Bio 160 Exam 3 Study Guide
Bio 160 Exam 3 Study Guide Bio 160
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This 13 page Study Guide was uploaded by Christina Bouchillon on Thursday March 31, 2016. The Study Guide belongs to Bio 160 at University of Tennessee - Knoxville taught by Dr. Madision in Spring 2016. Since its upload, it has received 108 views. For similar materials see Cellular and Molecular Biology in Biology at University of Tennessee - Knoxville.
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Date Created: 03/31/16
Exam 3 Study Guide Definitions you should memorize • Chromosome Genecarrying structure consisting of a single long molecule of doublestranded DNA and associated proteins (e.g., histones). Most prokaryotic cells contain a single, circular chromosome; eukaryotic cells contain multiple noncircular (linear) chromosomes located in the nucleus. • Sister chromatid The paired strands of a recently replicated chromosome, which are connected at the centromere and eventually separate during anaphase of mitosis and meiosis II. Compare with nonsister chromatids. • Centromere Constricted region of a replicated chromosome where the two sister chromatids are joined and the kinetochore is located. • Homologous chromosomes In a diploid organism, chromosomes that are similar in size, shape, and gene content. Also called homologs. • Histonesone of several positively charged (basic) proteins associated with DNA in the chromatin of eukaryotic cells • Nucleosomea repeating, beadlike unit of eukaryotic chromatin, consisting of about 200 nucleotides of DNA wrapped twice around eight histone proteins • Chromatinthe complex of DNA and proteins, mainly histones, that composes eukaryotic chromosomes. Can be highly compacted (heterochromatin) or loosely collected (euchromotin) • Spindle apparatus The array of microtubules responsible for moving chromosomes during mitosis and meiosis; includes kinetochore microtubules, polar microtubules, and astral microtubules. • Centrosomestructure in animal and fungal cells, containing two centrioles, that serves as a microtubule organizing center for the cell’s cytoskeleton and for the spindle apparatus during cell division • Centriolesone of two small cylindrical structures found together within the centrosome near the nucleus of a eukaryotic cell (not found in plants). Consists of microtubule triplets and is structurally identical with a basal body • Kinetochores A protein complex at the centromere where microtubules attach to the chromosome. Contains motor proteins and microtubulebinding proteins that are involved in chromosome segregation during M phase. • Cell plateA flattened saclike structure formed in the middle of a dividing plant cell from Golgi derived vesicles containing cell wall material; ultimately divides the cytoplasm into two separate cells. • Cleavage furrow A pinching in of the plasma membrane that occurs as cytokinesis begins in animal cells and deepens until the cytoplasm is divided into two daughter cells. • Haploid (1) Having one set of chromosomes (1n or n for short). (2) A cell or an individual organism with one set of chromosomes. • Diploid (1) Having two sets of chromosomes (2n). (2) A cell or an individual organism with two sets of chromosomes, one set inherited from the mother and one set from the father. • Polyploidythe state of having more than two full sets of chromosomes, either from the same species (autopolyploidy) or from different species (allopolyploidy) • Aneuploidy (adjective: aneuploid) The state of having an abnormal number of copies of a certain chromosome. • Ploidy The number of complete chromosome sets present. Haploid refers to a ploidy of 1; diploid, a ploidy of 2; triploid, a ploidy of 3; and tetraploid, a ploidy of 4. • Haploid number The number of different types of chromosomes in a cell. Symbolized as n. • Diploid number the number of chromosomes present in the body cells of a diploid organisms • Sex chromosomes Chromosomes that differ in shape or in number in males and females. For example, the X and Y chromosomes of many animals. • Autosomes Any chromosome other than a sex chromosome (i.e,. any chromosome other than the X or Y in mammals). • Gene A section of DNA (or RNA, for some viruses) that encodes information for building one or more related polypeptides or functional RNA molecules along with the regulatory sequences required for its transcription. • Allelea particular version of a gene • Unreplicated chromosome • Replicated chromosome • Bivalent The structure formed