Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
AP Bio Unit 6B
gene expression & regulation
| Question | Answer |
|---|---|
| Transcription | the synthesis of RNA using information in the DNA |
| Translation | the synthesis of polypeptides using the information in the mRNA |
| Where does transcription occur in the eukaryotic cell? | in the nucleus |
| Where does translation occur in the eukaryotic cell? | free ribosomes |
| Where does transcription occur in the prokaryotic cell? | cytoplasm |
| Where does translation occur in the prokaryotic cell? | cytoplasm |
| What is the central dogma of molecular genetics? | DNA to RNA to protein |
| How many nucleotide bases are there? | 4 |
| How many amino acids are there? | 20 |
| How many unique triplets exist? | 64 |
| Template Strand | DNA strand that is used to produce an mRNA transcript |
| What is the start codon? | AUG |
| How many codons code for amino acids? | 61/64 |
| What direction does transcription occur? | synthesized in the 5' to 3' direction |
| What direction does translation occur? | mRNA read in the 5' to 3' direction |
| What two ideas are evidence of common ancestry and evolution? | DNA and RNA as carriers of genetic information and common genetic code |
| RNA polymerase | catalyst for RNA synthesis that pries DNA strands apart & joins together the RNA nucleotides |
| Does RNA polymerase require a primer to begin synthesis? | no |
| Transcription unit | the stretch of DNA downtream from the promoter that is transcribed into an RNA molecule |
| TATA box | nucleotide sequence that contains TATA (thymine, adenine, thymine, adenine) that is part of the promoter |
| How is the 5' end of the primary transcript processed? | a cap is added |
| How is the 3' end of the primary transcript processed? | an enzyme adds a poly-A tail (50-250 adenine nucleotides) |
| What do the 5' cap and poly-A tail do? | facilitate the export of the mature mRNA from the nucleus and help protect the mRNA from degradation by hydrolytic enzymes and help ribosomes attach to the 5' end of the mRNA it is in the cytoplasm |
| Introns | noncoding regions of the DNA |
| Exons | coding regions of the DNA |
| What are the two components of spliceosomes? | proteins and small RNAs |
| Spliceosome | a variety of proteins & several small RNAs that recognize the splice sites |
| What do spliceosomes work? | they bind to several short nucleotide sequences along an intron which is released and then the spliceosome joins together the 2 flankings exons |
| Ribozyme | an RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing |
| How are splice sites recognized? | small RNAs recognize special sequences at the intron ends |
| Alternative Gene Splicing | when some introns have sequences that regulate gene expression and when genes encode for more than one kind of polypeptide, dependent on which segments are treated as exons |
| mRNA | carry DNA's information from the nucelus to the cytoplasm |
| tRNA | a translator for the series of codons along an mRNA molecule |
| rRNA | ribosomal RNA makes up ribosomes |
| Anticodon | a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA |
| How is tRNA joined with it's amino acid? | substrate binding |
| Wobble | flexible pairing at the 3rd base of a codon that allows some tRNAs to bind to more than one codon |
| Eukaryotic ribosome structure | small subunit and large subunit with 3 binding sites where tRNAs attach and then turn mRNA into a strand of amino acid |
| What do differences in prokaryotic and eukaryotic ribosomes allow for? | thye have different molecular compositions which allows some antibiotic drugs to only inactive bacterial ribosomes |
| E site | exit site where discharged tRNAs leave the ribosome |
| P site | holds the tRNA that carries the growing polypeptide chain |
| A site | holds the tRNA that carries the next amino acid to be added to the chain |
| What is always the first amino acid in the new polypeptide? | methione (met) |
| Release factor | a protein shaped like an aminoacyl tRNA that triggers translation termination |
| How is translation terminated? | addition of a water molecule instead of an amino acid which breaks the bond between amino acid and tRNA |
| How does the lack of compartments in a prokaryotic cell results in a difference in gene expression? | transcription and translation can occur simultaneously and there is no RNA processing allowing for the newly made protein to diffuse more quickly to the site of function |
| Single nucleotide-pair substitution | replacement of one nucleotide and its partner with another pair of nucleotides |
| Silent mutation | no effect on the amino acid produced by a codon because of redundacy in the genetic code |
| Nonsense mutation | change an amino acid codon into a stop codon; most lead to a nonfunctional protein |
| Missense mutation | code for an amino acid but an incorrect amino acid |
| Frameshift mutations | mutations where the number of nucleotides inserted/delted is not a multiple of three causing a shift in the reading frame so that all subsequent amino acids are altered |
| Promoter | site where RNA polymerase can bind to DNA and begin transcription |
| Operator | the on/off switch for the operon positioned within the promoter |
| Repressor | binds to the operator and blocks attachment of RNA polymerase to the promoter, preventing transcription of the genes |
| Regulatory Genes | expressed continously at a low rate that encodes repressor proteins |
| Operon | stretch of DNA including the operator, promoter, and genes controlled |
| The lac operon is a ... | inducible operon |
| The trp operon is a... | repressible operon |
| When a repressor is bound to the operator of the lac operon, is the operon off or on? | on |
| Inducible operon | operon is usually off but can be turned on |
| Repressible operon | operon is usually on but can be repressed through allosteric binding |
| DNA methylation | addition of methyl groups (usually to cytosine) in order to more densely pack the chromatin and reduce transcription |
