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chapt 18 group stack
| Question | Answer |
|---|---|
| Why is condensation of the chromosomes before cell division VERY important? (DNA Packaging p-4) | The chromosome would be hard to manipulate. |
| Where does DNA "live" and package? (DNA Packaging p-4) | DNA lives in the nucleotide region within a chromosome. |
| What is a chromatin a combination of? (DNA Packaging p-4) | A chromosomes combination of histone proteins and DNA is referred to as chromatin. |
| What is H1 necessary for? (DNA Packaging p-4) | H1 is needed to hold together pericentric heterochromatin, the chromatin region which is close to the center of each chromosome. If cells are deprived of H1 then more heterochromatin is diffused. H1 also helps to regulate the given genes. |
| Name the steps of DNA packaging. DNA Packaging p-4) | 1. Double-stranded DNA wraps around each of the 8 histones 2 times, which forms the nucleosome. 2. Forms Chromatin fibers: coils of nucleosomes. 3. Chromatin fibers are condensed into chromosomes during cell division. |
| What is Euchromatin? (DNA Packaging p-4) | Euchromatin is a lightly packed form of chromatin and is rich in gene concentration. |
| What is the main difference between Euchromatin and Heterochromatin? (DNA Packaging p-4) (DNA Packaging p-4) | Euchromatin is found in both cells with nuclei (Eukaryotes) and cells without nuclei (prokaryote) and is lightly packed, while heterochromatin is only found cells with nuclei (eukaryote), and is tightly packed. |
| What are proto-ocogenes? | version of cellular genes that code for proteins that stimulate cell growth and division |
| What are ocogenes? | cancer causing genes |
| What is p53? | a tumor-suppressor gene, promotes the synthesis of cell cycle-inhibiting protein |
| What is the ras gene? | (rat sarcoma) a G protein that relays a signal from a growth factor receptor on the plasma membrane to protein kinases |
| What are predispositions? | APC allele for colorectal cancers and BRCA2 or BRCA1 for breast cancer |
| What are tumor suppressor genes? | encode proteins that prevent uncontrolled cell growth |
| Who is Peyton Rous? | discovered a virus that causes cancer in chickens |
| What are three genetic changes that make a proto-oncogene into a oncogene? | translocation, amplification, point mutation |
| What is an example of a tumor suppressor gene? Period 6 | P53; A cell that promotes the synthesis of cell cycle-inhibiting proteins. Without this gene, there would be excessive cell growth, which will lead to cancer. |
| What is an oncogene? Period 6 | An oncogene is a cancer-causing gene. |
| What is predisposition? Period 6 | When genetic changes occur to produce a cancer cell. This is why cancer may run in families. |
| What is one cause of predisposition? Period 6 | An individual inheriting an oncogene. |
| What are three things that can lead to cancer-causing mutations? Period 6 | X-Rays, chemical carcinogens, and certain viruses. |
| What is one way a proto-oncogene can become an oncogene? Period 6 | Possible answers include a point mutation (when a single nitrogen base is changed, which may change the protein made) in a control element or within the proto-oncogene, amplification of a proto-oncogene, or the movement of DNA within the genome. |
| What is the multistep model of cancer development? Period 6 | These are the genetic steps needed to produce a cancer cell. Multiple mutations are needed for the abnormal growth of cells. |
| How can viruses contribute to cancer development? Period 6 | Viruses may integrate their genetic materials into the DNA of cells, leading to abnormal growth. |
| Why are operons and feedback inhibition advantageous to prokaryotes? (Transcription control in prokaryotes PD 6) | It allows prokaryotes to save energy and resources by only producing enzymes when needed. |
| (4) What is the significance of genetic variation? | The diversity of alleles of genes within a population allows for natural selection and therefore evolution |
| (4) What is random fertilization? | The random genetic makeup of a zygote resulting from pairing up 1 of the 8.4 million possible chromosome combinations of a sperm with 1 of the 8.4 million possible chromosome combinations of the egg, due to independent assortment. |
| (4) What are mutations and why are they important? | A change in genetic material that usually results from an error in DNA replication. These changes can be harmful or helpful to the individual. Mutations a large source of genetic variation and can lead to evolution. |
| (4) What is independent assortment of chromosomes? | It allows for multiple combinations of different chromosomes, due to the various arrangements of chromosomes on the metaphase palte during mitosis I of meiosis |
| (4) What is crossing over? | The exchange of corresponding genetic material between nonsister chormatids in homologous pairs |
| (4) What is synapsis? | The process in which the replicated homologous pair of chromosomes comes together |
| (4) What is a chiasma? | the site at which crossing over occurs |
| (4) What are recombinant chromosomes and how are they created? | the chromosomes with sections of maternal and paternal DNA. This is the result of crossing over. |
| Name one of the five different histone types that are used in DNA Packaging. | H2A, H2B, H3, H4 or H1 |
