transcription - protein synthesis Flashcards
(27 cards)
define transcription
where 1 gene of DNA is copied into MRNA in the nucleus
why does a copy of the gene of interests have to be tuned into mRNA
as DNA molecules is too big to leave the nucleus, therefore it would be unable to leave and attach to ribosome
why can’t the DNA molecule leave the nucleus
we wouldn’t want DNA to leave the nucleus as in the cytoplasm there are enzymes which couldn’t damage the DNA
explain the whole reason as to why a copy of DNA is made
as DNA molecule is too big to leave the nucleus and if it did leave the nucleus there are enzymes in the cytoplasm which could damage the DNA this is why mRNA is made
what makes the cope of 1 gene from DNA
mRNA
What is mRNA compared to DNA
its a much shorter molecule as its only a copy of 1 gene
What does mRNA being a shorter molecule than DNA allow
Therefore as its a shorter molecule it is small enough to fit through the nuclear pores in the nuclear envelope so it can move to the cytoplasm and attach to ribosomes
Why is mRNA able to carry the genetic code to the ribosome in cytoplasm
as it is a shorter molecule than DNA which means it is able to fit through the nuclear pore in the nuclear envelope which means it can move into cytoplasm and attach to ribosomes
why is transcription important
as it allows the genetic code to be carried to ribosomes in the cytoplasm which allows protein to be made
what is the first stage of transcription
the DNA helix needs to unwind to expose the 2 strands
why do the 2 strands of DNA need to be exposed
as 1 of the strands of DNA chain acts as a template to make mRNA
why is only 1 of the strands of DNA needed to act as a template for mRNA
as mRNA is single stranded so only 1 strand is needed
what is DNA helicase used for in transcription
its used to unwinds the double helix and break the hydrogen bonds between the bases of the 2 strands of DNA
how is one step of transcription similar to DNA replication
as to unwind the double helix and break the hydrogen bonds between the bases of the 2 strands of DNA the enzyme DNA helices is used.
what is DNA helicase
DNA helices is an enzyme that unwinds and unzips a DNA strand
what bonds does DNA helicase break
DNA helicase breaks the hydrogen bonds between the complementary base pairing
After DNA helicase had broken the hydrogen bonds what happens
now 1 astrand of DNA is exposed and ready to be used as template
what happens once 1 strand of DNA is ready to act as a template
due to there being free floating mRNA nucleotides in the nucleus they align opposite the exposed comxlemantoy DNA bases
what happens after the free floating MRNA aligns opposite the exposed complementary DNA bases
RNA polymerase will join the nucleotides together by phosphodiester bonds
what bond is formed when RNA polymerase joins the base pairs together
Phosphodiester bonds
what happens after once the strand of DNA and the strand of mRNA have complementary base paired
the there is an entire copy of mRNA called pre mRNA
what is the molecule formed after RNA polymerase has complementary base paired the strands together
pre mRNA
why is it called pre mRNA
as it has to be modified before it leaves the nucleus
what type of cell is pre mRNA present in
only eukaryotic cells so bacteria etc not prokaryotic
