module 7 part 1 Flashcards
What is the starting point of the central dogma?
he starting point is DNA.
What happens to DNA in the central dogma?
DNA undergoes transcription to produce an RNA transcript.
What are the three types of RNA that can be produced?
The three types of RNA are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).
What happens to mRNA after transcription?
mRNA is processed and then translated to produce a polypeptide.
What is the final product of translation?
The final product of translation is a polypeptide.
What is the genetic code?
The genetic code is the set of rules by which the nucleotide sequence in DNA or RNA is translated into a sequence of amino acids in a protein.
How does the genetic code specify a string of amino acids?
The nucleotide sequence in DNA or RNA is read in codons (sets of three nucleotides), each of which codes for a specific amino acid.
How many nucleotides are in one “word” of the genetic code?
One “word” of the genetic code consists of three nucleotides, called a codon.
How can we distinguish different “words” (codons) in the genetic code?
Each codon corresponds to a specific amino acid or a stop signal, distinguishing the “words” by their unique three-nucleotide sequence.
Where does a gene start and where does it end?
A gene starts with a start codon (usually AUG) and ends with a stop codon (e.g., UAA, UAG, or UGA).
Are there punctuation marks in the genetic code?
Yes, the genetic code has punctuation marks: start and stop codons act as signals to begin and end translation.
How many amino acids are encoded by the genetic code?
There are 20 amino acids encoded by the genetic code.
How many nucleotides are used to code for amino acids?
4 nucleotides (A, T, C, G in DNA, or A, U, C, G in RNA) are used to code for amino acids.
How many possibilities would there be for codons if 1 nucleotide coded for 1 amino acid?
If 1 nucleotide coded for an amino acid, there would be 4 possibilities (4¹).
How many possibilities would there be if 2 nucleotides coded for 1 amino acid?
If 2 nucleotides coded for an amino acid, there would be 16 possibilities (4²).
Why do we need 3 nucleotides to code for each amino acid?
With 3 nucleotides (a triplet codon), there are 64 possible combinations (4³), which is enough to code for all 20 amino acids and still allow for redundancy (more than one codon for some amino acids).
How many triplet codons are there in the genetic code?
There are 64 triplet codons in the genetic code.
How many amino acids are encoded by the genetic code?
The genetic code encodes 20 amino acids.
What is the role of the codon AUG?
AUG is the initiation codon, signaling the start of translation.
How many codons signal the end of translation?
3 codons (UAA, UAG, UGA) act as stop codons, signaling the end of translation.
What does it mean that the genetic code is “degenerate”?
The genetic code is degenerate, meaning that multiple codons can code for the same amino acid.
What did Charles Yanofsky’s experiment demonstrate?
Yanofsky’s experiment showed that a gene’s nucleotide sequence is collinear with the amino acid sequence of the encoded polypeptide.
What organism did Yanofsky use in his experiment?
He used Escherichia coli (E. coli) in his study.
What gene did Yanofsky study in E. coli?
He studied the trpA gene, which encodes a subunit of tryptophan synthetase.
What was the focus of Yanofsky’s experiment?
He compared mutations in the trpA gene to specific amino acid substitutions in the tryptophan synthetase enzyme.
What did Yanofsky examine to understand the relationship between DNA mutations and protein changes?
He looked at the order of DNA mutations and the order of amino acid sequence changes in the tryptophan synthetase protein.
What did Yanofsky’s experiment demonstrate about the relationship between a gene and the encoded protein?
Yanofsky’s experiment demonstrated that a gene’s nucleotide sequence is collinear with the amino acid sequence of the encoded polyp
What is meant by “collinear” in Yanofsky’s experiment?
“Collinear” means that the order of nucleotides in the gene directly corresponds to the order of amino acids in the protein.
What gene did Charles Yanofsky study in his experiment?
He studied the trpA gene in Escherichia coli, which codes for a subunit of tryptophan synthetase.
What method did Yanofsky use to connect mutations in the gene to amino acid changes?
: He compared mutations in the trpA gene to specific amino acid substitutions in the tryptophan synthetase enzyme.
What did Yanofsky’s experiment reveal about codons?
Yanofsky’s experiment showed that a codon is composed of more than one nucleotide.
Can different point mutations affect the same amino acid?
Yes, different point mutations can affect the same amino acid due to the degeneracy of the genetic code.
How are codons related to nucleotides in the genetic code?
Each nucleotide is part of only one codon, and codons for amino acids do not overlap.
What did Yanofsky observe about point mutations and their effects?
Yanofsky found that each point mutation altered only one amino acid in the encoded protein.
How many nucleotides are in a codon?
A codon is composed of three nucleotides.
What determines the reading frame for a gene?
The starting point of the gene establishes the reading frame.
Why is the reading frame important in translation?
The reading frame is important because it determines how the codons are grouped and read during translation to ensure the correct amino acids are added to the polypeptide chain.
What happens if the reading frame is shifted?
A frameshift mutation (adding or deleting nucleotides) can shift the reading frame, potentially altering the entire amino acid sequence after the mutation.
different sets of mutations generate either a ____ or a _____
mutant;normal phenotype
What determines the phenotypic effect of a frameshift mutation?
It depends on whether the reading frame is restored.
Do most amino acids have more than one codon?
Yes, most amino acids are encoded by more than one codon.
What happens in a deletion mutation? cat ate the rat
One or more nucleotides are removed from the sequence.
Example: “The cat ate the rat.” becomes “Thc ata tet her
What happens in an insertion mutation? cat ate the rat
One or more nucleotides are added to the sequence.
Example: “The cat ate the rat.” becomes “The cat tat eth era t…”
What happens in a deletion and insertion mutation? the cat ate the rat
Both nucleotides are removed and added, shifting the sequence.
Example: “The cat ate the rat.” becomes “Thc att ate the rat.”
