BM110 Test questions

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  • Created by: amykane
  • Created on: 26-03-18 17:46
What does a lack of Vitamin C result in?
A condition called scurvy
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What are symptoms of scurvy?
bleeding, swollen gums, and wounds that fail to heal
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What were sailors given in order to prevent scurvy?
Barrels of fruit juices and a dose everyday of 'grog' (rum)
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What makes us and guinea pigs different from other animals?
We can't produce our own vitamin C
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Why can't we produce vitamin C?
We have a mutation in the gulonolactone oxidase gene (GULO) which makes a key vitamin C synthesising enzyme
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Who is most recent history of Vitamin C in human health driven by?
Linus Pauling - the double nobel prize winning scientist and pacifist
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Why did he believe vitamin C was a miracle health drug?
He believed the bodies vital energy-generating processes produced reactive oxygen species/free radicals that could damage cell and its DNA - leading to cancer. He proposed that vitamin C could neutralise this because of it's anti-oxidant properties.
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What should you find on the side of your cereal packet?
The %RDA values (recommended dietary allowance?
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What is the current RDA for vitamin C?
For adult non-smoking men and women - 60mg/day
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What is the RDA to prevent scurvy?
46mg/day
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What is meant by vitamin c being 'labile' in the food industry?
it is susceptible to degradation
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What is vitamin C chemical name?
ascorbic acid
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How are we able to measure the amount of a chemical?
absorbance of light (spectroscopy) molecular weight (mass spectrometry) chemical bond properties (nuclear magnetic resonance) migration properties (chromatography) its chemical activity.
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Which of these is seen as an indirect measurement of concentration?
The last of them (activity) as it is assumed that twice the concentration would produce twice the activity. this method was used in the lab that day.
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What was measured during this lab?
the anti-oxidant activity of Vitamin C
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What is oxidation?
Gain of oxygen/ loss of hydrogen (electrons)
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What is reduction?
gain of hydrogen or electrons
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What is an anti-oxidant (ascorbic acid)?
a reducing agent - would be oxidised in the process of neutralizing the ROS
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What is an assay?
Experimental procedures designed to measure a substance’s concentration or activity
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What is the role of iodine and starch in this experiment?
Iodine (oxidising agent) and starch (for detection)
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What does the ascorbic acid do to iodine during the experiment?
Ascorbic acid is reducing iodine by producing hydrogen ions that essentially donate electrons to iodine (‘reduction is gain of electrons’).
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What does the iodine do to ascorbic acid during the experiment?
iodine oxidises ascorbic acid by removing two of its hydrogen atoms.
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What type of reaction is this?
a redox reaction
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What would happen if we reduced the concentration of ascorbic acid by half?
Not all of the iodine would be converted to iodide.
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What happens if ascorbic acid is present?
the iodine is quickly reduced to iodide ions, and no blue-black iodine-starch product is observed
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What happens when all available ascorbic acid is oxidised?
the next drop of added iodine solution reacts with starch and you will see the blue-black colour.
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When is the 'endpoint' of the titration?
when you have added just enough iodine such that the permanent blue-black colour is maintained for 20 seconds in the flask.
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What is starch?
a polymeric chain of sugars
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Why do iodine and starch combine to make a blue-black colour?
Starch forms a helix in solution. Within the central tube of this helix, Iodine and iodide combine to form the triiodide ion. This chain of amylose and triiodide has a blue coloration
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What are natural products?
mall chemical entities produced by plants, bacteria, fungi etc. they are generally produced from the organisms secondary metabolism.
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What is secondary metabolism?
the biochemical pathways not principally designed to provide energy or structural materials for the organism, but rather to fulfil useful functions such as antimicrobial protection or attraction of pollinating species.
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What type of bacteria does penicillin work against?
gram positive
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What did the Chinese Pharmacologist Tu Youyou receive a nobel prize for?
He discovered artimisin, extracted from sweet wormwood plant
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What is artimisinin?
an anti-malarial drug
