Understanding Genetic Engineering and its Uses

Genetic Engineering: Techniques and Applications

Although the structure of DNA was discovered in the mid-twentieth century by Francis Crick and James Watson, a breakthrough occurred in the 1970s with the development of two crucial biological tools:

  • Identification of restriction enzymes.
  • The polymerase chain reaction (PCR).

These tools, along with a greater understanding of genes, ushered in the era of Biotechnology, a science integrating natural sciences and engineering to utilize organisms, cells,

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Respiratory Tract Anatomy, Function, and Blood-Brain Barrier

Respiratory Tract: Composition and Function

The respiratory tract includes:

Nose (nasal cavity) -> Pharynx (nasopharynx, oropharynx, laryngopharynx) -> Larynx -> Trachea -> Bronchi (primary, secondary (lobar), tertiary (segmental) -> Bronchioles -> Terminal bronchioles -> Respiratory bronchioles -> Alveolar ducts -> Alveoli

Trachea

  • Tough but flexible “windpipe”, anterior to esophagus
  • Attached to cricoid cartilage (at about C6 vertebral level) & ends within mediastinum
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Stem Cell Reprogramming and Therapeutic Applications

Reprogramming Adult Cells to Pluripotency

Can terminally differentiated adult cells be reprogrammed to become pluripotent?

  • Yes, this was demonstrated by semi-starving cells from a mammary cell donor, effectively reversing their maturation (dedifferentiation). The process involved taking an enucleated egg from a donor and fusing it with the mammary cell. The resulting cell was cultured to form an embryo, which was then implanted into a surrogate sheep. This sheep carried the embryo to term and gave
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Drug Elimination, Mechanisms, and Therapeutic Levels

Renal Drug Elimination

Renal elimination is the primary route for drug removal from the body, involving several kidney excretion mechanisms.

Enterohepatic Recirculation (Biliary Excretion)

Some drugs are excreted through bile, which is released into the duodenum to aid fat emulsification during digestion.

Pulmonary Elimination

The respiratory mucosa can eliminate volatile substances like anesthetics and alcohol.

Elimination Through Glands

Elimination can occur through glands, notably the mammary gland,

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Understanding Biomembranes: Structure, Function, and Properties

Understanding Biomembranes

A necessary condition for life is the existence of a barrier separating cell contents from the environment, since the cells must retain an internal environment appropriate to carry out the numerous chemical reactions necessary to sustain life. Biomembranes are the place where many chemical reactions take place. They regulate the entry and exit of materials from the cell. Some membranes are selectively permeable barriers that regulate the flow of molecules inwards and outwards,

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Small and Large Intestine: Composition, Function, and Models

Composition and Function of the Small Intestine

Digestion within the small intestine produces a mixture of disaccharides, peptides, fatty acids, and monoglycerides. The final digestion and absorption of these substances occur in the villi, which line the inner surface of the small intestine.

  • The crypts at the base of the villi contain stem cells that continuously divide by mitosis, producing:
    1. More stem cells
    2. Cells that migrate up the surface of the villus while differentiating
  • Columnar epithelial cells
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