Cell Reproduction http://tbn2.google.com/images?q=tbn:spK6vnBHuv7DlM:http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

The cell cycle Interphase and Mitosis

DNA replication Chromatid Sister Chromatids For most of a cells life chromosome is a single copy of DNA looking like But during the “s” phase of interphase the chromosome copies itself making sister chromatids joined in the middle by a centromere Chromatid Sister Chromatids

Chromatid sister chromatids (because the DNA is copied)

Mitosis When a cell go through the phases Prophase Metaphase Anaphase Telophase to make two “daughter” cells that are exactly identical to the original “parent” cell

Cell parts to know Chromosomes: the reason they look like an x would be because the DNA has been copied. Each side of the x is a copy of the other. Spindle fibers: hold chromosomes in an orderly fashion Centrioles: in animal cells they hold spindle fibers and stretch them to opposite sides of cell Nuclear membrane breaks down and reforms during the process.

Mitosis: cell reproduction to make exact copies of cells prophase Interphase Mitosis: cell reproduction to make exact copies of cells metaphase anaphase telophase 2 daughter cells in Interphase http://www.pbs.org/wgbh/nova/miracle/divi_text_03.html

Interphase “normal” cell not dividing just doing its job. DNA does reproduce. Chromatids form sister chromatids. Chromosomes Nuclear membrane

Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase Nuclear membrane breaks apart Chromosomes spread out in cell Spindle fibers form stretching from one side of cell to the other Nuclear membrane Chromosome chromatid Spindle fiber

Prophase Plant Cell Animal Cell Spindle fibers Centrioles Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase Chromosomes line up in center of cell Held by the spindle fibers

Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase Chromosomes split Sister chromatids move to opposite ends of cell chromatids

Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase 2 nuclear membranes reform around chromatids Cell membrane splitting into two cells CYTOKINESIS it the term to describe the division of the cytoplasm and it’s contents which happens when 2 cell membranes are formed. Nuclear membrane

Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Interphase - again 2 new cells Exact copies with the same chromosomes of original cell cytoplasm

http://www.youtube.com/watch?v=JHRBJgq50dk Crazy mitosis song Mitosis Animation http://www.cellsalive.com/mitosis.htm http://www.youtube.com/watch?v=JHRBJgq50dk Crazy mitosis song

Drawing are simplified with only 4 chromosomes. Human cells have 46 chromosomes a human skin cell with 46 chromosomes will make more skin cells with 46 chromosomes by doing mitosis

Mitosis slides under microscope Mitosis quiz Stop motion video or flip book

Cancer Cancerquest: 11 min cancer overview http://www.cancerquest.org/cancer-biology-animations.html# cancer overview from MD Anderson: http://www.videomd.com/Cancer-what-is-it-fv-791.aspx 6 min Cancer detection and treatment: http://video.healthination.com/hn/cancer-treatments/cancer-surgery.html watch cancer surgery, radioation and chemotherapy, Website:http://www.insidecancer.org/

A different type of cell division!

This cell is in the process of dividing This cell is in the process of dividing. What are two ways this is different from mitosis? The chromosomes are lined up in pairs not single file as in mitosis– homologous pairs Pieces of the chromosomes have traded places – crossing over

How are the daughter cells produced at the end different from mitosis? Daughter cells have half the DNA that the parent cell has. The chromosomes in each of the 4 daughter cells are different as a result of crossing over. Parent cell Parent cell

Meiosis, What’s the big deal? Meiosis is the reason that in sexually reproducing organisms genetic information varies between parent and offspring, Genetic information varies between offspring from the same parents.

Meiosis insures genetic variation which is essential for evolution. Species genes/traits change from generation to generation. With a GREAT deal of time this can produce significant changes

Meiosis: process to make sex cells Daughter cells made from Meiosis are NOT identical to the “parent” cell. Regular body cell 46 chromosomes Sperm and egg 23 chromosomes Also crossing over happens where pieces of the original chromosomes exchange places.

MEIOSIS: to make sex cells with half the original DNA. Parent cell MEIOSIS: to make sex cells with half the original DNA. 4 daughter cells with half of DNA from parent cell

Homologous chromosomes Organisms have pairs of chromosomes with corresponding DNA sequences one from each parent. homologous chromosomes are the same size, their centromeres are in the same position, they have the same number of genes, arranged in the same order. n a biological cell, a chromosome pairs with another chromosome during meiosis. This pairing (synapsis) happens between two chromosomes that are homologous, i.e. chromosomes having the same genes at the same loci but possibly different alleles. For example, two chromosomes may have genes encoding eye color, but one may code for brown eyes, the other for blue http://www.biology-online.org/dictionary/Homologous_chromosome

Meiosis: CROSSING OVER While paired up during prophase I, sections of DNA are exchanged between homologous chromosomes. This insures that the chromosomes in sex cells produced are not identical to the parents chromosomes. This is one reason each offspring produced by a parent is unique from any other.

Mitosis vs. Meiosis Parent cell Parent cell 4 daughter cells with half of DNA from parent cell 2 daughter cells with identical DNA to parent cell 2 diploid somatic cells 4 haploid gametes

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__comparison_of_meiosis_and_mitosis__quiz_1_.html animation comparing meiosis and mitosis http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/difficult_multiple_choice.html questions starting at 15 http://www.sciencegeek.net/Biology/review/U3Review.htm 30 question quiz http://www.biologycorner.com/quiz/qz_meiosis.html 3 question quiz http://www.sumanasinc.com/webcontent/animations/content/meiosis.html very good animation of meiosis

Vocabulary for Bio Somatic cell: a body cell that has the organisms complete diploid set (2N) of chromosomes. Diploid = 2N: a cell that contains both sets of homologous chromosomes from the parent. Gamete: sex cell, sperm or egg cell containing the haploid (1N) set of chromosomes Haploid = 1N: a cell containing 1 set of genes Zygote: fertilized egg 2N

In Humans 46 chromosomes total The chromosome you get from your mom and dad contain similar types of information. For example you get genes for eye color from your mom and genes for eye color from your dad. The chromosomes can be matched up in pairs called homologous chromosome pairs. http://www.miscarriage.com.au/images/pages/karyotype_normal.jpg

Mistakes in meiosis: non-disjunction Non disjunction: when an error occurs in cell division * homologous chromosomes do not separate * Or sister chromosomes do not separate

2 ways nondisjunction can occur http://warunee.chs.ac.th/c15x11nondisjunction.jpg

Normal nondisjunction in Meiosis I

Normal nondisjunction in Meiosis II

A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes. (http://learn.genetics.utah.edu/content/disorders/whataregd/)

Disorders Most disorders are due to changes within one chromosome not a change to an entire chromosome. Cystic fibrosis (thick mucus in respiratory system) Sickle Cell disease (malformed red blood cells that get stuck in capillaries) Lou Gehrig’s disease/ALS (loss of muscle control) Due to a change in entire chromosome Down’s Syndrome /trisomy 21 Edward’s Syndrome Trisomy 18 Patau syndrome Trisomy 13 Klinefelters syndrome XXY Turner’s Syndrome XO XYY

Trisomy: a third copy of a chromosomes Trisomy: a third copy of a chromosomes. A few smaller copies can be tolerated in humans for example Chromosome 21 results in down syndrome, However most trisomys are lethal Monosomies: one missing copy of a chromosome, a female can survive with just one X chromosome, however most monosomies are lethal Triploid: 2 extra chromosomes this is always lethal in humans but does exist in plants

Mitosis: results in two cells with identical chromosomes Meiosis: results in four cells with different chromosomes