BIOTECHNOLOGY Flashcards
define biotechnology
the use of natural cellular processes to make products that are of use to humans
define genome
complete set of genetic information of an organism
define genome
complete set of genetic information of an organism
why do we use gel electrophoresis?
technique used to separate DNA fragments according to their size
what does the gel in gel electrophoresis allow?
gel = porous
dna is cable to travel through ‘maze’ separating smaller fragments which move through quicker and larger fragments which don’t travel through as fast or as long
what is the purpose of a dna ladder
is a standard sample of known sizes which is out into the gel aswell so that the exact fragments in the sample can be determined through comparing them to the ladder
what is the gel stained with
dna binding - dye
allowing dna fragments to be seen as bands
what is the purpose of the electric current in gel electrophoresis
makes dna move through gel , towards the positive electrode
what is the purpose of the buffer solution in gel electrophoresis
carries charge and completes the circuit
what does the loading dye allow?
allows dna to sink into wells and shows dye-front to know when to stop the system
why is dna negatively charged and what does this allow?
due to the phosphate group (negative charge) allowing to to move toward the positive electrode
what does PCR stand for?
polymerase chain reaction
what is the purpose of the PCR process?
used to make millions of copies of a particular region of dna
amplifies DNA to make enough to be analysed
what are the 6 components needed in a PCR test
dna sample
primers
nucleotides
taq polymerase
buffer mix
PCR tube
what characteristic must the dna polymerase used in PCR have and what polymerase is usually used?
Heat-stable
Taq polymerase is usually used due to its high heat-tolerance which can withstand high temperatures and not denature
what is the role of the buffer solution in PCR and what does it contain?
necessary to create optimal conditions for Taq polymerase
contains:
Mg ions - cofactor dna polymerase and stabilise negative charge of DNA phosphate
other components optimise ph for polymerase to prevent denature
what are primers and how many are required in each reaction?
short sequence of nucleotides that provide a starting point for Taq polymerase
2 primers used
what temperature is required for denaturation?
96 degrees
what occurs during denaturation?
strongly heated to completely separate / denature dna strands
providing 2 single stranded templates
what temperature is required for annealing to occur?
55-65 degrees
what occurs during annealing?
reaction is cooled allowing primers to bind to the complimentary sequences on the single stranded template dna
what temperature is required for extension to occur?
72 degrees
what occurs during extension?
the temperature is raised so that Taq Polymerase extends the primers, synthesising new strands
what is the PCR machine called?
Thermocycler
what are restriction enzymes used for?
cutting the dna into fragments at specific points called recognition sites
capable of cutting sticky ends (staggered)
or blunt ends (same cut)
what does STR stand for
SHORT TANDEM REPEATS
what are short tandem repeats?
2-5 nucleotides in the non-coding region on your genome which can be presented in varying numbers or repeats
more mutations can occur
define dna sequencing
the process of determining the sequence of nucleotides in a piece of dna
what do dideoxynucleotides lack?
the OH (hydroxyl) group on the 3’ carbon of the sugar ring
this means no further nucleotides can be added to it
define recombinant dna
the process of recombining fragments of dna from different sources
what are 3 reasons to do recombinant dna
introduce new genes into species
replace faulty genes
make useful proteins
make identical dna copies
why are plasmids used in recombinant dna ?
bacteria already carries plasmid and can then uptake plasmid with inserted gene inside
what is used to paste dna and plasmids together in recombinant dna?
dna ligase
where to restriction enzymes cut dna?
at specific recognition sites
why is the same restriction enzyme used to cut both plasmid and gene if interest?
creates the same complimentary sticky ends
allowing to anneal / joined together
what is recombinant dna used for (3)
biopharmaceuticals
gene therapy
gene analysis
what is the aim of gene therapy
find a faulty/mutated gene and replace it by inserting a healthy/functioning gene
what does exvivo gene therapy do
cells are removed from body and genes are edited / replaced OUTSIDE OF BODY and then transplanted back into body
what does invivo gene therapy do?
