Ch. 12: mitosis, Meiosis, and life cycles. How does a plant grow? Cell cycle – Activities of a...
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Transcript of Ch. 12: mitosis, Meiosis, and life cycles. How does a plant grow? Cell cycle – Activities of a...
The Events of the Interphase
• Interphase:
– Divided into 3 phases:
G1 –
S –
G2 – cell growth after DNA replication; cell prepares to divide
Cell Division or “M” phase
• Cell Division consists of two parts
1. Mitosis:
2. Cytokinesis:
• What needs to happen to the chromosomes prior to Mitosis?
• During mitosis?
Each chromatid has one DNA molecule
Centromere
Sister chromatids
1. How do sister chromatids compare genetically?
2. What happens to sister chromatids during mitosis?
Sketch of one duplicated chromosome
Mitosis: sister chromatids separate
Two-chromatidchromosome
Interphase
S-Phase: DNA Replication
One-chromatidchromosome
One-chromatidchromosome
The number of chromosomes in each daughter cell is the same as the number of chromosomes in the parent cell
Mitosis: Division of the Nucleus• Four Stages:
1. Prophase – 1. .2. .3. Chromosomes attach to spindle fibers
2. Metaphase – Spindle fibers align the chromosomes at the equator of the cell
3. Anaphase –
4. Telophase – nuclear envelope forms around each cluster of chromosomes
Normal Karyotype of Human
Chromosomes
• Karyotype =
• How many pairs of chromosomes in this Karyotype?
• Paired chromosomes are homologous =
Diploid cell: 3 sets of homologous
chromosomes
One set ofnon-homologouschromosomes
Haploid cell
One set of non-homologous
chromosomes
Haploid cell
Stages of Meoisis1. Interphase – same as mitosis (G1, S, G2)2. Meiosis I
a) Prophase I –
b) Metaphase I – c) Anaphase I – d) Telophase I –
3. Meiosis IIa) Prophase II – chromosomes attach to spindleb) Metaphase II – chromosomes align at equatorc) Anaphase II – sister chromatids separated) Telophase II – cells divide, end result = 4 haploid
daughter cells