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Biology Test #4
| Question | Answer |
|---|---|
| Transcription | synthesis of RNA under direction of DNA |
| mRNA | carries genetic message from DNA to the protein synthesizing machinery of the cell |
| Translation | synthesis of polypeptide, which occurs under the direction of mRNA |
| Ribosomes | complex particles that facilitate the orderly linking of amino acids into polypeptide chains. |
| In eukaryotic cells, transcription occurs in the... | Nucleus |
| primary transcript | initial RNA transcript, also called pre-mRNA when transcribed from a protein-coding gene |
| triplet code | set of 3 nucleotide long words that specify the amino acids for polypeptide chains |
| template strand | DNA strand that provides the pattern, or template, for ordering the sequence of nucleotides in an RNA Transcript |
| Codon | 3-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code |
| Reading Frame | On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis |
| RNA polymerase | an enzyme that links ribonucleotides into a growing RNA chain during transcription |
| Promoter | a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place. |
| Terminator | In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detatch from the DNA |
| Transcription Unit | a region of DNA that is transcribed into an RNA molecule |
| What are the 3 stages of transcription? | initiation, elongation, and termination. |
| Transcription initiation complex | the completed assembly of transcription factors and RNA polymerase bound to a promoter |
| TATA box | A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex. |
| RNA processing | modification of RNA transcripts, including splicing out of introns, joining of exons, and alteration of the 5 prime and 3 prime ends |
| 5 prime cap | a modified form of guanine nucleotide added onto the nucleotide at the 5 prime end of a pre-mRNA molecul |
| poly-A tail | a sequence of 50 to 250 adenine nucleotides added on the 3 prime end of a pre-mRNA molecule |
| RNA splicing | after synthesis of a eukaryotic primary RNA transcripts, the removal of portions (introns)of the transcript that will not be included in the mRNA |
| introns | a noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed |
| exons | a sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed. |
| spliceosome | a large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons |
| ribozymes | an RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing |
| alternative RNA splicing | a type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons and which as introns |
| domains | a taxonomic category above the kingdom level. the three domains are archaaea, bacteria, and eukarya. also an independently folding part of a protein |
| tRNA (transfer RNA) | and RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA |
| anticodon | a nucleotide triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule |
| aminoacyl-tRNA synthetases | an enzyme that joins each amino acid to the appropriate tRNA |
| wobble | flexibility in the base-pairing rules in which the nucleotide at the 5 prime end of a tRNA anticodon can from hydrogen binds with more than on ekind of base in the third position (3 prime end) of a codon |
| Ribosomal RNA (rRNA) | the most abundant type of RNA, which together with proteins makes up ribosomes |
| P site (peptidyl site) | one of a ribosomes three binding sites for tRNA during translation. the P site holds the tRNA carrying the growing polypeptide chain. |
| A site (aminoacyl site) | one of a ribosomes three binding sites for tRNA during translation. the A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain |
| E site (exit site) | one of a ribosomes three binding sites for tRNA during translation. the E site is the place where discharged tRNA's leave the ribosome. |
| polyribosomes (polysomes) | a group of several ribosomes attached to, and translating, the same messanger RNA molecule. |
| signal peptide | a sequence of about 20 amino acids at or near the leading (amino)end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell |
| signal recognition particle | a protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER. |
| mutation | a change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. Mutations can also occur in the DNA or RNA of a virus |
| point mutations | a change in a gene at a single nucleotide pair |
| base-pair substitution | a type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides. |
| Missense Mutations | a base-pair substitution that results in a codon that codes for a different amino acid. |
| Nonsense Mutation | a mutation that changes an amino acid codon into one of the three stop codons, resulting in a shorter and usually nonfunctional protein. |
| Deletion | a deficiency in a chromosome resulting from the loss of a fragment through breakage. AND/OR a mutational loss of one ore more nucleotide pairs from a gene |
| Insertion | a mutation involving the addition of one or more nucleotide pairs to a gene |
| frameshift mutation | a mutation occuring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons |
