View
228
Download
0
Category
Tags:
Preview:
Citation preview
Chapter 12
Biology
Cell Division
Allows unicellular organisms to reproduce
Growth and Repair of multicellular organisms.
How Prokaryotic Cells Divide
Prokaryotic cells lack a nucleus and other membranous organelles.
Divide by Binary Fission
Chromosome Is Singular
Prokaryotic chromosome contains mostly DNA and some associated proteins
Asexual reproduction requires a single parent; offspring are genetically identical to parent.
Eukaryotic Chromosomes and the Cell Cycle
• Karyokinesis – nuclear division
• Cytokinesis – division of the cytoplasm
A. Chromosomes
• Histone proteins organize chromosomes.
• Each species has a characteristic number of chromosomes.
A. Chromosomes
• a. Diploid (2n) number includes two sets of chromosomes of each type.
• b. Haploid (n) number contains one of each kind of chromosome.
A. Chromosomes
• Sister chromatids are two parts of a chromosome
• Centromere---a region of constriction on a chromosome
Mitosis
• Centrosomes
– responsible for organizing the spindle.
– main microtubule organizing center of the cell
Mitosis
• The centrosome has divided before mitosis begins.
• Each centrosome contains a pair of barrel-shaped organelles called centrioles; plant cells lack centrioles.
Mitosis Diagram
B. How Animal Cells Divide
• 1. Mitosis:– Interphase
– Prophase
– Pro-metaphase
– Metaphase
– Anaphase
– Telophase.
Mitosis Movie
B. How Animal Cells Divide
Prophase
• a. Chromatin condenses and chromosomes become visible.
• b. Nucleolus disappears and the nuclear envelope fragments.
• c. Short microtubules radiate out from the pair of centrioles located in each centrosome; form starlike asters.
B. How Animal Cells Divide
Prometaphase
• a. attachment of chromosomes to the spindle and movement as they align at the metaphase plate (equator).
B. How Animal Cells Divide
Metaphase
• a. Chromosomes align at the metaphase plate.
B. How Animal Cells Divide
Anaphase
• a. Two sister chromatids of each duplicated chromosome separate at centromere.
• b. Daughter chromosomes, each with a centromere and single chromatid, move to opposite poles.
B. How Animal Cells Divide
Telophase
• a. Spindle disappears.
• b. Chromosomes decondense and return to chromatin; the nuclear envelope reforms and nucleoli reappear.
• c. Cytokinesis is nearly complete.
Cytokinesis in Animal Cells
• a. Cleavage furrow indents the plasma membrane between the two daughter nuclei at a midpoint; progressively divides cytoplasm during cell division.
Mitosis Video
C. How Plant Cells Divide
• 1. Plant meristematic tissue in tips of roots and shoots
• 2. Stages are same as in animal cells.
• 3. Plant cells - no centrioles, and asters do not form.
Cytokinesis in Plant Cells
• Golgi apparatus produces vesicles that move to the midpoint between the daughter cell nuclei
• Vesicles fuse, forming a cell plate
How the Cycle is Controlled
• 1. Some cells divide continuously
• 2. Other cells are arrested in at different stages
Mitosis Stages
How the Cycle is Controlled
• 4. Enzymes known as cyclin-dependent kinases (Cdks) regulate passage of cells through these checkpoints
How the Cycle is Controlled
• Oncogenes (cancer-causing genes) may code for cyclins that no longer function as they should.
Cancer Cells
Cancer Radiation
Cancer Histroy
Cancer Causes
Cancer
• Angiogenesis the formation of new blood vessels.
• Malignancy and Metastasis ability to move and movment of cancer cells to a new location.
Cancer Treatment
Cancer Genetics
The End.
Regular naps prevent old age.....especially if you take them while driving.I don't approve of political jokes...I've seen too many of them get elected.Shopping tip: You can get shoes for 85 cents at bowling alleys.After all is said and done, usually more is said than done.I am a nobody, nobody is perfect, therefore I am perfect.I married my wife for her looks...but not the ones she's been giving me lately!How come we choose from just two people for president and 50 for
Miss America?“Isn't having a smoking section in a restaurant like having a peeing section in a
swimming pool?The next time you feel like complaining, remember: Your garbage disposal
probably eats better than thirty percent of the people in this world.Sex is hereditary. If your parents never had it, chances are you won't either.Women should not have children after 35. Really...35 children are enough.I was on a date recently, and the guy took me horsebackriding. That was kind of
fun, until we ran out of quarters.Every time I walk into a singles bar I can hear Mom's wise words: Don't pick that
up, you don't know where it's been.
Recommended