8c Flashcards
what is the purpose of gene expression?
explaining how cells decode and use the info in their gametes
what are the 2 sequential processes that allow information encoded in genes to be copies as RNA and expressed as proteins?
Transcription and translation
Explain what is meant by the “one gene–one polypeptide hypothesis,”?
suggests that each gene in an organism’s DNA is responsible for encoding a single polypeptide or protein.
One gene - one enzyme (polypeptide) hypothesis was originally proposed by? and later on?
Archibald Garrod in 1901
beadle and Tatum(1941)
central dogma?
states that genetic information flows from DNA to RNA (transcription) and then from RNA to protein (translation)
define transcription
process by which the information encoded in DNA is made into a complementary RNA
define mRNA
The segments of DNA transcribed into RNA molecules that can encode proteins
Define ncRNA
segments of DNA copied into RNA that are not involved in encoding proteins
define translation
process of synthesizing a specific protein by using the info encoded in the mRNA on a ribosome.
_________ are building blocks of proteins?
polypeptides
Most of genes are__________ into mRNA, and then the mRNA is ___________ into polypeptide.
transcribed
translated
where does central dogma occurs in prokaryotes and why?
both transcription and translation occur in the cytoplasm due to the absence of nucleus
where does transcription and translation occurs in eukaryotes?
transcription -nucleus
translation - ribosomes - rough endoplasmic membrane-cytoplasm
define gene
organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately formation of a functional product.
what are the 4 things that a gene is composed of?
promoter
regulatory sequences
transcribed region
terminator
promoter?
site in the DNA where RNA polymerase binds to begin transcription
regulatory proteins
sites binding to regulatory proteins control whether a gene is turned on or off.
transcribed region
region of a DNA that is transcribed into an RNA molecule
terminator?
signals the end of gene transcription and encourages RNA polymerase to cease synthesis, releasing the transcribed RNA molecule.
what is required for initiation of transcription?
transcription factors (TFs) binding to the promoter region
function of RNA polymerase?
catalyzes the synthesis of RNA from a DNA template during transcription
what facilitates binding of RNA polymerase to the promoter region?
Transcription factors(TRs)
In eukaryotes, the promoter often contains a ________ box, while in prokaryotes, it includes a _________ box (________) + what’s the use of these elements
TATA
Pribnow box, TATAAT
help initiate and regulate the transcription of genetic information.
in a given gene during translation how many strands a as template
only one aka the template strand
how is the dna template read
3’ - 5’
In what direction is the RNA synthesized
5’ - 3’
what are the 3 stages of transcription
Transcription initiation
transcription elongation
transcription termination
_____________ unwinds the DNA
RNA polymerase II
products of transcription?
RNAs(mRNA,tRNA,rRNA)
define elongation in transcription
where RNA polymerase reads the DNA template and sequentially adds complementary RNA nucleotides to synthesize the growing RNA chain in the 5’ to 3’ direction.
what nucleotide incorporates thymine into RNA during elongation of transcription?
uracil
where does transcription ends?
termination site(terminator)
transcription ends with an _______ signal for _______.
AAUAAA
polyadenylation
define polyadenylation
addition of a poly-A tail to the 3’ end of an mRNA molecule during transcription. This modification enhances mRNA stability and facilitates its export from the nucleus and translation in the cytoplasm.
what are the 2 types of termination in translation?
1.Rho independent (intrinsic) termination
2. Rho (ATPase) dependent termination
define, Rho (ATPase) dependent termination
occurs when the rho protein disassociates the RNA polymerase and moves it off of the template.
define, Rho independent (intrinsic) termination
when the RNA forms a hairpin structure which displaces RNA polymerase and stops transcription.
_________- transcription is more complex
eukaryotic
what is the location of transcription in prokaryotic vs eukaryotic
prokaryotic- cytoplasm
eukaryotic- nucleus
initiation of transcription in prokaryotic vc eukaryotic?
prokaryotic- a single sigma factor
eukaryotic- 5 generational transcriptional factors
what type of polymerase is involved in transcription for prokaryotes vs eukaryotes?
prokaryotes- a single type of
eukaryotes- three types of (I, II & III)
What is transcribed by the diff polymerase of eukaryotes?
RNA POLYMERASE I: transcribes RNA GENES
RNA POLYMERASE II :mRNA, miRNA, snRNA, and snoRNA genes
RNA POLYMERASE III : tRNA and 5S rRNA genes
