Essential Principles of Cell Biology and Biochemistry
Biological Molecules: Lipids and Their Functions
Lipids are organic molecules that are insoluble in water, with an oily, waxy, or fatty consistency. Their functions are to store energy, to participate in muscle contraction, to act as insulators, and to make up part of the cell membranes. There are three kinds of lipids:
- Fatty acids and waxes: These are only made up of carbon, hydrogen, and oxygen.
- Phospholipids: These also contain phosphorus and nitrogen. They are made up of a polar head with a phosphate
V-n graph
- Which of the following statements best describes Darwin’s theory of evolution by natural selection? – Darwin’s theory emphasized that populations vary and change over time.
- Which of the following observations would provide evidence supporting Lamarck’s proposed evolutionary mechanism of “inheritance of acquired characteristics”? – A decrease in tail length in dogs after 20 generations of dogs that had their tails docked (cut off) as puppies.
- Darwin originally defined evolution as descent
Indole-3-acetic Acid (IAA): Mechanism of Cell Expansion and Plant Development
Plant cell expansion is a turgor-driven process, where water uptake into the vacuole generates internal pressure. For the cell to enlarge, its cell wall must be extensible. This is tightly regulated by hormones, especially auxin, the primary being Indole-3-acetic acid (IAA).
IAA promotes cell elongation particularly in young, growing tissues (e.g., coleoptiles, root tips) by modifying the mechanical properties of the cell wall.
Cell Wall Structure and Extensibility
The plant cell wall is a semi-rigid,
Read MoreUnderstanding Prebiotic Synthesis and Evolutionary Theories
Prebiotic Synthesis
The prebiotic synthesis: after the experiences concerning the Pasteur problem of the origin of life, which has taken more than 60 years, was addressed anew in 1920. A new version of spontaneous generation was devised, applicable at the beginning of the progressive association of life. This involves the origin of simple inorganic molecules to form more complex organic molecules through the condensation of simple molecules.
Organic formation occurs within the “soup” of molecular
Early Earth Life Origins and Biological Classification
Part 5: Early Earth, Origin of Life, and Evolution
Characteristics of Early Earth & Prebiotic Simulation
Early Earth lacked oxygen and an ozone layer, resulting in high UV radiation, noxious gases, frequent electrical storms, and abundant water.
The prebiotic simulation (1950s) recreated these early Earth conditions in the lab, leading to the formation of amino acids—the basic building blocks of life. This supports the chemical evolution hypothesis.
Hypotheses for the Origin of Life
- Chemical Evolution
Key Concepts in Evolutionary Biology and Genetics
Key Evolutionary and Genetic Concepts
Fixism
Belief that all species were created as we see them today. Species are therefore immutable.
Lamarckism
Evolutionary theory proposed by Lamarck. It considers that living beings change throughout their lives as a result of the use or disuse of organs. Body modifications acquired are transmitted to the offspring. Also called evolutionism.
Genotype
The combination of specific alleles of a cell of an individual for the full genome, or more often, a particular gene.
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