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Cells! Most cells are between 2m and 200m Most cells are between 2m and 200m A micrometer is 1 millionth of a meter! A micrometer is 1 millionth of a meter! Too small to be seen with naked eye Too small to be seen with naked eye

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Your body cells are the same size as when you were born!

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Why cant organisms be one big giant cell?

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Limits 1. Diffusion limits cell size A cell 20 cm wide would require months for nutrients to get to the center A cell 20 cm wide would require months for nutrients to get to the center

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Limits 2. Metabolism limits cell size Larger cells produce more waste Larger cells produce more waste Larger cells require more materials Larger cells require more materials

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Surface Area : Volume All cells want: All cells want: Surface AreaVolume

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Limits 3. DNA limits cell size Larger cells need more DNA Larger cells need more DNA (more things to manage) (more things to manage)

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So, if too big is a problem, whats the solution? Cellular Division! Cellular Division!

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Cellular Division Process by which a growing cell divides forming two daughter cells Process by which a growing cell divides forming two daughter cells

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Keeping Cells Identical The instructions for making cell parts are encoded in the DNA Each new cell must get a complete set of the DNA molecules

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DNA Replication DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands

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Identical Daughter Cells Parent Cell Two identical daughter cells

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Asexual Reproduction A single cell dividing to make 2 new, identical daughter cells A single cell dividing to make 2 new, identical daughter cells Binary Fission Binary Fission Mitosis Mitosis Occur in somatic cells (body cells) Diploid number of chromosomes (2n)

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Prokaryotic Chromosome The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane

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Steps in Binary Fission Cells increase their cell mass slightly DNA & cell components are replicated Each cell divides into 2 daughter cells

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E. Coli Dividing by Binary Fission

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Eukaryotic Chromosomes All eukaryotic cells store genetic information in chromosomes All eukaryotic cells store genetic information in chromosomes Most eukaryotes have between 10 and 50 Most eukaryotes have between 10 and 50

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Eukaryotic Chromosomes Human body cells have 46 chromosomes or 23 identical pairs Human body cells have 46 chromosomes or 23 identical pairs

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Eukaryotic Chromosomes Each chromosome is composed of a single, tightly coiled DNA molecule Each chromosome is composed of a single, tightly coiled DNA molecule Chromatin Chromatin

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Compacting DNA into Chromosomes DNA is tightly coiled around proteins called histones DNA is tightly coiled around proteins called histones

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Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids Duplicated chromosomes are called chromatids Held together by the centromere Held together by the centromere Called Sister Chromatids

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DNA in nucleus is a mass of chromatin Chromatin condenses into chromosomes which duplicate to form sister chromatids Sister chromatids can be called a chromosome as well! DNA Vocabulary

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Karyotype A picture of the chromosomes from a human cell arranged in pairs by size

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Karyotype First 22 pairs are called autosomes Last pair are the sex chromosomes XX female or XY male

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Boy or Girl? Y - Chromosome X - Chromosome The Y Chromosome Decides

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Steps in Binary Fission Review!

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E. Coli Dividing by Binary Fission

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Chromosomes in Dividing Cells

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Cell Life Cycle What does the cell do in its life time? Growth (G1) Synthesis (S) Growth (G2) Mitosis Cytokinesis

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Mitosis The Different Steps The Different Steps http://www.stolaf.edu/people/giannini/flashanimat/celldivision/crome3.swf

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What does a cell need TO DO to divide? Interphase Grow- gets bigger Grow- gets bigger Synthesize- copy DNA Synthesize- copy DNA Grow again- double its organelles Grow again- double its organelles Time frame varies Time frame varies Different cells divide at different rates Different cells divide at different rates

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Mitosis Division of the nucleus Division of the nucleus Only occurs in eukaryotes Only occurs in eukaryotes Doesnt occur in some cells such as brain cells Doesnt occur in some cells such as brain cells

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Mitosis 1. Prophase Nuclear envelope disappears Nuclear envelope disappears Chromatin condenses into chromosomes Chromatin condenses into chromosomes Spindle fibers begin to attach centrioles to the chromosomes at the centromere Spindle fibers begin to attach centrioles to the chromosomes at the centromere

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Mitosis 2) Metaphase Chromosomes line up in the center Chromosomes line up in the center

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Mitosis 3) Anaphase Sister chromatids separate Sister chromatids separate Spindles pull them apart towards the opposite ends of the cell Spindles pull them apart towards the opposite ends of the cell

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Mitosis 4) Telophase Sister chromatids are at ends Sister chromatids are at ends Cytokinesis begins Cytokinesis begins

