Acquired Immunity: Types, Mechanisms, and Pathologies" »

Circulatory System Elements

The circulatory system includes:

• Veins, arteries, and capillaries: These vessels transport blood throughout the body.
• Heart: This organ pumps the blood.

Arteries vs. Veins

Arteries and veins differ in structure and function:

• Arteries: Have thick, elastic walls that stretch and spring back, propelling blood forward. They carry blood away from the heart.
• Veins: Have thinner walls that cannot stretch as much. They often have valves to prevent the backflow of blood, carrying blood to the heart.

Capillary Structure and Function

Capillaries form a network connecting arteries and veins throughout the body. Their walls are only one cell thick, facilitating the diffusion of nutrients and oxygen into tissues. This process occurs via... Continue reading "Circulatory and Excretory Systems: Structure and Function" »

Neck Anatomy

The head and neck join the upper chest. The neck comprises skin, fibrous muscles, major vascular elements, lymph nodes, organs (cervical larynx, cervical trachea), and glands (thyroid and parathyroid).

The skeletal neck includes the cervical spine.

• Platysma (2): Thin ring from the superclavicular zone to the face, deep chin.
• Sternocleidomastoid (2): Lateral neck, from the thorax to the temporal and occipital mastoid bones.
  • Origin: Lower insertion and command of the sternum and below the clavicle.
  • Lateral/External: External jugular vein, ending with the subclavian, used for serum.
  • Medial/Internal: Vasculo-nervous bundle, primitive carotid artery, internal jugular vein, neurogastric nerve.
  • Double Innervation: Branches of the nerve cord and