chapter 5 Flashcards
Gave the name central dogma to the two-step process denoted DNA-RNA-protein
Crick
is the synthesis of a single-stranded RNA copy of a segment of DNA
Transcription
is the conversion of the messenger RNA base-sequence information into the amino acid sequence of a polypeptide.
Translation
The production of an RNA by transcription of a gene is one step of
Gene expression
encodes the amino acid sequence of a polypeptide. translation of this produces a a polypeptide
mRNA (messenger RNA)
with ribosomal proteins, makes up the ribosomes-structures on which mRNA is translated.
rRNA (ribosomal RNA)
brings amino acids to ribosomes during translation.
tRNA (transfer RNA)
with proteins, forms complexes that are used in eukaryotic RNA processing to produce functional mRNA’S.
snRNA (small nuclear RNA)
The enzyme that catalyzes the process of transcription is _______
RNA POLYMERASE aka DNA-dependent RNA polymerase.
Unlike DNA polymerases, RNA polymerases can initiate new RNA chains; in other words no ________ is needed.
primer
The process of transcription occurs in three stages _______,_________, and _________.
initiation, elongation, and termination
a sequence upstream of the start of the gene that encodes the RNA. The RNA polymerase interacts with it, and defines the direction for transcription and, thus dictates to the enzyme which DNA strand is the template strand where transcription is to begin.
Promoter
specifies where the transcription stops in synthesis.
terminator
Only one type of RNA polymerase is found in bacteria noted as the complete enzyme
holoenzyme or core enzyme
a polypeptide that ensures the RNA polymerase binds properly in a stable way only at promoters.
sigma bond.
There are two types of regulatory proteins: _________, and ________
activators: stimulate transcription by making easier for RNA polymerase to bind or elongate an RNA strand, repressors: inhibit transcription by making it more difficult for RNA polymerase to bind or elongate an RNA strand.
RNA polymerase has two proofreading activities:
one similar to DNA, and the other cleaves the RNA at that position before resuming RNA synthesis in the forward direction.
When transcription is terminated there are two types of signal termination:
I. Rho-dependent terminators (type II terminators), and Core RNA polymerase terminates transcription: these are called Rho-independent terminators (type I terminators).
Rho-independent terminators consist of an inverted repeat sequence that is of ____, _____ base pairs. creates a hairpin structure.
A, T
Rho-dependent terminators consist of ______ rich, and ______ poor sequences that have no hairpin structure.
C, G
secondary structures occur only in ________
hairpin structures RNA TERMINATION SITES
There are three different types of polymerases in eukaryotic transcription which are _______, ________, and _________
RNA POL I, RNA POL II, AND RNA POL III
located in the nucleolus, catalyzes the synthesis of three of the RNA’s found in ribosomes.
RNA POL I
located in the nucleoplasm synthesizes messenger RNA’S and some small nuclear RNA’s
RNA POL II
located in the nucleoplasm synthesizes: 1. transfer RNA’s 2. 5S rRNA a small rRNA molecule found in each ribosome 3. the snRNA not made by RNA pol II
RNA POL III
There are two general regions of the promoter where treanscription starts in eukaryotic cells these are
the core promoter,and the promoter proximal elements.
is the set of cis-acting sequence elements needed for the transcription machinery to start RNA synthesis at the correct site. is responsible for the TATA BOX or TATA ELEMENT also called the GOLDBERG-HOGNESS BOX
core promoter
specify where the transcription machinery assembles and determine where transcription will begin.
The Inr and TATA (Inr=initiator)
Accurate initiation of transcription of a protein-coding gene involves the assembly of RNA polymerase II and a number of other proteins called _________ on the core promoter.
General transcription factors (GTFs)
there are two fundamental differences in transcription with prokaryotic cells and eukaryotic cells
prokaryotic cells can “couple” which is transcribe and translate the mRNA at the same time, where as the eukaryote must first transcribe in the nucleus and then move the mRNA out of the nucleus into the cytoplasm to be translated.
bacterial mRNAs often are ________ meaning they contain the amino acid coding information from more than one gene
polycistronic
eukaryotic mRNAs typically are ________ meaning that they contain the amino acid-coding information from just one gene.
monocistronic
in eukaryotes in general, protein-coding genes typically have non-amino acid-coding sequences called _______
introns.
A segment of a protein-coding gene and its precursor mRNA (pre-mRNA) that does not specify an amino acid sequence.
introns
a segment of a protein-coding gene and its precursor (pre-mRNA) that specifies an amino acid sequence and is retained in the functional mRNA.
exon
processing of Pre-mRNA to mature mRNA explain what must be removed_______
introns must be removed from the pre-mRNA while still in the nucleus leaving only the exons thus changing the # of base pairs and therefore allowing the mRNA to be translated.
The splicing of mRNA occurs in the ______ in an area called the _______
nucleus, spliceosome
small nuclear RNAs associated with proteins and play a role in the removal of introns.
small ribonucleoprotein particles (snRNPs) pronounced snurps!!
in the splicing steps the snRNPs function through ______ _______, and _______
RNA-RNA, RNA-protein, protein-protein
an RNA molecule that has catalytic activity
ribozyme aka RNA enzymes
helps mRNA move from the nucleus to the cytoplasm and is made up of 50-250 adenine nucleotides
Poly (A) tail
5’ modification adds a 7 methyl guanine nucleotide to the 5’ end, protects the strand against itself
5’ capping
In both prokaryotes and eukaryotes the mature biologically active form of mRNA consists of 3 main parts______, _________, __________
the first is a 5’ untranslated leader sequence, then a central protein coding sequence including a start codon and stop codon, and finally a 3’ UTR trailer sequence.
