BSC2011 Summer 2013 Exam 2 Study Guide 1 Describe a duplicated or replicated chromosome Replicated Chromosome 2 sister chromatids joined at a centromere o Joined by cohesin proteins 2 To what does the cell cycle refer and what events stages steps etc are involved Cell Cycle The series of events that take place in a cell leading to its division and duplication replication Two parts o The cell cycle creates new cells allows cells to grow o Cell growth o Mitotic cell division 3 Why do cells organisms need to regulate or control the cell cycle 1 BSC2011 Summer 2013 Exam 2 Study Guide Make sure that the cells are developing functioning properly Get rid of old damaged diseased malfunctioning cells 4 How do cells organisms regulate or control the cell cycle Explain the role of checkpoints Explain the chemical control system that gets cells through the G2 checkpoint Cell cycle regulated by molecular signals in the cytoplasm checkpoints Three major checkpoints G1 G2 and M checkpoints The presence or absence of specific chemical signals determines whether a cell stops or proceeds through a checkpoint in the cell cycle G1 Restriction Checkpoint o Signals determine whether the cell A Pauses enters G0 where the cell hangs out and does the job it was intended to do B Passes the G1 checkpoint and enters S synthesis C Passes the G1 checkpoint and undergoes apoptosis cell death G2 Checkpoint o Cell assess if preparations are ok o o Maturation Promoting Factor MPF A particular cyclin Cdk complex If yes signals direct the cell to enter M mitotic phase needed to get through the G2 checkpoint Cyclin is gradually synthesized during S and G2 Cyclin concentration high enough binds to is activated by a particular Cdk protein complex now called MPF MPF signal moves the cell through the G2 checkpoint into mitosis MPF NOT at G1 checkpoint M Checkpoint o Cell assesses if mitosis proceeded successfully o If yes signals direct the cell to enter cytokinesis cell division 2 BSC2011 Summer 2013 Exam 2 Study Guide 5 What is the general purpose of mitotic cell division Describe the step wise process of mitotic cell division Compare the number of chromosomes before the start of mitosis at each step and at the end Mitosis Cell division that preserves the parental number of chromosomes in the two daughter cells o Asexual reproduction General purpose of Mitosis o Create new cells quickly replication o Growth repair Replace worn out or damaged cells Enable multicellular organisms to grow Mitosis diploid 2n diploid 2n Interphase o G1 o Synthesis S Cell grows in size and synthesizes mRNA proteins Chromosomes DNA replicate Centrosomes replicate Rapid cell growth protein synthesis o G2 Prophase o Centrosomes move to opposite poles o Spindle microtubules start to lengthen o Nuclear membrane begins to dissolve o Nucleolus disintegrates o DNA begins to condense into distinct replicated chromosomes o Nuclear membrane is gone o Chromosomes are clearly distinct o A kinetochore kt appears at each centromere o Spindle is complete Prometaphase 3 BSC2011 Summer 2013 Exam 2 Study Guide Metaphase o Aster forms o Spindle microtubules move the chromosomes o Chromosomes line up single file along the midline equator metaphase plate Anaphase o Centromeres split o Spindle microtubules pull apart sister chromatids toward opposite poles Telophase Cytokinesis o Spindle disassembles o Nuclear membrane reforms o Nucleolus reappears o 2 diploid 2n daughter cells o Same number of chromosomes as parent cell o Identical DNA sequences as parent cell Result of Mitosis Clones of parent cell 4 BSC2011 Summer 2013 Exam 2 Study Guide 6 What do cancer and the cell cycle have to do with one another What do cancer and gene regulation have to do with one another Cancer A genetic disease caused by mutations to genes Cancer causing mutations usually involve tumor suppressing genes TSGs proto oncogenes POGs and other genes that regulate the cell cycle Ex Normal tumor suppressing genes TSGs restrict cell division o TSG mutation uninhibited cell growth cancer Ex Normal proto oncogenes POGs stimulate cell division o POG mutation overstimulated cell growth cancer 7 Compare contrast somatic vs germ cells aka sex cells or gametes with respect to location in an organism function how they are formed and chromosome number Location in Organism Function Somatic Body Cells Everywhere in the body except the ovaries testes Fertilization sexual reproduction Many different types with Gametes Sex Cells Germ Cells Ovaries testes 5 BSC2011 Summer 2013 Exam 2 Study Guide Method of Formation Meiotic cell division Chromosome the of chromosomes for a given species Humans 23 haploid many different functions Mitotic cell division Full of chromosomes for a given species Humans 46 diploid 8 Describe a karyotype What does a karyotype reveal Why are karyotypes useful Karyotype An orderly display showing the number and types of chromosomes in a diploid cell arranged in homologous pairs o Uses visible condensed chromosomes from a cell undergoing mitosis Karyotypes can be useful to detect o Abnormal chromosome number o Abnormal chromosome size o Sex 9 What does it mean when we say that in eukaryotes chromosomes exist in pairs What are the two chromosomes that make up a pair called How are they similar to each other How are they possibly different from each other In eukaryotes chromosomes exist in pairs that are made up of one maternal and one paternal chromosome The two chromosomes that make up a pair are called homologous Homologous chromosomes have the same chromosomes o Length o Centromere position o Staining pattern o Genes for the same characteristics at corresponding loci o Sequences of DNA within the chromosome Homologous chromosomes can have different 6 BSC2011 Summer 2013 Exam 2 Study Guide 10 Compare contrast diploid chromosome number with haploid chromosome number In what types of cells are these different numbers of chromosomes found Haploid n Having only one set of chromosomes o Found in gametes sex cells 1 maternal set of chromosomes in an egg n 23 1 paternal set of chromosomes in a sperm n 23 Diploid 2n Having two sets of chromosomes o A maternal set a paternal set o Exist in pairs o Found in somatic body cells Ex Human skin cell 2n 46 11 What is the general purpose of meiotic cell division Describe the step wise process of meiotic cell division Compare the number of chromosomes before the start of meiosis at each step and at the end Meiosis Requires two cell divisions and
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