Kaplan Biochemistry: Chapter 7 RNA and Genetic Code

Question 1

Is eukaryotic mRNA monocistronic or polycistronic

Answer 1

monocistronic. one piece of mRNA codes for one gene.

Question 2

imprinted gene

Answer 2

genes whose expression is determined by the parent who contributed it.

Question 3

missense mutation

Answer 3

mutation where one amino acid substitues for another

Question 4

nonsense mutation

Answer 4

mutation where the codon now encode for a premature STOP codon.

Question 5

freamshift mutation

Answer 5

when nucleotides are added or deleted causing a shift in how the codons are read.

Question 6

template strand is ___ to ___, and mRNA stransd is built ___ to ___

Answer 6

template strand is 3’ to 5’, and mRNA strand is built 5’ to 3’

Question 7

which strand of DNA is the sense strand

Answer 7

5’ to 3’

Question 8

which strand of DNA is the antisense strand, or the noncoding strand?

Answer 8

3’ to 5’

Question 9

which strand of DNA is the template strand?

Answer 9

3’ to 5’

Question 10

mRNA is synthesized ___ to ___

Answer 10

5’ to 3’

Question 11

TF: RNA polymerase requires a primer

Answer 11

FALSE> DNA polymerase requires an RNA primer, but RNA polymerase does not.

Question 12

what type of polymerase synthesizes hnRNA/mRNA? Which one makes rRNA? Which one makes tRNA?

Answer 12

RNApol I: rRNA RNApol2: mRNA RNApol3: tRNA

Question 13

T/F RNA polyermase proofreads its work

Answer 13

FALSE. only DNA polymerase can proofread (DNA POLII)

Question 14

what is hybridization? polymerization?

Answer 14

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.

Question 15

what post translational processes are seen in a prokaryotic cell?

Answer 15

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

Question 16

splicing of eukaryotic introns from hnRNA occurs by the

Answer 16

spliceosome

Question 17

which two modifications are added to the ends of an mRNA/HnRNA strand before being transported out of the nucleus?

Answer 17

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.

Question 18

during ribosomal protein synthesis, proteins are synthesized from ___ terminus to ___ terminus

Answer 18

during ribosomal protein synthesis, proteins are synthesized from Nterminus to C terminus

Question 19

how is the completed polypeptide chain removed from the final tRNA?

Answer 19

the two get hydrolyzed

Question 20

what is transduction

Answer 20

horizontal gene transfer in bacteria where bacteriophages transmit genomic material

Question 21

what is transformation

Answer 21

direct uptake of genetic material from the environment– not mediated by viruses

Question 22

what is conjugation

Answer 22

horizontal gene transfer process in bacteria which plasmid DNA is transferred from one bacteria to another via a sex pillus.

Question 23

you’d find a signal sequence on what kind of protein

Answer 23

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.

Question 24

what is prenylation

Answer 24

a type of POST translational process that consists of addiping lipids groups to membrane bounds enzymes.

Question 25

which one of these processes is NOT a post-translational process? 1) prenylation 2) phosphorylation 3) glycosylation 4) polyadenylation 5) carboxylation

Answer 25

Polyadenylation. this is a post-transcriptional process, not translational.

Question 26

T/F Each operon is a single gene

Answer 26

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.

Question 27

two types of operons in prokaryotes

Answer 27

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.

Question 28

what is an operon

Answer 28

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.

Question 29

the trp operon is a ___ system

Answer 29

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.

Question 30

the lac operon is a ___ system

Answer 30

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.

Question 31

T/F: histone acetylation occurs in eukaryotes

Answer 31

true. it only occurs in eukaryotes. acetylation and methylation of DNA does not occur in prokaryotes

Question 32

acetylation of DNA ____ the gene, and methylation of DNA ____ the gene.

Answer 32

acetylation of DNA EXPRESSES the gene, and methylation of DNA SILENCES the gene.

Question 33

would heterochromatin be methylated of acetylated

Answer 33

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.

Question 34

the coding strand of DNA is the strnad that runs ___ to ___

Answer 34

coding strand = 5’ to 3’

Question 35

the template/non coding strand of DNA is the strand the runs __- to ___

Answer 35

template = noncoding strand = negative strand = 3’ to 5’.

Question 36

name

Answer 36

adenine and guanine. Purines

Question 37

name

Answer 37

cytosine, thiamine, uracil. pyrimidines