Transcription
What are the 3 steps of transcription?
Initiation, elongation, termination
The genetic code is made up of which bases?
A, U, G, C
What happens during the first step (initiation) of translation?
mRNA assembles with a ribosome & recognizes the AUG start codon to begin translation
What are mutations?
Heritable changes in genetic information
What is gene regulation?
The process of turning genes on & off.
What occurs during initiation?
RNA polymerase binds to the promoter, DNA strands unwind/unzip
The genetic code is read how many letters at a time?
3
What happens during the second step (elongation) of translation?
The ribosome binds the amino acids by breaking the bonds between them & their tRNAs, the tRNA floats away to make room for another tRNA to bind
What are the 2 general types of mutations & the definitions of each?
Gene-change in one or a few nucleotides chromosomal-change in number or structure of chromosome
Why is gene regulation important?
So the right genes will be turned on or off at the right times
What happens during elongation?
RNA polymerase uses a DNA strand as a template to make the complementary RNA strand
Codon
What happens during the third step (termination) of translation?
Translation stops when the ribosome comes to a STOP codon, the ribosome releases the polypeptide chain of amino acids into the cytoplasm along with the mRNA strand, the polypeptide chain folds to become a functional protein
Gene mutations are also known as these & include 3 types called?
Point mutations; substitutions, insertions, & deletions
Explain the purpose of the TATA box in eukaryotic gene regulation.
The TATA box acts as a helper sequence showing RNA polymerase the correct area to bind to the promoter.
What happens during termination?
RNA polymerase crosses one of the STOP codons & transcription stops
If you have the following DNA sequence, what is the complementary RNA sequence and corresponding amino acid?
TACCTAGAG
AUGGAUCUC
Met, Asp, Leu
How many types of RNA are used in the translation process?
3
Chromosomal mutations include these types of mutations?
Deletions, duplications, inversions, & translocations
Why is eukaryotic gene regulation so much more complex than prokaryotic gene regulation?
Because eukaryotic cells need to become specialized/differentiated to perform their necessary functions.
What happens during the RNA editing process?
Sections of the mRNA strand are cut out (introns) & the remaining pieces (exons) are spliced back together again
If you have the following DNA sequence, what is the complementary RNA sequence and corresponding amino acid?
CAGTTACCCAACGGTATT
GUCAAUGGGUUGCCAUAA
Val, Asn, Gly, Leu, Pro, STOP
Ribosomes are composed of how many subunits?
2
What kind of mutation occurs in sickle-cell anemia? Explain the effects of the mutation.
Substitution mutation in the Hb gene resulting in sickle-shaped RBCs leading to increased blood clotting and thus cardiovascular incidents.
Explain what the lac operon is & how it works in prokaryotic gene regulation.
The lac operon is a group of 3 lactose genes located on the DNA of E. coli. These 3 genes must be turned on in order for E. coli to use lactose as a food source. When lactose is not present, a repressor protein binds to the operator preventing RNA polymerase from binding to its promoter. When lactose is present, it binds to the repressor protein changing its shape & causing it to let go of the DNA. RNA polymerase can then bind to its promoter & begin transcription.