AllImagestakenform:<br />Audeirk, D. Audesirk, J & Byers, B. (2008) Biology with Physiology: Life on Earth. New Jersey. : Pearson.<br />
ASEXUAL REPRODUCTION.<br />Paramecium sp. Is a protists, a microorganism.<br />Yeast, a unicellular fungus reproduces asexually.<br />Hydra a sea animal, reproduces a sexually. It starts growing a bud until it grows big enough to be an independent organism.<br />
PROKARYOTIC CELL CYCLE.<br />Prokaryotic Cell Cycle consist of DNA growth and former cell division.<br />Cell Division in Prokaryotic cells is called BINARY FISSION.<br />
EUCARYOTIC CELL CYCLE.<br />This cycle consist of the following main phases:<br />Interphase(Yellow).<br />Cell Division (Light Blue).<br />Interphase has 4 phases: G1,G0, S and G2.<br />Cell Division could be either:<br />Mitosis or Meiosis<br />
CHROMOSOME.<br />A human chromosome consist of a single DNA double helix and some proteins called Histones and scaffolds.<br />Chromosomes are a compact DNA container.<br />
CHROMOSOME.<br />These are the main features of chromosomes:<br />Genes: sequences of DNA that have an specific function.<br />Centromere: it joins two parts of the chromosome, it does NOT have to be at the center.<br />Telomeres: the “end” of the chromosome, they maintain the equilibrium and seal the chromosome’s material.<br />
DUPLICATED CHROMOSOME.<br />A duplicated chromosome consist of two identical chromosomes. <br />
KARYOTYPE.<br />A karyotype is the full set of chromosomes located at each cell of an organisms. All this chromosomes are located at the nucleus.<br />They consist of homologues pairs. For example, chromosome 1 consists of two identical chromosomes. They share the same genes at the same order and the same length. <br />Exception: sexual chromosomes.<br />This photo is from a male, since it has XY, if it were from a women’s it would be XX.<br />
Spindle Microtubules grab the chromosomes.</li></ul>Metaphase:<br /><ul><li>Spindle Microtubules align the chromosomes along the cells’ “Equator”.</li></li></ul><li>MITOTIC CELL DIVISION.<br />Anaphase:<br /><ul><li>Sister chromatids are separated and moved to opposite sides of the cell. Microtubules push each pole apart.</li></ul>Telophase:<br /><ul><li>Microtubules start extending, nuclear envelop reforms and spindle microtubules disappear.</li></li></ul><li>CYTOKINESIS: ANIMAL CELLS.<br />Microfilaments attached to the plasmas membrane start contracting the cell’s Equator, until it divides in two. <br />
CYTOKINESIS: PLANT CELL.<br />During Cytokinesis in plan cells, once the cell is divided , the Golgi Apparatus starts sending vesicles with carbohydrates (cellulose) to start creating a cell wall in-between both daughter nuclei. <br />
CELL CYCLE CHECKPOINTS.<br />Checkpoints throughout the cell cycle:<br /><ul><li>After G1 : Is your DNA suitable and intact for it to synthesize?
After G2: Has DNA replication successfully occurred?
After Metaphase: Are all the chromosomes aligned at the Equator?</li></li></ul><li>FIRST CHECKPOINT.<br />Cycling-dependent kinases are proteins that are assigned to control the progress of the cell cycle.<br />
ALLELES.<br />Homologues have same of different Alleles. Alleles are variations of the same gene, that determine different characteristics. <br />
MEIOTIC CELL DIVISION.<br />Both members of a pair of homologues chromosomes are replicated before Meiosis. One chromosome is parental and the other is maternal.<br />
MEIOSIS I.<br />After MEIOSIS I, each daughter cell receives one of each pair of homologues chromosomes.<br />
MEIOSIS II.<br />After MEIOSIS II, sister chromatids separate into independent chromosomes and each daughter cell receives one of these chromosomes. <br />
CROSSING OVER.<br />Crossing Over occurs at Prophase I and it adds genetic diversity to the chromosomes.<br />
METAPHASE I.<br />Homologues chromosomes are paired up taking as a reference the Equator. Each PAIR of chromatids gas a single functional kenitochore.<br />In MITOSIS, each sister chromatids have one kenitochore.<br />
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