Ecology: Population, Ecosystems, and Trophic Structure
ITEM 4. Population Level and Ecology
4.1. Key Concepts
- Species: A set of individuals with similar morphological appearance, sharing the same anatomical and physiological characteristics, capable of interbreeding and producing fertile offspring.
- Population: A group of organisms of the same species inhabiting the same space and time.
- Community: A set of populations living in a common environment, characterized by interrelationships between them.
4.2. Ecosystems: Biotic and Abiotic Factors
An ecosystem is
Read MoreProkaryotic and Eukaryotic Gene Regulation Mechanisms
Gene Regulation: Operons and DNA-Binding Motifs
Repressors are usually near the promoter. Regulation by a repressor that blocks protein transcription is called negative regulation. Activators, contrary to repressors, potentiate the activity of RNA polymerase at the promoter; this is upregulation. Adjacent promoters are common.
An operon is defined as the group of genes and the promoter that act together in regulation. The lactose operon (Lac) is subject to negative regulation. In the absence of lactose,
Read MoreMale & Female Reproductive Systems: Fertilization
Male Gametes
Sperm cells are produced continuously in the seminiferous tubules. They move up to the epididymis, at which time they complete their maturation and develop a flagellum with which they swim very quickly. They are small and numerous, unlike the eggs. Hundreds of millions mature daily. Output is performed by ejaculation, in which semen is expelled. Semen is a liquid formed by sperm and prostatic seminal lubricant. Sperm remain alive between 3 and 5 days in the vagina, at which time fertilization
Read MoreMicroorganisms: Characteristics, Classification, and Lifestyles
Microorganisms
Microorganisms are living things that can only be seen with a light or electron microscope. They are everywhere where there is moisture, temperature, and food suitable for development and reproduction. Leeuwenhoek gave them that name.
Characteristics
They are extremely small, and their physiological and ecological properties are peculiar. They have active metabolism (influencing the environment they live in), reproduce quickly (high number; the proliferation of microorganisms causes
Read MoreIndividualized Drug Dosing: Narrow Therapeutic Range
Why Must Drug Doses Be Adjusted Individually for Drugs with a Narrow Therapeutic Range?
Drug dosage must be adjusted individually due to variations in:
- Pharmacokinetic Processes: Differences in absorption, distribution, metabolism, and excretion. These are the main determinants of inter- and intra-individual variability.
- Pharmacodynamic Processes: Changes in drug-receptor binding. This may be due to genetic factors, environmental factors, or disease.
Why is Health Education Important for Side Effects
Read MoreHuman Reproductive System: Anatomy and Function
The Male Reproductive System
The male reproductive system includes:
- Testes: Two organs that produce sperm and testosterone. They are located outside the abdominal cavity in a pouch called the scrotum.
- Genital Tract: The epididymis and vas deferens, which collect and transport sperm from the testicles to the exterior through the urethra.
- Accessory Glands: The prostate and seminal vesicles produce secretions that allow the maturation of sperm and serve as a vehicle, constituting semen.
- Penis: The external