Evolution Theories: Lamarck, Darwin, and the Modern Synthesis
Lamarck’s Theory of Evolution
Inheritance of Acquired Characteristics: This theory posits that modifications acquired by parents during their lifetime are passed on to their offspring.
Lamarck observed that fossils in deeper strata represented simpler life forms, while surface strata contained more complex organisms, suggesting a progression from simple to complex life.
He argued for the existence of a biological evolution process where primitive forms gave rise to better-organized life forms.
Lamarck’
Read MoreChromosome Mutations: Number and Structure Variations
Lecture 15: Chapter 8
Chromosome Mutations: Variation in Number and Arrangement
Visualizing Chromosomes
Cytogenetics: The study of chromosomes within cells.
Chromosomes are designated based on the relative placement of their centromere. (See Figure 2.3 for visualization).
Human Karyotypes and idealized banding patterns group chromosomes: A(1-3), B(4-5), C(6-12), D(13-15), E(16-18), F(19-20), G(21-22).
Chromosome Numbers
Key terms include Aneuploidy, Euploidy, and Polyploidy. (Refer to Table 8.1 for examples)
Read MoreNeurons, Hormones, and Nervous System Function
Synapses and Neurotransmitters
Synapses are connections between neurons that transmit nerve impulses. A neurotransmitter is a chemical substance that produces the nerve impulse across the synapse.
Neuron Structure
Neurons possess filamentous extensions that facilitate connections with other neurons and organs throughout our body. We distinguish two main parts:
- Soma: Contains the nucleus and the main part of the cytoplasm.
- Extensions: There are two types:
- Dendrites: Short and highly branched extensions
Predator-Prey Dynamics, Symbiosis, and Ecosystem Interactions
Predator and Prey Relationships
Predators possess traits or skills that help them catch and kill their prey. Different types of predators have different skills and traits. For example, a cheetah uses its speed to catch prey. On the other hand, tigers have colors that let them blend with the environment so that prey cannot see them easily.
Prey generally have some way to protect themselves from being eaten. Different types of organisms protect themselves in different ways:
- Run Away: When a rabbit is
Human Anatomy: Digestive, Connective Tissues, and More
The Human Body: Anatomy and Physiology
Digestive System
The digestive system consists of the gastrointestinal tract (alimentary canal) and accessory digestive organs. The stages of digestion include:
- Ingestion: Food enters the mouth.
- Mastication: Chewing and mixing with saliva.
- Deglutition: Food moves to the pharynx and esophagus.
- Peristalsis: Wave-like contractions move food.
- Digestion: Mechanical and chemical breakdown.
- Absorption: Nutrients pass through the GI tract.
- Defecation: Waste elimination.
The
Read MoreUnderstanding Genetic Mutations: Types, Causes, and Repair Mechanisms
Mutations: An Overview
Mutations: Genetic material randomly modifies, which is of great importance in evolution.
Somatic cell mutations do not pass to descendants.
Germline cell mutations can be passed on and fixed in offspring.
- Negative mutations can be lethal.
- Beneficial mutations drive evolution.
Mutagenic agents can be physical, chemical, or biological.
Types of Mutations
- Gene mutations: Affect the gene.
- Chromosomal mutations: Affect chromosomal structure.
- Genomic mutations: Affect the number of chromosomal