Ch 11: Cell Cycle and Cell Division
Part 1: Somatic eukaryotes and prokaryotes- Asexual is Mitosis Only
● Cell Division Process: double in size divide by 2. Initiation, DNA Replication,
DNA Segregation, Cytokinesis.
● Prokaryotic cell division: ori and ter.
●
Prokaryotic Cell Division Eukaryotic Cell Division
Rapid Complex, slower
Environmental Signals Internal Signals, sometimes external
Asexual, 2 new cells, clones of OG Entire organism reproduction single celled.
Multicellular results in more cells within
organisms, not always clones (growth and
development, repair of tissues).
● Cell Cycle somatic euk: G1, S, G2, Mitosis. If there is no division, cells go into G0. Spindle
Apparatus.
- G=growth. S=DNA synthesis
-
Prophase (after interphase) Chromosomes Condense, spindle
assembly
Prometaphase Nuclear breakdown, chromosomes attach
to spindle
Metaphase Chromosomes form 1 line @ equator
Anaphase Chromatids migrate to poles 2 lines
Telophase Chromosomes decondense and nuclear
reforms (2 cells)
Cytokinesis not Mitosis, after. 2 cells finalize. Plant cell wall reforms or
just membrane. Plant=cell plate.
Animal=contractile ring.
● Cdks, R point, Checkpoints
- Cdk: Cyclin-dependent kinases are always present, active sites not always exposed.
Cyclin proteins are made only at certain points in cycle, bind to cdk and active site
exposed. Substrate+ATP bind. PROTEIN+ATP->PROTEIN&P+ADP
- The presence or absence of cyclin dictates Cdk activity which leads to cell cycle
regulation.
- Restriction Point: G1-S commitment to cell division. Cdk is active, so cyclin is present.
- Checkpoints: between G2-M regulates entry to Mitosis. Mostly DNA damage, incomplete
replication, or chromosomes being unattached to spindle.
● Dna molecules interact with histones to form nucleosomes
, ● Cell Death: Necrosis=damage or starved cell dies unexpectedly. Apoptosis=programmed cell
death, signal activated, caspases. In both, parts are recycled.
Part 2: Sexual Reproduction- Mitosis and Meiosis
● Gametes instead of somatic cells. Meiosis generates genetic diversity, as offspring are not
identical to parents.
●
Somatic Cells Gametes- fusion of 2 forms diploid zygote
Cells not specialized for reproduction Specialized for reproduction
Has homologous pairs of chromosomes (2) Only 1 set chromosomes
1 homolog in the pair per parent 1 homolog each pair of chromosomes
Diploid or 2n Haploid n
● Sexual Reproduction 2n→n in half. The result is 4 haploid daughter cells prior to fertilization.
Meiosis has 1 and 2.
- Meiosis: nucleus divides 2x but DNA is replicated 1x.
-
Meiosis 1 Meiosis 2
DNA replication occurs before this No DNA replication
Homologous chromosomes pair along Chance assortment→genetic diversity
entire lengths
Pairs separate but individual Sister chromatids separated (individual
chromosomes stay together chromosomes)
- Meiosis 1 is the separation of homologous chromosomes.
- Meiosis 2 is the separation of sister chromatids
● Crossing over: exchange of genetic material between non-sister chromatids. Inc genetic
variability. Chiasma. The 4 chromatids form a tetrad.
● Independent Assortment at anaphase 1: random chance which member of homologous pair goes
to which daughter cell. Also random fertilization.
● Errors: nondisjunction failure to separate→aneuploidy where chromosomes are either lacking or
excess.
Ch 12: Inheritance, genes, chromosomes.
● Mendel’s Experiment: P (1 homo dom and 1 homo rec) → F1 (100% hetero) → F2 (3
phenotypically dominant: 1 pheno recessive)
● Law of Segregation: each organism has 2 copies of a gene but only 1 version/copy goes into
gamete. Meiosis.
● Law of Independent assortment: genes for different traits are inherited independently of each
other. Meiosis and genetic crossing
● Fruit flies: alleles do not assort independently
● Character vs. Trait: feature vs description of feature ex. Color (C) is purple (T).
