Bacterial Conjugation, Transformation, and Transduction
A) Conjugation
It is a process by which a donor bacterium transmits DNA through its pili to a recipient bacterium.
Plasmid
The ability to give or receive DNA is a property determined by the presence of episomes, fragments of DNA in donor bacteria that transfer to other bacteria during conjugation.
2) Transformation
It is a process by which bacteria incorporate DNA from the lysis of other bacteria in their surrounding environment. Bacteria capable of capturing environmental DNA are termed competent.
DNA and RNA Structure and Function in Cells
DNA and RNA: Structure and Function
Alternative DNA Structures
While the Watson-Crick double helix (B-form DNA) is well-known, other forms exist, notably A-DNA and Z-DNA. B-DNA is the predominant form in biological systems and is crucial for DNA-protein interactions within the nucleus.
B-Form DNA
This is the standard double helix structure observed in most biological contexts.
A-Form DNA
A-DNA arises from B-DNA under dehydrating conditions. It is a right-handed double helix, but wider and shorter than
Read MoreDisease Classification and Etiology
Disease Classification
Genetic Diseases
Hereditary diseases are caused by modifications in the genome passed down through generations. Sex-linked inherited diseases occur when the modification is on a sex chromosome, affecting only one sex. Mitochondrial diseases are inherited through modified mitochondrial DNA, always originating from the mother.
Degenerative Diseases
These diseases involve impaired regenerative ability. Sometimes, the body loses its ability to regenerate (e.g., Parkinson’s and Alzheimer’
Read MoreMalaria: Causes, Symptoms, Transmission, and Prevention
Malaria
What is Malaria?
Malaria is an acute febrile infectious disease caused by a unicellular parasite. It is characterized by high fever, chills, sweats, and headaches, occurring in cyclical patterns depending on the infecting parasite species. An initial symptomatic phase, marked by malaise, headache, fatigue, and muscle pain, typically precedes the classic malaria fever.
Symptoms
The characteristic malaria paroxysm begins with chills lasting 15 minutes to an hour, followed by a fever phase with
Read MoreOrigin and Evolution of Life: From Cells to Humans
Modern Theories on the Origin of Life
Chemical Evolution
The primitive atmosphere’s chemical compounds facilitated the synthesis of simple organic compounds essential for life. This early atmosphere lacked free oxygen. Gases reacted through intense radiation, forming small organic molecules. Rain washed these chemicals into the oceans, creating the “primeval soup.” These molecules reacted with water, forming biological building blocks. These interacted, forming giant molecules. Microstructures emerged
Read MorePhotosynthesis: Light and Dark Reactions, Calvin Cycle
Photosystems
Photosystem I (PSI)
Able to absorb light of λ <700 nm.
Photosystem II (PSII)
Capable of absorbing light of λ <680 nm.
If a photon hits an electron in a photosynthetic pigment molecule, the electron captures the photon’s energy and jumps to a more distant orbit. It can be lost, ionizing the atom. The molecule, now oxidized, seeks electrons, which are supplied by the photolysis of water.
Absorption of light by the reaction center chlorophyll causes it to release an electron, which travels