| Histone acetylation | acetyl groups are added to histones causing the chromatin to be more loosely packed and enable transcription enhancing gene expression |
| Heterochromatin | DNA is tightly wrapped around histones |
| Euchromatin | DNA is loosely wrapped around histones |
| Genomic imprinting | where methylation permanently regulates expression of either the maternal or paternal allele of particular genes at the start of development |
| Epigenetic inheritance | inheritance of traits transmitted by mechanisms not involving the nucleotide sequence itself |
| Enhancer | group of distal control elements that are typically associated with only 1 gene |
| General transcription factors | essential for the transcription of all protein-coding genes |
| Protein degradation | proteins are tagged with ubiquitin and then degraded by proteasomes |
| What do most noncoding RNAs do? | they help regulate gene expression |
| What do siRNA do? | highly specific and they bind to mRNA and are complementary along the entire length triggering mRNA degradation |
| What do miRNA do? | less specific so they block translation |
| Triplet code | a series of nonoveralapping, three-nucleotide words that gene to protein information flow is based on |
| Codon | mRNA base triplets that during translation are read in a 5' to 3' direction |
| Transcription initiation complex | a promoter that is binded to RNA polymerase II & completed assembly of transcription factors |
| How is transcription terminated in in bacteria? | polymerase stops transcription at end of terminator |
| How is transcription terminated in in eukaryotes? | RNA polymerase II transcribes the polyadenylation signal sequence |
| RNA processing | enzymes in the eukaryotic nucleus modify pre-RNA before the genetic messages are dispatched to the cytoplasm |
| Terminator | the sequence signaling the end of transcription |
| Signal-recognition particle (SRP) | binds to the signal peptide and escorts ribosome to a receptor protein built into the ER membrane |
| Polyribosome/Polysome | result of multiple ribosomes transalting a single mRNA simultaneousl |
| Point mutations | changes in just one nucleotide pair of a gene |
| Nucleotide-pair insertions/deletion | additions/losses of nucleotide pairs in a gene which have a much worse effect on resulting protein than substitutions do as they can result in a frameshift mutation |
| What type of pathway do inducible enzymes usually function in? | catabolic pathways |
| What type of pathway do repressible enzymes usually function in? | anabolic pathways |
| Operon model | a mechanism for gene expression control in bacteria |
| Differential gene expression | expression of different genes by cells with the same genome |
| What determines the lifespan of mRNA? | siRNA |
| Protein processing | folding, cleaving, adding sugar groups, and targeting for transport and degradation through ubitquitin tagging which triggers proteasomes to degrade the proteins |
| Coding strand | DNA strand whose base sequence is identical to the base sequence of the mRNA strand |
| Antisense DNA | non-coding DNA strand that serves as the template for mRNA transcript produced |
| Transcription factors | mediate the binding of RNA polymerase and the intiitation of transcription |
| RNA splicing | removes introns and joins exons to create an mRNA molecule with a continuous coding sequence |
| What are the 3 properties of RNA enable it to function as an enzyme? | it can form a 3D structure because of its ability to base-pair with itself, some bases in RNA contain functional groups that may participate in catalysis, RNA may hydrogen-bond with other nucleic acid molecules |
| Often, different exons code for different | domains in a protein |
| Exon shuffling | a molecular mechanism for the formation of new genes |
| What is found on either end of a tRNA? | anticodon on one side and an amino acid on the other side |
| What binds an amino acid with its tRNA? | aminoacyl-tRNA synthetase using ATP |
| Do eukaryotes or prokaryotes have larger ribosomal subunits? | eukaryotes |
| Stop codons | UAA, UAG, UGA |
| Which subunit binds to the mRNA first? | small subunit |
| When does elongation stop? | when a stop codon in the mRNA reaches the A site of the ribosome |
| Natural selection has favored bacteria that | produce only the gene products needed by that cell |
| Operons are almost always found in | bacterial cells |
| Corepressor | a molecule that cooperates with a repressor protein to switch an operon off |
| When tryptophan is present | the operon is off |
| When lactose is present | the operon is on |
| Both trp and lac operon regulation involves | negative control of genes |
| What acts as a "death tag" for mRNA | siRNA |
| What acts as a "death tag" for proteins? | ubiquitin |
| Control elements | segments of noncoding DNA that serve as binding sites for transcription factors that help regulate transcription |
| Mediator proteins | transmits signals from the transcription factors to the polymerase |
| Is prokayrotic or eukaryotic mRNA more long-lived? | eukaryotic mRNA |
| RNA interference (RNAi) | the blocking of gene expression by siRNAs |
| Small nuclear RNA | processes initial mRNA to its mature form in eukaryotes |
| Inducer | a molecule that inactives the repressorto turn an operon on |
| What causes genes to turn on or off? | signals from their external and internal environments |
| lacZ | encodes an enzyme β-galactosidase that splits lactose into monosaccharides |
| lacY | encodes a membrane-embedded transporter called lactose permease that helps bring lactose into the cell |
| lacA | not clear if this helps break down lactose |
| β-galactosidase | splits lactose into glucose and galactose |
| What molecule accumulates when glucose is scarce? | cAMP |
| cAMP receptor protein (CRP) when bound to cAMP | attaches upstream of the lac promoter and increases affinity of RNA polymerase for the lac promoter, stimulating gene expression |
Created by:
theshan