| What makes up a nucleosome? | 1 of each of the four histone types: H2A, H2B, H3, H4 |
| What are loop domains? | the structure of the fibers in chromatid. It consists of a chromatin fiber looped around itself to be made thicker. |
| Does the amino end of a histone point out of a nucleosome or in? | it points out in order to allow the nucleosomes to bind with each other in later steps. |
| (6) What are the three mechanisms that contribute to the genetic variation in sexual reproduction? | Independent assortment, crossing over, and random fertilization |
| (6)What is the importance of having genetic variation? | natural selection, evolution, and each organism having unique traits. |
| (6)What are recombinant chromosomes? | The product of crossing over, a chromosome containing both maternal and paternal genes |
| (6) Where and when does crossing over take place? | In prophase 1 of meiosis, at the chiasma, or "X" shape connection between sister chromatids |
| (6)Through the fusion of male and female gametes, what is the number of possible diploid combinations? | 70 trillion |
| (6)What is the key factor that determines the "success" of the outcome of genetic variation | the enviornment |
| (6) | |
| (6) | |
| 6th Q4 Why do transcription regulating bacteria cells have an advantage over those that don't? (A.S., H.Q., N.S.) | They can conserve resources and energy that would be wasted otherwise. |
| 6th Q4 In what two ways is the metabolic pathway that creates tryptophan regulated.(A.S., H.Q., N.S.) | Metabolic control of tryptophan occurs by feedback inhibition and operons regulating expression of genes. |
| 6th Q4 Why is coordinate control of related genes advantageous? (A.S., H.Q., N.S.) | Grouping functionally related genes is advantageous because the whole cluster only requires one on-off switch. |
| 6th Q4 What is the on-off switch part of the gene called? (A.S., H.Q., N.S.) | The on-off switch is called the operator. |
| 6th Q4 Where is the operator located in relation to the promoter? (A.S., H.Q., N.S.) | The operator is inside or immediately after the promoter. |
| 6th Q4 What is the difference between an operator and an operon?(A.S., H.Q., N.S.) | The operator is the on-off switch, whereas the operon is the cumulative of the promoter, the operator and the genes. |
| 6th Q4 Explain how the trp operon, the first of its kind discovered, a repressible operon. (A.S., H.Q., N.S.) | A product, of the seperate gene trpR, called trp repressor is initially off. Trp repressor itself is turned on by tryptophan and then binds to the operator and turns the operator off. |
| 6th Q4 Explain how the lac operon is a inducible operon. (A.S., H.Q., N.S.) | Lac operon's repressor, in contrast to trp operon's, is initially active and deactivates the operator. Then when allolactose binds with the repressor, the repressor is deactivated and the operator is switched on. |
| 4th: What three things make up the operon? | The operator, promoter, and DNA |
| 4th: Why is the operator known as the "on/off" switch? | It can disable transcription to occur |
| 4th: How do operons use homeostasis? | The operons use feedback loops to regulated the output of genes to react to environmental changes. |
| 4th: What is an example of negative feedback loop with tryptophan? | The repressor binds to the operator and blocks transcription, when tryptophan can activate the repressor by allosteric control. |
| 4th: What does the trp operon make? | It makes the amino acid found in bacteria, called tryptophan. |
| 4th: What does the lac operon make? | It make lactase, which is needed to make lactose. |
| 4th: Why must glucose levels be low? | For the lac operon to become active. |
| 4th: What must bind to DNA and RNA in order for transcription to occur? | The promoter |
| What is an activator? (period 4, t2) | a protein that binds to DNA and stimulates gene transcription. |
| 4th The point at which nonsister chromatids are crossed to exchange corresponding sections of DNA | chiasma |
| 4th 1.hromosomes that contain sections of DNA from more than one direct source | recombinant chromosomes |
| 4th The exchange of genetic material betweenhomologous pairs | 1.crossing over |
| 4th It allows for multiple combination of different chromosomes, due to the various arrangements chromosomes had have during mitosis I of meiosis | 1.independent assortment of chromosomes |
| 4th.The random combination of gametes resulting from pairing up 1 of the 8.4 million possible chromosome combinations of a sperm with 1 of the 8.4 million possibly chromosome combinations of the egg, due to independent assortment. | random fertilization |
| 4th . A change in genetic material that usually results from an error in DNA replication. These changes can be harmful or helpful | mutation |
| 1.The diversity of alleles of genes within a population | genetic variation |
| 1.The process in which the replicated homologous pair of chromosomes comes together | synapsis |
| P6 T4 Why is using operons advantageous to prokaryotes? (SD, HL, AS) | It allows them to only make enzymes when needed, therefore they conserve energy and resources. |
| P6 T4 What is a key advantage of grouping genes of related function into one transcription unit? (SD, HL, AS) | A single on/off switch (the operator) can control the whole segment of those genes. |
