Ch 14-2 Flashcards
What is the role of RNA polymerase in transcription?
RNA polymerase synthesizes RNA from a DNA template
What are the key components of transcription?
RNA polymerase
●
Promoter (start site)
●
Terminator (stop signal)
Define upstream and downstream in the context of nucleotide sequences.
Upstream: A sequence located before another sequence
●
Downstream: A sequence located after another sequence
What are the three stages of transcription?
Initiation
●
Elongation
●
Termination
Describe the initiation stage of transcription.
DNA unwinds, and RNA polymerase binds to the promoter region.
How does the initiation of transcription differ in bacteria and eukaryotes?
Bacteria: RNA polymerase directly recognizes and binds to promoter sequences.
●
Eukaryotes: Requires transcription factors to mediate RNA polymerase II binding and initiation.
What is the TATA box, and where is it located?
A sequence about 25 nucleotides upstream of the start site in most eukaryotic promoters
What is the purpose of end modifications to pre-mRNA in eukaryotes?
Facilitate export from the nucleus
●
Protect mRNA from degradation
●
Aid in ribosome attachment
Define introns and exons.
Introns: Non-coding regions within eukaryotic genes.
●
Exons: Coding segments that are spliced together.
What are ribozymes?
RNA molecules that act as enzymes.
Which process transfers information from DNA to mRNA?
a) Translation
b) Transcription
c) Replication
d) Termination
B
What is the start codon?
a) UAA
b) UGA
c) UAG
d) AUG
D
What signals the end of transcription?
○
a) Start codon
○
b) Promoter
○
c) Terminator
○
d) Transcription factor
C
In which direction is RNA synthesized during elongation?
○
a) 3’ to 5’
○
b) 5’ to 3’
○
c) N-terminus to C-terminus
○
d) C-terminus to N-terminus
B
What is the function of the promoter in transcription?
○
a) Region of attachment for RNA polymerase
○
b) Signal to stop transcription
○
c) Site of mRNA degradation
○
d) Initiates translation
A
What role do transcription factors play in eukaryotic transcription?
a) Directly synthesize RNA
b) Remove introns from pre-mRNA
c) Mediate RNA polymerase II binding
d) Transport mRNA out of the nucleus
C
What sequence is often found about 25 nucleotides upstream of the start site in eukaryotic promoters?
a) Poly-A tail
b) 5’ cap
c) TATA box
d) Terminator sequence
C
What is the function of the poly-A tail in eukaryotic mRNA?
○
a) Initiates translation
○
b) Protects mRNA from degradation
○
c) Binds to the promoter region
○
d) Serves as a template for protein synthesis
B
What is the process of removing introns from pre-mRNA called?
○
a) Transcription
○
b) Translation
○
c) Splicing
○
d) Replication
C
What characteristic of RNA molecules allows them to function as enzymes (ribozymes)? *
a) Linear structure *
b) Inability to form hydrogen bonds *
c) Ability to base pair and form a 3-dimensional shape *
d) Presence of deoxyribose sugar
C
The process of synthesizing RNA from a DNA template is called
Transcription
What is the start codon that codes for methionine.
AUG
The three stop codons are
1) UAA
2) UGA
3) UAG
The __ is a region on DNA where RNA polymerase binds to initiate transcription.
Promoter
The sequence that signals the end of transcription is called the __
Terminator
In eukaryotes, the __ is a crucial promoter element located upstream of the transcription start site.
TATA box
__ factors are proteins that help regulate transcription by binding to DNA
Transcription
The __ and __ tail are modifications added to eukaryotic mRNA.
5’ cap and poly A
__ are noncoding sequences that are removed from pre-mRNA.
Introns
__ are RNA molecules with catalytic activity.
Ribozymes
T/f
Transcription occurs in the cytoplasm of eukaryotic cells.
F
Transcription occurs in the nucleus of eukaryotic cells.
T/f
RNA polymerase is responsible for adding nucleotides to the growing RNA chain during transcription.
T
T/f
The promoter region is located downstream of the coding sequence.
F
The promoter region is located upstream of the coding sequence.
T/f
In bacteria, RNA polymerase can directly bind to the promoter region without the need for transcription factors.
True
T/f
The TATA box is a sequence commonly found in prokaryotic promoters.
F
The TATA box is a sequence commonly found in eukaryotic promoters.
T/f
The addition of a 5’ cap and a poly-A tail helps to stabilize mRNA and protect it from degradation.
T
T/f
Exons are non-coding sequences that are removed during RNA splicing.
False
Exons are coding sequences that are retained during RNA splicing.
T/f
Alternative RNA splicing can result in the production of different protein isoforms from a single gene.
T
T/f
Ribozymes are proteins with enzymatic activity.
F
Ribozymes are RNA molecules with enzymatic activity
T/f
The genetic code is universal, meaning the same codons code for the same amino acids in all organisms.
T
