Biology 1002B Study Guide - Final Guide: Alternative Splicing, Polysome, Horizontal Gene Transfer

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28 Jul 2020
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Bio 1002B Final Exam Review
Cycle 1
Defining Life and its Origins
Cell is the fundamental unit of life all life is composed of cells
Seven characteristics of life
o Display order
o Use energy
o Reproduce
o Respond to stimuli
o Homeostasis
o Grow and develop
o Evolve
Cells arise from the growth and division of other cells but the first cells could not have
o Life must have come from a mixture of primordial molecules
EARTH’S TIMELINE
o 0 present
o 1.2 - multicellular eukaryotes
o 2.1 unicellular eukaryotes
o 2.5 rapid increase in oxygen in atmosphere
o 3.3-3.7 prokaryotic cells, oxygenic photosynthesis
o 4 first evidence of life
o 4.5 organic molecules
o 4.6 formation of earth
prokaryotes gave rise to eukaryotes
o endocytosis membranous pockets fell in
o endosymbiosis mito and chlo went inside eukaryotes
How were building block molecules formed in the absence of life?
o Reducing atmosphere
Water vapour, ammonia, hydrogen, carbon dioxide, methane (no oxygen)
Can form complex molecules as oxygen is not present
UV light could have provided the energy
Miller-Urey proved organic molecules could be formed by this atmosphere
o Deep sea vents
Organic molecules have originated from deep sea vents in the ocean floor
How polymers were made?
o Reducing atmosphere only makes monomers, polymers are what makes life
o Requires enzymes
Macromolecules to life
o Shifts in temp and energy can create organic from inorganic
o Life evolved in steps
RNA, protein, DNA
Self-replication of RNA
Association between amino acids and nucleotides
Formation of membrane-enclosed compartments
Development of metabolic pathways
Lipid spheres may have led to the development of cells
o Membrane defines compartment
RNA can carry info and catalyze reactions
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o Central dogma DNA to RNA to protein
o RNA can hold information like DNA but degrades faster
Unstable uracil not found in DNA
DNA is double stranded error in one strand does not mean mutation
o Ribozymes RNA molecules that act as catalysts
Single stranded, can fold into 3D shapes like proteins
o Could have evolved RNA to protein to DNA
The first cells relied on anaerobic metabolism
o Heterotroph obtain carbon from organic molecules
o Autotroph obtain carbon from the environment in an inorganic form (carbon dioxide)
Anoxygenic photosynthesis hydrogen sulfide was used instead of water
Oxygenic photosynthesis led to the rise in oxygen in the atmosphere
o Cyanobacteria use water as an electron donor
o Oxygenic photosynthesis relies on the oxidation of water for electrons
All life shares common characteristics
o Cells made up of lipid molecules forming a bilayer
o Genetic system based on DNA
o System of information transfer central dogma
o System of protein assembly from a pool of amino acids by translation using mRNA and tRNA
and ribosomes
o Reliance on proteins as the major catalytic molecule
o Use of ATP as chemical energy
o Breakdown of glucose by the metabolic pathway of glycolysis to make ATP
The Cell
Cell theory
o All organisms are composed of one or more cells
o The cell is the basic structural and functional unit of all living organisms
o Cells arise only from the division of pre-existing cells
Unicellular functionally independent organism
o Yeasts, bacteria, archaea
Multicellular activities of life divided among cells
o Plants, animals
Why are cells small?
o Surface area must be enough for the volume it contains
o Some may fold their membranes to increase SA
Parts of the cell main
o Plasma membrane lipid bilayer with proteins
Transport proteins channels that allow
selective substances to enter
o Cytoplasm
o Organelles
o Cytosol aqueous solution containing ions and
organic molecules
o Cytoskeleton protein based framework to maintain shape
o Nucleus only present in eukaryotes
Nucleoid DNA containing region with no membrane (pro)
Prokaryotic cells
o Spherical, rodlike, spiral
o Genetic material in the nucleoid
Chromosomes singular, circular
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o Plasma membrane surrounded by cell wall
o Most have flagella to allow them to move protein fibres that extend from the surface
Eukaryotic cells
o Have a nucleus enclosed by a membrane holds genetic information
Nuclear envelope two membranes
Nuclear pores membrane proteins
Chromosome many single, linear chromosomes
Nucleoli contained in nucleus, forms around genes for rRNA
o Plasma membrane (plants also have a cell wall
o Endomembrane system interrelated membranous sacs that divide the cell into functional and
structural components
Nuclear envelope, ER, Golgi, lysosomes, vesicles, plasma membrane
o Endoplasmic reticulum formed by single membrane
Rough has ribosomes on surface
Attach and fold into their final form
Chemical modifications
Proteins then delivered to other regions of the cell
o To golgi complex
Smooth no ribosomes
Creation of lipids
Breaks down toxins
o Golgi complex membranous sacs
Receive proteins from the ER
Chemically modified
Regulates movement of several proteins
Secretory vesicles
Exocytosis release of contents to exterior
Can fuse with the membrane, allow surface to grow
Endocytosis bringing of molecules into the cell
Pinching off of the plasma membrane
o Lysosomes membrane bound vesicles that contain enzymes for digestion
Only in animals, not plants
pH is more acidic if it is broken, proteins will not function
autophagy digest organelles not functioning properly
phagocytosis some types of cells engulf bacteria to break them down
o Mitochondria cellular respiration
Energy molecules broken down into water and carbon dioxide to release energy
Requires oxygen
Double membrane bound
Inner membrane ETC
Inner compartment matrix
o Contains DNA and ribosomes
o ATP generating reactions occur here
o Cytoskeleton connected system of protein fibres
Microtubules
Tubulin
Hollow cylinder of monomers
Polar
Radiate towards the centrosome
Create centrioles
Separation of chromosomes
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