Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Hyaloplasm and Cytosol: Structure and Functions

The intracellular environment of the plasma membrane consists of a liquid solution called hyaloplasm or cytosol. The combination of the cytosol and all organelles forms the cytoplasm.

Structure of the Cytosol

The cytosol is an aqueous liquid that contains between 70% and 80% water. The remaining components are proteins, as well as small organic molecules, including amino acids, carbohydrates, and ATP.

The cytosol can exist in two physical states:

• Gel state: Has a viscous consistency.
• Sol state: Has a fluid consistency.

Functions of the Cytosol

The cytosol acts as a regulator of intracellular pH, functioning as a buffer that maintains a constant pH in the cytoplasm. Its functions include:

• Glycogenesis:

UN Declarations on Stem Cells and Cloning

The UN Resolution adopted on 23 March 2005 states that practices contrary to human dignity, such as reproductive cloning, must be prohibited. It solemnly declares that:

• a) Member States shall take all necessary measures to adequately protect human life in the application of life sciences.
• b) Member States shall prohibit all forms of human cloning as they are incompatible with the protection of human dignity.
• c) Member States shall prohibit genetic engineering techniques that may be contrary to human dignity.

Biomedical Law in Spain

In Spain, the Biomedical Law passed in 2007 allows for therapeutic cloning and the obtaining of embryonic stem cells, provided they do not lead to the creation of an embryo for...

Stem Cells: Types and Functions

Stem cells possess the unique ability to multiply indefinitely and generate specialized cells.

• Pluripotent cells: Capable of producing most tissues in an organism, though they cannot form an embryo.
• Totipotent cells: Can transform into any type of tissue. A totipotent cell placed in a uterus is capable of developing into a fetus and a new individual.
• Multipotent cells: Found in adults, these generate specific specialized cells, though research suggests they can sometimes produce different tissue types.

Understanding HIV and AIDS

What is AIDS?

Acquired Immunodeficiency Syndrome (AIDS) is a disease affecting humans infected with HIV. A person is diagnosed with AIDS when their body, due to immunodeficiency caused by HIV,...

Anatomic Exploration Techniques

Radiography and X-Ray Imaging

Radiography: X-rays are able to traverse opaque bodies and are absorbed by organs according to their density. This technique can define the risk of organs such as the bone and show the skeleton organization.

Sonography and Ultrasound Technology

Sonography: This involves traversing a living tissue with an ultrasonic wave. The boundary between two bodies is determined by the difference between the capacities of each reflection. Exploration uses the soft organs like the liver or kidneys in prenatal care.

Endoscopy and Internal Examinations

Endoscopy: The introduction of optical fibers through natural orifices of the body to examine inside the cavity, such as the bronchi, the digestive tract,...

Theory of Pangenesis

Charles Darwin proposed that all cells emit gemmules that travel through the blood to the gonads, congregating there, each contributing to the creation of offspring.

Theory of the Continuity of Germ Plasm

Friedrich Weismann postulated the existence of discrete particles, the determinants, located in the chromosomes of the zygote, so that each factor would contribute to the formation of a body part. During embryonic development, the determinants of each cell entering into mitosis would be shared by their daughter cells. Finally, each cell is left alone with the determinants necessary for differentiation; for example, intestinal cells receive only the determinants of the intestine.

Weismann also coined the terms somatic, to refer...

Excretory Organs

Malpighian Tubes

These are typical of insects. They consist of thin tubular outgrowths of the digestive tract with a closed end in contact with the body cavity and an open end in the digestive tract. Hemolymph is filtered through them, and water is recovered in the upper intestine.

Green Glands

Exclusive to crustaceans, these are located at the base of the antennae or jaws. They consist of a sac that collects waste products, a tubule where useful substances are reabsorbed, and a bladder from which waste is removed through a pore called the nephridiopore.

Metanephridia

Found in annelids and mollusks, these are tubes open at both ends. The inner end opens to the body cavity and is shaped like a funnel surrounded by cilia (nephrostomes)...

Key Animal Phyla Characteristics

Vertebrates: Backbone & Internal Skeleton

Vertebrates derive their name from the dorsal spine (vertebral column) present in adults, which replaces the embryonic notochord. This structure anchors a rigid internal skeleton, providing essential support and enabling mobility. Vertebrates include several distinct classes:

• Fish: These are aquatic animals that breathe through gills and possess fins for locomotion. While sharks have a skeleton made of cartilage (cartilaginous fish), in most fish species, bone replaces cartilage in adulthood (bony fish).
• Amphibians: Amphibians, such as frogs and salamanders, can inhabit most terrestrial environments. However, they require moist conditions and typically return to water

Fundamentals of Protein Synthesis

1. Information for Protein Synthesis

Question: Which part of the cell contains the information needed to synthesize a protein?

Answer: Deoxyribonucleic Acid (DNA), primarily located in the nucleus.

2. Cellular Organelles for Protein Production

Question: What are the cellular organelles responsible for making proteins, and where are they located in the cell?

Answer: Ribosomes, which are primarily located in the cytoplasm and on the endoplasmic reticulum.

3. Understanding RNA (Ribonucleic Acid)

Statement: RNA, or Ribonucleic Acid, plays a crucial role in gene expression and protein synthesis.

4. RNA Nucleobases

Question: Name the four nucleobases found in RNA.

Answer: Cytosine, Guanine, Adenine, and Uracil.

5. The Process

Flow of Genetic Information

The transcript originates within the nucleus. To assemble amino acids into proteins, a molecule is required to act as an intermediary between DNA and ribosomes; this intermediary is mRNA. The formation of RNA is called transcription.

During translation, a peptide chain is synthesized using the information contained in mRNA, involving rRNA and tRNA, which carry amino acids to the ribosomes. The genetic transfer from parents to offspring occurs through the following steps:

• Complementarity of nitrogenous bases.
• Replication and transcription into mRNA.
• Translation by tRNA and rRNA.

Due to replication mechanisms, some viruses have altered the standard flow of genetic information, utilizing RNA-replicase to copy RNA or reverse...