3. CELL DIVISION 2 types of cell division Mitosis -daughter cells are genetically identical Meiosis -daughter cells are genetically different
4.
5.
6. CELL DIVISION Interphase: 4 stages Gap 0 (G 0 ): - Cell rest cycle - may be temporary or permanent (where cells are functional but no new cells are produced (i.e. neuron) G 0
7. CELL DIVISION Interphase: 4 stages Gap 1 (G 1 ): - Rapid growth (4hr) - cell takes in nutrients for energy, growth, repair - Cells either go into S or G 0 after G1 G 0
8. CELL DIVISION Interphase: 4 stages S phase (S): - 10 hrs - DNA synthesis/ replication - the cell duplicates its genetic material to make an identical copy of its DNA G 0
9. CELL DIVISION Interphase: 4 stages Gap 2 phase (G 2 ): - 3-4hr - second period of growth in preparation for cell division -cell grows larger in size G 0
10. CELL DIVISION S phase (S): Let’s take a closer look - the cell duplicates its DNA - what is DNA? Deoxyribose nucleic acid - Contains genetic information in coded form
11.
12. CELL DIVISION S phase (S): Let’s take a closer look Nucleotide bases enable the coding of genetic information A – adenine T – Thymine G – Guanine C – Cytosine
13.
14.
15.
16.
17.
18. CELL DIVISION S phase (S): Let’s take a closer look Which ones are A&T? Which ones are C&G? A&T A&T C&G C&G
19.
20.
21.
22.
23.
24. CELL DIVISION S phase (S): Let’s take a closer look … Back to interphase where DNA duplication occurs. Normally After duplication DNA duplication
25. CELL DIVISION How does all of the DNA remain organized in the nucleus? Why does it not tangle?
26. CELL DIVISION DNA strands are wrapped around histone proteins which act as “ spools ”
41. CELL DIVISION Mitosis and cytokinesis: Haploid and Diploid Haploid = 1 set of chromosomes (ex. n=23 chromosomes) Diploid = 2 sets of chromosomes (ex. 2n= 46 chromosomes) 2n 4n 4n 2n 2n
42. CELL DIVISION Karyotype: Photograph of chromosomes taken at the metaphase stage of mitosis. Homologous pairs are identified and placed together. Homologous pair daddy mommy
43.
44. CELL DIVISION Karyotype: Technique But during mitosis, chromosomes are in DUPLICATED pairs. So each homologous pair consists of 2 X-shaped chromosomes Scientists can cut the photographs so that only one chromatid of every chromosome is displayed
45. CELL DIVISION Homologous pairs Identified by -chromosome length -centromere position -banding pattern -satellite endings and any other physical characteristics
46. CELL DIVISION Recall: 2 types of cell division Mitosis -daughter cells are genetically identical Meiosis -daughter cells are genetically different
47.
48. CELL DIVISION Meiosis I: Prophase I -start with 2x the normal amount of chromosomes -chromosomes condense -nuclear membrane dissolves -centrioles split -chromosomes come together in homologous pairs, forming tetrads -they overlap in a process called synapsis - crossover of chromatids causing exchange of segments of DNA Same as mitosis
49. CELL DIVISION Meiosis I: Prophase I -chromosomes come together in homologous pairs, forming tetrads -they overlap in a process called synapsis - crossover of chromatids causing exchange of segments of DNA tetrad
51. CELL DIVISION Meiosis I: Metaphase I -chromosomes attach themselves to spindle fibres -chromosomes line up at equatorial plate Anaphase I - Homologous pairs separate and move to opposite poles of the cell Same as mitosis, except the chromosomes are no longer identical . Same as mitosis, except the chromosomes are no longer identical .
