Test 3: Transcription Flashcards
Central Dogma
The concept that DNA encodes RNA, and RNA encodes protein, describing the flow of genetic information in cells.
Gene expression is the process of using information from a __ to produce a __ product, such as a protein.
gene; functional product
Transcription
The process of copying DNA to mRNA
Translation is the process where three __ correspond to one __ in the __ sequence during protein synthesis.
mRNA nucleotides; amino acid; polypeptide
Promoter is a __ that indicates where __ begins __ a gene
DNA sequence; RNA polymerase; transcribing
Template strand is the DNA strand that is used as a template for __ during __.
mRNA synthesis; transcription
Transcription Bubble
The region where the DNA double helix unwinds during transcription to allow mRNA synthesis.
What is the nucleotide difference between mRNA and DNA?
all of the T nucleotides are replaced with U nucleotides
In an RNA double helix, A can bind with U by what bond?
2 hydrogen bonds, just like A-T
The DNA of prokaryotes is organized into a
circular, double stranded, DNA chromosome
Operons are blocks of __ in __ cells that are transcribed into a single __ and often encode __ with related functions.
genes; prokaryotic; mRNA; proteins
Regulatory molecules in prokaryotic cells that can affect the expression of operons (3)
activators, inducers, repressors
Repressors
Proteins that bind to operator regions and prevent transcription of a gene.
Activators
Proteins that bind to an enhancer and increase the transcription of a gene in response to external stimuli.
Inducers
Small molecules that activate or repress transcription based on the cell’s needs and substrate availability.
Eukaryotic transcription is the process of transcribing__ in eukaryotes, involving multiple __ (shape)__and extensive __ processing before translation.
genes; linear chromosomes; mRNA
Eukaryotes also employ three different polymerases that each transcribe a different subset of genes;
RNA polymerase I, II & III
RNA Polymerase II is an __ located in the __ of eukaryotic cells that synthesizes all __ and __.
enzyme; nucleus; protein-coding; pre-mRNAs
TATA Box
A DNA sequence in eukaryotic promoters
Transcription Factors
Proteins that assist RNA polymerase bind to the promoter to initiate transcription in eukaryotic cells
Types of transcription factors that regulate eukaryotic transcription(2);
General (or basal) transcription, specific transcription
General (or basal) transcription factors
assist RNA polymerase by binding to the promotor
Specific transcription regulate when and where __ is produced
mRNA
Enhancers
Regions in eukaryotic genes that bind specific transcription factors and increase transcription.
DNA Bending Proteins
Proteins that bend DNA to bring enhancer and promoter regions together
Preinitiation complex is formed before__, involving __.
transcription starts; RNA polymerase
Histones
protein molecules DNA is coiled around (in chromatin)
Chromatin are __ and __ in __ cells when not dividing
DNA; proteins; eukaryotic
Nucleosomes are __ complexes with 146 __ wound around eight __
DNA-histone; nucleotides; histones
FACT Complex
Protein complex that moves histones during transcription
Termination Signals
Signals for RNA polymerases I and III to end transcription
The three most important steps of pre-mRNA processing are
the addition of stabilizing and signaling factors at the 5′ and 3′ ends of the molecule, and the removal of the introns.
Exons
Coding sequences in eukaryotic genes (ex-on:expressed)
Introns
Noncoding sequences in eukaryotic genes, removed during processing (int-ron:intervening)
Each intron is marked with specific nucleotides: GU at the __ end and AG at the __ end of the intron
5′; 3′
5’ cap is added to 5′ end of __ to __ and aid __.
pre-mRNA; protect; translation
Poly-A Tail is a String of residues added to __ end of __ for__(2).
3′; pre-mRNA; stability and export
Splicing
Process of removing introns and connecting exons in pre-mRNA
Spliceosomes
Complexes of proteins and RNA that carry out splicing
Transcription Main Steps
- Initiation (transcription factors help mRNA to attach to the promoter)
- Elongation (new RNA transcript strand is build longer)
- Termination (RNA polymerase detaches when it gets to the end)
5’ & 3’ UTR
Untranslated portion of the mRNA
The non-template strand is identical to the __ except that __.
mRNA; T nucleotides in the DNA are replaced by U nucleotides in the mRNA
the following are part of the primary transcript (pre-mRNA) before RNA processing
exon, intron, 5’ & 3’ UTR
the following are NOT part of the primary transcript (pre-mRNA) before RNA processing
promotor, 5’ cap, poly-A-tail
RNA nucleotide composition (3)
PBS (phosphate group, ribose sugar and nitrogen containing base (either A, C, G, or U)
If three bases are deleted from the coding region of a gene, what will happen? (select all that apply)
the reading frame after the deletion will not change; an amino acid will be missing from the polypeptide that is produced
If three bases are inserted into the coding region of a gene, what will happen?
an extra amino acid will be added to the polypeptide that is produced; the reading frame after the insertion will not change
If a mutation changes a gene sequence so that a codon in the mRNA changes from AAG to UAG (stop codon), what will happen?
the polypeptide will be terminated early; the mRNA will be the same length as the original mRNA
Main molecule for DNA replication
DNA polymerase
Main molecule in translation
Ribosomes
Main molecule in transcription
RNA polymerase
What is NOT found in mature mRNA after RNA processing is complete?
Everything is there BUT the intron and promoter