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What are essential oils?
Common secondary metabolites in plants that can be used in medicine and perfumery.
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What method was used to extract the oils?
distillation
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what is distillation?
this is when the heated plant material gives off volatile chemicals in the gaseous phase which are then turned back into liquid and collected using lower temperature condensation
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Co-distillation with water is used to solve what two problems?
(1) they do not dissolve in/mix with water which makes their extraction difficult. (2)Even though the essential oils we want are relatively volatile, the temperature required to turn them into a gas can lead to their chemical degradation.
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How do water and oils work together?
They work together as a two-phase "heterogeneous azetrope" - means that their individual vapour pressures interact to the extent that they evaporate and co-distil at a much lower temperature
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Why couldn't artimisinin be extracted this way?
would degrade EVEN if this lower-temperature extraction approach is used.
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At the end of the distillation what two layers will be formed?
(1)the lower ‘hydrosol’ which is largely water with some tiny droplets of oil within (2) the upper ‘essential oil’ layer that we will go on to test.
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During the mictrotitre plate Resazurin was used, what is this?
a metabolic dye which is blue
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What does it mean when the dye is irreversibly turned to a pink product (resorufin))?
when there is metabolically active organisms present
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What does is mean if the dye remains blue?
that there is metabolic inactivity (i.e. the test agent has cytotoxic activity)
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What is kanamycin?
antibiotic used to treat severe bacterial infections and tuberculosis
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What is the 3-dimensional structure of a protein determined by?
the sequence of amino acids
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What are the important motifs that polypeptide chains can adopt?
alpha helices, beta sheets and globular regions
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Give examples of some functions proteins carry out.
(1) structural (cytoskeletal) (2) DNA binding (transcription factor) (3) protein interacting (4) channel forming (5) enzymatic (6) transmembrane receptor (7) through action as a ligand/signalling molecule.
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Regarding to the last lab, some species of proteins have developed an usual function - what is this function?
they are able to absorb light at a specific wavelength and then emit it at a different wavelength.
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What is excitation?
absorbing the energy of light
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what is emission?
releasing a smaller amount of light energy
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With GFP, what parts of the spectrum does it absorb and emit light?
absorbs from the blue part of the spectrum (wavelength around 400nm) and releases at the green part of the spectrum (wavelength around 500nm)
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Of the 238 amino acids that make up GFP, how many are absolutely required for the fluorescent properties and which amino acids are they?
3 - a SERINE-TYROSINE-GLYCINE trio
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How are these amino acids able to have flourescent properties?
These three amino acids undergo chemical modification to form the ‘lighthandling’ core of the protein
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What is the core of the protein called?
Chromophore
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Who won the nobel prize in 2008 for GFP discovery?
Roger Tsien, Martin Chalfie, Osamu Shimomura
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What is the name of the jellyfish found in Puget Sound, pacific ocean?
Aequorea Victoria
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Which two proteins were extracted from Aequorea Victoria?
Aequorin (bioluminescence) and Green Fluorescent protein
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What did Chalfie do with the GFP in 1990
He expressed the GFP in bacteria
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Which protein was isolated from the coral species Discosoma?
RFP - red fluorescent protein
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What happens if you link a mitochondrial protein to GFP?
GFP will be 'dragged' to mitochondria to light it up
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what is CRE-LoxP?
a tool used to alter DNA
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what does the CRE enzyme do?
rearranges DNA when it recognises two LoxP signals in a stretch of DNA.
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What happens if the LoxP signals point in the same direction?
the intervening DNA will be deleted
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what happens if the LoxP signals point in opposite directions?
intervening DNA will be flipped/inverted
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Other cards in this set

Card 2

Front

What are symptoms of scurvy?

Back

bleeding, swollen gums, and wounds that fail to heal

Card 3

Front

What were sailors given in order to prevent scurvy?

Back

Preview of the front of card 3

Card 4

Front

What makes us and guinea pigs different from other animals?

Back

Preview of the front of card 4

Card 5

Front

Why can't we produce vitamin C?

Back

Preview of the front of card 5
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