Protein Synthesis Flashcards
what are the two main stages of protein synthesis?
the two main stages of protein synthesis are transcription and translation.
what does protein synthesis start with?
protein synthesis starts with a gene.
what is the central dogma of molecular biology?
the central dogma is DNA = RNA = Protein
DNA to RNA = Transcription
RNA to Protein =
Translation
There is a flow of?
information in the cell from DNA to protein.
what is the intermediate molecule?
the intermediate molecule is RNA
what is the monomer of ribonucleic acid?
the monomer of rna is ribonucleotide
what are the components of a ribonucleotide?
- nitrogenous base: a, u, c, g
- phosphate group
- sugar: ribose
what are the differences between rna and dna?
rna is single stranded, dna is double stranded
rna contains uracil instead of thymine
rna contains ribose sugar instead of deoxyribose
what are the 3 types of rna?
- messenger rna
- ribosomal rna
- transfer rna
which one of the 3 types of rna carries the information to make an amino acid?
mrna
what enzyme is responsible for making rna from dna?
the rna polymerase is responsible for making rna from dna
what is transcription?
dna to rna
transcription is a process by which an rna molecule is synthesized from dna.
how many strands of dna are used to make rna? and what is it called?
only one strand of dna is used to make rna. this strand is called the template strand.
what happens in dna replication?
both strands act as a template for the synthesis of a new strand: semiconservative replication
unlike dna replication, transcription is…?
unlike dna replication, transcription is asymmetric. only one strand of dna is used as a template for transcription.
rna synthesis occurs in what direction?
rna synthesis occurs in 5’ to 3’ direction.
therefore the start of a gene is at the?
3’ end of the template strand.
rna polymerase uses the?
template strand to add in complementary bases.
unlike dna polymerase, rna polymerase does not require the use of?
primer
the synthesized rna molecule will be ___ to the template strand and ___ to the nontemplate strand (except for us replacing ts)
the synthesized rna molecule will be complementary to the template strand and identical to the non template strand.
this is the sequence of nontemplate dna: 5’ GCTATAGGCC 3’. write the sequence of the template strand of dna. what is the sequence of mrna indicating the 5’ and 3’ ends.
template strand of dna:
3’ CGATATCCGG 5’
mrna strand:
5’ GCUAUAGGCC 3’
what are the 4 stages of transcription?
- binding of rna polymerase to dna
- initiation
- elongation
- termination
BIET
first step is binding of rna polymerase to dna. how does rna polymerase know where the start of a gene is?
rna polymerase knows where the start of a gene is due to specific sequences along the dna that mark where the beginning of a gene is. these are alled promoters.
once the rna polymerase has binded…?
transcription can be initiated
whats the next step after rna polymerase has binded to the dna?
initiation: the rna polymerase unwinds the dna forming a transcription bubble. rna synthesis begins.
whats the next step after initiation?
elongation: rna polymerase adds complementary nucleotides to the growing chain
whats after elongation?
at a specific sequence, rna polymerase and the newly formed rna transcript detaches from the dna
where does this process take place in prokaryotes vs eukaryotes?
in prokaryotes: transcription and translation occurs in the cytoplasm
in eukaryotes:
transcription occurs in the nucleus but translation occurs in the cytoplasm
how is the information in mrna used to make the polypeptide?
- mrna carries the genetic code from dna
- the mrna is made up of codons. the codon is base triplets of mrna that code for each amino acid.
- one codon specifies one amino acid
the genetic code is?
degenerate
what does it mean by the genetic code is degenerate?
more than one codon can specify for a single amino acid. for example, there are 6 codons for serine.
codon for guu, aug, cua?
valine, methionine, leucine
how many nucleotides in length must a mrna be if it produces a polypeptide that is 100 amino acids long?
300 nucleotides
if the 4 nucleotides acug were written in all possible triplet combinations, there would be a total of how many different codons?
64 possible codons
of the 64 codons, only ___?
61 direct amino acids into polypeptides. the remaining 3 are stop codons which are useless and will terminate translation.
the genetic code is?
- degenerate
- universal, all organisms use the same code.
- nonoverlapping: there is a single starting point with only one way in which the nucleotides are read this is called the reading frame.
the codon that begins translation is
aug.
what is the genetic code?
the genetic code is the way by which the nucleotides on the mrna are converted into amino acids in the polypeptide.
below is a portion of a gene sequence on the template dna strand. what is the amino acid sequence?
3’ TACGTATCT 5’
rna: 5’ AUGCAUAGA
amino acid:
met, his, arg
