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Lecture 9

BIOL 1000 Lecture Notes - Lecture 9: Transfer Rna, Proteoglycan, Nuclear Membrane

by OneClass90790 , Fall 2010
7 Pages
64 Views
Fall 2010

Department
Biology
Course Code
BIOL 1000
Professor
Michael Gadsden
Lecture
9

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Lecture 9
DNA Repair
May happen because of UV light or a Cytisine becoming Uracil by spontaneous de-amination)
o CNH2 COOH
o Another way is that DNA Polymerase accidentally inserts U into DNA (as DUTP [instead
of DTTP])
Note: Many chemotherapeutic drugs affect the cell so that it increases the
amount of DUTP
WHY? If DUTP [] is increased by drugs, increase level of U in DNA there is a high
degree of repair
The repair system is then overwhelmed and this leads to DNA
fragmentation and then death of the cell
This process targets fast dividing cells (Cancer, hair etc.) and that’s why
cancer patients are bald
Excision Repair
o Remove misinserted base
I.E. via Uracil-DNA-glycosylase
o Enzyme removes a small gap of nucleotides
This is like when RNA Primase is has to be removed
o Fill in gap by DNA Poly
Proofreading by DNA Polymerase
o Enzyme will notice that there is not good H bonding and it will reverse, splice and repair
the base
o Note: Retrovirus polymerases are highly mutagenic
Repair Mechanisms:
o DNA Polmerases
Mismatch Repair
o Repair enzymes recognise mispaired base
o Enzymes remove multiple bases
o DNA Poly repairs bases
o Ligase combines two sets together
Eukarya
DNA contained in nucleus... etc.
Organelles:
o Generally something that is membrane encased and has a particular function
Ribosome is NOT and organelle because it is not membrane bound
o Compartments in a cell with a specific function (usually metabolic)
o With a degree of permanence
Endomembrane Nucleus
o Connection found in the ER membrane (pores) and many folds
Plant Vs. Animal Cells
o Generally same thing
o Vacuole and Cell wall in Plant
Rough and Smooth ER
o Rough covered in Ribosomes so that the RNA can be quickly translated into prioteins
o Smooth synthesize fatty acids and alcohol
Liver cells have many of these because detoxification occurs in the liver
Golgi Apparatus
o Processes and packages proteins, lipids and other molecules
Vacuole
o Stores nutrients
o Retains and degrades waste
o Provides support
Lysosomes
o Where particles are degraded in the cell
o Degrade and recycle materials
o Very acidic and thus if it bursts, the enzymes won’t work
Note: acid helps degrade
Disorders
Tay-Sachs Disease
o Untreatable genetic disorder
Cannot degrade gangliosides Lipids + sugars
See Sheet
Ganglioside is found in high [] on nervous tissue membranes
Endosymbiosis
All DNA in nucleoid
Essentially the ideology is that the nuclear envelope got two very similar membranes
Mitochondria came in (aerobic bacteria) and they became part of the cell
o For some reason, the mitochondria wasn’t eaten and it gained an evolutionary
advantage
o Host cell offers protection, and the mitochondria provides ability to aerobically respire
Photosynthetic Bacteria followed the same process and became chloroplasts
Viewing some cells allow us to believe this process

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Description
Lecture 9 DNA Repair  May happen because of UV light or a Cytisine becoming Uracil by spontaneous de-amination) o CNH 2 COOH o Another way is that DNA Polymerase accidentally inserts U into DNA (as DUTP [instead of DTTP])  Note: Many chemotherapeutic drugs affect the cell so that it increases the amount of DUTP  WHY? If DUTP [] is increased by drugs, increase level of U in DNA there is a high degree of repair  The repair system is then overwhelmed and this leads to DNA fragmentation and then death of the cell  This process targets fast dividing cells (Cancer, hair etc.) and that’s why cancer patients are bald  Excision Repair o Remove misinserted base  I.E. via Uracil-DNA-glycosylase o Enzyme removes a small gap of nucleotides  This is like when RNA Primase is has to be removed o Fill in gap by DNA Poly  Proofreading by DNA Polymerase o Enzyme will notice that there is not good H bonding and it will reverse, splice and repair the base o Note: Retrovirus polymerases are highly mutagenic  Repair Mechanisms: o DNA Polmerases  Mismatch Repair o Repair enzymes recognise mispaired base o Enzymes remove multiple bases o DNA Poly repairs bases o Ligase combines two sets together Eukarya  DNA contained in nucleus... etc.  Organelles: o Generally something that is membrane encased and has a particular function  Ribosome is NOT and organelle because it is not membrane bound o Compartments in a cell with a specific function (usually metabolic) o With a degree of permanence  Endomembrane Nucleus o Connection found in the ER membrane (pores) and many folds  Plant Vs. Animal Cells o Generally same thing o Vacuole and Cell wall in Plant  Rough and Smooth ER o Rough – covered in Ribosomes so that the RNA can be quickly translated into prioteins o Smooth – synthesize fatty acids and alcohol  Liver cells have many of these because detoxification occurs in the liver  Golgi Apparatus o Processes and packages proteins, lipids and other molecules  Vacuole o Stores nutrients o Retains and degrades waste o Provides support  Lysosomes o Where particles are degraded in the cell o Degrade and recycle materials o Very acidic and thus if it bursts, the enzymes won’t work  Note: acid helps degrade Disorders  Tay-Sachs Disease o Untreatable genetic disorder  Cannot degrade gangliosides  Lipids + sugars  See Sheet  Ganglioside is found in high [] on nervous tissue membranes Endosymbiosis  All DNA in nucleoid  Essentially the ideology is that the nuclear envelope got two very similar membranes  Mitochondria came in (aerobic bacteria) and they became part of the cell o For some reason, the mitochondria wasn’t eaten and it gained an evolutionary advantage o Host cell offers protection, and the mitochondria provides ability to aerobically respire  Photosynthetic Bacteria followed the same process and became chloroplasts  Viewing some cells allow us to believe this process Plant Cell Wall  Provides strength and increased water resistance  Provides protection because it cannot be digested by humans  Between cells, Plasmodesmata allow water and other molecules to pass between neighboring cells o Plasmodismota allows cell to cell communication o A direct connection between two cells Extra Cellular Matrix  Surface layer that surrounds cells o i.e. Glycocalyx o Differences are what they are made out of o Large polysaccharides, proteins, proteoglycans (large protein – sugar molecules) o Allow cells to move past each other or have flexibility (cartilage)  Also helps protect cell from external acids etc. Cytoskeleton  Dynamic structure (3D) that fills the cytoplasm  Anchors organelles and proteins and membrane prioteins in place  Involved in the transmission of signals from the surface or Extracellular space and matrix to inside the cell  Signal Transduction o External Signal  i.e. hormone or a cytokine o Binds to plasma membrane receptor that then induces a molecular cytoplasmic signal to be made to affect the inside of the cell  i.e. turn proteins or genes on/off o Turns an external signal to an internal signal  Involved in cell movement and mobility  Three types: o Microtubule o Intermidiate Filament o Microfilament  Microtubules o Inside cell, radiate from nucleus to cell periphery  Actin o Periphery of animal cell  Intermediate Filament o Made from many different protein subunits o Often cell specific o One can ID the origin of a cancer cell by the Intermediate Filament it contains  M
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