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Biology Chapter 17 Study Guide
Terms in this set (39)
What stages does DNA expression occur in? Explain these two stages
Translation: mRNA to proteins
Transcription: DNA to RNA
What strand of DNA is read during transcription
The Template Strand of double stranded DNA is read
What base pairs does RNA polymerase add to form RNA
U, A, C, G
Instead of a primer, what does RNA polymerase need to bind at the promoter during initiation of transcription
What is the difference between an apoenzyme and a holoenzyme in regards to being activated or inactivated
What binds to RNA polymerase, forming a holoenzyme? How does this affect RNA polymerase in regards to transcription
Protein sub unit called Sigma Factor
Is helicase used in transcription?
Helicase is used in transcription. It unwinds double stranded DNA as it adds complementary RNA nucleotides
How many RNA polymerases does bacteria have? How many do eukaryotes have?
Bacteria have one RNA polymerase
Eukaryotes have three distinct types of RNA polymerases
Do eukaryotes use sigma factors? If not, what?
They use transcription factors
What do bacterial promoters have an affinity for? How many bases make up the promoter? What are the 2 key sequences in a promoter called
Have an affinity to Sigma Factor of RNA polymerase. The promoters are composed of 40-50 base pairs. They have two key sequences: -10 box and -35 box
Where is the -10 box located? Where is the -35 box located
-10 box is located 10 bases upstream from the transcription start site (+1 site)
-35 box is located 35 bases upstream from the +1 site.
Is it RNA polymerase or the sigma factor that has an affinity for DNA and makes initial contact
How does RNA polymerase complementary base pair with he template strand of DNA
RNA polymerase uses ribonucleoside triphosphates to complementary base pair with the template strand of DNA
In which direction does RNA polymerase synthesize RNA in elongation?
5' to 3' direction
In bacteria, what codes for the hairpin structure? What does the hairpin structure do? What causes the hairpin structure to form
The transcription terminal signal codes for RNA that forms a hairpin structure. The structure cases the RNA polymerase to separate from the RNA transcript ending transcription
What is the box called found in eukaryotes? Where is it found?
TATA box. It is centered about 30 base pairs upstream of the +1
In eukaryotes, what group of proteins bind to the DNA promoter to initiate transcription
Basal Transcription Factors bind tot he DNA promoter and initiate transcription
What does the Poly-A tail do?
extends the life of an mRNA by protecting it from degradation
Why do eukaryotes have "pre-mRNA"? How does the mRNA need to be altered to process it fully into actual mRNA
In eukaryotes the product of transcription is an immature primary transcript (pre-mRNA)
Before eukaryotic primary transcripts can be translated, non coding regions called introns and spliced out, and coding regions called exons are pieced together
What is a spliceosome?
Splices out introns and brings exons together to form mRNA
What are the two additions to the mRNA in eukaryotes?
Addition of the cap: recognition signal for the translation machinery
Addition of the poly-A tail: protects the mRNA from degradation
What are the three participants in translation?
What are the three sites found in ribosomes?
A site: where tRNA comes in contact with next Amino Acid
P site: contains the growing polypeptide
E site: exit site
Can transcription and translation occur simultaneously in bacteria? In eukaryotes? If possible, in either, explain how.
In bacteria, transcription and translation can occur simultaneously. Bacterial ribosomes begin translating an mRNA before RNA polymerase has finished transcribing it.
In eukaryotes, transcription and translation are separated
What is it called when multiple ribosomes attach to mRNA
Where does transcription occur in eukaryotes? Where does translation occur in eukaryotes?
Transcription occurs in the nucleus
Translation occurs in the cytoplasm
What does aminoacyl tRNA synthetases do to tRNA
Uses ATP to "charge" the tRNA by adding amino acids
Once the tRNA is covalently liked to its corresponding amino acid, what is this compound called?
What is the sequence at the 3' end of every tRNA?
Why is it that the tRNA folds in on itself so much? What is the positive result of this?
What is the role of ribosomes during translation?
Ribosomes facilitate the interaction between mRNA and tRNA and catalyze the peptide bond between amino acids
There are two subunits that compose a ribosome. What are their names, what is their function, and what is each subunit constructed of
Large subunit, this is where peptide bonds form
Small subunit, this holds the mRNA in place during translation
What are the Svedberg levels of the large and small units, and the entire ribosome, both in prokaryotes and eukaryotes
What are the three phases of translation
Where is it that the small subunit attaches to on the mRNA in bacteria?
at the Shine Dalgarno sequence
What is the first aminoacyl tRNA that binds to the start codon at the P-site carry?
What is translocation? What energizes this?
The ribosome moves 3 nucleotides at a time, the empty tRNA exits at the E-site. A newly charged tRNA enters at the A-site.
What is it that causes termination
starts when the A site encounters a stop codon
What are the three ways of post-translational modification
Molecular chaperones: speed folding of the protein
Folding determines a protein's shape and therefore its function
Function groups such as a phosphate can be added to proteins inducing the protein to become activated
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