by synapsed homologous chromosomes during prophase of meiosis I. Also known as a tetrad. • Nonsister chromatidsThe chromatids of a particular type of chromosome (after replication) with respect to the chromatids of its homologous chromosome. Crossing over occurs between nonsister chromatids. Compare with sister chromatids. • Fertilizationfusion of the nuclei of two haploid gametes to form a zygote with a diploid nucleus • Zygotethe cell formed by the union of two gamates; a fertilized egg • Synapsis The physical pairing of two homologous chromosomes during prophase I of meiosis. Crossing over is observed during synapsis. • Chiasma (plural: chiasmata) The Xshaped structure formed during meiosis by crossing over between nonsister chromatids in a pair of homologous chromosomes. • Crossing over The exchange of segments of nonsister chromatids between a pair of homologous chromosomes that occurs during meiosis I. • NondisjunctionAn error that can occur during meiosis or mitosis, in which one daughter cell receives two copies of a particular chromosome and the other daughter cell receives none. • Dominant allele Referring to an allele that determines the same phenotype when it is present in homozygous or heterozygous form.. Compare with recessive. • Recessive allele Referring to an allele whose phenotypic effect is observed only in homozygous individuals. Compare with dominant. • Homozygous Having two identical alleles of a gene. • Heterozygous Having two different alleles of a gene. • Genotype All the alleles of every gene present in a given individual. Often specified only for the alleles of a particular set of genes under study. Compare with phenotype. • Phenotype The detectable traits of an individual. Compare with genotype. • Linked genes means that the genes are located on the same chromosome and inherited together. • Unlinked genes genes are located on different chromosomes and are not always inherited together. • Xlinked Inheritance patterns for genes located on the mammalian X chromosome. Also called Xlinkage. • Ylinked Inheritance patterns for genes located on the mammalian Y chromosome. Also called Ylinkage. • Autosomal The inheritance patterns that occur when genes are located on autosomes rather than on sex chromosomes. • Monohybrid crossa mating between two parents that are both heterozygous for one given pair • Dihybrid crossa mating between two parents that are heterozygous for two different genes • Testcross The breeding of an individual that expresses a dominant phenotype but has an unknown genotype with an individual having only recessive alleles for the traits of interest. Used to order to infer the unknown genotype from observation of the phenotypes seen in offspring. • Multiple allelism The existence of more than two alleles of the same gene. • Polymorphism(1) the occurrence of more than one allele at a genetic locus in a population (2) the occurrence of more than two distinct phenotypes of a trait in a population • Pleiotropythe ability of a single gene to affect more than one trait • Genebygene interaction one trait is influenced by the alleles of two or more different genes. • Genebyenvironment interaction an individual’s phenotype is often as much a product of the environment as it is the product of the genotype, the combined effect of genes and environment is know as genebyenvironment interaction. • Polygenic inheritance of quantitative traitshaving many genes influence one trait • Parental strand A strand of DNA that is used as a template during DNA synthesis. • Daughter strand The strand of DNA that is newly replicated from an existing template strand of DNA. • Semiconservative replication The way DNA replicates, in which each strand of an existing DNA molecule serves as a template to create a new complementary DNA strand. It is called semiconservative because each newly replicated DNA molecule conserves one of the parental strands and contains another, newly replicated strand. • Conservative replication the bases turn outward to serve as a template for the synthesis of an entirely new double helix all at once, which would result in an intact parental molecule and a daughter DNA molecule consisting entirely of newly synthesized strands. • Dispersive replication if the parental double helix were cut wherever one strand crossed over another and DNA was synthesized in short sections by extending each of the cut parental strand to the next strand crossover, so stretches of old DNA would be interspersed with new DNA down the length of each daughter