Chapter 7 DNA And RNA Flashcards
Protein synthesis, an enzyme that attaches the correct amino acid to a tRNA molecule to from a “charged” amino acyl-tRNA
aminoacyl-tRNA synthetase
Production of different mRNAs (and proteins) from the same gene by splicing its RNA transcripts in different ways
Alternative splicing
Set of three consecutive nucleotides in a transfer RNA molecule that recognizes, through base-pairing, the three-nucleotide codon on a messenger RNA molecule; this interaction helps to deliver the correct amino acid to a growing polypeptide chain.
anticodon
Group of three consecutive nucleotides that specifies a particular amino acid or that starts or stops protein synthesis; applies to the nucleotides in an mRNA or in a coding sequence or DNA.
codon
Segment of eukaryotic gene that is transcribed into RNA and dictates the amino acid sequence of part of a protein
Exon
Unit of heredity containing the instructions that dictate the characteristics or phenotype of an organism; in molecular terms, a segment of DNA that directs the production of a particular protein or a functional RNA molecule.
Gene
Process by which a gene makes a product that is useful to the cell organism by directing the synthesis of a protein or an RNA molecule with a characteristic activity
Gene expression
Protein that assemble on the promoters of eukaryotic genes near the start site if transcription and load the RNA polymerase in the correct position
General transcription factors
Special tRNA that initiates the translation of an mRNA in a ribosome. It always carries the amino acid methionine
Initiator tRNA intron
RNA molecule that specifies the amino acid sequence of a protein
mRNA
Addition of multiple adenine nucleotides to the 3’end of a newly synthesized mRNA molecule
Polyadenylation
DNA sequence that initiates gene transcription; includes sequences recognized by RNA polymerase and its accessory proteins
Promoter
Enzyme that degrades proteins by hydrolyzing their peptide bonds
Protease
Large protein machine that degrades proteins that are damaged, misfiled, or no longer needed by the cell; its target proteins are marked for destruction primarily by the attachment of a short chain of ubiquitin
Proteasome
RNA molecule that forms the structural and catalytic core of the ribosome
rRNA
Large macromolecule complex, composed of RNAs and proteins, that translate a messenger RNA into a polypeptide chain
Ribosome
RNA molecule with catalytic activity
Ribozyme
Molecule produced by the transcription on DNA; usually single-stranded, it is a polynucleotide composed of covalently linked ribonucleic subunits
RNA
Modification of the 5’ end of a maturing RNA transcript by the addition of a an atypical nucleotide
RNA capping
Enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors
RNA polymerase
Modification that a precursor mRNA undergoes as it matures into an mRNA. Typically includes 5’ capping, RNA splicing, and 3’ poladenylation
RNA processing
Process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature messenger RNA.
RNA splicing
RNA molecule produced by transcription that is complementary to one strand of DNA
RNA transcript
RNA molecule of around 200 nucleotides that participates in RNA splicing
Small nuclear RNA (snRNA)
Large assembly of RNA and protein molecules that splices introns out of pre-mRNA in the nucleus of eukaryotic cells
Spliceosome
Process in which RNA polymerase uses one strand of DNA as a template to synthesize a complementary RNA sequence
transcription
Small RNA molecule that serves as an adaptor that ‘reads” a codon in mRNA and adds the correct amino acid to the growing polypeptide chain
transfer RNA (tRNA)
Process by which the sequence of nucleotides in a messenger RNA molecule directs the incorporation of amino acids into protein
Translation
Protein that promotes the proper association of ribosomes with mRNA and is required for the invitation of protein synthesis.
Translation initiation factor
Code of proteins (RNA polymerase II)
mRNAs
Form the core of the ribosomes structure and catalyze protein synthesis (RNA polymerase I and III)
rRNAs
Regulate gene expression (RNA polymerase II, III)
miRNAs
Serve as adaptors between mRNA and amino acids during protein synthesis (RNA polymerase III)
tRNAs
Used in RNA splicing, gene regulation, telomere maintenance, and other processes (RNA polymerase II, III)
Other noncoding RNAs
What protein _____ can recognize part of the RNA, then travel up the RNA to bump the RNA polymerase off the DNA?
Rho
Nuclease recognizes a site in the RNA and cuts the RNA off from the elongating strand?
Termination occurs by cleavage
What direction does an RNA chain elongate?
5’-to-3’ direction, must be an available 3’ hydroxyl group for the incoming triphosphate to react with
What bond connects the 5’ phosphate group of the nucleotide to the 3’ hydroxyl group of another nucleotide within a strand of nucleic acid?
Phosphodiester bond
Process by which protein is created at a ribosome?
Translation
All RNA is created by what process?
Transcription
Where does RNA processing occur?
Nucleus in eukaryotes
What is happening in the picture?
RNA polymerase II (only!) has a. C-terminal tail with repeating amino acid pattern.
These amino acids can be phosphorylation to provide binding sites for the enzyme involved in processing.
