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[BIOL 1000] - Final Exam Guide - Comprehensive Notes for the exam (26 pages long!)


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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BIO 1000: Molecular Biology & Genetics
September 20th 2016
Tlisa Ghany
Chapter 1: Light & Life
Variable wavelength - distance between 2 peaks. Typically measured in nanometers (10 -9 m)
Visible light - The visible region of the electromagnetic spectrum that humans can detect with
their eyes. (400 – 700nm) Although you cannot see certain wavelengths, you can see their
effects. (EX: uvrays, xrays etc)
How Does light interact with matter?
Reflected off the object
Transmitted off the object
Absorbed by the object
Photons – excite electrons from ground to excited state.
How is light captured?
Pigments (ex: chlorophyll, retinal)
Pigments
All have conjugated systems of delocalized electrons
Carbons linked by alternating single/double bonds
Electrons capture photons/energy which can be used to do work
Light as a source of energy
Light and life are linked through photosynthesis and cellular respiration
All life depends on light either directly or indirectly.
Many organisms use light as information
Photoreceptor - light sensor (retinal & protein) pigment goes from dark (cis) to light (trans).
This causes a change in memory protein which causes further change within the cell. (EX:
Chlamydomonas – contains eyespot and rhodopsin. Which swims towards light to maximize
photosynthesis. Vision requires brain to understand signals sent from eye to brain)
Eyes
Organ used to sense light which is important for vision.
Vision requires the brain to interpret signals fent to the brain from the eye
Types of Eyes
Compound eyes (flies have these) -> Ommatidium (unit of compound eye)
Ocellus
Camera eye (squids)
Human eye
oIris is colour portion of eye, made of smooth muscles
oLens focuses light onto retina (limits light)
oRetina contains photoreceptors
oVitreous humor
oOptic nerve – takes signals from eye to brain
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Cells from light & dark
Rod Cells
oFor night vision
orodopsin
Cone Cells
oFor colour vision
oPhotopsin & retinal & rosopsin
Only have pigments in photoreceptors at the back of the retina to produce colour vision
signal, retinal
Cone cells in the retina of the eye allow light of different wavelengths to be interpreted
as color in the brain.
Light waves -> The cone cell -> the brain -> colour
Dichoromatic – colour blindness [2 different opsins (S,M)]
Trichormatic – colour vision [3 different opsins (S,M,L)]
Role of Opsins
Opsin is protein composed of a string of amino acids
Colourblindness is recessive allele
Selection of DNA on chromosome that codes for opsin protein (opsin gene)
The section of DNA on a chromosome that codes for an opsin protein is called an opsin
gene
oOSShort wavelength blue light
oOMmedium wavelength green light
Dichromatic (x-chromosome)
oOLLong wavelength red light
The L gene arose through gene duplication and gene mutation of the M
gene on the X-chromosome.
The L opsin differs from the M opsin in three significant places in the
amino acid sequence:
Position 180: alanine to serine
Position 277: phenylalanine to tyrosine
Position 285: alanine to threonine
GENE -> PROTEIN -> FUNCTIONAL UNIT (PHOTORECEPTOR) -> CELL -> ORGANISM
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