| Mutagens | a chemical or physical agent that interacts with DNA and causes a mutation |
| Cell Division | the reproduction of cells |
| Cell Cycle- | an ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two; the eukaryotic cell cycle is composed of interphase |
| Genome | the genetic material of an organism or virus; the complete complement, of an organisms or virus’s genes along with its noncoding nucleic acid sequences. |
| Chromosomes | a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins. |
| Somatic Cells | any cell in a multicellular organism except a sperm or egg |
| Gametes | a haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote. |
| Sister Chromatids | either of two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids are eventually separated during mitosis or meiosis II |
| Centromere | the specialized region of the chromosome where two sister chromatids are most closely attached |
| Chromatin | the complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope. |
| Mitosis | process nuclear division in eukaryotic cells conventionally divided into 5 stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei |
| Cytokinesis | the division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II. |
| Meiosis | a modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with hald the number of chromosome sets as the original cell. |
| Mitotic (M) phase | the phase of the cell cycle that includes mitosis an cytokinesis. |
| Interphase | the period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the cell cycle. |
| G0 Phase | a nondividing state occupied by cells that have left the cell cycle. |
| G1 Phase | the first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins |
| S (synthesis) phase | the synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated |
| G2 Phase | the second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs. |
| Prophase | the first stage of mitosis, in which the chromatin condenses, the mitotic spindle begins to form, and the nucleolus disappears, but the nucleus remains intact |
| Prometaphase | the second stage of mitosis, in which discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosome |
| Metaphase | the third stage of mitosis, in which the spindle is complete and the r chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate |
| Anaphase | the fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell. |
| Telophase | the 5th and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun. |
| Mitotic Spindle | an assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis. |
| Centrosome | structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. A centrosome has two centrioles |
| Aster | a radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis |
| Kinetochore | a structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle. |
| Metaphase plate | an imaginary plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located. |
| Cleavage | The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. The succession of rapid cell divisions without significant growth during early embryonic development that converts the zygote to a call of cells. |
| Cleavage Furrow | The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate |
| Cell Plate | a double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis |
| Binary Fission | a method asexual reproduction by “division in half.” In prokaryotes, binary fission does not involve mitosis; but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process. |
| Origin of replication | site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides. |
| Checkpoint | a control point in the cell cycle where stop and go-ahead signals can regulate the cycle |
| Cell Cycle Control System | a cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle. |
| Cyclin | a cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle. |
| Cyclin-dependent kinase (Cdks) | a protein kinase that is active on when attached to a particular cyclin |
| MPF- maturation-promoting factor | a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase |
| Growth factor | A protein that must be present in the extracellular environment for the growth and normal development of certain types of cells. A local regulator that acts on nearby cells to stimulate cell proliferation and differentiation. |
| Density-Dependent inhibition | the phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with another one |
| Anchorage dependence | the requirement that a cell must be attached to a substratum in order to divide. |
| Transformation | the conversion of a normal animal cell to a cancerous cell. A chance in genotype and phenotype due to the assimilation of external DNA by a cell. |
| Metastasis | the spread of cancer cells to locations distant from the original site. |
| Describe the flow of genetic information in a cell, from DNA to protein. | DNA-info goes to, by transcription RNA, goes to by translation Proteins Perform its job/function in its correct location, either in or out of the cell. |
| Gene expression occurs in two major steps. What are these two steps? In a eukaryotic cell, where does each take place? | Translation, and transcription Transcription- carries code Translation- translates the code. Transcription takes place in the nucleus Translation takes place in the cytoplasm and Endoplasmic Reticulum |