strand. • Telomere The end of a linear chromosome that contains a repeated sequence of DNA. • Explain the five big ideas of biology (FBIs) and how they relate to what we have learned –Evolution: Populations of organisms have changed over time through both selective and nonselective evolutionary processes. –Structure and Function: All living systems (organisms, ecosystems, etc.) are made of structural components whose arrangement determines the function of the systems. –Information Flow and Storage: Information (DNA, for example) and signals are used and exchanged within and among organisms to direct their functioning. (mitosis&meiosis) –Transformations of Energy and Matter: All living things acquire, use, and release matter and energy for cellular / organismal functioning. –Systems: Living systems are interconnected, and they interact and influence each other on multiple levels. • Describe the roles of cell division in living organisms: responsible for reproduction of all organisms Meiosis single cell divides twice to produce 4 cells that contain half the original amount of genetic information= sex cells= egg and sperm (gametes) –daughter cells are genetically different from parent cell allows for genetic variation in population Mitosis process in which a eukaryotic cell nucleus splits in two, followed by division of the parent cell into two daughter cells. Daughter cells= genetically identical to parent cell • Describe each phase of interphase (#1) (“Between phase”) Cell cycle= G1 S G2 Mitosis (M phase)(cell division) growing/preparing to divide cells spend most of their time in interphase G1 phase (“growth 1”,“gap 1”) growth, new organelles made S Phase DNA is replicated (synthesized), occurs in nucleus G2 phase (gap 2) Growth and preparation for cell division • Describe and draw each phase of mitosis Mitosis division of nucleus, division of cytoplasm 2 sister chromatids separate to form independent daughter chromosomes 1 copy of each chromosome goes to each of the 2 daughter cells identical genetic information .(#2) Prophase chromosomes condense, spindle apparatus begins to form (#3)Prometaphase nuclear envelope breaks down. Microtubules contact chromosomes at kinetochores. (#4) Metaphase chromosomes complete migration to middle of cell (#5) Anaphase sister chromatids separate into daughter chromosomes and are pulled to opposite poles of the spindle apparatus (#6) telophase the nuclear envelope reforms, and chromosomes decondense • Compare the processes of cytokinesis in animal and plant cells Plants polar microtubules left over from spindle define the region where new plasma membranes will form vesicles from golgi apparatus carry components for new cell wall to middle of cell vesicles fuse to form cell plate cell plate grows and eventually fuses with existing plasma membrane divides into 2 daughter cells Animals begins with formation of cleavage furrow (ring of actin filaments form inside plasma membrane) myosin motor proteins bind to actin filaments and use ATP to contract which cause the filaments to “slide” ring shrinks and tightens and pulls membrane with it plasma membrane pinches inward, eventually pinches into 2 individual cells • Compare binary fission in bacterial cells to mitosis in eukaryotic cells 1.Binary fission occurs among prokaryotes (cells that do not contain a nucleus). 2.Mitosis occurs among eukaryotes (cells that have a nucleus). 3.Binary fission does not include spindle formation (mitotic apparatus) and sister chromatids in its process, making it a faster means of cellular division than mitosis. 4.Binary fission does not have the four distinct cellular phases (from G1 down to the final mitotic phase) that are seen in mitosis. • Explain the relationship between MPF and (1) cyclin, (2) Cdk, and (3) the enzymes that phosphorylate MPF, dephosphorylate MPF, and degrade cyclin MPF is a dimer that consists of a cyclin and a CDK it is turned on by phosphorylation and dephosphorylation at the activating site, and dephosphylation at the inhibitonary site Enzymes that degrade cyclin reduce MPF levels • Explain the G, G, 1nd 2 phase checkpoints Checkpoints points in cell cycle that allow a cell to “decide” whether to proceed with division G1 checkpoint Cell will pass checkpoint if: 1. cell size is adequate, 2. nutrients are sufficient, 3. social signals are present, & 4. DNA is undamaged G2 checkpoint (after s phase) cell will pass if: 1. chromosomes have replicated successfully, 2. DNA is undamaged, 3. activated MPF is present M phase checkpoint cell