THE CELLULAR BASIS OF INHERITANCE CHAPTER 9

Why Is Cell Reproduction Essential for Life? #1) Maintain/Heal the Body – TO REPLACE LOST OR DAMAGED CELLS Example: Every minute of the day we lose about 30,000 to 40,000 dead skin cells off the surface of our skin.

Why Is Cell Reproduction Essential for Life? #2) GROWTH - Increase body size by increasing the number of cells in the body

Why Is Cell Reproduction Essential for Life? #3) REPRODUCTION = TO CREATE A COMPLETE NEW ORGANISM. 2 TYPES OF REPRODUCTION: a) ASEXUAL b) SEXUAL

ASEXUAL REPRODUCTION How Many Parents? SINGLE PARENT OFFSPRING ARE GENETICALLY IDENTICAL TO EACH OTHER AND TO PARENT. SEEN IN UNICELLULAR ORGANISMS AND SOME MULTICELLULAR ORGANISMS SUCH AS PLANTS,FUNGI, AND SOME ANIMALS LIKE SPONGES AND STARFISH. How Many Parents?

SEXUAL REPRODUCTION 2 PARENTS GENETIC MATERIAL (CARRIED IN EGG AND SPERM) FROM EACH PARENT COMBINES EACH OFFSPRING IS GENETICALLY DIFFERENT FROM PARENTS Egg and Sperm are produced through cell division

REVIEW: WHY DO CELLS DIVIDE AND PRODUCE NEW CELLS? For Maintenance of the body (multicellular organisms) For Growth For Reproduction (multi- and unicellular organisms)

STARTS WHEN A CELL IS “BORN” & ENDS WHEN IT REPRODUCES. The “CELL CYCLE” STARTS WHEN A CELL IS “BORN” & ENDS WHEN IT REPRODUCES. CELL CYCLE PRODUCES CELLS NEEDED FOR GROWTH & MAINTENANCE OF THE BODY

The “CELL CYCLE” Cell is not dividing (Most of the time) Cell is Nucleus divides first Cytoplasm divides last

The “CELL CYCLE” HAS 2 MAIN STAGES: INTERPHASE MITOTIC PHASE cell isn’t dividing MITOTIC PHASE cell is dividing

INTERPHASE WHAT IS IT? WHAT HAPPENS DURING IT?

INTERPHASE LONGEST STAGE (90% OF THE CELL CYCLE) THE CELL GROWS & PERFORMS ITS JOB AS A CELL

INTERPHASE IN THIS STAGE DNA EXISTS AS A MASS OF VERY LONG THIN FIBERS CALLED _________________. CHROMATIN

INTERPHASE CELL ALSO PREPARES TO REPRODUCE (CELL DIVISION) BY INCREASING ITS NUMBER OF ORGANELLES & BY MAKING COPIES OF ALL ITS _____________. DNA muy importante!!! EACH DNA STRAND IS COPIED & THE 2 COPIES ARE JOINED AT ONE SPOT CALLED THE __________________. CENTROMERE

DNA IN CHROMATIN FORM

What Happens Next?! After the cell has made all its preparations, then it divides! On to the Mitotic Phase!!

MITOTIC PHASE SHORTEST STAGE of the CELL CYCLE THIS IS WHERE 1 CELL DIVIDES INTO 2 CELLS OCCURS IN 2 STEPS: 1) MITOSIS 2) CYTOKINESIS

MITOSIS All about the Nucleus! In this stage the nucleus divides into 2 and the chromosomes are evenly divided up. Each daughter nucleus receives a complete set of chromosomes

MITOSIS CHROMOSOMES CHROMATIDS ____________________. SISTER ALL THE DUPLICATED CHROMATIN FIBERS NOW COIL UP (GET SHORTER & THICKER) & ARE CALLED ____________________. EACH CHROMOSOME IS MADE UP OF 2 IDENTICAL HALVES CALLED ______________ . CHROMOSOMES SISTER CHROMATIDS

MITOSIS The SISTER CHROMATIDS SEPARATE & GO TO OPPOSITE ENDS OF THE CELL FORMING 2 NEW “DAUGHTER” NUCLEI

CYTOKINESIS The CYTOPLASM DIVIDES BETWEEN THE 2 NEW “DAUGHTER” NUCLEI FORMING 2 NEW CELLS

The “CELL CYCLE” Cell is not dividing (Most of the time) Cell is MITOTIC PHASE INTERPHASE Nucleus divides first Cytoplasm divides last MITOSIS CYTO- KINESIS

Name the Structure! ? ? ? ? Chromosomes Centromere ? ? Centromere ? SISTER CHROMATIDS ?

CELL CYCLE ______________ = series of events that cells go through as they grow and develop cells alive cell cycle

CELL CYCLE INTERPHASE – non-dividing phase G1- Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G2- Grow bigger, make organelles & molecules needed for cell division

CELL DIVISION MITOSIS – Nuclear division Prophase Metaphase Anaphase Telophase Cytokinesis – Cytoplasm divides G0 – cell stops dividing (Ex: nerve cell)

INTERPHASE (G1 - S - G2) Can’t see chromosomes In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Can’t see chromosomes DNA gets copied (S) Cell gets ready to divide

PROPHASE 1st dividing phase DNA scrunches into chromosomes Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1st dividing phase http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html DNA scrunches into chromosomes Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes

________ region organizes spindle CENTROSOME Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm

METAPHASE Chromosomes line up in ___________ middle Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

ANAPHASE Centromeres split Centrioles pull chromatids_______ apart Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

two TELOPHASE (reverse prophase steps) See ______ nuclei Nuclear membrane & nucleolus return Chromosomes spread out as chromatin Centrioles disappear Spindle fibers disappear Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html

CYTOKINESIS Cytoplasm splits into 2 cells CLEAVAGE FURROW ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW

CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ Plant cells separate cytoplasm by growing a _______________ down the middle. CELL WALL CELL PLATE http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Interphase Cytokinesis Telophase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Centromere Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming