Molecular Biology: RNA, DNA, and Embryonic Development

Posted on Dec 16, 2024 in Biology

  • Types of RNA:
    • Messenger RNA (mRNA) is the type of RNA that carries information from DNA to ribosomes.
    • Transfer RNA (tRNA) and ribosomal RNA (rRNA) are key elements in the translation process, and various types of RNA regulators.

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  • Operon model: The model of prokaryotic gene regulation: the operon model was proposed in 1961 by Francois Jacob and Jacques Monod. The phenomenon that inspired the idea was enzyme induction. Groups of genes that encode related proteins are grouped into units known as operons.
  • Operon consists of: an operator, a promoter, a regulator, and a structural gene. The regulator gene codes for a protein that sticks to the operator, obstructing the promoter (and therefore the transcription), the structural gene. The regulator does not have to be adjacent to other genes in the operon. When removing the repressor protein, transcription can occur.

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  • DNA: The genetic material of most living organisms which controls heredity and is located in the nucleus of cells.
  • It consists of: a nucleic acid is composed of two strips called nucleotides. The two strips are arranged in spiral form a double helix and joined by hydrogen bonds between the nucleotide bases. Genetic information is contained in sequence along the molecule, which can make exact copies of itself by a process called replication, thus passing genetic information to daughter cells when cells divide.
  • Recombinant DNA: DNA is a molecule composed deliberately artificial in vitro by binding to DNA sequences from two organisms of different species that are not normally found together
    • Consists: By introducing recombinant DNA into an organism to produce a genetic modification that allows the addition of new DNA to the body leading to the modification of existing features or the expression of new traits
    • Use: The recombinant DNA is a result of using various techniques that molecular biologists use to manipulate DNA molecules and differs from genetic recombination that occurs without human intervention within the cell
    • Process: The process involves taking a DNA molecule of an organism is a virus, a bacterium, plant or laboratory handling and put it back into another body.
    • Purpose: This can be done to study the expression of a gene to produce proteins in the treatment of a genetic disease, vaccines, or economic and scientific purposes.
  • Spermatogonia: rounded male diploid cell, where after a series of divisions originate espermacitos and of these, the sperm.
  • Blastula: is an early stage of embryonic development in animals, in mammals is called a blastocyst.
  • Blastula Types:
      • Celoblastula
      • Stereoblastula
      • Discoblastula
      • Periblastula
  • Epigenesis: the process of development of an individual, through which its structure is different and more complex, the paradigmatic case is the growth, which from a zygote develops a complex cellular structure and organic.
  • Crossover is the process by which two chromosomes pair up and exchange sections of DNA.
  • Process: usually occurs when paired regions of chromosome breaks and then reconnect to another chromosome.
    • Result: The result of this process is an exchange of genes, called genetic recombination.
  • Experiment Roux: In 1888 tried to find out how they are generated, from the egg, the organization of the individual.
    • Methodology: Taking frog eggs that had just broken for the first time, played a series of experiments in which destroyed one of the two cells and observed the development of another.
    • Results: found that only half embryo always get: sometimes the front half, others later, or one half lengthwise.
    • Conclusion: From these experiments they could induce the egg was the only one that had all the information necessary for embryonic development, whereas after the first division, the daughter cells retained only a portion of those guidelines. The fertilized egg divides into two cells, one Roux pierced with a needle, the other cell remained undamaged embryo splitting and Medium format.
  • Spemann’s experiment:
    • Method “a”: In eggs of salamanders and frogs appear in the newly fertilized egg a region called the gray crescent. Spemann constrains salamander egg with a child’s hair, so that the gray crescent will be divided into two halves.
    • Result “to”: From each normal embryo developed, but first they had developed the core, and then the other.
    • Method “b”: Another experiment consisted in constraining an egg so that the gray crescent stay in one half of the egg.
    • Output “b”: This half causing a normal embryo while the other became an amorphous mass of unorganized cells
    • Conclusion: Spemann had failed to prove that during the early development, each of the nuclei of the developing organism has all the genetic information that existed in the original zygote.
  • Map embryonic stage: This period extends from the 3rd week until the 8th week, in which daughters embryonic give rise to its own tissues and organ systems. Following the formation of organs, appear the main characters of the body.
    • Derivatives: gives rise to organs and structures in contact with the outside world: CNS and PNS, sensory epithelium of the ear, nose and eye, skin and its annexes, the pituitary gland, mammary glands, sweat glands and tooth enamel.
  • Eggs: The eggs varies according to species, their size is variable. One of the main factors controlling egg size is the quantity of nutrient reserve or call yolk, yolk or deutoplasma.
    • Types:
      • Isolecitos: They are small eggs with little amount of yolk that is distributed evenly throughout the egg. Typical of those species in which the embryo does not feed on the nutrient reserves but does the mother’s body or the external environment to leaving early (coelenterates, echinoderms).
      • Telolecitos: are larger with larger yolk. They are distinguished: telolecitos egg yolk 50% (amphibians). The yolk is accumulated in the posterior hemisphere of the egg forming the vegetative plant or where the yolk. The other 50% is constituted by the protoplasm and nucleus and is called the animal hemisphere. Telolecíticos eggs with 90% of yolk (birds) in them is the nucleus with the cytoplasm around and around in this set is the yolk or yolk and everything is surrounding the cell membrane, eventually the shell that protects the egg as feature is one of the poles has a inner tube. The embryo is nourished by the nutrient reserves of the interior.
      • Centrolecitos: they have accumulated yolk in the center. Would the nucleus surrounded by yolk and the cytoplasm around it (arthropods).