The Cell Cycle Mitosis Meiosis cell division Bio 2 Review Test 2 I Types of Cells and Chromosomes i Somatic diploid 2n 2 sets of chromosomes mom plus dad Muscle cells skin cells liver cells ii How many chromosomes in a diploid human cell iii How many autosomal chromosomes do we have s NOT Meiosis iv Go through Mitosis 1 No crossing over start and end with the same of chromosomes 2 One round of Interphase G1 S G2 a G1 cell is growing in order to accommodate 2x organelles DNA Cell is 2n b S DNA REPLICATION SISTER CHROMATIDS ONLY PRESENT AFTER S PHASE cell is still 2n but now sister chromatids are present Cell is 2n c G2 Preparing to divide protein synthesis and structure syn thesis for cell division MPF signal G2 checkpoint NALS d What are the 3 checkpoints of Interphase CHEMICAL SIG G1 if pass cell continues to S phase if doesn t pass goes to G0 what happens here 2 things apoptosis or repair G2 MPF cyclin CDK a Cyclin must be in a high enough concen tration in order for CDK to bind 3 One round of Mitosis P PM M A T C M a PROPHASE Centrosomes move to opposite pole Spindle formation Chromatin condensing forming distinct chromo somes b PRO METAPHASE Kinetochore appears location Function 1 In centromere 2 Attaches sister chromatids to the spindle fibers c METAPHASE d ANAPHASE Chromosomes align SINGLE FILE along M plate Sister chromatids face opposite poles SISTER CHROMATIDS SPLIT FROM EACHOTHER Now each is a distinct chromosome e TELOPHASE AND CYTOKINESIS Nuclear membrane reforms cell membrane pinches in and forms TWO separate cells Each with identical DNA as parent cell 1 Don t need variation of alleles i e do not need crossing over to occur when just forming new somatic cells skin cells are all the same doesn t matter however you may still have different al leles on homologous chromosomes 4 cancer cells do not exhibit these two things a density dependent inhibition they will not be signaled to stop dividing if they touch another cell next to them b anchorage dependence they do not need to attach to a substrate so they will grow on top of each other and not in one uniform layer cancer cells have telomerase activity why does this help them to survive 1 What are telomeres Just know definition a non coding repetitive nucleotide se quences at the ends of eukaryotic chro mosomes b When normal cell s telomeres decrease sign that cell will commit apoptosis c Difference between proto oncogenes and tumor suppressing genes division normal tumor suppressing genes TSGs restrict cell 1 suppress depress slow down 2 P53 normal proto oncogenes POGs stimulate cell divi 1 pro lets go sion mors division up cell division mutations in these types of genes cause cancer tu 1 result in uncontrolled cell division 2 p53 mutation cell cannot be told to slow cell 3 proto onco gene mutation cell is told to speed d Difference between centrosome centrioles and centromere 1 Centrosome this is a microtubule orga nizing center where the centrioles are housed 2 Centrioles these contain microtubules needed for spindle formation 3 Centromere holds together 2 sister chro matids b Germ Gametes eggs and sperm haploid n 1 set of chromosomes mom or dad i How many chromosomes in a haploid human cell ii How many sex chromosomes do we have s iii Go through Meiosis NOT Mitosis 1 Begin as a diploid cell and end as haploid cells 2 Meiosis I REDUCTION DIVISION reduce divide of chromosomes by a After meiosis 1 is the cell haploid or diploid VERY IMPORTANT TO UNDERSTAND b Prophase 1 How does it differ from Prophase of mitosis 2 main ways 1 CROSSING OVER occurs here chiasma be tween homologous chromosomes NOT sister chromatids 2 Homologous chromosomes pair up c Metaphase 1 How does it differ from Metaphase of mitosis 1 main way 1 TETRADS formed and are on the metaphase plate homologous chromosomes are NOT stacked one on top of another like mitosis 2 LAW OF INDEPENDENT ASSORTMENT genetic variation d Anaphase 1 HOMOLOGOUS CHROMOSOMES SEPARATE AND GO TO OPPOSITE POLES e Telophase and Cytokinesis Result is 2 HAPLOID cells Sister chromatids still at tatched at centromere 3 Meiosis II Exactly the same process as Mitosis however 4 haploid cells are formed and they are GENETICALLY DIFFERENT DUE TO CROSSING OVER a Crossing over trading of alleles c Alleles are different versions of the same KIND of gene i Example Flower color 2 alleles red or white ii For any chromosome alleles may be the same or different 1 i e can have either two red two white or 1 white and 1 red d What can a Karyotype tell show us i Definition an orderly organization of chromosomes ii Give 3 things 1 of chromosomes 2 any chromosomal abnormalities or chromosomal breakage downs syndrome aneuploidy cri du chat 3 sex of individual XX or XY MENDELIAN GENETICS I What does True Breeding mean a Difference between Dominant uppercase and Recessive low i What does a dominant genotype look like 2 possibilities ercase alleles 1 PP 2 Pp 1 pp ii What does a recessive genotype look like 1 possibility b BB or bb think pure bred HOMOZYGOUS c P generation 1st parental generation d F1 is first offspring generation e F2 is second offspring generation f In a True Breed cross PP X pp homozygous DOMINANT x ho mozygous RECESSIVE i ii F1 generation PHENOTYPIC ratio is 1 1 F1 generation GENOTYPIC ratio is 1 1 resultant offspring are all HETEROZYGOUS Pp F2 generation PHENOTYPIC ratio is 3 1 Pp x Pp F2 generation GENOTYPIC ratio is 1 2 1 resultant off spring are PP Pp and pp Trick FOR SINGLE GENE CROSSES ONLY a When question asks for how many GENOTYPE combinations iii iv II i Homozygous X Homozygous 1 combination PP or pp or Pp ii Homozygous X Heterozygous 2 combinations PP or Pp Pp or pp OR iii Heterozygous X Heterozygous 3 combinations PP Pp and pp b When question asks for how many PHENOTYPE combinations i Homozygous X Homozygous 1 combination all domi nant or all recessive ii Homozygous dominant X Heterozygous 1 combination all dominant iii Homozygous recessive X Heterozygous 2 combinations iv Heterozygous X Heterozygous 2 combinations 3 domi nant and 1 recessive c When question asks for possible gamete combinations If trait is homozygous PP or pp use 1 If trait is heterozygous Pp use 2 i ii iii Example PpTtGgRRbb 1 Pp 2 gamete combos 2 Tt 2 gamete combos 3 Gg 2 gamete combos 4 RR 1 gamete combo 5 Bb 2 gamete combo so how many possible gamete combina tions 2x2x2x1x1 16 You try WwaaBbnnKKPpCc a III More than one trait a What is a DIHYBRID cross i More than 1 trait both parents are heterozygous for
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