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 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.

http://www.pbs.org/wgbh/nova/miracle/divi_text_03.html

Interphaseprophase

metaphase

anaphasetelophase

2 daughter cells in Interphase

Mitosis: cell reproduction to make exact copies of cells

Interphase “normal” cell not

dividing just doing its job.

DNA does reproduce. Chromatids form sister chromatids.

ChromosomesNuclear membrane

Animal Cell Plant 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

Spindle fiber

chromatid

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Centrioles

Metaphase Chromosomes line up

in center of cell Held by the spindle

fibers

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase Chromosomes split Sister chromatids

move to opposite ends of cell

chromatids

Animal Cell Plant 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

Animal Cell Plant 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.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. 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

4 daughter cells

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

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.

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

2 daughter cells with identical DNA to parent cell

4 daughter cells with half of DNA from parent cell

Parent cell

2 diploid somatic cells 4 haploid gametes

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

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

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)

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