Notes, abstracts, papers, exams and problems of Biology

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

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." »

Interaction

Interaction is the set of processes through which a living being obtains information from the environment, takes decisions, controls its actions, and coordinates the functioning of the body itself.

Obtaining Information

There are various mechanisms responsible for obtaining information from the exterior and the interior of the body. These mechanisms are called receptors.

Analysis of the Information and Elaboration of a Response

This process is carried out by the nervous system and the endocrine system. The elaborated response is an order that is transmitted to the organs via different procedures.

Execution of a Response

The effectors, which are the organs responsible for carrying out a response, are as varied as the possible responses... Continue reading "Interaction: Obtaining, Analyzing, and Executing Responses in Living Beings" »

Unit 5: Cell Nutrition

All living beings need food used as follows:

• For growth: it provides the substances needed for making new cells and tissues.
• As a source of energy: required for the chemical reactions which take place in living organisms to keep them alive.
• For replacement: of worn and damaged tissues, for example, red blood cells that break down each day and to replace the skin which is worn away and to repair wounds.

Nutrition can be defined as obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Several systems are involved in cell nutrition: this process is carried out by organ systems which working together allow cells to obtain matter and energy.

• Digestive

Trachea

Trachea are elongated cells, with thick walls and lose their cytoplasm at maturity, so they are dead cells. The terminal walls dissolve and form continuous tubes called vessels.

Sieve Tube

These cells are at the end to end and form long sieve tubes. Polyhedral cells of epithelium lining the trachea have cilia that beat synchronously to move substances.

DNSO

The fibers are arranged in different directions and at different levels, allowing them to endure stretching in all directions.

Internal Environment

Unicellular organisms trade directly with the extracellular environment they live in, while multicellular organisms rely on an internal environment as an intermediary between the external and intracellular environments.

Benefits

• Cells provide

Nutrition: Function and Importance Nutrition includes all processes to get the materials of development and the energy we need to live like .--- La Nutricion: Nutrition is a long process. One step is to take food. Function in the 4 processes involved Nutrition: Circulation - the digestive process, respiration, and excretion Feeding and Nutrients To live, we need the nutrients that food contains. The main groups are carbohydrates, fats, proteins, water, vitamins, and minerals - A diet is complete when it contains all types of nutrients. A balanced diet is when it gives us the necessary amount of each nutrient.