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Cell Bio ch 7
| Question | Answer |
|---|---|
| Transcription is also known as _____ synthesis | mRNA |
| Translation is also known as _____ synthesis | Protein |
| The _____ of gene expression is regulated by each individual cell | Level |
| Use one strand of DNA as a template to make a complementary strand of RNA | Transcription |
| The energy for transcription comes from what? | Nucleoside triphosphates |
| The enzyme behind transcription is _____ _____ | RNA polymerase |
| In both replication and transcription, it is carried out by several enzymes including a _____ | Polymerase |
| In both replication and transcription, produces a linear polymer of nucleotides connected by _____ bonds | Phosphodiester |
| In both replication and transcription, synthesis is _____ prime to _____ prime | 5', 3' |
| In both replication and transcription, what are the four distinct nucleotides? | ATP, UTP, CTP, GTP |
| Synthesis of RNA is _____ prime to _____ prime (just like for DNA) | 5', 3' |
| Uracil can base pair with _____ (just like thymine can) | Adenine |
| Base-pairing interactions in a single RNA molecule can result in complex folds (ribozymes!) | Secondary structure |
| TYPES OF RNA: copy of a structural gene | mRNA |
| TYPES OF RNA: this is translated | mRNA |
| TYPES OF RNA: makes up ribosomes (in combination with protein) | rRNA |
| TYPES OF RNA: carries amino acids to ribosome during translation | tRNA |
| TYPES OF RNA: splicing | snRNAs |
| TYPES OF RNA: regulate gene expression | miRNAs |
| Eukaryotic cells have _____ different RNA polymerases | Three |
| Each RNA polymerase transcribes specific types of _____ | Genes |
| RNA POLYMERASES: transcribes most rRNA genes | RNA polymerase I |
| RNA POLYMERASES: transcribes protein-coding genes and miRNA genes | RNA polymerase II |
| RNA POLYMERASES: transcribes tRNA genes and 5S rRNA gene | RNA polymerase III |
| Transcription is the same basic reaction that occurs during _____ | Replication |
| What are the two main differences between transcription and replication? | One strand used as template, only short segment of the DNA strand is separated |
| RNA polymerases can start de novo (from _____) | Nothing |
| RNA polymerases don't _____ (1 mistake in 10^4 nucleotides) | Proofread |
| RNA molecules are much _____ than DNA molecules | Shorter |
| There is _____ gene per RNA (transcript) in eukaryotes | One |
| There can be more than one gene per RNA (transcript) in _____ | Prokaryotes |
| Strand that is used to make RNA | Template strand |
| Non-template strand; has same sequence as mRNA | Coding strand |
| During transcription, how many strands of DNA are used as template? | One |
| Once bound to DNA, the _____ could move either left or right, copying either the lower or upper strand | Polymerase |
| Genes can exist anywhere on the DNA and can run in _____ directions | Opposite |
| Signal sequences in the DNA specify... | Where transcription starts, which strand to be used as template, where transcription stops |
| GENE PARTS: sequence of DNA that specifies starting point and direction (which strand) | Promoter |
| GENE PARTS: main point of control | Promoter |
| Promoter sequences are recognized and bound by _____ _____ and other proteins | RNA polymerase |
| GENE PARTS: sequence of DNA that specifies where transcription will stop | Terminator |
| GENE PARTS: sequence that actually encodes the protein | Coding region |
| GENE PARTS: part of mRNA that is translated | Coding region |
| There are parts of a gene that are not part of the _____ sequence; a portion of these areas do get transcribed | Coding |
| Where transcription is initiated (the exact nucleotide) | Transcriptional start site |
| Where transcription stops | Transcriptional stop site (termination site) |
| What is the beginning of transcription called? | Initiation |
| _____ is a critical point of control determining whether or not a gene will be expressed | Initiation |
| Bacterial and eukaryotic organisms use essentially the same enzyme, which is what? (regulation of the process is very different though) | RNA polymerase |
| INITIATION IN BACTERIA: RNA polymerase and an associated _____ bind DNA loosely, and slide along it until they reach a promoter | Sigma factor |
| INITIATION IN BACTERIA: transcription begins, and then the _____ _____ dissociates | Sigma factor |
| INITIATION IN BACTERIA: RNA polymerase continues on, until it reaches the _____ | Terminator |
| In bacteria, the key promoter elements are at _____ and _____ | -35, -10 |
| EUKARYOTIC TRANSCRIPTION INITIATION: much more complicated than bacterial initiation; must deal with _____ structure | Chromatin |
| EUKARYOTIC TRANSCRIPTION INITIATION: initiation is NOT done by polymerases alone; requires _____ _____ _____ | General transcription factors (GTF) |
| EUKARYOTIC TRANSCRIPTION INITIATION: more elaborate _____ mechanisms than bacterial initiation | Control |