| Draw a ribose and a deoxyribose sugar. What is the difference between these? Now draw the phosphate group and the base that are present when those sugars are part of nucleotides. Number the carbons of the sugar, and be sure to say why each is important! | the only difference between the 2 is carbon prime 2. Page 87. |
| What macromolecules make up chromosomes? Which of these stores and encodes the genetic information? | DNA, and protein DNA stores and encodes genetic information. |
| When we talk about anti-parallel strands of DNA, what does that mean? | One of the strands of DNA is flipped directionality, so 5 prime on the top of one strand and 3 prime at the bottom of one strand, would be 3 prime at the top of the other strand and 5 prime on the bottom of the other strand. |
| Describe the backbone of a strand of DNA. Is that backbone charged? If so, what is contributing to its charge, and is the charge positive or negative? | The backbone is composed of a phosphate group and a sugar. It is charged negatively because of the oxygens that are attached to the phosphate groups |
| If one strand of a DNA molecule has the sequence 5Õ A T G C T G A A 3Õ, write the sequence of the complementary strand | 3 T A C G A C T T 5 |
| What is a codon? Explain the triplet nature of the genetic code | A codon is a group of 3 nucleotides (base pairs) that code for an amino acid, or a “stop.” Triplet nature- several different codons can code for one amino acid |
| If I made a mutation in the promoter of a gene, such that ___________ can no longer bind to it, would it still be transcribed? Explain your answer | RNA polymerase. No it cannot still be transcribed because an RNA strand wouldnt be made. |
| What building blocks does RNA polymerase use to make RNA? | Cytosine, Adenine, Uracil, and Guanine |
| What are the three types of RNA? Which one is translated into protein? | rRNa, tRNA, mRNA rRNA- part of ribosome complex, so ribosome RNA mRNA- is translated into the protein, messenger RNA tRNA- Transfer RNA, transfer amino acids into polypeptides. |
| What happens at the promoter anyway? | RNA polymerase binds to it, and it also contains an operator which controls the access of RNA polymerase. |
| Which end of a pre-mRNA molecule ÒgrowsÓ during the elongation phase of transcription? (the 5Õ end or the 3Õ end?) | the 3 prime end grows during the elongation phase |
| What is the function of the transcriptional terminator? How is this different than the function of a stop codon? | terminator tell RNApolymerase fall off DNA strand & release mRNA.Terminator deals w/ DNA strand.Stopcodon 3nucleotides, stops+of aminoacids by prevent tRNA brought in,once stop codon hit it releases a ribosome.Stop codon deal with ribosome,in translation |
| Describe the processing that occurs for eukaryotic transcripts. Be sure to include the end modifications (and their function), as well as what happens ÒinternallyÓ within a transcript. | mRNA is released from the DNA strand, and then goes through RNA processing which removes the introns from the mRNA, but caps it with a 5 prime cap, and it adds a poly A tail. |
| Is there DNA that encodes (is complementary to) the poly(A) tail? Explain your answer. | No, because it was not part of the DNA. It wasnt transcribed from the original DNA strand, it was added during RNA Processing. |
| Are exons or introns included in the mature mRNA for a eukaryotic gene? | Exons are included, introns are not, they are removed during RNA processing. |
| In a euk cell, where is the DNA stored? a. the cell membrane b. ribosomes c. nucleus d. nucleoid | nucleus |
| Which enzyme acts in the mouth to digest polysaccharides? | amylase |
| DNA is a polymer of a. amino acids b. nucleotides c. fatty acids d. monosaccharides | nucleotides |
| Which bonds hold the 2 DNA strands in a DNA molecule together? a. ionic b. polar covalent c. nonpolar covalent d. hydrogen | hydrogen |
| Which pair is held together tighter in a DNA molecule? a. A & T b. A & C c. G & A d. G & C | A & T |
| A DNA strand has the sequence ATGCCT- what is its complement? a. TCCGTA b. AGGCAT c. TACGGA d. ATGCCT | TACGGA |
| Going from DNA to mRNA is a. translation b. transcription | transcription |
| The phosphate group is attached to a. C#5 b. C#2 c. C#1 d. C#3 | C#5 |
| Which C of the sugar tells you ribose vs deoxyribose? a. 1 b. 2 c. 3 d. 4 e. 5 | 2 |
| Which C of the sugar has the base? a. 1 b. 2 c. 3 d. 4 e. 5 | 1 |
| The promoter is made of a. DNA b. mRNA c. rRNA d. protein | DNA |
| What is at the 3Õ end of a eukaryotic transcript? a. a modified G cap b. a poly(A) tail c. a promoter d. both a & b | a poly(A) tail |
| What is the function of the transcriptional terminator? How is this different than the function of a stop codon? | Transcriptional terminator- its what release the RNA, has anti codon complementary to the stop codon. Stop Codon- The stop codon is what brings in the transcriptional terminator. |
