Chapter 10: Gene Expression, Transcription & Translation Flashcards
What are the 2 key processes of gene expression?
Ch 10.1
1) Transcription
2) Translation
Ch 10.1
What is transcription?
Ch 10.1
The synthesis of RNA from a DNA template (produces an RNA copy of a gene)
Ch 10.1
Where does Translation occur?
Ch 10.1
In the messenger RNA (mRNA)
Ch 10.1
What happens during Translation?
Ch 10.1
a sequence of bases in an mRNA is “translated” into an amino acid sequence of a polypeptide
Ch 10.1
Gene Expression is highly accurate, which is why it utilizes a specific amino acid sequence
What is the Central Dogma of Gene Expression?
Ch 10.1
Central Dogma: steps of principles
DNA to RNA to PROTEIN
Ch 10.1
TRUE or FALSE: Some viruses use an RNA template instead of DNA
Ch 10.1
Template: Blueprint of nucleotide bases for replication
TRUE
Ch 10.1
TRUE or FALSE: Information from the same DNA molecule can be used multiple times during transcription
Ch 10.2
TRUE; since transcription doesnt alter DNA, information from the same DNA molecule can be used multiple times
Ch 10.2
Define GENE:
Ch 10.2
the Molecular Definition of a gene
A unit of nucleotide sequences of DNA that can be trancribed to RNA and produce a protein (gene expression)
Ch 10.2
Sometimes it produces more RNA instead of a protein for gene expression
What is the function of a Promoter?
Ch 10.2
Signals the beginning of transcription
Ch 10.2
What does the Transcribed Region contain?
Ch 10.2
Contains information that specifies a amino acid sequence
Ch 10.2
What is the function of a Terminator?
Ch 10.2
Signals the end of transcription
Ch 10.2
Define Regulatory Sequence
Ch 10.2
Happens before the promoter, and controls the amino acid sequences to regulate gene expression in an organism
Ch 10.2
Promoter is the beginning of transcription
What are the 3 stages of Transcription?
Ch 10.2
1) Intiation
2) Elongation
3) Termination
Ch 10.2
What happens during the Initiation stage of transcription?
Ch 10.2
The Initiation stage is the first stage of transcription
Happens in the promoter and functions as the recognition site, where DNA strands are separated to form an open complex
Ch 10.2
What happens during the Elongation phase of Transcription?
Ch 10.2
RNA polymerase synthesizes RNA
Ch 10.2
Template Strand used to form Coding Strand
Which direction is transcription synthesized?
Ch 10.2
5’ to 3’ direction
Ch 10.2
What happens during the Termination phase of transcription?
Ch 10.2
This is the last stage of transcription
RNA polymerase reaches a terminator, releases transcription, dissociates from DNA
Ch 10.2
Terminator: Signals end of Transcription
What is the difference between transcription in eukaryotes and prokaryotes?
Ch 10.2
Eukaryotes use extra protein
Ch 10.2
Eukaryotes have 3 forms of RNA polymerase (I, II, III) whereas bacteria have a single RNA polymerase
A gene that contains the information for the sequence of amino acids in a polypeptide is called a __________.
10.0
a protein-encoding gene
RNA molecules that do not code polypeptides are called…
10.0
non-coding RNAs (ncRNAs)
During transcription, ____ is used as a template to make _______.
10.1
DNA, RNA
During translation, the information within____ is used to make ________.
10.1
mRNA, a polypeptide
What are the three stages of transcription?
10.2
10.2
initiation, elongation, and termination
10.2
Label the image.
10.2
1) promoter
2) terminator
3) transcribed region
4) regulatory sequence
10.2
During the elongation stage of transcription, nucleotides bind to the template strand and are covalently connected in which direction?
10.2
5’ to 3’ (5 prime to 3 prime)
10.2
Label the image.
10.2
1) initiation
2) elongation/synthesis of the RNA transcript
3) termination
T or F: the basic features of transcription are similar among all organisms
10.2
TRUE :D
A DNA template with the sequence 3’ - TACAATGTAGCC - 5’. Transcribe it into an RNA sequence reading.
10.2
5’ - AUGUUACAUCGG - 3’
What is the one difference between the transcription of eukaryotic genes and the transcription of bacterial genes?
10.2
the transcription of eukaryotic genes tends to involve a greater number of protein components than bacterial genes
The stage of bacterial transcription in which sigma factor causes the binding of RNA polymerase to the promoter is _________.
10.2
initiation
Transcription of eukaryotic genes involves more _________ of protein components.
10.2
complexity
Before leaving the nucleus, pre mRNA transcripts are modified by splicing, as well as the addition of ______ and _____ to the ends of the mRNA.
10.3
caps; tails
What RNA is used during transcription present in eukaryotes?
10.3
pre-mRNA
What happens during splicing?
10.3
To become a functional mRNA, many pre-mRNAs undergo an RNA modification known as splicing, in which introns are removed and the remaining exons are connected to each other.
What are the functions of the cap?
