gene expression Flashcards
define genome (1)
all the DNA in an organism
define proteome (1)
the entire range of proteins that an organism is able to produce
why do antibodies bind to transcription factors? (2)
- antibody and transcription factors have specific tertiary structures
- complementary
name and describe the roles of 2 enzymes used to insert DNA fragments into plasmids. (2)
DNA ligase- joins DNA to plasmid
restriction enzyme- cuts plasmid
suggest 2 features of the structure of different proteins that enable them to be separated by gel electropheresis (2)
- different R groups
- charge
describe how alterations to tumour suppressor genes can lead to development of tumours. (3)
- increased methylation of tumour suppressor gene
- mutation in tumour suppressor gene
- amino acid sequence altered
- results in uncontrollable cell division
describe how STRs could be removed from a sample of DNA (2)
- restriction endonucleases
- cut DNA at specific base sequences
OR
at recognition sites
explain the importance of knowing the base sequences in PCR (2)
- for primers
- to produce a complementary base sequence
give 2 features of STRs that enable them to be separated by gel electropheresis (2)
- number of nucleotides
- (Negative) charge
give 2 reasons why bacteria are able to use human DNA to make human proteins (2)
- genetic code is universal
- mechanism of transcription/ translation is universal
suggest and explain 1 reason why bacteria may not be able to make every human protein (1)
- cannot splice so cannot remove introns
explain the purpose of a marker gene (1)
- shows the gene has been taken up
scientists used a radioactively labelled DNA probe to show that cells contained SUT1 gene.
describe how they would do this (4)
- extract DNA and add restriction endonucleases
- separate fragments using gel electropheresis
- treat DNA to form single strands
- probe binds to base pair with the SUT1 gene
- use autoradiography to show bound probe
when SUT1 gene is transcribed, sense SUT1 mRNA is made. the scientists genetically modified plants by inserting an extra gene, producing antisense SUT1 mRNA.
type A- genetically modified
type B- not genetically modified
suggest how production of antisense SUT1 mRNA in type A would reduce expression of the SUT1 gene. (4)
- antisense mRNA is complementary to sense mRNA
- antisense mRNA binds to sense mRNA
- ribosomes would not be able to bind
- less translation of mRNA/ less production of SUT1
