Kaplan Biochemistry: Chapter 7 RNA and Genetic Code Flashcards
Is eukaryotic mRNA monocistronic or polycistronic
monocistronic. one piece of mRNA codes for one gene.
imprinted gene
genes whose expression is determined by the parent who contributed it.
missense mutation
mutation where one amino acid substitues for another
nonsense mutation
mutation where the codon now encode for a premature STOP codon.
freamshift mutation
when nucleotides are added or deleted causing a shift in how the codons are read.
template strand is ___ to ___, and mRNA stransd is built ___ to ___
template strand is 3’ to 5’, and mRNA strand is built 5’ to 3’
which strand of DNA is the sense strand
5’ to 3’
which strand of DNA is the antisense strand, or the noncoding strand?
3’ to 5’
which strand of DNA is the template strand?
3’ to 5’
mRNA is synthesized ___ to ___
5’ to 3’
TF: RNA polymerase requires a primer
FALSE> DNA polymerase requires an RNA primer, but RNA polymerase does not.
what type of polymerase synthesizes hnRNA/mRNA? Which one makes rRNA? Which one makes tRNA?
RNApol I: rRNA RNApol2: mRNA RNApol3: tRNA
T/F RNA polyermase proofreads its work
FALSE. only DNA polymerase can proofread (DNA POLII)
what is hybridization? polymerization?
hybridization: when 2 nucleic acid STRANDS bind to form DOUBLE STRANDED STRUCTURE. aka ANNEALINING polymerization: linking subunits together to form a single strand of DNA or RNA.
what post translational processes are seen in a prokaryotic cell?
none. posttranscriptional processing helps stabilize mRNA so it can survive protein translation in the cytoplasm. it also involves cutting out introns, which prokaryotes do not have. post translational modifications are only seen in eukaryotic cells
splicing of eukaryotic introns from hnRNA occurs by the
spliceosome
which two modifications are added to the ends of an mRNA/HnRNA strand before being transported out of the nucleus?
1) 5’ CAP: added and recognized by the ribosome as a binding site. it protects the mRNA from degradation in the cytoplasm 2) 3’ Poly-a-tail: called polyadenylation. a bunch of adenines are added to the 3’ end of the mRNA transcript and protects the message against rapid degradation.
during ribosomal protein synthesis, proteins are synthesized from ___ terminus to ___ terminus
during ribosomal protein synthesis, proteins are synthesized from Nterminus to C terminus
how is the completed polypeptide chain removed from the final tRNA?
the two get hydrolyzed
what is transduction
horizontal gene transfer in bacteria where bacteriophages transmit genomic material
what is transformation
direct uptake of genetic material from the environment– not mediated by viruses
what is conjugation
horizontal gene transfer process in bacteria which plasmid DNA is transferred from one bacteria to another via a sex pillus.
you’d find a signal sequence on what kind of protein
a secretoryprotien. a signal sequence directs the ribosome to move the protein to the endoplasmic reticulum so that the protein can be translated directly into the lumen and the rough ER. there are other specific signal sequences for proteins directed for the nucleus, lysosomes, and cell membrane.
what is prenylation
a type of POST translational process that consists of addiping lipids groups to membrane bounds enzymes.
which one of these processes is NOT a post-translational process? 1) prenylation 2) phosphorylation 3) glycosylation 4) polyadenylation 5) carboxylation
Polyadenylation. this is a post-transcriptional process, not translational.
T/F Each operon is a single gene
false. its a cluster of genes under the control of a single promotor: only one mRNA strand is produced with the cluster of genes because operons are found in prokaryotes – prokaryotes are polycistronic in which an mRNA strand can encode for multiple genes at a time.
two types of operons in prokaryotes
1) inducible systems: the pressor is bound tightly to the operator system and acts as a roadblock. RNA polymerase is unable to get from the promotor to the structural gene because the repressor is in the way. to remove the block, an inducer OPERPON must bind to the repressor protein and move it out of the way 2) repressible systems: allows for constant production of a protein product. the repressor made by the regulator gene is INACTIVE until it binds to a corepressor. the corepressor-repressor protein complex binds to the operator DNA site to prevent transcription.
what is an operon
a cluster of genes under the control of a single promotor that is NONTRANSCRIBABLE (does not produce a protein) that can bind a repressor protein to prevent transcription of downstream genes.
the trp operon is a ___ system
repressive system. when tryptophan is high in the local environment, it acts as a co-repressor. the binding of two tryptophans to the repressor causes the repressor to bind to the OPERATING DNA REGION. Thus, the cell turns off its machinery to synthesize its own tryptophan.
the lac operon is a ___ system
inducible system– lactose instigates gene transcription. induced when lactose binds to the operon and represses it, which allows for gene transcription of the genes that the operon was originally blocking from being transcribed, which allows for lactose-digesting enzymes to be made. when the lactose is not present, the operon is active and blocks genes needed to begin lactose digestion.
T/F: histone acetylation occurs in eukaryotes
true. it only occurs in eukaryotes. acetylation and methylation of DNA does not occur in prokaryotes
acetylation of DNA ____ the gene, and methylation of DNA ____ the gene.
acetylation of DNA EXPRESSES the gene, and methylation of DNA SILENCES the gene.
would heterochromatin be methylated of acetylated
heterochromatin is non-transcribable regions of tightly coiled DNA. because it cannot be transcribed, it is likely that it is methylated, since methylation aids in DNA silencing.
the coding strand of DNA is the strnad that runs ___ to ___
coding strand = 5’ to 3’
the template/non coding strand of DNA is the strand the runs __- to ___
template = noncoding strand = negative strand = 3’ to 5’.
name
adenine and guanine. Purines
name
cytosine, thiamine, uracil. pyrimidines