Part 1: Somatic eukaryotes and prokaryotes- Asexual is Mitosis Only
● Cell Division Process: double in size divide by 2. Initiation, DNA Replication,
DNA Segregation, Cytokinesis.
● Prokaryotic cell division: ori and ter.
●
Prokaryotic Cell Division Eukaryotic Cell Division
Rapid Complex, slower
Environmental Signals Internal Signals, sometimes external
Asexual, 2 new cells, clones of OG Entire organism reproduction single celled.
Multicellular results in more cells within
organisms, not always clones (growth and
development, repair of tissues).
● Cell Cycle somatic euk: G1, S, G2, Mitosis. If there is no division, cells go into G0. Spindle
Apparatus.
- G=growth. S=DNA synthesis
-
Prophase (after interphase) Chromosomes Condense, spindle
assembly
Prometaphase Nuclear breakdown, chromosomes attach
to spindle
Metaphase Chromosomes form 1 line @ equator
Anaphase Chromatids migrate to poles 2 lines
Telophase Chromosomes decondense and nuclear
reforms (2 cells)
Cytokinesis not Mitosis, after. 2 cells finalize. Plant cell wall reforms or
just membrane. Plant=cell plate.
Animal=contractile ring.
● Cdks, R point, Checkpoints
- Cdk: Cyclin-dependent kinases are always present, active sites not always exposed.
Cyclin proteins are made only at certain points in cycle, bind to cdk and active site
exposed. Substrate+ATP bind. PROTEIN+ATP->PROTEIN&P+ADP
- The presence or absence of cyclin dictates Cdk activity which leads to cell cycle
regulation.
- Restriction Point: G1-S commitment to cell division. Cdk is active, so cyclin is present.
- Checkpoints: between G2-M regulates entry to Mitosis. Mostly DNA damage, incomplete
replication, or chromosomes being unattached to spindle.
● Dna molecules interact with histones to form nucleosomes
, ● Cell Death: Necrosis=damage or starved cell dies unexpectedly. Apoptosis=programmed cell
death, signal activated, caspases. In both, parts are recycled.
Part 2: Sexual Reproduction- Mitosis and Meiosis
● Gametes instead of somatic cells. Meiosis generates genetic diversity, as offspring are not
identical to parents.
●
Somatic Cells Gametes- fusion of 2 forms diploid zygote
Cells not specialized for reproduction Specialized for reproduction
Has homologous pairs of chromosomes (2) Only 1 set chromosomes
1 homolog in the pair per parent 1 homolog each pair of chromosomes
Diploid or 2n Haploid n
● Sexual Reproduction 2n→n in half. The result is 4 haploid daughter cells prior to fertilization.
Meiosis has 1 and 2.
- Meiosis: nucleus divides 2x but DNA is replicated 1x.
-
Meiosis 1 Meiosis 2
DNA replication occurs before this No DNA replication
Homologous chromosomes pair along Chance assortment→genetic diversity
entire lengths
Pairs separate but individual Sister chromatids separated (individual
chromosomes stay together chromosomes)
- Meiosis 1 is the separation of homologous chromosomes.
- Meiosis 2 is the separation of sister chromatids
● Crossing over: exchange of genetic material between non-sister chromatids. Inc genetic
variability. Chiasma. The 4 chromatids form a tetrad.
● Independent Assortment at anaphase 1: random chance which member of homologous pair goes
to which daughter cell. Also random fertilization.
● Errors: nondisjunction failure to separate→aneuploidy where chromosomes are either lacking or
excess.
Ch 12: Inheritance, genes, chromosomes.
● Mendel’s Experiment: P (1 homo dom and 1 homo rec) → F1 (100% hetero) → F2 (3
phenotypically dominant: 1 pheno recessive)
● Law of Segregation: each organism has 2 copies of a gene but only 1 version/copy goes into
gamete. Meiosis.
● Law of Independent assortment: genes for different traits are inherited independently of each
other. Meiosis and genetic crossing
● Fruit flies: alleles do not assort independently
● Character vs. Trait: feature vs description of feature ex. Color (C) is purple (T).
