Flatworms, Roundworms, and Plant Structures
Platyhelminthes (Flatworms)
Introduction – Flatworms have bilateral symmetry.
Bilateral Symmetry – Symmetry that divides the body of a living being into two equal parts from a longitudinal section.
Habitat – Flatworms are found in:
- Wet soil – Geoplana
- Freshwater – Dugesia
- Saltwater – Notoplana and Stylochus
- Inside living organisms, as parasites – Taenia, Schistosoma, Fasciola
Structure – Flatworms are elongated animals with a flattened dorsoventral body, segmented or unsegmented. They have digestive and
Read MoreInfectious and Non-Infectious Diseases: An Overview
Infectious Diseases
Infectious diseases originate from the colonization of the body by infectious agents or vermin infestation.
Routes of Transmission
Infectious agents can be transmitted from a sick individual through:
- Direct Contagion: Occurs from person to person.
- Indirect Contagion: Transmission through various mediums:
- Air: Microorganisms from a sick person pass to a healthy person through coughing or sneezing, transmitting respiratory diseases like tuberculosis.
- Water: A significant transmission
Exploring DNA, Genetics, and the Human Genome Project
DNA, Genes, and Proteins
Key Concepts
- DNA (Deoxyribonucleic Acid): A molecule composed of four repeating units (cytosine, guanine, thymine, and adenine) combined in various sequences.
- Nucleotides: The building blocks of DNA, consisting of a phosphate group, a sugar, and a nucleobase.
- Proteins: Essential molecules for life, formed by chains of amino acids. There are 20 different amino acids.
- Gene: A segment of DNA that codes for a specific protein. It’s the basic unit of genetic information.
- Karyotype:
Osmosis, Carbohydrates, Lipids, and Proteins in Cells
Osmosis: Diffusion of Water
Osmosis is the movement of water from a hypotonic (diluted, more water) medium to a hypertonic (concentrated, less water) medium across a semi-permeable membrane. Water moves until the concentrations are equal (isotonic), and osmosis stops.
Osmotic Processes in Cells:
Cells are surrounded by isotonic media to prevent harmful osmotic processes. Animal cells are more sensitive due to their thin plasma membrane.
Processes Affecting Cells:
1. Plasmolysis: Occurs when a cell is
Read MoreEthylene and Polyamines: Plant Growth Regulators
UNIT 20 – Ethylene and Polyamines
Definitions
Methionine: An amino acid formed from S-adenosylmethionine (SAM), a precursor in metabolic pathways, including ethylene and polyamine biosynthesis.
Ethylene: A developmental regulatory molecule (hydrocarbon, C2H4) in plants and animals. It has a simple chemical structure and is active in gaseous form. Its effects occur at very low concentrations and are evident in virtually all life cycle stages.
Triple Response: Ethylene’s effect in seedlings, causing reduced
Read MoreCell Biology and Nutrition Essentials
ITEM 1 Cell Parties
Mitochondria
Oval organelles that provide energy.
Reticulum
Sacks and interconnected channels where proteins and lipids are produced.
Vacuoles
Contain water and dissolved substances.
Lysosomes
Transform substances into simpler ones.
Cytoskeleton
Complex filaments forming a network.
Centrioles
Two hollow cylinders with walls formed by filaments.
Ribosomes
Small particles, free or attached, that manufacture proteins.
Golgi Apparatus
Stacks of membranous sacs that package substances manufactured
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