| What is a codon? Do all codons specify an amino acid? | A codon is a sequence of 3 nucleotides. All codons don’t code for an amino acid, a stop codon is not an amino acid, but a start codon is an amino acid. |
| In a eukaryotic cell, where does translation happen | Ribosomes |
| There are three types of RNA. Now that you know about translation, explain the role of each type of RNA in translation. | tRNA- transfer RNA, brings in new amino acids mRNA- message RNA, what comes out of nucleus and codes for what needs to be made rRNA- ribosomal RNA, what makes up ribosomes. |
| Describe (in words or with a quick sketch) the structure of a tRNA molecule. Be sure to indicate where it interacts with the mRNA and where the amino acid is attached. | it looks like a clover. the amino acid is attached at the top, and the anti codon is at the bottom, it interacts with mRNA at the bottom, where the anticodon is |
| Which specifies the amino acid brought into the ribosome: the tRNA anticodon or the mRNA codon? | mRNA |
| So if a tRNA has an anticodon of GUA, what is the amino acid carried on that tRNA? | CAU, which would be histonine |
| Briefly explain what happens at each of the P, E and A sites of a ribosome. (and be sure you are familiar with the general structure of a ribosome!) | P site- peptidayl site, builds the amino acid, where actual linking occurs. A site- attachment site, where codon and anti codon form a hydrogen bond. E site- exit site, where tRNA leaves. |
| Describe (words and draw) the initiation complex for translation. (Be sure you can also still describe how initiation of transcription occurs!) | Start codon, figure 17.17 |
| Be sure you can explain HOW the peptide bond formation process occurs, and what is being transferred from one tRNA to another in the process. | the tRNA comes in with its amino acid, and transfers it to the polypeptide, hydrolysis is brought in to release the tRNA. |
| What happens when a stop codon arrives in the A site? Is there a corresponding tRNA? | In brings in a release factor, and the release factor breaks apart the ribosome. No, there is no corresponding tRNA. |
| For each of the following protein destinations, group them according to which ÒpathwayÓ (e.g. bound or free ribosomes/ endomembrane/cytoplasm) they will follow in terms of protein localization (so put them together in the proper groupings) | Free ribosome- stays in cell, in the cytosol/cytoplasm -nucleus -cytoplasm -mitochondria Bound ribosome- leaves the cell, in the endomembrane. -cell membrane -secreted out of the cell -ER -lysosome |
| What is a KDEL sequence? | directs protein, tells it whether its going to stay in the ER (endoplasmic reticulum) |
| Predict the location of a GFP that has only a SS- | would be bound. would go all the way through secretion, leave the cell. |
| Predict the location of a GFP that has only a KDEL (but no SS) | Free ribosome, would be in cytoplasm. |
| Predict the location of a GFP that hasboth a SS and a KDEL-bound | would be in ER (endoplasmic reticulum) |
| Predict the location of a GFP that has a SS and a mutated KDEL- | Bound, would be secreted all the way out of the cell. |
| What part of the tRNA binds to the codon? a. 3Õ end b. anticodon c. promoter | anticodon |
| What type of bonding occurs between the codon and the anticodon? a. peptide b. hydrogen c. ionic d. covalent | hydrogen |
| After translation, what has to happen? a. protein has to fold b. protein has to be targeted to its final location c. protein may have to have oligosaccharides added to it d. all of the above | all of the above |
| Where does RNA polymerase work? a. nucleus b. cytoplasm c. mitochondria d. cell membrane | nucleus |
| Where does cytochrome c oxidase work? a. nucleus b. cytoplasm c. mitochondria d. cell membrane | mitochondria |
| Which would be secreted out of the cell? a. cytochrome c oxidase b. RNA polymerase c. insulin d. histones | insulin |
| Endomembrane system order is... | Er to Golgi to vesicles, then secreted out of the sell. or the lysosomes, but they have to have the sequence to get to the lysosomes. |
| proteins are made in... | ribosomes |
| What kinds of modifications can happen to proteins as they pass through the ER and the Golgi? Would RNA polymerase ever pass through the ER and Golgi? Is RNA polymerase involved in transcription or translation? What does it actually do. | can obtain structure,carb can attach to protein,can obtain a monosphosphate,the+of monophophate can make it go to lysosome.RNApolymerase never pass through the ER or the Golgi.RNA polymerase involved in Transcription.RNApolymerase makes next mRNA strand. |
| Which organelle is not working properly in children with I cell disease? Explain WHY that organelle is not working properly in children with I cell disease (what exactly is it failing to do in people with I cell disease?) | The organelle that is not working properly is the lysosome. The lysosome is not working because, of a defective phosotransferase , therefore causing the waste to exit the cell, causing a build up of waste material. |
| What does Signal Recognition Particle (SRP) bind to? What is the effect of this binding? | signal peptide, the effect of this is it brings it to the ER. |