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Cytokinesis Means division of the cytoplasm Means division of the cytoplasm Division of cell into two, identical halves called daughter cells Division of cell into two, identical halves called daughter cells Begins interphase again Begins interphase again

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Cytokinesis In animal cells, cleavage furrow forms to split cell In animal cells, cleavage furrow forms to split cell In plant cells, cell plate forms at the equator to divide cell In plant cells, cell plate forms at the equator to divide cell

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Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell

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Daughter Cells of Mitosis Have the same number of chromosomes as each other and as the parent cell from which they were formed Have the same number of chromosomes as each other and as the parent cell from which they were formed Identical to each other, but smaller than parent cell Identical to each other, but smaller than parent cell Must grow in size to become mature cells (G 1 of Interphase) Must grow in size to become mature cells (G 1 of Interphase)

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Identical Daughter Cells Chromosome number the same, but cells smaller than parent cell What is the 2n or diploid number? 2

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Watch the clip! http://highered.mcgraw- hill.com/sites/0073031216/student_view0/ exercise13/mitosis_movie.html http://highered.mcgraw- hill.com/sites/0073031216/student_view0/ exercise13/mitosis_movie.html http://highered.mcgraw- hill.com/sites/0073031216/student_view0/ exercise13/mitosis_movie.html http://highered.mcgraw- hill.com/sites/0073031216/student_view0/ exercise13/mitosis_movie.html

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Mitosis Video Clip

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Regulating the Cell Cycle CYCLINS - proteins that regulate the cell cycle in eukaryotes Internal regulators respond to events inside the cell Internal regulators respond to events inside the cell Example: dont start metaphase until chromosomes are in pairs Example: dont start metaphase until chromosomes are in pairs External regulars respond to events outside the cell External regulars respond to events outside the cell Example: sense cells nearby Example: sense cells nearby

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Regulating the Cell Cycle CANCER = disease of mitosis Cells not responding to signals to stop dividing! Cells not responding to signals to stop dividing! Missing density-dependent signals Missing density-dependent signals

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Healthy, dividing cell Damage to cell Damage control Stop cell division Assess damage Cellular repair Successful repair Return to Return to cell cycle cell cycle Failed repair Cancer Cancer Extensive damage Cell death modified from Biology of Cancer by R.W. Phillis and S. Goodwin

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Four Mitotic Stages Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase

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Review of Mitosis

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Mitosis in Onion Root Tips Do you see any stages of mitosis?

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Name the Stages of Mitosis: Interphase Early prophase Mid-Prophase Late Prophase Metaphase Late Anaphase Early Anaphase Early Telophase, Cytokinesis

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Identify the Stages Early, Middle, & Late Prophase Late Prophase MetaphaseAnaphase Late Anaphase Telophase Telophase & Cytokinesis ? ? ?? ? ??

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Locate the Four Mitotic Stages in Plants Metaphase Prophase Anaphase Telophase

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Types of Reproduction Asexual Reproduction: a single cell dividing to make 2 new, identical daughter cells Examples: Binary Fission Mitosis

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Types of Reproduction Asexual Reproduction: a single cell dividing to make 2 new, identical daughter cells Occur in somatic cells (body cells) Diploid number of chromosomes (2n)

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Types of Reproduction Sexual Reproduction: a single cell dividing to make 4 new, genetically different daughter cells Occur in gametes (sex cells) Haploid number of chromosomes (1n) Daughter cells are NOT identical

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Types of Reproduction Sexual Reproduction: a single cell dividing to make 4 new, genetically different daughter cells Example: Meiosis (more on this later)

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Microscope Review What is the correct way to hold a microscope? What is the correct way to hold a microscope? Two hands! Two hands! Support arm and base of microscope! Support arm and base of microscope! What objective lens do I use to first focus an image? What objective lens do I use to first focus an image? low low

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Microscope Review When do you use the coarse adjustment knob? When do you use the coarse adjustment knob? ONLY ON LOW ONLY ON LOW NEVER TOUCH COARSE ADJUSTMENT ON ANY OTHER OBJECTIVES! NEVER TOUCH COARSE ADJUSTMENT ON ANY OTHER OBJECTIVES! If I am looking at an image on the 40x objective lens, what is my TOTAL magnification? If I am looking at an image on the 40x objective lens, what is my TOTAL magnification? 40x objective x 10x ocular = 400x total magnification 40x objective x 10x ocular = 400x total magnification

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Your Turn! Mitosis Microscope Lab Mitosis Microscope Lab