Chapter 7, 8, 9 Applications & Experimentation Flashcards
1
Q
What are ddNA nucleotides used for?
A
- used for base sequencing
- lacks -OH on C-3
- in sequencing machine DNA is mixed w/ DNAP, nucleotides, ddNA
- replication is repeated 4 x w/ A, T, C, G
- fragments of DNA separated by gel electrophoresis
- fluorescent markers attached to indicate base sequences
2
Q
What is the promoter’s function in transcription?
A
- close to start of gene (non-coding)
- RNAP binds to promoter
- repressor proteins can inhibit transcription by bindings to the promoter
- transcription factors bind to the promoter first in eukarytoes
3
Q
Uses of bioinformatics & genomes
A
- computers store / analyse data
- case sequences are main data
- sequencing initially was only possible w/ individual genes
- now WHOLE genomes sequenced
- locating genes OR searching for conserved sequences in dif. organisms
- evolutionary links
3
Q
Uses of bioinformatics & genomes
A
- computers store / analyse data
- case sequences are main data
- sequencing initially was only possible w/ individual genes
- now WHOLE genomes sequenced
- locating genes OR searching for conserved sequences in dif. organisms
- evolutionary links
4
Q
Describe the Hershey & Chase Experiment
A
- aim: determine if DNA OR proteins carry genetic material
- used E coli & bacteriophage virus
- grew bacteriophage in 2 radioactive cultures (either P or S)
- P –> DNA, S –> proteins
- the 2 samples injected their genetic material into E coli cells
- centrifugation used to separate solid + liquid medium
- E coli examined for radioactive material
- only radioactive P, no S detected –> DNA is genetic material
5
Q
Findings of X-Ray diffraction data
A
- clear images of diffraction patterns produced
- observed cross in centre of DNA –> helical DNA
- angle of cross shape = steepness of angle of helix
- distance b.w horizontal bars = turns of helix are 3.4 nm apart
6
Q
X-Ray Diffraction Mechanisms
A
- beam of X-ray is directed at material
- some of it is scattered by particles in material = diffraction
- X-ray detector is placed close to sample to collect scattered rays
- sample can be rotated in 3D
- diffraction pattern recorded using X-ray film
6
Q
Epigenetics
A
- epigenome = pattern of chemical markers in DNA of cell
- env. factors influence gene expression
- fluorescent markers can detect methylation patterns
- cytosine in DNA is converted to methylcytosine by addition of (-CH3)
- catalysed by enzyme + ONLY happens when there is a guanine on 3’ side of cytosine in base sequence
- patterns of methylation established during embryo dev.
7
Q
Tandem Repeats
A
- regions where adjacent sections of DNA have same base sequence
- # of repeats varies b/w dif individuals in some tandem repeats
- known as variable number tandem repeats
- DNA sample cut by restrictions enzymes into fragments
- amplified at specific gene sites w/ PCR
- fragments separated by gel electrophoresis
- fluorescent label attached to dif tandem repeats
- data from several loci at one time uniquely identify individuals
- simlarities b/w fragment patterns to determine paternity
- DNA profiling based on variable numbers of tandem repeats
8
Q
What did Maurice Wilkins contribute to our understanding of DNA?
A
he developed a method for producing DNA arrays (orderly arrangement) since it can’t be crystallised
9
Q
What did Rosalind Franklin produce?
A
She developed a high-resolution detector that produced clear DNA diffracting patterns
10
Q
Radioactive Labelling
A
- radioisotopes are used
- same chemical structure as other elements but they are radioactive
- e.g. C-14 is used to label organic compounds or CO2 & HCO3- for photosynthesis experiments
11
Q
How can short day plants be induced to flower?
A
- greenhouses w/ blinds to stimulate chrysanthemums
- when the night is not long enough, they can induce flowering by closing blinds
- extending nights artificially
12
Q
Outline factors affecting germination
A
- water: rehydrates seeds
- oxygen: cell respiration
- warmth: enzyme activity
- 2 treatments (control w/ all factors, experimental missing 1 factor)
13
Q
Models for Water Flow in Xylem - ADHESIVE PROPERTIES
A
glass capillary tube (water rises up glass) - mercury is NOT adhesive do doesn’t rise
14
Q
How is respiration rate measured using potometers?
