Introduction to Cell Biology
Cytoskeleton
The cytoskeleton is dynamic, adaptable, and consists of three networks:
- Microtubules
- Microfilaments
- Intermediate Filaments
These three are ATP catalysts.
Microtubules
Composed of the protein tubulin, measuring 25 nm, microtubules form the mitotic spindle and are used in vesicle transport. They are found throughout the cell from the core to the membrane.
Unlike the other two components, microtubules have a channel in the middle. They are organized by proteins called MAPs (Microtubule-Associated
Read MoreProteins: Structure, Classification, and Functions
Proteins: An Overview
Proteins are essential biomolecules primarily composed of carbon, hydrogen, oxygen, and nitrogen. They may also contain sulfur, and some types contain phosphorus, iron, magnesium, copper, and other elements. Proteins are polymers of smaller molecules called amino acids, which are linked together by peptide bonds.
Amino Acids
Amino acids are characterized by a carboxyl group (-COOH) and an amino group (-NH2). The remaining two carbon valencies are saturated with a hydrogen atom
Read MoreThe Circulatory and Lymphatic Systems: A Comprehensive Guide
1. The Blood Circulatory System
Composition of Blood
The blood circulatory system consists of the heart (pump), blood, and blood vessels (tubes). Blood is contained within the vessels and never directly contacts cells, exchanging substances across thin capillary membranes.
Blood is composed of 55% plasma (a yellow liquid containing water, proteins, lipids, and carbohydrates) and 45% cells. These cells, produced in the bone marrow, are:
- Erythrocytes (red blood cells)
- Thrombocytes (platelets)
- Leukocytes
Milk Processing and Preservation: Techniques and Methods
Milk Processing and Preservation
Homogenization
Homogenized milk ensures uniform fat distribution by passing it through a fine filter, breaking down and spraying fat droplets for better consistency.
Pasteurization and Sterilization
Pasteurization eliminates non-sporulated microorganisms at lower temperatures, while sterilization targets spores at higher temperatures.
Thermization
Thermization, a brief heating process (15 seconds at 67-78°C) before cream separation, prevents organism proliferation.
Lactose
Read MoreBiotechnology and Genetic Engineering: Applications and Advancements
Biotechnology
Biotechnology encompasses techniques using biochemical changes from microorganism metabolic activity. It’s applied in agribusiness for environmentally friendly products, reducing reliance on chemical industries. Other applications include organic product production and processing, medicine, pharmacology, waste disposal, environmental sanitation, and mining.
Genetic Engineering
Genetic engineering manipulates and transfers DNA between organisms, creating new lineages within a species.
Read MoreEndocrine System and Muscle Physiology: Hormones, Contraction & More
Endocrine System and Muscle Physiology
Motor Neuron Axon Terminal
- Action potential reaches axon terminal of motor neuron.
- Voltage-gated Ca2+ channels open, allowing Ca2+ to enter the motor neuron.
- Vesicles fuse with axon terminal membrane, releasing acetylcholine (ACh) into the synapse (always excitatory between motor neuron and muscle cell).
- ACh diffuses to the skeletal muscle cell membrane and binds to nicotinic acetylcholine receptors (nAChR).
- nAChR are activated, allowing ions to enter the muscle