10.3
1) 5’ cap is recognized by cap-binding proteins, which are needed for the proper exit of mRNAs from the nucleus
2) after an mRNA is in the cytosol, the cap structure helps to prevent its degradation
3) the cap structure is recognized by other cap-biding proteins that enable the mRNA to bind to a ribosome for translation
What is the function of a poly A tail?
10.3
1) aids in the export of mRNAs from the nucleus
2) stabilizes a eukaryotic mNA so that it can exist for a longer period of time in the cytosol
What complex precisely removes introns?
10.3
the spliceosome
What is the spliceosome composed of?
10.3
subunits known as snRNPs (“snurps”) that contain small nuclear RNA and a set of proteins
_____________ _____________ allows complex eukaryotes to use the same gene to make different proteins.
10.3
alternative splicing
Splicing occurs in 4 steps. Label the images with the correct steps.
10.3
1) first 2 snRNP subunits bind to the 5’ splice site and branch site
2) additional units bind to the 3’ splice site and other locations which create a spliceosome; the intron forms a loop
3) 5’ splice site is cut; the 5’ end of intron is covalently attached to the branch site and 2 snurp units are released
4) the 3’ splice site is cut; exon 1 covalently attaches to exon 2; intron loop is released with rest of snurp units and all get degraded.
:D
Define the genetic code.
10.4
a code that specifies the relationship between the sequence of nucleotides in the condons found in mRNA and the sequence of amino acids in a polypeptide
The genetic code is read in groups of __#__ nucleotides called codons. There are __#__ different codons. 1 ___ codon; 3 _____ codons; and 61 ______.
10.4
1) 3
2) 64
3) start
4) stop
5) codons that specify amino acids
T or F: More than 1 codon can specify the same amino acid.
10.4
TRUE :)
This is a diagram of a bacterial mRNA. Label the image.
10.4
1) ribosomal-binding site
2) start codon
3) stop codon
4) coding sequence
What genetic code is the start codon? What about the stop codons?
10.4
start codon: AUG
stop codons: UAA, UAG, UGA
Codons are read in a sequential and on-overlapping manner in the ______________ direction; this means it reads from right to left.
10.4
5’ to 3’
________ are involved in translating the nucleotide base sequence of the mRNA into the amino acid sequence of the polypeptide.
10.4
transfer RNA (tRNA)
The _______ in a tRNA corresponds to the amino acid that it carries.
10.4
anticodon
The codon 5’-GAC-3’ specifies aspartic acid. What would be the anticodon of a tRNA that recognizes this aspartic acid codon?
10.4
3’-CUG-5’
The reading frame of an mRNA begins with a _____ codon, and is read a series of ______ codons.
10.4
start; adjacent
Which two scientists discovered that synthetic RNA triplets can act like codons, causing a tRNA molecule to bind to the ribosome?
10.4
Nirenberg and Leder
What is the function of mRNA?
10.5
contains the information for the sequence of amino acids in a polypeptide according to the genetic code
What is the function of tRNA?
10.5
a molecule with two function sites: one (anticodon) binds to a codon in mRNA; and the second site (3’ single-stranded region) is where a specific amino acid is attached
What are translation factors? Describe the function.
10.5
they are proteins needed for the three stages of translation: 1) initiation factors required for assembly of mRNA, first tRNA and ribosomal units; 2) elongation factors needed to synthesize polypeptide and 3) release factors needed to recognize stop codon and disassemble translation machinery
The ribosomal subunits contain two types of macromolecules, what are they?
10.5
protein and RNA
What is the function of the ribosome in translation?
10.5
it catalyzes the formation of covalent bonds between adjacent amino acids to make a polypeptide
The structural features that are common to all species of tRNA contain what?
10.5
1) 2-D cloverleaf structure with 3 loops and a stem containing an anticodon
2) 3’ single-stranded region (amino acid attachment site)
3) 3-D structure involving additional folding
Cells make many different tRNAS, each encoded by a different gene OR the same gene. Which answer is correct?
10.5
a different gene
The enzymes that catalyze the attachment of amino acids to tRNA molecules are known as….
10.5
aminoacyl-tRNA synthetases
When a tRNA has its amino acid attached, what is it called?
10.5
a charged tRNA
What serves as the site of translation?
10.5
ribosomes
Ribosomes contain 3 discrete sites where tRNA may be located. What are they called and label them on the diagram.
10.5
1) aminoacyl (A) site
2) peptidyl (P) site
3) exit (E) site
What amino acid is specified by the start codon?
10.4
methionine
Polypeptide synthesis occurs during the ____ stage of translation.
10.6
elongation
_______ occurs when a stop codon is reached in the mRNA.
10.6
termination
T or F: The 3 stop codons are recognized by a tRNA in the stage of termination.
10.6
FALSE; the 3 stop codons are recognized by a RELEASE FACTOR, and NOT tRNA
Where does translation occur in bacterial cells? What about eukaryotic cells?
10.6
cytoplasm in bacterial cells; cytosol in eukaryotic cells
