Chapter 3

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  • Created by: Kittykiah
  • Created on: 19-03-19 22:37
how do you calculate magnification
(I AM triangle)
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whats the definition of resolution?
the distant apart that two objects can be in order to be seen as separate (visual detail)
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whats the definition of magnification?
how much larger the image is compared to the original
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whats the first step to cell fractionation?
homogenisation
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what does homogenisation mean
grind the tissue to break open the cells
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what happens next?
filtering
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what does filtering do?
gets rid of unbroken cells and debris so they dont contaminate the pellet
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what happens next?
centrifuged (spun)
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why does it go in a centrifuge?
to separate the organelles to form pellets at the bottom
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what pellet is formed first at low speeds?
nucleus
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what pellets are formed next?
mitochondria
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what are the lightest and therefore formed at high speeds?
ribosomes and lysosomes
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why is the solution before cell fractionation isotonic?
to make it the same concentration in and out the cell so nothing comes or leaves. (prevents organelle bursting by osmosis.)
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why is the solution cold?
reduces enzyme activity so they do not destroy the organelles
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why is the solution buffered?
so the enzymes/proteins do not denature as the ph is controlled
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why can the electron microscope able to resolve objects well?(high resolving)
the beam has a very short wavelength.
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how can the beams be focused?
they are negatively charged so electromagnets can be used.
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what are the two types of electron microscope?
Transmission and scanning.
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how are the specimens prepared for a transmission electron microscope?
cut into thin slices
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how does it make a black and white picture?
where the electrons are absorbed it appears darker
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does the transmission electron microscope create a 2D or 3D image?
2D
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why can the full resolving power be achieved in practice?
hard to prepare the specimen properly (cut thin enough), a higher energy electron beam is required which may destroy the specimen
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why can living specimens not be observed?
it in a vacuum therefore they would get no air so only dead can be observed
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whats the difficulty with the staining process?
its complex and the image will still be in black and white
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what does a artefact mean and why are they an issue?
they result from how the specimen has been prepared and appear on the finished photomicrograph that are not apart of the natural specimen so we can be unsure on what exists in the real form
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whats the differences in preparing the specimen for a scanning microscope?
they do not need to be thin.
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whats the difference in procedure of a scanning microscope?
the electrons do not penetrate they only scan the surface and the image is 3D
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does a scanning microscope have a higher or lower resolving power?
lower
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can a light microscope view live specimens?
yes
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what radiation is used to view specimens in a light microscope?
light instead of electron
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what is a eukaryotic cell?
animal and plant
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whats in a animal eukaryotic cell?
nucleus, mitochondria, endoplasmic reticulum (rough and smooth), golgi apparatus, lysosomes, ribosomes, cell membrane
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whats in a plant eukaryotic cell?
nucleus, mitochondria, endoplasmic reticulum, golgi apparatus, lysosomes, ribosomes, cell membrane, cell wall, vacuole, chloroplasts
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what does a nucleus do?
retain the genetic material in the form of DNA and chromosomes, manufacture ribosomal RNA and ribosomes, acts as the control centre of the cell through the production of mRNA and tRNA hence protein synthesis
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what surrounds the nucleus
the nuclear envelope
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describe the nuclear envelope
it has a double membrane. the outer membrane is continuous with the endoplasmic reticulum, controls the entry and exit of materials in and out
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whats on the nuclear envelope?
nuclear pores
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what do the nuclear pores do?
allow the passage of large molecules, such as messenger RNA
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whats the name of the fluid jelly-like material thats inside the nucleus?
nucleoplasm
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whats inside the nucleus that hold the genes?
chromosomes
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whats the spherical region in the middle of the nucleus?
the nucleolus
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what happens in the nucleolus?
manufactures ribosmal RNA and assembles the ribosomes.
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whats on the outside of the mitocondria?
a double membrane
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what does the inner of the two membranes form?
folded to form cristae
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what do the cristae do?
provides a large surface area for the attachment of enzymes and other proteins involved in respiration.
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what makes up the remainder of the mitochondria?
the matrix
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what does the matrix contain?
protein, lipids, ribosomes, DNA
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what do these allow the mitchondria to do?
to control the production of some of their own proteins. (many enzymes that are involved in respiration found in the matrix)
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Card 2

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Card 3

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Card 4

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whats the first step to cell fractionation?

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Card 5

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what does homogenisation mean

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