| What signals that a protein should go to the lysosome? What happens in lysosomes? Why are lysosomes Òideally suitedÓ to carry out their role (why wonÕt lysosomal activity occur in the cytoplasm?) | A phosotransferase signals a protein to go to the lysosome, which is a signal that is in the Golgi. Breaks down proteins, which are waste most of the times, or it brings in proteins that act as enzymes to break down the waste. |
| What happens when a short stretch of amino acids is translated, and that stretch of amino acids contains an ER signal sequence? What if some of the leucines in that SS were replaced by histidines? What would happen to the localization of that protein? | translation stops,then signal-recognition particle(SRP)identifies sequence,then brings protein & ribosome to the(ER).Would go from being noncharged to charged.Would stay in the cytoplasm because its mutated cant be moved through the endomembrane system. |
| What is a ÒKDELÓ sequence? | directs protein, tells it whether its going to stay in the ER (endoplasmic reticulum) |
| Predict the location of a GFP that has only a SS- | would be bound. would go all the way through secretion, leave the cell. |
| Predict the location of a GFP that hasonly a KDEL (but no SS) | Free ribosome, would be in cytoplasm. |
| Predict the location of a GFP that has both a SS and a KDEL- | bound, would be in ER (endoplasmic reticulum) |
| Predict the location of a GFP that has both a SS and a mutated KDEL | Bound, would be secreted all the way out of the cell. |
| What is mitosis? How do the products of mitotic cell division compare to one another? How do they compare to the parent cell? Does that parent cell still exist? | Mitosis is the reproduction of cells, for things such as skin and hair. The products of mitotic cell are division identical to one another. Compared to the parent cell they have the same genetic material. No, that parent cell doesn’t exist. |
| What are the general steps that a cell needs to carry out in order to completely divide? | prophase, prometaphase, metaphase, anaphase, and telophase. And interphase, starts a G1 then to S, then to G2, then the cell divides. |
| During which stage of the cell cycle does a cell get a signal to divide? | It gets the signal to divide during, G1 |
| What is the difference between G1 and G0? b. What happens during each stage of interphase? (make sure you can put them in the correct order) | G1- is where it decides if its going to divide G0- is where the cell is a continual stage of maintenance. |
| A chromosome has replicated. What does it look like after replication? How does this compare to what it looks like prior to replication? | After replication it looks like an X rater than a single chromatid. Before it was a single strand of a chromatid. |
| centromere- | is a waistband, it is a sequence, it holds the chromosome together |
| promoter | a sequence, its the site where RNA polymerase binds to |
| terminator | a LARGE sequence, on DNA, stops the addition of nucleotides, or tells RNA polymerase to stop. |
| stop codon | a sequence, tells ribosome stops the addition of amino acids. |
| sister chromatid | its a protein and DNA, stores hereditary information |
| Cyclin dependent kinase(cdk) | protein, regulatory molecules that drive the stages of interphase. |
| What protein (or protein complex) is responsible for driving the cell to enter the next stage of the cell cycle? | Cyclin dependent kinase (cdk) |
| Describe the levels and activity of both cyclins and cdks at different stages in the cell cycle (in general terms). | The cyclin levels are low during the G1 phase and rise during the S and G2 phase and fall suddenly during M phase. Figure 12.17 |
| What does a kinase do? | it transfers phosphate groups, from one molecule to another one. |
| If p53 is technically a nuclear protein, is it translated on bound or free ribosomes? | Free ribosome |
| What is Li-Fraunemi syndrome? Why do people with Li-Fraunemi syndrome develop cancer at an early age? | It the mutation of the p53 gene, they die because the p53 gene cannot repair, or kill damaged DNA, so the damaged DNA continues to spread. |
| Chromosomes separate during a. mitosis b. G1 c. G2 d. cytokinesis | mitosis |
| A chromosome has two sister chromatids. The cell with that chromosome is most likely in a. G0 b. G1 c. G2 | G2 |
| The centromere is a. where RNA polymerase binds b. one of the two DNA molecules present in a replicated chromosome c. a DNA sequence at the constriction of a chromosome d. the specialized proteins that form the scaffold of the chromosome | a DNA sequence at the constriction of a chromosome |
| Which is an active kinase? a. cdk b. cyclin c. cyclin/cdk d. all of the above | cyclin/cdk |
| Normal cell with DNA damage.. a. keeps dividing (who cares) b. p53 remains unstable c. p53 is stabilized, goes to nucleus, mediates transcription, fix problem d. a & b | p53 is stabilized, goes to nucleus, mediates transcription, fix problem |
| ÒFixingÓ the problem a. pause and repair b. die c. what problem? Keep dividing anyway. d. a or b | pause and repair, and die |
