The Flow Of Genetic Information From DNA To RNA Flashcards
What is the DNA genotype expressed as?
As proteins, which provides the molecular basis for phenotypic traits.
How does DNA specify traits?
By dictating protein synthesis.
Where is the molecular chain of command from?
- From DNA in the nucleus to RNA &
- RNA in the cytoplasm of proteins
The synthesis of RNA under the direction of DNA is known as?
Transcription
The synthesis of proteins under the direction of RNA is known as?
Translation.
What is the hypothesis that was based on the inherited metabolic disease?
One-gene-one enzyme hypothesis
What is the hypothesis for proteins?
One-gene-one enzyme hypothesis.
What is the hypothesis for polypeptides?
One-gene-one polypeptide hypothesis, recognizes that some proteins are composed of multiple polypeptides.
What is the genetic information written in?
In codons, translated into amino acid sequences.
What provides the code for constructing a protein?
The sequence of nucleotides in DNA.
The construction of protein require a ….
Conversation of a nucleotide sequence to an amino acid sequence.
Transcription rewrites the…
DNA code into RNA, using the same nucleotide “language “
What is the flow of information from a gene to a protein based on?
Triplet code.
What is a codon?
The genetic instructions for amino acid sequence of a polypeptide chain, written in DNA & RNA as a series of non-overlapping three base “words”
Translation involves switching from?
The nucleotide “language “ to the amino “language “.
What does each codon specify?
Amino acid
The genetic code dictates how …
Codons are translated into amino acids.
Three nucleotides specify?
One amino acid.
61 codons correspond to?
Amino acids.
What does AUG code for & what is its function in transcription?
It codes for methionine & signals the start of transcription.
These three codons UAA, UGA, & UAG signal the end of?
Translation.
18 of the 20 amino acids can be specified by more than one triplet codon, this is termed?
Redundant/Degenerate.
Unambiguous defines what property of the genetic code?
Each triplet specifies only a single amino acid.
A single coding dictionary is used by almost all organisms, what term is used to describe this?
Nearly universal.
How is the genetic code commaless/without punctuation?
No internal punctuation is used in the code; once translation of mRNA begins, the codons are read one after the other with no breaks between them (until a stop codon is reached).
How is the genetic non-overlapping ?
After translation commences, any single ribonucleotide within the mRNA is part of only one triplet.
What is the role of mRNA?
It encodes amino acid sequences & conveys genetic messages from DNA to the translation machinery of the cell.
Eukaryotic mRNA exits the nucleus via _ to enter the _.
Nuclear pores ; cytoplasm.
Eukaryotic mRNA has?
Introns & Exons.
What is the function of tRNA during translation?
It is language interpreter, converting the genetic message of mRNA into a language of proteins.
How does tRNA perform its interpreter task?
By picking up the appropriate amino acid & using an anticodon to recognize the appropriate codons in the mRNA.
What are the triplet bases on tRNA called?
Anticodons.
The triplet bases on tRNA recognize _ on the _.
Codons; mRNA.
What builds polypeptides?
Ribosomes.
What takes place on the surface of ribosomes?
Translation.
What is the function of ribosomes?
They coordinate the functioning of mRNA & tRNA, & ultimately the synthesis of polypeptides.
What are the the subunits of the ribosomes, & what is each subunit composed of?
- Small & Large
- They are composed of ribosomal RNAs & proteins.
Ribosomal subunits come together during translation & have binding sites for?
mRNA & tRNA.
The start of an mRNA message is marked by?
An initiation codon.
What are the 3 stages of translation?
- Initiation
- Elongation
- Termination
Name the three structures that initiation brings together?
- mRNA
- A tRNA bearing the first amino acid
- Two subunits of ribosomes.
What does initiation establish?
Where translation will begin.
In the first step of initiation; an mRNA molecule binds to a _ & the first _ binds to _ at the _.
Small ribosomal subunit ; tRNA ; mRNA ; start codon.
The start codon reads AUG & codes for methionine ; so the first tRNA has the anticodon_.
UAC.
For the ribosome to function, the small ribosome subunit is joined by?
A large ribosomal subunit.
What are the regions on the large ribosomal subuni
E (exit) site
P(peptidyl) site
A (aminoacyl) site
The first tRNA occupies the _ site, which will hold the growing _.
P ; polypeptide chain.
The _ site is available to receive the next _.
A ; tRNA.
_ adds amino acids to the polypeptide chain , until a _ terminates translation.
Elongation ; stop codon
Name the 3 steps involved in a cycle of elongation.
- Codon recognition
- Peptide bond formation
- Translocation
In which step does the anticodon of an incoming tRNA molecule, carrying its amino acid, pair with the mRNA codon in the A site of the ribosome?
Codon recognition.
What happens during peptide chain formation?
The new amino acid is joined to the chain.
In tranalocation, the _ is released from the _ site on the large subunit, the _ moves briefly into the 3rd site on the ribosome, known as the _ site?
tRNA ; P ; uncharged tRNA ; E (exit).
What is the complex formed during translocation?
mRNA-tRNA aa2-aa1 complex.
This complex shifts in which site direction & by a distance of how many nucleotides?
P site direction ; 3 nucleotides.
The process of translocation requires?
Several protein elongation factors ( EFs)
On which site do the triplet codons (UAG, UAA, or UGA) appear to signal termination?
A site
The stop codons do not specify an amino acid, therefore they do not call for _ in the A site.
tRNA.
What happens when a stop/termination/ nonsense codon is encountered?
The finished polypeptide is still attached to the terminal tRNA at the P site, & the A site is left empty.
The termination codon signals the action of a _?
GTP-dependent release factor .
The GTP-dependent release factor stimulates …
Steps leading to the release of the polypeptide chain from the terminal tRNA & subsequently from the translation complex.
What happens to the tRNA in the end?
It is released from the ribosome, which then dissociates into its subunits.
