Evolution and Origin of Life

• Earth formed 4.6 billion years ago (bya).
• First evidence of life appeared 3.5 bya.
• First eukaryotes emerged 2,400 million years ago (mya).
• First animals (trilobites and cyanobacteria) evolved 800 mya.
• Cambrian explosion occurred 500 mya that allowed for more ATP aerobic respiration.
• Ozone layer was created and protected animals 500 mya.
• Vertebrates appeared 500 mya.
• Modern humans evolved 2.2 mya.
• In the 1920s scientists suspected organic molecules appeared in early Earth's oceans because of the low oxygen.
• In the early 1950s Miller and Urey found all macromolecules were formed in their experiment.
• Darwin had 3 postulates for natural selection: characteristics are heritable, competition for resources, offspring characteristics vary.
• Darwin went to the Galápagos Islands and South America which was crucial for making observations and collecting fossils.
• Allopatric speciation splits the gene pool due to geographic isolation or mutations.
• Dispersal is when a few members move.
• Vicariance is when a natural situation arises.
• Sympatric speciation occurs in the same geographical area can be prezygotic or postzygotic .
• As the "fittest" genes are passed on, the population changes to better fit the environment.
• Prokaryotes lack a true nucleus and membrane-bound organelles.
• Prokaryotes' genetic material is in a nucleoid region.
• Prokaryotic cells are smaller (1-10 micrometers) and reproduce asexually through binary fission.
• Prokaryotes' DNA is in a single circular chromosome, with smaller (70S) ribosomes.
• Bacteria have peptidoglycan in their cell walls.
• Archaea have unique lipids in their cell walls, and live in extreme environments.
• Bacteria are common in many habitats and include pathogenic species.
• Archaea aren't known to cause disease and are often extremophiles.

Benefits of Bacteria

• Bacteria in the human gut break down food and absorb nutrients, produce essential vitamins, and keep microbes in check.
• Rhizobium converts nitrogen gas that plants can use, which is vital for plant growth.
• Bacteria breaks down dead organisms and waste.
• Bacteria release nutrients back into the soil for ecosystems and plant life.
• Bacteria produce medicines like insulin, vaccines, antibiotics, and vitamins.
• Genetic engineering uses bacteria to carry and replicate genes.
• Bacteria make foods like yogurt, cheese, sourdough bread, and fermented vegetables.
• Bacteria help preserve food and enhance flavor and texture.
• Bacteria break down pollutants and are used in bioremediation.
• Bacteria are used in labs to study genes, evolution, and disease mechanisms.

Endosymbiotic Theory

• Some organelles like mitochondria and chloroplasts were once free-living prokaryotic cells.
• These prokaryotic cells were engulfed by a larger host cell where they formed a mutualistic relationship.

Eukaryotic Cells & Organelles

• Nucleus controls the cell with DNA and has nuclear pores for material exchange.
• Nucleolus produces ribosomes inside the nucleus.
• Ribosomes make proteins and are found in the cytoplasm or attached to rough ER.
• Rough ER synthesizes and folds proteins for export or use in the membrane and has ribosomes on its surface.
• Smooth ER makes lipids, detoxifies drugs, and stores calcium; it has no ribosomes.
• Golgi Apparatus modifies, sorts, and packages proteins and lipids for transport.
• Mitochondria produces ATP through cellular respiration and is known as the "powerhouse".
• Lysosomes contain digestive enzymes that break down waste, old cell parts, and foreign material (mainly in animal cells).
• Peroxisomes contain enzymes that break down fatty acids and detoxify harmful substances.
• Cytoplasm supports organelles and is the site of many reactions.
• Cytoskeleton supports cell shape, enables movement, and aids in cell division.
• Cell Membrane controls what enters/leaves the cell and maintains homeostasis with a phospholipid bilayer and proteins.
• Cell Wall provides structure and protection.
• Chloroplasts site of photosynthesis (converts sunlight to glucose) and contains chlorophyll.
• Central Vacuole stores water, nutrients, and waste and maintains turgor pressure.