passes checkpoint if: 1. chromosomes have attached to spindle apparatus, 2. chromosomes have properly segregated and MPF is absent • Explain how defects in cell cycle regulation leads to cancer Cancer occurs in cells when cellcycle checkpoints have failed defects that make the proteins required for cell growth active when they shouldn’t be defects that prevent tumor suppressor genes from shutting down the cell cycle • Explain how the G checkp1int is subject to social control social control when cells divide in response to signals from other cells (best interest of individual) G1 phase “decides” to continue cell division only when cell is correct size Cancer cells have broken down the social controls of G1 checkpoint • Describe the roles of meiosis Meiosis single cell divides twice to produce 4 cells that contain half the original amount of genetic information= sex cells= egg and sperm (gametes) –daughter cells are genetically different from parent cell allows for genetic variation in population responsible for sexual reproduction • Explain how genetic variation arises from meiosis and fertilization Genetic variation is caused by “crossing over” (in prophase I) crossing over is the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring. causes new combinations of alleles within a chromosome different of that of the parent • Describe and draw the key events of each phase of meiosis (#1) Interphase uncondensed chromosomes replicate in parent cell (#2) Early Prophase I chromosomes condense, spindle apparatus forms, nuclear envelope begins to break down. pairing of homologous chromosomes (#3) Late prophase I multiple crossover points visible, nuclear envelope is broken down (#4) Metaphase I migration of bivalents (4 chromatids from 2 homologous chromosomes) to middle of cell is complete (#5)Anaphase I homologs separate and begin moving to opposite poles of the spindle apparatus (#6) Telophase I and cytokinesis chromosomes move to opposite poles of spindle apparatus; apparatus disassembles (#7) Prophase II spindle apparatus forms (#8) Metaphase II chromosomes line up at the middle of the spindle apparatus (#9) Anaphase II sister chromatids separate, begin moving to opposite poles of spindle apparatus (#10) Telophase II and cytokinesis chromosomes move to opposite poles of the spindle apparatus; apparatus disassembles • Compare meiosis and mitosis • Interpret a karyotype Karotype the number and visual appearance of the chromosomes in the cell nuclei of an organism or species. A regular human cell has 46 chromosomes: 44 autosomes, which come in pairs, and 2 sex chromosomes, which specify gender (XX for female and XY for male). The pairs of autosomes are called "homologous chromosomes." One of each pair came from mom and the other came from dad. Can be used to diagnose genetic disorders (ex down syndrome) • Explain when nondisjunction can occur occurs where chromosome pairs fail to separate properly during meiosis I (homologous chromosomes) or meiosis II (sister chromatids) • Describe the possible consequences of nondisjunction in autosomes and sex chromosomes during meiosis in humans mistakes in meiosis are leading cause of miscarriages Down syndrome trisomy of chromosome 21 (trisomy, most common to be viable in humans) Klinefelter syndrome XXY, XXYY, XXXY OR XXXXY Turner syndrome XO (1 sex chromosome, female) • Determine whether nondisjunction occurred during meiosis I or meiosis II and in which parent nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell = 2 gametes with n + 1 chromosomes and 2 gametes with n− 1 chromosomes A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell = 2 gametes that are normal, one with n − 1 chromosomes, and one with n + 1 chromosomes, • Explain why nondisjunction in meiosis occurs more frequently in women than men The difference between female oogenesis and male spermatogenesis is the prolonged halt of oocytes in late stages of prophase I for many years up to several decades. Male gametes on the other hand quickly go through all stages of meiosis I and II. Another important difference between male and female meiosis concerns the frequency of recombination between homologous chromosomes: In the male, almost all chromosome pairs are joined by at least one crossover, while more than 10% of human oocytes contain at least one bivalent without any crossover event. • Compare and contrast asexual and sexual reproduction • Predict whether, in a species that alternate between asexual and sexual reproduction, sexual reproduction occurs during times