DNA: The Carrier of Genetic Information – Replication, Transcription, and Translation
DNA as Carrier of Genetic Information
Molecular biology studies the mechanisms responsible for transmitting and expressing genetic information, ultimately determining cellular functions and structures. A central question was identifying the molecule responsible for conserving, transmitting, and expressing this information—the molecular nature of the gene. Experiments by Griffith (1928), Avery, MacLeod, and McCarty (1944), and Hershey and Chase (1952) led to the acceptance of DNA as the genetic
Read MoreExploring the Central Dogma, Genetic Engineering, and Immune Responses
Central Dogma of Molecular Biology
The central dogma describes how DNA replicates a part of its message using a messenger RNA (mRNA) molecule. This transcript carries the genetic information used by ribosomes for protein synthesis (translation). An exception to this dogma exists in some viruses, where RNA can produce DNA via reverse transcriptase.
Genetic Code
The genetic code defines the relationship between nucleotides (bases) of a polynucleotide and amino acids. Three bases form a codon, which
Read MoreCellular Respiration & Photosynthesis: Processes & Cycles
Cellular Respiration
Role in Cellular Respiration
- Glucose: This organic molecule is oxidized (loses H+) in the presence of oxygen to CO2 and H2O.
- Oxygen: The final electron acceptor and proton recipient, it reduces to H2O.
- NAD+ and FAD: Coenzymes that capture the H+ lost during the oxidation of organic molecules like glucose. These are reduced to NADH + H+ and FADH2, respectively. Subsequently, these reduced coenzymes yield hydrogen to oxygen.
- Electron Transport Proteins: Protein molecules located in
Structure and Function of Nucleic Acids: DNA, RNA, and Proteins
Structure of Nucleotides and Nucleosides
A nucleoside consists of a nitrogenous base (purine or pyrimidine) covalently linked to a five-carbon sugar (pentose, either ribose or deoxyribose) via an N-glycosidic bond. Examples of nucleosides include cytidine, uridine, adenosine, guanosine, thymidine, and inosine. Nucleosides can combine with a phosphate group (phosphoric acid: H3PO4) through the action of kinases, producing nucleotides, which are the basic building blocks of DNA and RNA molecules.
Nucleotide
Read MoreGametogenesis: Sperm and Egg Formation Explained
Gametogenesis
Gametogenesis is the formation of gametes (sex cells) from germ cells through meiosis. This process reduces the chromosome number in germ cells from diploid (double) to haploid (single), meaning half the number of chromosomes found in a normal cell of the species. In humans, the process that produces sperm is called spermatogenesis and occurs in the testes. The process that produces eggs is called oogenesis and occurs in the ovaries.
Gametogenesis involves two chromosomal and cytoplasmic
Read MoreExploring the Cell: A Comprehensive Guide to Organelles and Their Functions
Plasma Membrane
Characteristics
The plasma membrane consists of a lipid bilayer with proteins embedded within or attached to its surfaces.
Functions
The plasma membrane controls the entry and exit of substances, both qualitatively and quantitatively. This selective permeability allows the passage of small solvents and solutes while restricting larger ones. This process helps determine the cytoplasm’s composition through nutrient uptake and waste excretion.
Golgi Apparatus
Characteristics
The Golgi apparatus
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