A
- rate of water uptake is measured using potometer
- plant transpires, water drawn out of capillary tube
- movement of air bubble
- repeated measures of distance moved in 1 minute = transpiration rate
15
Q
Databases & antimalarial drugs (bioinformatics)
A
- malarial parasite (Plasmodium) resistant to most anti-malarial drugs –> urgent need for new drugs
- huge bioninformatics fatabases onc omputers help to identify chemicals (5655)
- inhibitors found for 6 of 9 enzymes & are not being researched
16
Q
Outline the end product inhibition of threonine dehydratase
A
- isoleucine (end-product) inhibits threonine dehydratase
- binds to allosteric site
- if there is excess of end product, whole pathway switched off
- intermediates do not build up
- e.g. of non-competitive inhibition
17
Q
Example of competitive inhibition
A
- O2 = competitive inhibitor
- for Rubisco
- prevents carbon fixation
- blocks active site for CO2
18
Q
Non-competitive Inhibition example
A
- cyanide ions = non-competitive inhibitor
- for cytochrome c oxidase
- prevents ETC from working
19
Q
Calvin’s Experiment
A
- aimed to elucidate carboxylation of RuBP
- chlorella sol. in thin glass vessel –> brightly lit
- supplied w/ CO2 & HCO3-
- replaced C-12 w/ C-14 (radioactive)
- took samples at short time intervals
- killed & fixed them w/ hot methanol
- extracted C-compounds, separated by double-way chromatography
- autoradiography –> to determine which compounds had C-14
- indicated order of formation = stages of cycle
20
Q
Outline the chemiosmotic theory.
A
- most ATP synthesis comes from electrochemical gradient
- across inner membranes of mitochondria
- using energy of NADH & FADH2
- paradigm shift
21
Q
What is electron tomography used for?
A
- to obtain 3D images of active mitochondria
- revealed that cristae are connected w/ intermembrane space b/w inner & outer membranes via narrow opening
- shape & volume of cristae change when mitochondria are active
22
Q
How is phloem transport rate measured using aphid stylets?
A
- aphids have long mouthparts = stylets
- push into plant tissue, pierce sieve tube
- high pressure in sieve tube pushes sap out
- C14 supplied to leaf
- time taken for radioactive sucrose to emerge from stylet measured at dif distances from leaf
23
Q
List the benefits of micropropagation.
A
- new varieties of plants can be bulked faster
- virus-free strains of existing varieties (shoot apex does not have viruses)
- large number of rare plants (e.g. orchids), reduced cost, no need to remove them from natural habitat
24
Q
Outline the steps of micropropagation.
A
- small piece of tissue removed from shoot apex of plant being cloned
- plant tissues & apparatus sterilised
- tissue placed on sterile nutrient agar
- w/ high auxin concentration –> cell growth + division
- lumps of tissue (Callus) grow, can be cut to grow more
- callus transferred to nutrient agar w/ less auxin, high cytokinin, & gibberellin
- roots + shoots grow, platelets separated, moved to soil
25
Q
Explain why mutualism in pollination is so important.
A
- more than 50% of the world’s 250,000 species of flowering plant depend on pollinators for reproduction
- plant obtains nectar (energy) + pollen (protein)
- importance of protecting ecosystems
26
Q
Plant hormone detection
A
- very tiny amounts of plant hormones in tissue hard to detect
- 5 groups of hormones, chemically diverse, dif extraction methods are needed
- microarrays detect changes in gene expression due to hormones
- hormones bind to proteins (activated)
- bind to promoters –> transcription
27
Q
Models for xylem transport - WATER DRAWN THROUGH CAPILLARIES IN CELL WALL
A
- use blotting / filter / chromatography paper
- water rises through pores in the paper made of cellulose walls
28
Q
Models for xylem transport - EVAPORATION = TENSION
A
- porous pot is similar to cell wall, so water adheres, has many narrow pore
- water evaporates from the surface
- water rises up the tube, drawn into pot