when environmental conditions are stable or times when conditions change rapidly stable conditions asexual reproduction unstable conditions sexual reproduction • Define and distinguish between complete dominance, incomplete dominance, and codominance Codominance both alleles are equally dominant and both alleles are visible in the hybrid genotype (AB bloodtype) Incomplete dominance one allele is PARTIALLY dominant to the other, heterozygous offspring have phenotype that is a mixture of the dominant and recessive phenotypes (red flower RR+ white flower rr= pink flower Rr) • Calculate probabilities of genotypes and phenotypes from a particular cross G g G GG Gg g Gg gg • Determine genotypic and phenotypic ratios from a particular cross 25% GG, 50% Gg, 25% gg • Explain why crossing over is said to break up linkage between alleles During meiosis, exchange of parts between homologous chromosomes breaks linkages between parietal chromosomes and forms recombinants with new allele combinations • Describe the structure of DNA Double helix antiparallel sugar phosphate backbone along exterior bases point inwards (A&T, C&G) • Describe the experiments and be able to interpret the results from the experiments that showed that DNA is the hereditary material and that DNA replication is semiconservative Hershey and Chase DNA replication is semiconservative because each helix that is created contains one strand from the helix from which it was copied. The replication of one helix results in two daughter helices each of which contains one of the original parental helical strands. • Write a sequence of doublestranded DNA that is 10 base pairs long, separate the strands, and without comparing them, write in the bases that are added during DNA replication 5’ CGGTAGATCG 3’ 5’ GCCATCTAGC 3’ • Draw and label a diagram of a replication bubble that shows (1) 5’ à 3’ polarity of the two parental DNA strands and (2) the leading and lagging daughter strands at each replication fork • Describe the process of DNA replication including the following terms: DNA polymerase I removes short RNA primer and replaces with a DNA nucleotide (on lagging strand) DNA polymerase III does initial synthesis, binds new RNA primer (on leading and lagging strands) dNTPs Deoxyribonucleotide triphosphate. A generic term referring to the four deoxyribonucleotides: dATP, dCTP, dGTP and dTTP. origin of replication where replication is initiated replication bubble setting of new DNA replication replication fork The point at which the two strands of DNA are separated to allow replication of each strand DNA helicase breaks hydrogen bonds between nucleotides SSBPsprevents hydrogen bonding from reoccurring keeps it a single strand Topoisomerase prevents twisting of the DNA that is ahead of replication fork leading strand strand of DNA that is being replicated continuously lagging strand requires a slight delay before it is replicated, and it must be replicated discontinuously in small fragments. Primer A primer is a strand of short nucleic acid sequences (generally about 10 base pairs) that serves as a starting point for DNA synthesis. Primase type of RNA polymerase that adds a short segment of RNA (to “prime it”) Okazaki fragments short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication DNA ligase joins pieces of DNA together and closes gap where the primer was removed sliding clampholds DNA polymerase in place during DNA synthesis • Describe the role of telomerase it catalyzes the synthesis of DNA from an RNA template that it contains adds DNA onto the end of a chromosome to prevent it from getting shorter • Compare proofreading, mismatch repair, and nucleotide excision repair 1proofreading When an incorrect base pair is recognized, DNA polymerase reverses its direction by one base pair of DNA and removes the mismatched base. Mismatch repair when mismatched bases are corrected after DNA synthesis is complete Nucleotide excision repair fixes thymine dimers and many other types of damage that distort the DNA helix • Explain the logical connections between failure of repair systems, increases in mutation rate, and high likelihood of cancerdeveloping - if errors in dna are not corrected they represent mutations. When DNA repair systems fail the mutation rate increases. As the mutation rate increases the chance that one or more cell cycle genes will be mutated increases. Mutations in these genes often result in uncontrolled cell division ultimately leading to cancer.
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