Flashcards in Chapter 10 Deck (48):
Who discovered the gene-enzyme relationship?
English physician Archibald Garrod
What did he propose as the solution to the disease alkaptonuria (accumulation of homogentistic acid)?
In healthy people, homogentistic acid is broken down to a harmless product by an enzyme. One gene on enzyme.
What did one gene one enzyme change to?
One gene one protein and later one gene one polypeptide.
What is transcription?
Information in DNA is copied onto rna
What is translation?
When the RNA sequence is used to create the amino acid sequence of a polypeptide.
Travels from nucleus to cytoplasm where it is translated into a protein.
The protein synthesis "factory"
Ribosomal DNA's (mRNAs)
RNA found within ribosomes.
Transfer RNA (tRNAs)
Binds to amino acids and recognizes the sequence. Builds the polypeptide chain.
What are the requirements for transcription?
DNA template, appropriate nucleoside triphosphates, and RNA polymerase
Catalyzes the synthesis of RNA from the DNA template
What is a promotor?
A special DNA sequence that eh RNA polymerase tightly binds to.
Transcription initiation site
Part of the promotor where transcription starts.
Th unwinding and copying of the DNA to RNA strand.
The first step of transcription. Preparing the materials for transcription
The process of ending transcription with the new transcript falling or being pulled from the DNA template.
Noncoding interrupting regions found in pre-RNA
Expressed regions that will be translated into amino acids.
The RNA transcript before it is modified.
Nucleic acid hybridization
DNA is denatured into 2 strands. A single strand of RNA is incubated with one DNA strand and binds if complementary. The DNA RNA bond is observed for gaps.
A single stranded nucleic acid used in nucleic acid hybridization
Removes introns from RNA and splice seconds together
Short stretches of DNA that appear with little variation at the boundaries of introns and exons.
Small nuclear ribonucleoproteins (snrnps)
Bind to consensus sequences and binds to the RNA at 5' end while another binds at 3' end.
A complex made up of snrnps and various proteins find near introns and exons.
5' cap of mrna
Added to the 5' end of the pre-mRNA as it's transcribed. Chemically modified molecule of GTP
Poly A tail of mRNA
Added to 3' end of pre-mRNA at the end of transcription. Sequence of 100 to 300 A nucleotides.
genetic information found in mRNA molecule consisting of a series of sequential, non-overlapping three letter "words".
AUG. Codes for methionine. Contains initiation signal for translation
UAA, UAG, or UGA. Contains termination signals for translation.
How is the genetic code redundant but not ambiguous?
Multiple codons can encode for the same amino acid, but one codon can't encode for more than one.
What does the universality of the genetic code suggest?
All life likely came from a common ancestors.
Often occurs though the switching of two codons that encode the same amino acid. No affect.
Results in a change to the amino acid sequence. Two codons are switched that do not encode the for the same amino acid, and so the sequence is effected.
result in premature stop codon. Mutation ends sequence prematurely
Results from insertion or deletion of one or more base pairs in the coding sequence. Shifts every codon after the mutation.
What are the key events in Translation?
tRNA must chemically read each mRNA codon correctly, and deliver the amino acids that correspond to each codon.
a triplet of bases found on the midpoint of each tRNA that is complementary to the mRNA codon.
What is Wobble
The third base in the codon sequence does not always need to be precise. Often another base (eg I) is substituted for the third base, that can pair with multiple bases. Thus there are less tRNA species then there are amino acids.
P (Polypeptide) Site
Site where start codon tRNA binds to the mRNA with its amino acid. This site is where the new polypeptide chain grows.
A (Amino Acid) Site
Site where new tRNAs bind to mRNA. The tRNA that landed in front of them transfers its amino acid(s) to this new tRNA as it moves into the Psite
E (Exit) Site
Site where tRNA is released after passing its amino acids onto the new tRNA.
Consists of charged tRNA and small ribosomal subunit, both bound with mRNA.
Polyribosome or polysome
Arrangement consisting of mRNA strand with multiple bead like ribosomes and their growing polypeptide chains.
A short stretch of amino acids that indicates where in the cell the new polypeptide belongs.
The cutting of a polypeptide chain into 2 or multiple pieces.
the addition of carbohydrates to proteins to form glycoproteins.