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

Understanding Nutrition and Eating

Nutrition refers to the process through which the body obtains the matter and energy it needs to grow, repair itself, and perform vital functions. Eating is the process through which we consume the foods that provide us with nutrients.

The Role of Nutrients

Nutrients are the substances cells need to perform vital functions; we get them from food. There are two types of nutrients:

• Organic: Carbohydrates, lipids, proteins, and vitamins.
• Inorganic: Water and minerals.

Classification of Foods

Energy Producing Foods

These are sources of energy, rich in carbohydrates and fats. Examples include butter, cream, and honey.

• Food energy: Foods release the energy they contain. This energy is measured in kilocalories (1 kcal = 1,

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

Classification of Human Tissue Types

Tissue: An integrated group of cells with a common function and structure.

Epithelial Tissues

• Pseudostratified Ciliated Columnar: Features a large cytoplasmic volume; functions in secretion and absorption (e.g., nasal passages).
• Cuboidal: Specialized for secretion; found in the epithelia of the kidney, salivary, and thyroid glands.
• Stratified Columnar: Lines the inner surface of the urethra.
• Stratified Squamous: Regenerates quickly at the base; protects against abrasion (e.g., vagina, anus, and esophagus).
• Simple Squamous Epithelium: Thin and leaky; facilitates exchange via diffusion (e.g., blood vessels and lung air sacs).
• Simple Columnar: Functions in the secretion of juices and absorption of nutrients (e.g.,

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" »