Understanding Energy Flow and Matter Cycles in Ecosystems
1. Energy Flow in Ecosystems In ecosystems, energy is transferred from one organism to another through trophic relationships. Flow of Energy is a unidirectional process. Ecosystems depend on a continuous power supply for energy functioning. The energy that enters an ecosystem comes from producers that use a small amount of light energy. This energy is called solar energy, which is used to perform the process of photosynthesis. Producers convert light energy into chemical energy. The part of the
Read MoreRenal Failure, Micturition & Bladder Disorders: An Overview
Renal Failure: Kidney Function and Dysfunction
Acute Renal Failure (ARF)
Causes of ARF
- Intrarenal: Acute tubular necrosis, nephrotoxins (drugs, chemicals), intratubular obstruction (hemoglobinuria, myoglobinuria).
- Prerenal: Circulatory issues leading to decreased kidney perfusion (e.g., hypovolemia, heart failure).
- Postrenal: Mechanical obstruction below the kidney (e.g., bilateral ureteral obstruction).
Phases of ARF
- Onset/Initiating Phase: Decreased urine output, increased serum creatinine.
- Maintenance
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.