Bacteria and Archaea: Chapters 26-28, 33-37

• Study notes for Chapters 26-28, 33-37

Chapter 26: Bacteria and Archaea

• Bacteria and archaea represent two of the three domains of life, showcasing significant evolutionary diversity.
• The microbiome refers to the diverse community of microorganisms inhabiting a particular environment, such as the human body or a specific soil type.
• Gram-positive bacteria have a thick peptidoglycan layer that retains crystal violet stain, appearing purple under a microscope, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, staining pink after counterstaining with safranin.
• Bacteria and archaea are studied through various methods, including culturing, microscopy, and molecular techniques like DNA sequencing, to understand their physiology, genetics, and ecological roles.
• Bacteria and archaea offer benefits such as nutrient cycling and are harmful as pathogens; furthermore, studying them entails costs related to research funding and infrastructure.
• Bacteria and archaea are prokaryotes because they lack a nucleus and other membrane-bound organelles, simplifying their cellular structure.
• Bacteria evolve resistance to antibiotics through mechanisms like mutation, horizontal gene transfer, and natural selection, posing a significant challenge to public health.
• Endospores are dormant, highly resistant structures formed by certain bacteria to survive harsh environmental conditions, allowing them to persist for extended periods until conditions become favorable again.

Chapter 33: Viruses

• A virus is a non-cellular infectious agent that replicates only inside the living cells of an organism.
• Viruses replicate by hijacking the host cell's machinery to produce viral components, which are then assembled into new virus particles.
• A capsid is the protein shell of a virus, enclosing its genetic material (DNA or RNA).
• Viruses consist of genetic material (DNA or RNA), a capsid, and sometimes a lipid envelope.
• Virus types include bacteriophages (infect bacteria) and retroviruses (use reverse transcriptase).
• Viruses are studied through cell culture, electron microscopy, and molecular techniques.
• Disease models like SIR (Susceptible, Infected, Recovered) and SIS (Susceptible, Infected, Susceptible) are used to understand and predict the spread of infectious diseases in populations.
• Vaccines stimulate the immune system to produce antibodies, providing protection against viral infections.

Chapter 27: Protists

• Protists are a diverse group of eukaryotic organisms that are not plants, animals, or fungi, and they evolved through endosymbiosis.
• Eukaryotes, the third domain of life, are organisms with cells containing a nucleus and other membrane-bound organelles, like protists, fungi, plants, and animals.
• Multicellular life evolved from single-celled protists through processes of cell aggregation, specialization, and cooperation.
• Most protists live in aquatic environments, such as oceans, lakes, and rivers, due to their need for moisture.
• Protists are not monophyletic because they do not share a single common ancestor exclusive to them but include ancestors of other groups like plants, animals, and fungi.
• Malaria is a disease caused by protist parasites of the genus Plasmodium, transmitted to humans through mosquito bites.
• Protists play a vital role in the carbon cycle by performing photosynthesis and fixing CO2 into organic compounds, serving as a food source and releasing oxygen.
• Endosymbiosis and secondary endosymbiosis are processes where one cell engulfs another, leading to the evolution of organelles like mitochondria and chloroplasts in eukaryotic cells.
• Protists evolved traits such as multicellularity, sexual reproduction, and specialized organelles.

Chapter 28: Green Algae and Plants

• Evolutionary relationships among green algae and plants reveal a close ancestry, with land plants evolving from green algae.
• Phylogeny illustrates the evolutionary relationships between different plant groups.
• Key differences among land plant groups include the presence or absence of vascular tissue, seeds, and flowers, reflecting adaptations to life on land.
• Alternation of generations is a life cycle in plants involving alternating haploid (gametophyte) and diploid (sporophyte) generations.
• Seed plants reproduce through pollination and fertilization, resulting in the formation of seeds that contain embryos.
• Key plant lineages include bryophytes (mosses), ferns, gymnosperms (conifers), and angiosperms (flowering plants), each with distinct features and adaptations.
• Plants are useful to humans for food, medicine, construction, and other purposes.
• Differences in plants, such as vascular tissue, seeds, and flowers, led to evolutionary divergence and adaptation to diverse environments.
• The evolutionary timeline of plants shows the sequence of major events, such as the origin of land plants, vascular tissue, seeds, and flowers, and how traits evolved.

Chapters 34, 35, 36, 37: Plant Biology

• The plant body is organized into roots, stems, leaves, and reproductive structures, each with specialized functions.
• Roots anchor the plant, absorb water and nutrients, and store food.
• Shoots support the plant, transport substances, and bear leaves and flowers.
• Leaves carry out photosynthesis, capturing sunlight to produce food.
• Nodes are points on the stem where leaves or branches originate.
• Buds are undeveloped shoots that can develop into new leaves, stems, or flowers.
• Plants are diverse in size and shape due to genetic variation, environmental factors, and adaptations to different habitats.
• Plants grow throughout their lives through cell division, elongation, and differentiation in meristems.
• Surface area to volume ratios (SA/V) affect gas exchange, nutrient absorption, and water loss in plants, influencing evolution and survival.
• Plants move water from roots to leaves through transpiration, cohesion, and adhesion in the xylem.
• Plants get sugars from the leaves to the roots through translocation in the phloem.
• Plants obtain nutrients from the soil through root uptake and symbiotic relationships with microorganisms and they get biomass from photosynthesis.
• Plants sense environmental cues, such as light, gravity, and touch, and respond with growth and development through hormones and signaling pathways.