Vertebrate Immune Response

• Innate immune response is the first line of defense that is a general response you are born with.
• Physical barriers like skin and mucus, chemical barriers like stomach acid, and inflammation are included in innate immune response.
• Phagocytic cells like macrophages and neutrophils "eat" pathogens during innate immune response.
• Natural killer (NK) cells destroy virus-infected and cancer cells during the innate immune response.
• Adaptive immune response is the second line of defense that is slower but specific responses that has memory.
• Lymphocytes are key players in the adaptive immune response that contain many types of cells.
• B cells make antibodies to target specific invaders.
• Helper T cells coordinate immune response.
• Cytotoxic T cells kill infected cells directly.
• Adaptive immune response starts with recognition of an antigen.
• Activation occurs when helper T cells activate B cells and cytotoxic T cells.
• In response, B cells produce antibodies and cytotoxic T cells kill host cells.
• Some activated B and T cells become memory cells for future defense.
• Antigens are molecules from pathogens that trigger an immune response.
• Antibodies are proteins made by B cells that bind to specific antigens.
• Vaccines stimulate the adaptive immune system to make memory cells without causing illness.

Protists

• Protists are unicellular eukaryotes that don't fit into the animal, plant, or fungi kingdoms.
• Animal-like (protozoa) protists are heterotrophs that move using structures like cilia.
• Plant-like (algae) protists are autotrophs that perform photosynthesis.
• Fungus-like protists absorb nutrients reproduce by spores.

Fungi

• Fungi are eukaryotic, heterotrophic, have cell walls made of chitin, and are mostly multicellular.
• Hyphae forms a network called mycelium.
• Fungi decompose dead organic material and recycle nutrients.
• Fungi form mycorrhizae with plant roots for better water/nutrient absorption.
• Lichens contain fungi + algae/cyanobacteria for pioneer species in harsh environments.
• Food and medicine such as mushrooms and antibiotics are derived from fungi.

Plants

• Bryophytes are nonvascular and reproduce via spores, and the gametophyte is dominant .
• Pteridophytes are vascular and reproduce via spores, and the sporophyte is dominant.
• Gymnosperms are vascular and reproduce using "naked" seeds and the sporophyte is dominant.
• Angiosperms are vascular and reproduce using seeds in fruit, andsporophyte is dominant.
• Plants alternate between gametophyte (n) and sporophyte (2n) stages which involves: Spores, Gametophyte, Gametes, Fertilization, Sporophyte.
• Substrates for photosynthesis includes carbon dioxide that water is absorbed through stomata of leaves.
• Products of photosynthesis include glucose, a simple sugar for energy and carbon, and oxygen.
• Plants uses photosynthesis in chloroplasts to convert light energy into chemical energy stored in glucose

Reproduction

• Asexual reproduction needs one parent, produces clones, faster/less energy, needs no gametes and is common in bacteria, fungi.
• Methods of asexual reproduction include binary fission, budding, fragmentation/regeneration, spore formation and vegetative reproduction .
• Sexual Reproduction needs two parents, involves gametes, results in genetic variation, takes more time and energy.
• Sexual reproduction is better for diversity in a changing environment to adapt to disease.
• Asexual reproduction is better for fast reproduction in stable environments.

Symbiosis

• Mutualism benefits both organisms like lichens, bees pollinating flowers.
• Commensalism benefits one organism without affecting the other.
• Parasitism benefits one organism while harming the other.
• Growth focuses on increasing size and cell number.
• Differentiation involves the specialization of cells.
• Terrestrial Adaptations for Plants-Cuticle, vascular tissue, roots, stomata, seeds and pollen, and lignin.
• Fungi- Hyphal growth and mycelium, spore production and Symbiotic Relationships.
• Animals- Respiratory adaptations, Water conservation, Limbs and support structures, Reproductive adaptations and Sensory Adaptations .
• Climate change is driven by human activities that increase greenhouse gas emissions.
• Effects range from rising sea levels and more frequent extreme weather events to disruptions in agriculture and biodiversity loss.
• To mitigate climate change comprehensive actions are needed by reducing emissions, transitioning to renewable energy, protecting ecosystems.