cells are NOT removed from the body
vector carries healthy genes into affected cells
what are 4 types of variation
new/different alleles
new/different combination of alleles
sexual reproduction randomness
failure of meiosis occurring properly
define gene mutations
changes in single genes so that traits normally produced by that gene are altered/not present at all
define chromosome mutations
all/part of chromosome is affected including multiple traits/genes
define a spontaneous mutations
give an example for chromosome and gene mutations
due to random error in a biological process
chromosome - cell division error
gene - dna replication error
define induced mutations and what causes these
due to exposure to mutagenic agents
giving rise to both gene and chromosome mutations
define mutagens
things that are known to mutate dna / increase the frequency of mutations occurring above the rate of naturally occurring mutations
give a physical example of mutagens
ionising radiation - UV light, X rays, radioactive waste
give a chemical example of mutagen
mustard gas
formaldehyde
altering dna structure and interfere with transcription
where does the mutation occur in germ-like mutations
occurring in reproductive cells
where are somatic mutations formed
inside of body in body cells
which out of germ line and somatic mutations are passed on to offspring
germ line mutations are passed to offspring
somatic are passed to daughter cells
which out of germ-line and somatic mutations effects the individual
somatic effects individual
germline effects individuals offspring
what are the 4 types of gene mutations
substitution
inversion
deletion
addition/insertion
define silent mutations
substitution of a base that still codes for the same amino acid as the original base
define missense mutations
substitution of a bad that codes for a different amino acid
the protein has a single amino acid different which may alter the function of the protein
define nonsense mutations
substitution of a base that leads to premature ‘stop codon’ to be coded for
protein synthesis stops earlier than it should causing the protein to not function properly
what happens during deletion of a gene mutation
nucleotide is lost/deleted from the sequence
leading to a frameshift of downstream codons to no longer being read properly
what is caused by insertion in gene mutations
nucleotide is inserted/added into dna sequence
causing downstream of codons to not be read properly (frameshift)
what occurs during inversion of a gene mutation
order of bases is swapped
resulting in altering protein function
what are the two types of chromosome mutations
chromosome block mutations
chromosome number mutations
what are the 2 types of chromosome block mutations
deletion
inversion
translocation
duplication
what are 2 types of chromosome number mutations
- polyploidy - extra set of chromosomes in cell (down syndrome)
- Aneuploidy - extra or missing chromosomes - non disjunction in cell division (turners)
define allele frequency
the frequency of alleles (variants of genes) in a population
define migration / gene flow
exchange of individuals between populations which removes or introduces alleles from a particular population
define natural selection
environment selects which individuals are more likely to live, reproduce and pass on their advantageous alleles and which die and are unable to reproduce due to disadvantageous alleles
define random genetic drift
change is frequency of existing alleles (gene variant) in a population due to random sampling of organisms
when is random genetic drift most effective
most effective / has a bigger effect in smaller populations where change has a large effect on gene pool
what may random genetic drift cause
variants / alleles to disappear to decrease genetic variation and cause initially rare alleles to become more frequent
define founder effect
small section of the population leaves a larger population to colonise a new habitat
gene pool of founder population is likely to differ from original population
how do founder effect populations become different from the original population
different selection pressures due to different environment
limited breeding alleles
define genetic bottleneck
population numbers decrease due to predation, disease, climate change or natural disaster
gene pool significantly differs from original due to some alleles being lost, small random group of alleles surviving
define emigration
removing alleles from a gene pool
define immigration
introducing alleles to gene pool
define isolation
development of separate gene pools
what are the 2 barriers of gene flow
geographical barrier - oceans, mountains, lakes, rivers
socioeconomic barrier - economic status, educational background, religious background
what do genetic diseases result in
changes to allele frequency’s within gene pools
what was Darwin’s 3 observations of natural selection
- VARIATION - members of species vary
- BIRTH RATE - all living organisms reproduce at rate greater than which food supply and resources increase
- NATURES BALANCE - although birth rate of animals is high, each species remains level
define struggle for existence
animals must compete /struggle because of excessive birth rate and limited resources
define survival of the fittest
those with characteristics that are favourable / best suited to the environment are more likely to survive, reproduce and pass on these traits /alleles
3 types of natural selection
directional selection
stabilising selection
disruptive selection
