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Study Guide

BIOL 1000- Final Exam Guide - Comprehensive Notes for the exam ( 55 pages long!)


Department
Biology
Course Code
BIOL 1000
Professor
Nicole Nivillac
Study Guide
Final

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York
BIOL 1000
Final EXAM
STUDY GUIDE

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9. Cell division
Dividing'of'one'cell'into'two.'
One$parent$cell'divides'into'two$daughter$cells'(parent'cell'does'not'exist'after'cell'division).'
'
3$Cell$Division$Functions$
reproduction'–'creation'of'new'individuals'
growth$and$development'–'increasing'the'number'of'cells'
tissue$renewal$and$repair'–'replacing'dead'or'damaged'cells'
'
'
1. Types$of$Cell$Division$
Bacteria$/$Archaea$cell$division:$2'daughters'
Mitosis:'cell'division'of'body$cells'(somatic'cells)'–'2'daughters'
Meiosis:'cell'division'resulting'in'germ$cells'(sperm'and'egg)'–'4'gametes/spores'
'
Bacteria$
Cell'Division'by'binary$fission'–'asexual'reproduction'can'result'in'rapid'population'growth'
'
'
2. Mitosis$
DNA'is'organized'into'chromosomes'that'are'made'of'chromatin'(DNA'and'associated'proteins).'
'
DNA'Replication'occurs.'
After'DNA'replicates,'it'condenses'(folds'and'coils).'In'this'form,'each'DNA'replicate'is'called'a'
chromatid.''Chromatids'always'occur'in'pairs'called'sister$chromatids.'
'
Chromatids$
Sister'chromatids'are'attached'by'cohesin$proteins'at'a'narrow'region,'the'centromere.'
Kinetochore$proteins'are'also'associated'with'the'centromere'(DNA'is'hidden'behind'them)'
Sister$chromatids$attached$=$one$chromosome,'composed'of'two'identical'sister'chromatids.'
'
Each'species'has'a'characteristic'number'of'chromosomes'in'each$somatic$cell.''
Humans'have'46'(23'pairs)'chromosomes.'
'
Homologous$Chromosomes$
Each'chromosome'of'a'homologous'pair'contains'the$same$genes$in$the$same$spots.'
Each'different'chromosome'(non'homologous)'contains'different'genes.'
'
Haploid$
Haploid$number,$n$=$the$number$of$different$chromosomes.'
In'humans,'n'='23'because'we'have'23'different'chromosomes.''
Because'we'have'2'of'each,'we'have'2n'='46.'Humans'are'diploid.'
Some'organisms'are'tetraploid'(4n)'or'octaploid'(8n).'
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Chromosomes$and$Cell$Division$
Individual'chromosomes'are'only$recognizable$during$mitosis'during'cell'division.'
When'the'cell'is'not'dividing,'chromosomes'are'thin'and'form'a'network'in'the'nucleus.'Individual'
chromosomes'are'not'recognizable.'
During'DNA'replication,'DNA$in$each$chromosome'is'replicated'(we'obtain'two'sister'chromatids)'
The$number$of$different$chromosomes$is$the$SAME$before,$during$and$after$replication.'n$=$23'
The$amount$of$DNA$changes'–'it'is'doubled.'
'
Replication$of$Chromosomes$
1. Chromosome'is'long'and'thin'(DNA'loosely'packed)'One'DNA'molecule.'
2. DNA'is'replicated'–'Condensation'occurs,'DNA'folds'and'coils,'we'have'2'DNA'molecules.'Two'
sister'chromatids'held'at'centromere,'still'one'chromosome.'
3. Cell'splits,'separation'of'sister'chromatids,'one'chromosome'in'each'cell.'
'
'
3. Interphase,$Mitosis,$Cytokinesis$
1. Interphase$
G1$Phase$–$First$Gap:$period'of'growth'-'the'cell'grows'and'produces'more'proteins'and'organelles$
S$Phase$–$DNA$Synthesis:$DNA'is'replicated'-'chromosomal'protein'are'duplicated$
G2$Phase$–$Second$Gap:'period'of'growth'in'preparation'for'division'because'it'needs'to'be'larger'
to'divide'into'two'cells$
Interphase'ends'here'in'parent'cell.'
If'the'cell'doesn’t'divide,'only'G1'phase'occurs.'Cell'grows'happily,'reaches'G0$when$cell$cycle$stops.'
DNA'will'never'replicate,'the'cell'will'not'enter'the'S'phase.'
'
Checkpoints$–$The$Cell$Cycle$Control$System,$controlling$cell$division$rate$
Cell'cycle'contains'3$major$checkpoints$–'towards'the'end'of'G1,'right'before'mitosis'(between'
G2'and'mitosis),'towards'the'end'of'mitosis'
Cell'cycle'stops$at$a$checkpoint'and'only'proceeds'if'given'a'go'signal.'
The'go'signal:'cyclin-dependant$kinases$(CDKs)$and$cyclins'
Why?$What$is$checked$at$checkpoints?$
- favourable'environmental'conditions'
- everything'that'should'have'occured'has'occured'
- no'components'are'damaged,'ie'DNA'
'
'
2. Mitosis$
The'division'of'one'nucleus'into'two'nuclei'containing'identical'genetic'material.'
Prophase'
Prometaphase'
Metaphase'
Anaphase'
Telophase'and'Cytokinesis'
'
'
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