What at the end of mRNA protest the 5’ end?
7mG cap
What is a 7mG cap?
A 5’ to 5’ linkage, which can’t be recognized by the nucleases in the cytoplasm.
What protects mRNA at the 3’ end?
polyA tail
How can polyA tail be formed?
1) A’s can be added to the 3’ end after the RNA is terminated via cleavage.
2) They can also bed added in the cytoplasm, allowing for a competition between the addition of A’s and the removal of A’s by nucleases.
Some sections of mRNA (introns) are removed via ______?
Splicing
Splicing is regulated by the 5’ ________, the 3’ ________, and the ___________?
1) Splice site (GU)
2) Splice site (AG)
3) Branchpoint A
What is an intron?
A segment of DNA or RNA molecule which does to code for proteins and interrupts the sequence of genes.
- Intron -> interrupts: Int = Int good way to memorize
What is an exon?
A segment of DNA or RNA molecule containing information coding for a protein or peptide sequence.
tRNA is produced as the ______?
Translator for protein synthesis
What is a lariat?
Discarded byproducts of RNA splicing
Explain process.
Step 1: 2’-OH of the Brnahcpoint A attacks the 5’ splicing elite to create the lariat.
Step 2: 3’-OH of Exon 1 attacks the 3’ splicing elite, removing the lariat and joining the exons.
This coordinated by SnRNPs (slurps) in the spliceosome. These use RNA as the catalyst.
tRNA folds into a _________ structure.
Secondary
Role of rRNA, tRNA, miRNA in protein synthesis?
rRNA: Catalyst
tRNA: translator
miRNA: regulator
The ribosome has ________ which catalyze translation?
4 rRNAs
Role of miRNA?
Regulators of translation. Complementary of mRNA and can trigger mRNA degradation or translation inhibition.
Size of miRNA?
18-22 nucleotides long
Translation is …?
Coded, catalyzed, and regulated by RNAs
Where does the splicing of pre-mRNAs take place?
Takes place in the nucleus as RNA is still being transcribed, splicing only begins after the RNA capping occurs which is after RNA polymerase has produced about 25 nucleotides of RNA
What is RNA capping?
Capping is the addition of a modified guanine nucleotide to the 5’ end of an RNA molecule and occurs almost immediately after transcription has begun.
In eukaryotic mRNA, the poly-A tail does what?
Promotes longer-term stability of the molecule
Which part of a gene are transcribed into RNA?
Introns and exons
- Introns are spliced out by the activity of the spliceosome, leaving only exons in the mature mRNA
Where is RNA translated?
Ribosomes located in the cytosol
What is the TATA box?
Region of the promoter in eukaryotes that recruits transcription factors that help RNA polymerase to begin the process of transcription.
Where on DNA of a gene does RNA polymerase release its newly made RNA?
Terminator site
What’s cellular mechanism creates proteins?
Translation
Explain how macromoléculaire synthesis works?
Translation is initiated when _____ come together?
RNA
Translation is coded, catalyzed, and regulated by ____ and _____?
RNAs and G-proteins
Polyribosome represents a series of ___?
Ribosomes that can simultaneously translate the same mRNA molecule, so the proteins they synthesize will be identical.
All charged tRNAs (with the exception of the initiator tRNA) fir bind to ____?
Ribosome at the A site - charged tRNA enters the A site by base-p[airing with the complementary codon on the mRNA molecule
What site does th charged initiator tRNA-fMet first bind on the ribosome?
Initiator tRNA, charged with methionine, is first loaded into the P site of the small ribosomal subunit, along with additional proteins called translation initiation factors. Binds to the 5’ cap of an mRNA molecule.
What part of a protein is synthesizers by a ribosome first?
N-terminus is the part of a protein that is synthesized by a ribosome first. N-terminus corresponds with the 5’, not the 3’, end of the mRNA.
What amino acid does tRNA always carry?
Methionine
What part of an mRNA molecule do ribosomal subunits first bind?
5’ end of the mRNA
How many amino acids can be added to a polypeptide chain per second?
Two amino acids
Translation takes place in a series of gour steps. Explain steps.
An aminoacyl-tRNA binds to the vacant E site on the ribosome; a peptide bonds forms; the large subunit of the ribosome trans locates, moving the bound tRNAs to the A and P sites; the small sub Int of the ribosome translocates, ejecting the tRNA from the A site.
Within the ribosome, the formation of peptide bonds is catalyzed by what?
An RNA molecule in the large ribosomal subunit.
RNA message is decoded by which of the following?
Catalytic activity of the ribosome
How do tRNAs become attached to the correct amino acid?
Enzymes called amino all-tRNA synthétases recognize tRNAs with a specific anticodon as well as the amino acid for that tRNA and catalyze a reaction to join them together. This is called “charging” a tRNA
What recognizes the codons in an mRNA?
Protein called release factor binds and catalyzes the addition of a water molecule to the carboxyl end of the polypeptide and releases it
