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[BIOL 1000] - Final Exam Guide - Ultimate 232 pages long Study Guide!


Department
Biology
Course Code
BIOL 1000
Professor
Nicole Nivillac
Study Guide
Final

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York
BIOL 1000
FINAL EXAM
STUDY GUIDE

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Light and Life
Light: Electromagnetic Radiation (Electric waves are perpendicular to magnetic)
Variable wavelength (distance b/t 2 peaks) & energy
-Typically measured in nanometers (10 -9 m)
- Wavelength and energy inversely related
What is Light?
Energy determined by 2 peaks of wavelength (Longer waves= less energy; Short wavelength=more energy)
Visible region of electromagnetic spectrum that humans can detect w/their eyes
How does Light Interact w/ Matter?
1. Reflected off object
2. Transmitted through the object (doesn’t interact)
3. Absorbed by the lab (more biologically relevant causes further advancements)
Photons excited e- from ground state to excited state. When electron falls back to excited state it releases
free energy which results in other processes
High is Light Captured?
Colour you see is the colour (wavelength) that is not absorbed by pigment
Pigments
Chlorophyll is pigment in photosynthesis
Organic compound give characteristic of colour – reflect certain wavelengths of light
E- in bonds of pigments respond to light of particular frequencies
E- emit all/part of absorbed energy as a photons of particular frequency.
Pigment: Shape Matters
Carbons linked by alternating single/double bonds
Conjugated system of “delocalized” e-. Can be easily excited - used to do work
Electrons capture phonon/energy which is used to do work
Ex: Chlorophyll
Light as Source of Energy?
Halobacterium uses photons of light energy to derive ATP synthesis
Sunlight provides energy that plants use to create sugars. Which releases energy to living things that digest them
Photosynthesis: plants capture sun & store it in chemical bonds of sugar & other food molecules
Respiration: plants, animals & fungi release energy stored in chemical bonds of food molecules & use it as fuel
Using light as Source of Information
Photoreceptors: Specialized structure in organisms that responds to light.
In humans, photoreceptors are specialized cells found in retina at back of eye. Responsible for vison (contrast & colour)
2 Types of Photoreceptors in Humans: Cones & rods
Made up of 2 things: pigment called retinol & protein. Change in pigment causes change in membrane protein. Protein changes
conformation you would get further changes within the cell which would lead to a response
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The Eye
An organs used to sense light
Important for vison, which distinguishes it from eyespot
Visions require the brain to interpret signals send to the brain from eye
Different types of eyes: ocellus, camera eye, compound eye
The Human Eye
Iris: contains pupil. Smooth muscles in iris control how much light enters. Limits light so it no damage to eye
Retina: layer in back of eye containing cells that’re sensitive to light. Trigger nerve impulses that pass via optic nerve to brain, where a
visual image is formed. Photoreceptors found here: Rods & cone
Vitreous humour: jellylike tissue helps maintain shape of eye
Optic nerve: takes signals from photoreceptors & sends it to the brain to be interpreted
Rod: they’re more sensitive to light/ dark changes-sensitive pigments. In dim room, rods used, no color, More rod cells than cone cells
Cone: not sensitive to light. Cones sensitive to 1/3 colours: Green, red, blue. Work well in light. Someone who is colour blind, might not
have particular cone or make be weak.
Colour (Chromatic) Vision: Cone Cells
Cone cells in retina of eye allow light of different wavelengths to be interpret as colour in brain
Light Waves-> Cone Cell -> The brain -> Colour
Opsin Response to Light
Opsin are light sensitive protein pigments near the surface of cones. Opsin on different cones are sensitive to different wavelengths of
light. Colours are identified by the brain based on responses from different opsins
Trichromatic Vision is the result of 3 different opsins (Short,Medium,Long)
The responses to light of each opsin protein (S,M,L) in trichromatic are shown to right
oOpsin S- Short Wavelength blue light
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