Getting Started What do you know about cell

Getting Started: • What do you know about cell theory? • Vocab/Concepts: –A lot. . . Brace yourself.

Cellular Division 2

Cell Division üAll cells are derived from pre- existing cells üNew cells are produced for growth and to replace damaged or old cells üDiffers in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) 3

Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules 4

DNA Replication üDNA must be copied or replicated before cell division üEach new cell will then have identical copy the DNA Original DNA strand Two new, identical DNA strands an of 5

Identical Daughter Cells Two identical daughter cells Parent Cell 6

Chromosomes 7

Eukaryotic Chromosomes üAll eukaryotic information in cells store genetic chromosomes ü Most eukaryotes have between 10 and 50 chromosomes in their body cells ü Human body cells have 46 chromosomes or 23 identical pairs 8

Eukaryotic Chromosomes üEach chromosome is composed of a single, tightly coiled DNA molecule üChromosomes can’t be seen when cells aren’t dividing and are called chromatin 9

Chromosomes in Dividing Cells üDuplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids 10

Karyotype ü A picture of the chromosomes from a human cell arranged in pairs by size ü First 22 pairs are called autosomes ü Last pair are the sex chromosomes ü XX female or XY male 11

Boy or Girl? The Y Chromosome Decides Y - Chromosome X - Chromosome 12

Cell Reproduction: Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells 13

The Cell Cycle 14

Five Phases of the Cell Cycle üG 1 - primary growth phase üS – synthesis; DNA replicated üG 2 - secondary growth phase collectively these 3 stages are called interphase üM - mitosis üC - cytokinesis 15

Cell Cycle 16

Interphase - G 1 Stage ü 1 st growth stage after cell division üCells mature by making more cytoplasm & organelles üCell carries on its normal metabolic activities 17

Interphase – S Stage üSynthesis stage üDNA is copied or replicated Two identical copies of DNA Original DNA 18

Interphase – G 2 Stage ü 2 nd Growth Stage üOccurs after DNA has been copied üAll cell structures needed for division are made (e. g. centrioles) üBoth organelles & proteins are synthesized 19

What’s Happening in Interphase? What the cell looks like Animal Cell What’s occurring 20

Sketch the Cell Cycle DNA Copied Cells Mature Daughter Cells prepare for Division Cell Divides into Identical cells 21

Mitosis 22

Mitosis üDivision of the nucleus üAlso called karyokinesis üOnly occurs in eukaryotes üHas four stages üDoesn’t occur in some cells such as brain cells 23

Four Mitotic Stages üProphase üMetaphase üAnaphase üTelophase 24

Early Prophase üChromatin in nucleus condenses to form visible chromosomes üMitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Nucleolus Chromosomes Cytoplasm Nuclear Membrane 25

Late Prophase üNuclear membrane & nucleolus are broken down üChromosomes continue condensing & are clearly visible üSpindle fibers called kinetochores attach to the centromere of each chromosome üSpindle finishes forming between the poles of the cell 26

Late Prophase Chromosomes Nucleus & Nucleolus have disintegrated 27

Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome 28

Review of Prophase What the cell looks like What’s happening 29

Spindle Fibers üThe mitotic spindle form from the microtubules in plants and centrioles in animal cells üPolar fibers extend from one pole of the cell to the opposite pole üKinetochore fibers extend from the pole to the centromere of the chromosome to which they attach üAsters are short fibers radiating from centrioles 30

Sketch The Spindle 31

Metaphase üChromosomes, attached to the kinetochore fibers, move to the center of the cell üChromosomes are now lined up at the equator Equator of Cell Pole of the Cell 32

Metaphase Asters at the poles Spindle Fibers Chromosomes lined at the Equator 33

Metaphase Aster Chromosomes at Equator 34

Review of Metaphase What the cell looks like What’s occurring 35

Anaphase üOccurs rapidly üSister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers 36

Anaphase Sister Chromatids being separated 37

Anaphase Review What the cell looks like What’s occurring 38

Telophase üSister chromatids at opposite poles üSpindle disassembles üNuclear envelope forms around each set of sister chromatids üNucleolus reappears üCYTOKINESIS occurs üChromosomes reappear as chromatin 39

Comparison of Anaphase & Telophase 40

Cytokinesis üMeans division of the cytoplasm üDivision of cell into two, identical halves called daughter cells üIn plant cells, cell plate forms at the equator to divide cell üIn animal cells, cleavage furrow forms to split cell 41

Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell 42

Mitotic Stages 43

Daughter Cells of Mitosis üHave the same number of chromosomes as each other and as the parent cell from which they were formed üIdentical to each other, but smaller than parent cell üMust grow in size to become mature cells (G 1 of Interphase) 44

Identical Daughter Cells What is the 2 n or diploid number? 2 Chromosome number the same, but cells smaller than parent cell 45

Review of Mitosis 46

Draw & Learn these Stages 47

Draw & Learn these Stages 48

Name the Mitotic Stages: Interphase Name this? Prophase Telophase Name this? Metaphase Anaphase 49

Eukaryotic Cell Division ü Used for growth and repair ü Produce two new cells identical to the original cell ü Cells are diploid (2 n) Prophase Metaphase Chromosomes during Metaphase of mitosis Anaphase Telophase Cytokinesis 50

Mitosis Animation Name each stage as you see it occur? 51