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

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" »

Cell Division Processes

Mitosis: Somatic Cell Replication

Mitosis is an equational division resulting in two identical daughter cells. This process covers the growth and repair throughout the life of organisms.

• Homologous chromosomes do not form pairs.
• Results in 2 identical daughter cells.
• Cells can undergo successive mitotic divisions.
• Occurs in somatic cells (all body cells, excluding germ cells).

Meiosis: Gamete and Spore Formation

Meiosis is the process of cell division that occurs in germ cells, resulting in genetically distinct reproductive cells (gametes or spores).

1. First Division: Reductional.
2. Second Division: Equational.

• Homologous chromosomes form pairs.
• Results in 4 daughter cells, genetically different from each other.
• Cells cannot undergo

Adaptation of the Alveoli

There are millions of alveoli (300-500 million in two lungs), providing a large surface area. There is a lot of blood around them. The wall is only one cell thick, so it is not difficult for gas to cross it.

Oxygen Transport and Destination

Oxygen travels through capillaries attached to the red blood cells to be transported to the respiring tissues. They form oxyhemoglobin by attaching to hemoglobin. It reaches all the body tissues.

Carbon Dioxide Production and Removal

It is produced in the respiring cells (in the mitochondria). It has to be removed. The carbon dioxide travels dissolved in the plasma.

Effects of Nicotine on the Body

Nicotine is a poisonous and addictive drug. It damages the heart, blood vessels, and nerves... Continue reading "Human Respiratory and Circulatory System Functions" »

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" »

Function of the Excretory System

The function of the excretory system is to remove the waste products that the body produces which are harmful to us.

Understanding Blood Pressure

Blood pressure is generated by the heart and is needed to keep the blood flowing. The value for a healthy person with normal pressure should be 120 over 80 mmHg (millimeters of mercury).

• The first number is the higher pressure caused as the left ventricle contracts to push blood out of the heart.
• The lower value is the pressure in the arteries during the time that the heart is filling with blood.

What is Hypertension?

Hypertension occurs when a resting person's blood pressure is higher than about 140/90 mmHg.

Causes and Risk Factors

It can be genetic, but you can also develop... Continue reading "Understanding Circulatory Health and Excretory Functions" »

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