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

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" »

Photosynthesis

Photosynthesis is the fundamental process by which plants manufacture carbohydrates from raw materials using energy from light.

The Process of Photosynthesis

• Green plants take in CO2 through their leaves via diffusion.
• Water is absorbed through the plant's roots by osmosis and transported to the leaves through xylem vessels (moving upwards).
• Chloroplasts containing chlorophyll are responsible for trapping light energy. This energy is used to break up water molecules and then to bond hydrogen and CO2 to form glucose.
• Glucose is usually changed to sucrose for transport around the plant or to starch for storage.
• Oxygen is released as a waste product or used by the plant for respiration.

Factors Limiting Photosynthesis

Three factors can limit... Continue reading "Photosynthesis and Diffusion: Biological Processes Explained" »

Neo-Darwinism and the Synthetic Theory

Neo-Darwinism, also known as the synthetic theory, is a revised version of the theory of natural selection, enriched by contributions from studies made in fields such as genetics, paleontology, and taxonomy after Darwin's time.

Punctuated Equilibrium

Punctuated Equilibrium (Punctualism) suggests that there are certain periods of intense speciation which interrupt, or punctuate, the equilibrium of the normal process of adaptation through natural selection.

Biodiversity and Biological Adaptation

Biodiversity refers to the quantity and variety of organisms that exist or have existed in the past, and the adaptation of organisms to different habitats.

Adaptation is the accumulation of changes in the characteristics... Continue reading "Evolutionary Biology: Neo-Darwinism and Hominid History" »

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" »