| What are the functions of general transcription factors? | Assemble on the promoter, position RNA polymerase, pull apart double helix, launch RNA polymerase |
| Many eukaryotic gene promoters contain a _____ box | TATA |
| The TATA box is usually located _____ base pairs UPSTREAM of the transcription start site (-25) | 25 |
| Which transcription factor binds the TATA box (found in many promoters)? | TFIID |
| Which transcription factor consists of TATA binding protein (TBP) and TBP associated factors (TAFs)? | TFIID |
| Which transcription factor distorts the DNA helix? | TFIID |
| Which transcription factor attracts other transcription factors to the site? | TFIID |
| After TFIID binds, then comes other transcription factors and RNA polymerase II, which forms what? | Transcription initiation complex |
| Which transcription factor pulls the double helix apart (using ATP)? | TFIIH |
| Which transcription factor phosphorylates RNA polymerase in the C-TERMINAL region? | TFIIH |
| Phosphorylation of RNA polymerase "releases" it from the transcription initiation complex, so that it can leave the promoter (and transcribe the gene) | TFIIH |
| Prokaryotes have no nucleus, so _____ have immediate access to the mRNA | Ribosomes |
| Prokaryotes have no nucleus, so ribosomes bind as soon as the mRNA emerges from RNA polymerase, even BEFORE _____ is finished | Transcription |
| In eukaryotes, mRNA must be exported to the _____ (where the ribosomes are) | Cytoplasm |
| In eukaryotes, the mRNA is extensively processed where? | Nucleus |
| In eukaryotes, mRNA processing includes... | Addition of 5' cap, polyadenylation of 3' end, splicing |
| Addition of a methyl guanine nucleotide to the 5' end of mRNA | 5' capping |
| In 5' capping, what is added to the 5' end of mRNA? | Methyl guanine nucleotide |
| What are the functions of the 5' cap? | Export from nucleus, stability, identification of transcript as mRNA, interaction with ribosome |
| Addition of adenine nucleotides to the 3' end of mRNA | Poly-A tail (polyadenylation) |
| In polyadenylation, what is added to the 3' end of the mRNA? | Adenine nucleotides |
| How many adenine nucleotides are usually in a poly-A tail? | A few hundred |
| What is the function of polyadenylation? | Export, stability, identification of transcript as mRNA |
| The coding region of genes (and therefore mRNAs) is interrupted by segments of non-coding sequence, also known as what? | Introns |
| Must be removed before mRNA can be translated | Introns |
| Coding regions of genes are called what? | Exons |
| The extent of the _____ sequence varies from gene to gene | Intron |
| The removal of introns from mRNA | Splicing |
| During splicing, _____ are cut out and _____ are re-joined | Introns, exons |
| Splicing is carried out by specialized enzymes called _____ that recognize "splice signals" in the mRNA sequence | snRNPs |
| Small nuclear ribonucleoprotein | snRNPs |
| Small nuclear ribonucleoproteins (snRNPs) consist of _____ and various proteins | snRNAs |
| Consists of snRNPs and some other proteins | Spliceosome |
| The RNA portion of snRNPs (the snRNAs) has the _____ function | Catalytic |
| Intron-exon _____ are marked by specific sequences that are recognized by splicing machinery | Junctions |
| Intron-exon junctions are marked by specific sequences that are recognized by splicing machinery; sequences present in BOTH the _____ and _____ are needed | Intron, exon |
| How do snRNPs recognize intron-exon junction? | Complementary base pairing |
| Loop-like structure produced by splicing (it's the intron after being removed) | Lariat |
| Splicing can produce several different _____ from a single gene | mRNAs |
| In splicing, all _____ will NOT be used to build the final mRNA | Exons |
| Splicing produces several different _____ from the same gene | Proteins |
| Exons generally specify _____ | Domains |
| Alternative splicing creates proteins with different combinations of functional domains; so, different combinations of _____! | Functions |
| Because the RNA does not form a duplex with DNA, multiple _____ can be produced simultaneously from a gene! (more than one polymerase on the DNA at a time) | Transcripts |
| In _____, regions of the DNA (genes) are transcribed into ss RNA | Transcription |
| Eukaryotic mRNAs are extensively processed before export to the _____ for translation | Cytosol |
| Splicing, capping, and polyadenylation take place where? | Nucleus |
| Splicing, capping, and polyadenylation take place _____ transcription is complete | Before |
| Technically, RNAs that have NOT yet been processed are termed what? | Pre-mRNAs |
| The export of mature mRNAs to the cytoplasm is mediated by what? | Nuclear pore complex |
| Mature mRNAs are marked by proteins bound to the... | Cap, poly-A tail, correct splice junctions |
| MRNA STABILITY: different mRNAs last for different amounts of time (before being _____) | Degraded |
| MRNA STABILITY: partially controlled by sequences in the what? | 3' UTR |