| P6 T4 What does it mean that the binding of repressors to operators is reversible? (SD, HL, AS) | The operator vacillates between two states: one w/o the repressor bound and one with the repressor bound, and the duration of each state depends on the number of active repressors around the operator. |
| P6 T4 What is a corepressor? (SD, HL, AS) | A small molecule that cooperates with a repressor protein to switch an operon off. |
| P6 T4 What is an example of how gene expression can respond to changes in the cell's internal environment related to the trp operon? (SD, HL, AS) | As tryptophan accumulates, more tryptophan molecules bind to trp repressors, which can then bind to the operator and shut down the production of enzymes. If the cell's tryptophan level is lower, than the trasncription of the operon's genes resumes. |
| P6 T4 What is the main difference between a repressible operon and an inducible operon? (SD, HL, AS) | In repressible operons a corepressor binds to the repressor, which turns off transcription whereas in a inducible operon, an inducer binds to the repressor, inactivates it, and turns on transcription |
| P6 T4 Do inducible enzymes function in catabolic or anabolic pathways? Repressible enzymes? (SD, HL, AS) | Inducible enzymes function in catabolic (break down things) pathways while repressible enzymes usually function in anabolic pathways (synthesize products). |
| P6 T4 When is gene regulation said to be positive? (SD, HL, AS) | When a regulatory protein interacts directly with the genome to switch transcription on. |
| What are histones? | Histones are proteins that are responsible for the first level of DNA packing in chromatin. They bind to the DNA. |
| What are nucleosomes? | Nucleosomes (beads on a string) are the combination of Histones and DNA wrapped together. |
| What is heterochromatin? | Tightly wound up chromatin which are temporarily not functional |
| What is euchromatin? | Less compacted, more dispersed chromatin which is functional. |
| How many histones are in one nucleosome? | eight |
| Does the amino end of a histone extend outward or inward from the nucleosome? | outward |
| What is a nucleoid? | The dense region of DNA in a bacterium that is not bounded by membrane. |
| What is chromatin? | The complex of DNA and protein. |
| Why is chromatin packing important? | Chromatin packing is important because it condenses the genetic material so it is safer and easier to move and divide. |
| What is an acetyl group (p4, T2) | -coch3 |
| Histone Aceetylation (p4, T2) | The attachment of acetyl groups to certain amino acids of histone proteins |
| Genomic Imprinting (p4,t2) | A phenomenon in which expression of an allele in offspring depends on whether the allele is imprinted from the male or female parent |
| Transcription Factor (p4,t2) | A regulatory protein that binds to DNA and affects transcription of specific genes |
| Enhancer (p4,t2) | A segment of eukaryotic DNA containing multiple control elements, usually located far from the gene whose transcription it regulates |
| Epigenetic Inheritance (p4,T2) | Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome |
| DNA Methylation (p4,t2) | Addition of methyl group causing gene inhibiton |
| Feedback inhibition shuts down the synthesis of what? | tryptophan |
| What is coordinate control? | it is when a single on/off switch can control the whole cluster of related genes |
| The on/off switch is a segment of DNA called? | an operator |
| RNA polymerase can bind to the promoter to do what? | to transcribe the genes for the operon to turn it on |
| What is a repressor? | a protein used to switch off RNA polymerase |
| A inducible operons is usually in what state? | an inactive state |
| In plants and some algae, how many times will the cell undergo mitosis? | 3 |
| What is the diploid stage in alteration of generations? | sporophyte |
| What is the haploid stage in alteration of generations? | gametophyte |
| Why is the life cycle of plants and some algae called alteration of generations? | Because the cells switch between sporophytes and gametophytes to produce the next generation of organisms. |
| Where is the only diploid stage found in fungi and most protists? | the single celled zygote |
| Of the three types of cycles, what is the common result? | Variation among offspring |
| What maintains a constant number of chromosomes for the next generations? | The alternation of fertilization and meiosis |
| What is the characteristic of the life cycle in animals? | Gametes are the only haploid cells |
| By what process does the fungi become a multicellular haploid organism p6 | Meiosis, then mitosis |
| In which life cycle is the organism mostly diploid? p6 | Animal Life Cycle |
| How do fungi increase genetic variation? p6 | By forming gametes by mitosis |
| Which stage is the dominant stage in the alternation of generations? p6 | TRICK QUESTION. It depends on the species |
| How does the sporophyte enter the gametophyte generation p6 | diploid sporophyte performs meiosis to make haploid spores |
| How is the animal life cycle different than the fungus life cycle? p6 | Fungus: primarily haploid Animal: Primarily diploid Also, Fungus can be unicellular |
| How does the gametophyte become a sporophyte? p6 | It produces gametes through mitosis that then combine during fertilization to form a diploid zygote |
| Can haploid cells perform meiosis? p6 | No |
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hamesapbio