Cell Biology: Levels of Organization, Biomolecules, and Functions
Levels of Organization in Biology
Levels of organization: Atom > Molecule > Organelle > Cell > Tissue > Organ > Organ system > Organism
Bioelements and Biomolecules
Bioelements: Chemical elements that make up living things. Bioelements join together to form biomolecules. Two types:
Inorganic Biomolecules
Inorganic biomolecules include water and mineral salts.
Water is the most abundant substance found in living things, making up about 65% of the human body. Mineral salts can be found
Read MoreHuman Digestive and Respiratory Systems: Health & Function
Digestive System: Function and Processes
Digestion takes place in the organs of the digestive tract.
Mouth
Digestion begins here through the mechanical actions of the teeth and tongue, and the chemical action of the enzyme amylase, present in saliva. Amylase transforms complex carbohydrates into simple sugars. This transformation contributes to the formation of the bolus.
Stomach
Gastric digestion of the bolus occurs here. The stomach walls secrete gastric juices that contain hydrochloric acid and enzymes
Read MoreOrigin of Life: Pasteur, Darwin, Miller & Evolution Explained
Act II: The Life
Scene I: The Early Word
What role did Pasteur and Darwin play in explaining the origin of life?
Pasteur demonstrated that microscopic germs are ubiquitous. He conducted an experiment isolating meat and vegetable broth, boiling it to sterilize it, and concluded that life does not arise spontaneously but is a process that takes time.
Darwin’s principle of evolution of species posits that species are modified by natural selection, where nature selects the fittest for survival.
What did
Read MoreUnderstanding Alleles and Genetic Concepts
Alleles
Alternative alleles of a gene, located at the same locus on homologous chromosomes, are responsible for different phenotypic manifestations of a trait.
Lethal Alleles
A lethal allele causes the death of a homozygous individual who possesses it.
Recessive Alleles
A recessive allele does not express itself in a heterozygote.
Multiple Alleles
Multiple alleles occur when a gene is represented by more than two alleles.
Autofecundation (Self-Fertilization)
Autofecundation is a mode of fertilization in
Read MoreCentral and Peripheral Nervous System, Bones, Muscles, and Heart
Central Nervous System
The central nervous system and encephalopathy (brain) is divided into two hemispheres. On its central surface, protrusions are called gyri and indentations are called sulci. The outermost part is gray matter. The cerebral cortex receives information from the organs, develops orders, stores and processes the information. In the inner zone is the white matter.
- Cerebellum: Below the brain, it is divided into two hemispheres and shows a series of cerebellar circumvolutions. It
Organic Substances, Nutrients, and Digestion
Organic and Inorganic Substances
Organic substances are mostly composed of carbon and hydrogen. Inorganic substances are not exclusive to living matter.
Types of Food
- Simple foods: Consist of a single type of nutrient, such as oil.
- Compound foods: Are composed of different nutrients.
Water is the most abundant compound. Mineral salts are dissolved in all body fluids.
Organic Constituents
- Carbohydrates: Such as glucose (which tastes sweet), starch, and cellulose.
- Lipids: Fats are substances that do not dissolve