| MRNA STABILITY: highly expressed proteins are usually _____ _____ mRNAs | Long lasting |
| MRNA STABILITY: proteins with low level expression are usually _____ _____ mRNAs | Short lived |
| The genetic code - amino acids are specified by a three _____ code | Nucleotide |
| The sequence of nucleotides in an mRNA is read consecutively in groups of how many? | Three |
| Each triplet sequence that encodes an amino acid is a _____ | Codon |
| Three nucleotides are equal to one _____ _____ | Amino acid |
| How many possible codons are there? | 4^3 = 64 |
| How many different amino acids are there? | 20 |
| There is more than one _____ per amino acid | Codon |
| Who synthesized protein in a test tube from synthetic nucleotides? | Nirenberg, Leder, Matthaei |
| What is the start codon? | AUG (methionine) |
| What are the stop codons? | UAA and UAG (tyrosine), UGA (tryptophan) |
| RNA is read from _____ prime to _____ prime | 5', 3' |
| Start signal; aka start codon; aka initiation codon | AUG |
| Stop signals; aka stop codons; aka termination codons; aka nonsense codons | UAA, UAG, UGA |
| Stop codons do NOT encode for _____ _____ | Amino acid |
| The coding sequence begins after the _____ codon | AUG |
| The coding sequence stops after which codons? | UAA, UAG, UGA |
| Sequence of mRNA proceeding from a start codon to a stop codon (all in the same frame) | Open reading frame (ORF) |
| How long is the typical tRNA? | 80 nucleotides |
| Contains an anticodon that base-pairs with mRNA | tRNA |
| tRNA contains an _____ that base-pairs with mRNA | Anticodon |
| tRNA is "_____" with a specific amino acid | Charged |
| tRNAs interact with mRNA via what? | Complementary base pairing |
| The sequence within the tRNA that binds to the CODON (via complementary base pairing) | Anticodon |
| Adding correct amino acids to a tRNA molecule | Charging |
| Covalently attach the correct amino acid to the tRNA | Aminoacyl tRNA synthetases |
| How many different synthetases are in cells? | 20 (one for each amino acid) |
| Aminoacyl tRNA synthetases use _____ for energy | ATP |
| The HIGH ENERGY bond between the amino acid and the tRNA drives _____ synthesis | Protein |
| How many codons encode amino acids? | 61 |
| How many different tRNAs do humans have? | 48 |
| Some tRNAs recognize more than one _____ | Codon |
| Mismatch is permitted between THIRD codon position and FIRST anticodon position | Wobble base pairing |
| Each ribosomal subunit is constructed in the _____ | Nucleus |
| In ribosomal subunits, the RNA has the _____ function | Catalytic |
| What are the three steps of translation? | Initiation, elongation, termination |
| Initiation is a critical step because it specifies the correct _____ _____ | Reading frame |
| What is the last point at which the cell can decide whether or not to go through with translation? | Initiation |
| The speed of _____ determines speed of protein production | Initiation |
| What are the three things needed for initiation? | Small ribosomal subunit, initiator tRNA in P-site, initiation factors |
| Initiator tRNA associates with _____ | AUG |
| Initiator tRNA carries _____ | Methionine |
| Initiator tRNA binds to SMALL subunit along with other initiator proteins _____ it associates with RNA | Before |
| The initiation of translation is _____ in eukaryotes and prokaryotes | Different |
| In eukaryotic initiation of translation, one mRNA = how many open reading frames? | One |
| In prokaryotic initiation of translation, one mRNA = how many open reading frames? | More than one |
| What is another name for the A-site? | Aminoacyl tRNA site |
| What is another name for the P-site? | Peptidyl tRNA site |
| What is another name for the E-site? | Exit |
| There is no _____ that binds to stop codons | tRNA |
| A _____ _____ binds in the A-site and the whole complex will be released | Release factor |
| Polypeptide chain is removed from tRNA in P-site via reaction with _____ | Water |
| mRNA nucleotide sequence directs incorporation of specific amino acids to make proteins via _____ | Codons |
| tRNAs act as adaptors that ensure proper amino acid insertion via _____ | Anticodons |
| Translation is orchestrated and catalyzed by _____ | Ribosomes |
| Which subunit provides catalytic function? | Large subunit |
| Which subunit interacts with the mRNA? | Small subunit |
| Each mRNA will be translated by multiple _____ (called polyribosomes or polysomes) | Ribosomes |
| So, one mRNA will lead to the synthesis of many identical _____ | Polypeptides |
| Every aspect of translation is _____ at some level | Regulated |
| Make use of DIFFERENCES between eukaryotic and prokaryotic cells | Antibiotics |
| Frequently target the ribosome | Antibiotics |
| Enzymes that break down proteins | Proteases |
| A machine that breaks down proteins | Proteasome |
| Proteins are usually marked for proteasome by _____ | Ubiquitination |
| Many proteins require further modification to be _____ | Active |
Created by:
stephanielynhannigan