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BIOL 1601 (1)

Test 1 Study Notes.docx

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York University
BIOL 1601
Rebecca Jubis

Biology 1000 Test #1 Study Notes CHAPTER 1 Light: portion of electromagnetic spectrum that we can see (380 – 750nm)  Made up of photons = packets of energy (shorter wavelengths, photons have higher energy)  Can be reflected, transmitted, absorbed  Pigments = molecules that absorb photons of light (absorb certain wavelengths  only if it is the exact amount of energy to raise electron from ground to excited state) o Conjugated System = C atoms w/alternating single/double covalent bonds  electrons not closely related with a particular C  more available to interact w/light o Colour of pigment based on wavelengths NOT absorbed (red + blue better at driving photosynthesis) o PE created  synthesize ATP, proteins, lipids o Some prokaryotes contain light-dependent proton pump , “bacteriorhodopsin”  Photoreceptors = light-sensing system (usually rhodopsin  consists of protein (opsin) that binds to pigment mlc) o Absorption of photon  retinal pigment mlc changes shape (cis or trans) changes opsin  changes in intracellular ion concentration and electrical signals  signals sent to brain  Eyes o Animals can sense light, compound eye in insects 1. “Eye Spot”  photoreceptors that can sense light eg. Euglena 2. “Cup” or “Ocellus”  photoreceptors at back = direction of light, shadows/images eg. Planaria 3. “Pin Hole”  shapes, light more focused (lens w/aq. solution, cornea) eg. Nautilus 4. “Primitive Lens”  danger of damage since open to environment 5. “Camera Eye”  our eyes, not perfect (blind spot – due to optic nerve) **ALL evolutionary stages still exist  Light Penetration o Only 73% penetrates top 10cm and decreases o No light at about 200m (phoic zone)  Light, Colour and Behavior o Circadian rhythms (circa = around, diem = day) o Set by hormone (melatonin) o Migration, reproduction, germination, sleep cycles, leaves uncurled during day to maximize SA for photosynthesis o Phototaxis = locomotion towards light (+ towards, - away) eg. Fireflies mating o Camouflage  relationships between plants and their pollinators (flower colour)  Coevolution = simultaneous evolution of adaptations in 2 or more populations that interact so closely that each is a strong selective force on the other eg. Bees that coevolved with white crab spider can see the spider (predator) more clearly o Bioluminescence  ATP excites electron in substrate mlc to higher level, when electron returns energy is released as photon of light  Attract mate/prey, camouflage, communication  Detriments of Light o Can damage biological molecules, incl. DNA  leads to mutations, “Dimer” where 2 nucleotide bases beside each other join  change in shape which prevents replication o Melanin to protect from UV damage (absorbs and oxidizes), carotenoids (pigments that absorb and dissipate excess light) o Vitamin D needed so calcium can be absorbed by the body  bone strength (some vertebrates don’t see the sun and evolved different way of absorbing calcium without producing vitamin D) o Ecological light pollution  migration, collisions CHAPTER 2/13/21 Cells:  CELL = nucleus and cytoplasm  CYTOPLASM = cytosol and extra-nuclear organelles  CYTOSOL = cell contents excluding organelles  ORGANELLE = membrane bound compartment  LUMEN = interior of organelle  Cell Theory o All organisms composed of one or more cells o Cell smallest unit of life o Cells derived from other cells (cell division) o Cells carry heritable information o Metabolic processes (energy production, etc) occur  Importance of Cell Size o Small cells have high SA to small V  facilitates the transport of material (ions, nutrients, waste) across the cell membrane (bigger cells less efficient)  Adaptations of larger cells  thin with many projections o Eukaryotic cells much bigger than prokaryotic  Compartmentalize, large area of internal membranes, specialized structures with specialized functions  Early Life o Panspermia = hypothesis that very simple forms of life are present in outer space and may have seeded early Earth  Since life arose very quickly, life is very resilient and could survive in space for years o Prokaryotes = simplest and earliest forms of life, bacteria and Archaea, lack nucleus, originally relied on anaerobic metabolism (no O2 in atmosphere  cyanobacteria oxidized water = formation of O2)  Chemoheterotrophs = obtain energy by oxidizing inorganic substances and use CO2 as their carbon source  Photohetertrophs = use light as energy and obtain carbon from organic molecules  Nitrogen Fixation = conversion of atmospheric nitrogen to ammonia (some do this)  Nitrification = conversion of ammonium to nitrate  Prokaryotic vs. Eukaryotic Cells o Both have: plasma membrane, ETC, transcription-translation machinery, DNA o Prokaryotes appear simpler in structure, have greatest metabolic diversity of all organisms (organelle = membrane-enclosed with a specialized function) o Prokaryotes reproduce by binary fission = asexual reproduction, produces exact copies of parent 1. DNA replication 2. Segregation 3. Cytokinesis o Oxidation-Reduction Reactions  first energy releasing reactions of primitive cells  Oxidize food molecules and use some of this energy to reduce molecules (eg. protein synthesis)  Not very efficient, multi-step processes eventually developed  ATP became the coupling agent that links energy-releasing reactions to those requiring energy  Bacteria o Gram Positive and Gram Negative Bacteria  positive (single, thick peptidoglycan layer [cell wall]), negative (thin, peptidoglycan sheath surrounded by outer membrane) **protects bacteria from cell wall weakening leading to cell rupture and death o Capsule  some bacteria, layer of polysaccharides surrounding cell wall, protects bacteria from extreme temps, desiccation, antibiotics, viruses, antibodies o Flagellum  used for locomotion, Pili  help bacteria adhere (to each other, surfaces, etc) o Pathogenic bacteria can cause disease via exo/endotoxins o Develop antibiotic resistance through mutation/acquiring resistance genes o DNA Organization – Bacteria  Singular, circular DNA (1 chromosome)  Contained in nucleoid  Some have plasmids  Archaea o 3 Types:  Euryarchaeota = methanogens (methane generating), extreme halophiles (salt), some extreme thermophiles (hot)  Crenarchaeota = most of the extreme thermophiles, pyschrophiles (cold), mesophiles (plankton)  Korarchaeota = known only from DNA sample o Some have peptidoglycan-like cell wall but no Gram staining o Flagella (same function but different components) o DNA Organization – Archaea  Singular, circular DNA (1 chromosome) in nucleoid  Plasmids may be present  Chromosomal DNA packaged with histone-like proteins  Eukaryotic Cells o Endomembrane System  Internal membranes that divide cell into compartments, “common” membrane ancestor, either directly connected to one another or can fuse portions of a membrane from another “related” organelle into their own (budding of vesicle, transport of vesicle in cy
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