52. CELL DIVISION Meiosis I: Telophase I -cleavage furrow forms -nuclear membrane reforms -chromosomes do NOT un-condense Same as mitosis
53. CELL DIVISION Meiosis II : Second cell division -cytoplasm separates -cells may become gametes Telophase II -sister chromatids from each chromosome separates and moves to opposite poles Anaphase II -chromosomes line up at equatorial plate Metaphase II -more spindle fibres form -chromosomes attach to spindle Prophase II Meiosis Phase
58. CELL DIVISION Division #1 (Meiosis I) Division #2 (Meiosis II) 46 92 92 46 46 23 23 23 23 DNA Replication Synapsis and crossing over Metaphase I, anaphase I, & telophase I Meiosis II Maternal Chromosome A Paternal Chromosome A DNA Replication Sister chromatids Synapsis and crossing over Metaphase I, anaphase I, & telophase I 92 92 46 46 23 23 23 23
59.
60.
61. CELL DIVISION How does this relate to Mendel? 2)Law of Independent Assortment: Alleles from different chromosomes assort independently during gamete formation. For example, the allele for pea shape and the allele for pea color is passed onto offspring without relation to one-another. Dihybrid cross
62. CELL DIVISION How does this relate to Mendel? All daughter cells are different Made possible by the final division in Meiosis II Made possible by different chromosomes having different alleles
64. CELL DIVISION New discovery: NASA finds new life form (December 02, 2010) - bacteria GFAJ-1 capable of using arsenic to build its DNA, RNA, proteins, and cell membranes - All other life on Earth is made of six components: Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. - Instead of using phosphorus, GFAJ-1 uses poisonous arsenic for its building blocks - found in Mono Lake, California by NASA scientist Felisa Wolfe-Simon and her team
65. CELL DIVISION New discovery: NASA finds new life form (December 02, 2010)
66. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment 46 44 48 22 22 24 24 46 46 46 23 23 23 23 Normal Meiosis Non-disjunction Non-disjunction: Failure of (homologous) chromosomes to separate
67. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment What are the possible zygotes when a normal gamete is joined with a non-disjunct gamete? Non-disjunct egg sperm 22 23 45 Monosomy egg Non-disjunct sperm 23 24 47 Trisomy
68. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment Aneuploidy: A condition that results when there is a missing or extra chromosome, resulting in changes to the normal chromosome number
69. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment Monosomy: A condition in which an individual has only one homologue of a specific pair of homologues
70. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment Trisomy: A condition in which an individual has three homologues of a specific chromosome.
71. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment Polysomy: A condition in which an individual has more than the normal number of a specific chromosome.
72. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment Haploid (n): having one copy of an entire chromosome (e.g. sex cells) Diploid (2n): having two copies of an entire chromosome (e.g. somatic cells) Triploid (3n): having three copies of an entire chromosome Polyploidy: A condition in which an individual has three or more copies of an entire chromosome
73. CELL DIVISION Mistakes during meiosis: Errors during Independent Assortment How is it possible to get 3 or more copies?
74. CELL DIVISION Broad flat face, slanting eyes, short, growth failure, mental disabilities, congenital heart disease #21 47 Down syndrome Characteristic Affected chromosome Final # of chromosomes Condition
75. CELL DIVISION Short, facial hair, undeveloped breast, degenerate ovaries, infertile X chromosome 45 Turner’s syndrome Characteristic Affected chromosome Final # of chromosomes Condition
76. CELL DIVISION Tall, longer limbs, poor beard growth, feminized physique, loose chest hairs, underdeveloped penis and testes, infertile X chromosome 47 or more Klinefelter’s syndrome Characteristic Affected chromosome Final # of chromosomes Condition
77. CELL DIVISION Normal male, tall, “aggressive” Y chromosome 47 or more Jacob’s syndrome Characteristic Affected chromosome Final # of chromosomes Condition
78. CELL DIVISION Normal female, “aggressive” X chromosome 47 or more Super female Characteristic Affected chromosome Final # of chromosomes Condition
Hinweis der Redaktion
Hornets kill bees: http://www.youtube.com/watch?v=L54exo8JTUs&feature=fvwrel Hornets from Hell: http://www.youtube.com/watch?v=R5QxUR-mZVM
![CELL DIVISION ,[object Object],[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)