exam questions Flashcards
describe how an isolated human insulin gene is inserted into a bacteria plasmid (4)
- restriction endonucleases cut open DNA at recognition site
- forming sticky ends
- same enzymes cuts open plasmid
- forms complementary sticky ends which bind to DNA
- DNA ligase joins gaps
suggest two ways that bacteria which take up modified plasmids can be identified (2)
- fluorescent dye: glowing bacteria have plasmid
- antibiotic resistant genes: survivors have plasmid
suggest why it is preferable to use genetically engineered sources of human insulin rather than insulin obtained from pigs (2)
- no religious objections
- cheaper
- more efficient
suggest one ethical objection to the use of stem cells from human embryos (1)
- form of abortion
- kills a potential human
explain what is meant by a restriction enzyme (3)
- enzyme which cuts through DNA
- at a specific site called a recognition site
- forming sticky ends
outline the formation of recombinant DNA (4)
- restriction endonucleases cut through DNA and forms sticky ends
- same enzyme cuts plasmid to form complementary sticky ends
- bind with hydrogen bonding
- ligase joins gaps in backbone
explain what is meant by recombinant DNA (1)
2 sources of DNA joined together
describe how genetic engineering has been used to produce human insulin (3)
- DNA is isolated using restriction enzymes
- plasmid bacteria is cut open using same enzymes
- forms complementary sticky ends
- gene is inserted into plasmid - forms H bonds
- ligase joins gaps in backbone
what are the advantages of using genetic engineering to produce human insulin (3)
- rapid process
- body won’t reject
- reliable supply
describe the role of restriction enzymes in genetic engineering (3)
- cut DNA at recognition sites
- cut plasmid
- form complementary sticky ends
describe the role of ligase in genetic engineering (2)
- joins sticky ends of DNA and plasmid
- seals DNA backbone
describe the role of DNA polymerase in genetic engineering (1)
forms double strand, used in PCR
explain the role of a promoter in genetic engineering (2)
turns on transcription & binds RNA polymerase
discuss benefits and problems with using gene therapy in treatment of diabetes rather than taking insulin (4)
benefits
- avoids injections
- less restriction on lifestyle
problems
- takes a long time to have effects
- rejection
suggest why humans have more DNA than bacteria (2)
- humans are eukaryotes
- so have larger proteins
- bacteria are much smaller
which enzyme removes the gene from the genome? (1)
restriction endonuclease
which enzyme inserts the gene into the new DNA? (1)
ligase
discuss the advantages and disadvantages of genetic screening (6)
advantages
- early intervention of treatment
- removes uncertainty
- can increase life expectancy
disadvantages
- false result
- presence may not result in condition
- distressing
how is the knowledge of genomes used in medicine? (4)
- screen for heritable disease
- early diagnosis
- target drug treatment
- develop more efficient drugs
explain the arguments against genetic screening (4)
- expensive
- moral issues
- false results
- there are many diseases we can test but have no treatment for
suggest how bioinformatic may be useful in determining whether a newly sequenced allele causes disease (2)
- base sequence of normal allele and alternatives are held in a database
- computational analysis allows comparisons to be made
explain why only selected sections of non-coding DNA are used when profiling a human (3)
- in most people, genes are same
- coding sequences would not provide unique profiles
- non coding DNA contains variables of repeating sequences
why are protease enzymes used before PCR? (1)
digest proteins associated with DNA to purify
why do proteins need to bind to substance in the agar gel in electrophoresis? (2)
- different proteins have different overall charges
- binding makes them all negatively charged
- so proteins will move in the same direction
what needs to be done with mRNA in order for rest of genetic modification to occur? (2)
- make single stranded DNA (cDNA)
- using reverse transcriptase
suggest one concern that people have about the genetic modification of bacteria (1)
resistance (antibiotic)
state 3 differences between somatic & germ line cell gene therapy (3)
- somatic cannot be passed to offspring
- somatic introduced to body cell, germ line introduced to gamete
- somatic is short term