| What would happen to a skin cell that LACKS p53 when its exposed to UV radiation? a.it would arrest until the DNA damage is repaired (good cell) b.it might die and peel off c.it would keep dividing, even in the presence of damaged DNA (cancer cell) | it would keep dividing, even in the presence of damaged DNA (cancer cell) |
| What happens if mutations convert some of the hydrophobic amino acids in an ER SS to hydrophilic or charged amino acids? | It would stop working, If you don't have a signal sequence it will either go to the nucleus, mitochondria or cytoplasm |
| Outline the steps that happen that allow a cell to pause, repair DNA &/or die in response to DNA damage. Hint: your answer should include terms like DNA repair genes, gene expression, p53, DNA damage checkpoint, phosphorylated p53 etc. | Gene expresion p53 to nucleus,helps expres gene.chekpoint chek 4 damaged DNA,that all protein r there it needs for synthesis, see if ready for next phase.If damaged,p53 transcribe DNArepair genes,to fix DNA damage.DNA damage bad=p53 activates suicide |
| Be sure you can find the 5, and 3 carbon of the sugar of a deoxyribonucleotide. What would be different if this were a ribonucleotide? Also be sure you can find the 5Õ end and 3Õ end of a single strand of DNA, and be able to say what you find at each end. | The 2 prime would be different, there would either be a hydrogen or an OH, not both. 5 prime end there would be a phosphate group. and 3 prime there would be have a hydroxyl group. figure 5.27 |
| Describe the structure of a DNA helix . What kind of bond is found between two nucleotides along the backbone? What is it formed between? | The backbone is composed of sugar phosphate groups and a deoxyribose. The bond that holds the strands together is hydrogen bonding. The bond found between two nucleotides is hydrogen bonding. Its formed between the 3 prime and 5 prime. |
| Why is a DNA molecule with a high GC content held together more strongly than a DNA molecule with a high AT content? | Because G and C have 3 hydrogen bonds, compared to A and T which only have 2 hydrogen bonds. |
| What role does helicase play in replication? a.joins Okazaki fragments on lagging strnd b.joins Okazaki fragments on leading str c.provides a 3ÕOH for DNA pol III to add nucleotides d.removes RNA primer e.separates two strands of DNA at replication f | it separates the two strands of DNA at the replication fork |
| Draw replication fork, show how the leading & lagging strands are being synthesized.Now draw same replication fork a little later on, show what happened on leading and lagging strands. do this again, but reverse your fork | draw |
| How is each Okazaki fragment made? (in what direction, continuously or discontinuously?) | Its made discontinuously |
| What enzyme Òjoins upÓ two Okazaki fragments? | ligase |
| Is there any RNA primer on the leading strand? Explain your answer. And what is the ÒpointÓ of having an RNA primer anyway? (i.e. why is a primer even needed?) | Yes, but just at the very start. Because its continuous, an RNA polymerase does not need to bind to the leading strand |
| What does Òsemi conservativeÓ mean? | half old DNA strand, half new DNA strand. |
| What type of nucleotide is added by DNA pol III, and what does it add to? | DNA is added by DNA polymerase 3, and it adds to both leading and lagging strands. |
| Describe a chromosome in a cell in G2 that is about to enter mitosis. | Its completely replicated, has 2 sets of chromosomes. |
| Why do chromosomes need to condense before anaphase of mitosis? | compacts them, starts to wrap around histones, and makes it easier to be pulled apart. |
| What is a spindle pole/centrosome- i.e. what does it ÒdoÓ for the spindle? | Spindle Pole sends out microtubules, which actually pulls apart the chromosomes, grabs at centromere and just pulls apar |
| Describe the structure of the mitotic spindle. How does the ÒarrangementÓ of microtubules in interphase compare to the ÒarrangementÓ of microtubules during mitosis? How do microtubules of the mitotic spindle interact with chromosomes ? | structure consists fibers made of microtubules & associated proteins. arrangement of microtubules in interphase are close together,but in mitosis they migrate opposite ends to pull chromosome apart. attach at the centromere and pull apart. figure 12.6 |
| We said that a DNA damage checkpoint acts during the cell cycle- review what happens at this checkpoint if DNA damage is present (not just outcomes, but the mechanism that leads to these outcomes). | It would phosphorylate p53 to come in and try to repair it, if damage is too great it will tell it to “die” apoptosis” |
| What is the difference between mitosis and cytokinesis? | Mitosis- is the separation of chromosomes Cytokinesis- splitting of the daughter cells. |
| Microtubules are made of a protein called tubulin. Microtubules are found in the cytoplasm. Is tubulin made on bound or free ribosomes? Does it have an ER SS? | Free, it doesn’t have a signal sequence. |
| DNA polymerase III works in the nucleus. Is it made on bound or free ribosomes? Does it have an ER SS? | Is a bound ribosome, so yes it does have an ER signal sequence. |
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tomtom90