Chromosomes and Cell Division New Cells Are Formed by Cell Division http:// www.alumni.ca/ ~laued3e/ chromosome.jpg
Jan 22, 2016
Chromosomes and Cell DivisionNew Cells Are Formed by Cell
Division
http://www.alumni.ca/~laued3e/chromosome.jpg
• About 2 trillion cells are produced by an adult human body every day.
• This is about 25 million new cells per second.
• Why would cells divide or reproduce?
Different Types of Cell Division
• 1. Bacteria reproduce by binary fission.– Binary Fission= a form of asexual
reproduction that produces identical offspring– If the offspring are identical, what is true about
the DNA?
• 2. Eukaryotic organisms undergoing growth, development, repair or asexual reproduction
• 3. The formation of gametes or sex cells
Rod-shaped Bacteria Dividing by Binary Fission
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html
Binary Fission Video Clips
• http://www.youtube.com/watch?v=gEwzDydciWc&feature=related
• http://www.youtube.com/watch?v=3cD3U2pgb5w&playnext_from=PL&feature=PlayList&p=91845E3E72841AFE&playnext=1&index=7
• http://www.youtube.com/watch?v=K0ZP8VtxUZ0&playnext_from=PL&feature=PlayList&p=91845E3E72841AFE&index=8
Eukaryotic cells form chromosomes before cell division
• gene = a segment of DNA that codes for a protein or RNA molecule
• As a eukaryotic cell prepares to divide the DNA and proteins associated with the DNA coil into a structure called a chromosome.
• Before DNA coils, the DNA is copied.• The two exact copies of DNA that make up
the chromosome are called chromatids.
• Genes are found on chromosomes
• They are sections of DNA
• Here is the gene for Parkinson’s Disease.
• The chromatids attach at a point called the centromere.
http://www.ams.org/new-in-math/cover/images/chromosome.gif
• Homologous Chromosomes = chromosomes that are similar in size, shape, and genetic content
• Each homologue in a pair of homologous chromosomes comes from one of the two parents.
• There are 46 chromosomes in human somatic or body cells or 2 sets of 23 chromosomes.
• Diploid= two sets of chromosomes• Haploid= one set of chromosomes• Zygote= a fertilized egg cell, the fusion of
two haploid gametes• autosomes= chromosomes that are not
directly involved in determining sex – 22 pairs
• Sex chromosomes= determine sex– XX=female XY=male
http://www.genomesize.com/rgregory/Chromosome.JPG
chromatids
• Karyotype = a photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size.
Is this a karyotype of a male or female?
Do you notice anything about this karyotype?
• Down’s
syndrome
http://www.ucl.ac.uk/~ucbhjow/bmsi/lec7_images/47_xx_21.gif
What do you notice about this karyotype?
• Turner Syndrome
http://www.antenataltesting.info/images/karyotypeTurners.jpg
• 1. Why is cell division important?
• 2. What are chromosomes made up of?
• 3. Where are genes found?
HomeworkDirected Reading 6-1