1.6 Use of genetic information Flashcards
Is DNA found in all living things?
Yes
The mechanism of coverting the information from DNA into proteins differs between living things, true of false?
False - it is the smae
What does the fact that all living things turn information from DNA into proteins support
The idea that all living things have a common origin
In what ways does the the DNA of different species differ?
Number of molecules (chromosomes)
Length
Sequence of Bases
What is the reason for different species possesses differences in DNA
Changes that have occured over billions of years
If organisms have a common feature, what does this mean?
Similar protein, which ould mean shared DNA sequences.
More difference is features between organisms = …
Less closely related - seperated longer ago
How do humans manipulate DNA
Breaking up the cells, sperating the nuclei (viacentrifuging techniques)
removing the nuclear membrane with special chemicals
Removing the histones and proteins from the DNA and isolating the DNA
Explain how genes are isolated
A sample collected from a tissue of a lving thing or dead organism is treated with chemicals and enzymes to extract the DNA which is sperated and purified
The DNA is cut up into fragments using restriction enymes yielding thousands of fragments of all different sizes
Where do restriction enzymes cut DNA
At specific sites - they are like chemical scissors
What is the name of a sequence of bases recognised by a restriction enzyme to cut at called and how many bases does it consist of
Restrcition site - typically 4-6 nucleotides
What is an example of a restriction enzyme
EcoR1
Where are restriction enzymes gathered from
Bacteria
Why do bacteria produce restriction Enzymes
To act as a defence mechanism against viral DNA by cutting it
What are the two ways a restriction enzyme can cut DNA
Straight through the middle, leaving blunt ends
Diagonally across the DNA leaving some bases exposed, leaving sticky ends
How is a desired gene isolated from other unwanted DNA fragments
Using a probe
What is a probe
A short segment of single strand DNA or RNA containing a base sequence complementary to the desired gene
What treatment are probes given to make them identifiable
Radioactively or fluroescently labbeled with a dye
What does PCR stand for
Polymerase chain reaction
What is the purpose of PCR
To artifically multiply DNA samples
Where is PCR carried out
artifically in a labratory (DNA photocopier)
What does PCR achieve
It amplfies small samples of DNA (e.g. from a crime scene) to a point where there is enough DNA to analyse DNA fingerprints and sequence DNA base pairings
Explain the first step of PCR
required DNA is added to a test tube and heated to seperate the 2 complimentary strands (breaking hydrogen bonds)
Explain the second step of PCR
DNA polymerase, DNA primers (stop DNA strands from recombining) and free nucleotides are added
Explain the third step of PCR
DNA is cooled to allow the binding of free nucleotides to the exposed bases
Each time replication occurs, the amount of DNA….
Doubles - allowing enormous amounf ot DNA to be generated in a short period o time
In 1 hour and afyer about 20 PCR cycles it is possible to multiply the sample of DNA by …..
a million times
Since DNA polymerase is an enzyme and therefore a protein, what happens to regular human DNA polymerase if it were to be used in PCR and how do we combat this
It would denature due to the high temps. Hence PCR uses polymerase extracted from bacteria found in the hot springs at yellowstone which do not denature at the required temp
In what areas of science is PCR used extensively
Evolution esearch
Pre-natal diagnoisis
Amplifying DNA from crime scenes for forensics
What is another name for DNA profling
DNA fingerprinting
What is DNA fingerprinting
a process that identifies variations in DNA base sequences
In paticular regions of the chromosones, there are long segments (up to 25%) that ….
don’t code for anyhing
What is found within long segments found in chromosones that don;t code for anything
Highly repetitive base sequences called ‘junk repeats’
The frequency of junk repeats is the near exact same between every person, T or F
False, it is extremely varied
What is the name for the amount of time a highly repetitive seuqnce of bases is found
Variable number tandem repeates (VNTR
In a human chromosome, it is possible for one person to have the base sequnce CA repreated 170 times whilst only 58 times in another. T or F
True
Are junk repeat patterns unique to an individual?
Yes, like a fingerprint
What does identifiying the junk repeat pattern of a person’s DNA enable
DNA to be exactly matched to a paticular person
Explain the process of DNA profiling
- Samples of DNA can be broken up into fragments using restriction enzymes
Restriction enzymes cut the DNA at specific sites
Since every person’s DNA is different (except for identical twins), the length of resulting fragments will be different between people - DNA fragments are then seperated according to their size, using a process called electrophoreis
Explain the process of electrophoresis
- DNA fragments are placed at one end of a flat rectangular gel.
- Electrodes (positive and negative) are attached toeither end of the gel
- An electric current is passed through the gel
- the phosphate groups on a DNA molecule are negatively charged - consequently they move to the positive electrode
- Smaller DNA fragments move faster than long ones
- The pattern on the electrophoresis gel is transferred to a nylon sheet.
- Radioactiv probes are added, whcih stick to specific DNA sites producing a pattern
- A banding pattern called a DNA fingerprint is created, due to the DNA fragments being sperated according to size
- Each DNA fingerprint is unique, due to the different lengths of an individuals DNA fragments
DNA testing from samples of DNA left at a crime scene can be used to identify a criminal as DNa is different to each individual, hence auto radiographs or DNA fingerprints are used in criminal investigations
That’s a statement not a question. Dab
Name uses of DNA fingerprinting
Custody disputes - determining genetic relationships
Forensics
DNA that has been lefy for 3-4 years can’t still produce a DNA fingerprint
Flase, it can
PCR helps to facillitate the creation of DNA fingerprints because…..
It enables the amplification of a small sample of DNA
Is DNA profiling more accurate than blood-typing and fingerprints?
Yes
Do criminals have their DNA stored?
Yes all convicted criminals will have their DNA fingerprint stored to be accessed by detectives searching for potential suspects
Name an issue with potential use of DNA database
Could ne inconclusive or mis-interpretated
Name some uses of DNA databases
health insurance, missing persons, paternity testing, genetic disorders
What is DNA sequencing
The process of determining the nucleotide base sequence of a target DNA molecule
Is gel electrophoresis a form od DNA sequencing
YEs - it is a form of DNA sequencing known as the chain termination method
What does DNA sequencing enable
Mapping of species genome
Wat is an electropherogram
is a plot of DNA fragment sizes, typically used for genotyping such as DNA sequencing. T
What are some ethical issues related to the collection of genetic information
How will humans use the new technology
Who will have access to the information
Who will control the use of and access to the new information
Privacy of all citizens
What are some economic issues related to the collection of genetic information
Cost to collecte, store and administer a database
does the cost justofy the gains
should the money be spent in other areas - healthcare, education, environement
What are some cultural issues related to the collection of genetic information
Different cultures have different values and place different importance on genetic information
cultures view abortions and genetic disorders with different views
Religious considerations
Are we playin god?
zsome genetic disrders more prevalent in some societies e.g. thalassemia, sickle cell anemia
