PowerLecture: Chapter 9 How Cells Reproduce

Henrietta says… “Congratulations, you survived Photosynthesis and Respiration!... Welcome to Chapter 9”

Fig. 9-2, p.141 Henrietta Lacks

Fig. 9-1, p.140 Henrietta’s Immortal Cells

HeLa Cells  Line of human cancer cells that can be grown in culture  Descendents of tumor cells from a woman named Henrietta Lacks  Lacks died at 31, but her cells continue to live and divide in labs around the world

Division Mechanisms Eukaryotic organisms Mitosis Mitosis Meiosis Meiosis Prokaryotic organisms Prokaryotic fission Prokaryotic fission

a One chromosome (unduplicated) b One chromosome (duplicated) one chromatid two sister chromatids one chromatid Fig. 9-3a, p.142 Stepped Art Chromosome

Kinetochore forms at centromere during nuclear division Kinetochore - a docking site for microtubules Fig. 9-3a, p.142 Stepped Art Chromosome

Organization of Chromosomes (the result of condensation of a chromosome) DNA and proteins arranged as cylindrical fiber DNA Histone A protein “spool” one nucleosome “bead” The smallest unit of a eukaryotic chromosome

core of histone fiber centromere (constricted region) multiple levels of coiling of DNA and proteins beads on a string DNA double helix nucleosome Fig. 9-4, p.143 Chromosome

DNA and Chromosomes Eukaryotic Chromosome Structure Eukaryotic Chromosome Structure Chromosome Supercoils Nucleosome DNA double helix Histones Coils

Chromosome Number  total # of chromosome types / cell ….(n)  Somatic cells diploid (2n) diploid (2n)  Gametes haploid (n) haploid (n)

Fig. 9-6a, p XX (or XY) Maintaining Chromosome Number

The Cell Cycle G1 S G2 Mitosis telophase anaphase metaphase prophase interphase Figure 9.5 Page 144

Interphase Interphase  Once S begins, the cycle automatically runs through G2 and mitosis  The cycle has a built-in molecular brake in G1  Cancer involves a malfunction of the “brakes”

Mitosis  nuclear division: ProphaseMetaphaseAnaphaseTelophase Then Cytoplasmic division

Fig. 9-15, p.153 cell at interphase nucleus cytoplasm telophase prophase anaphase metaphase

Stopping the Cycle  Some cells normally stop in interphase Neurons in human brain Neurons in human brain Arrested cells do not divide Arrested cells do not divide  Adverse conditions can stop cycle Nutrient-deprived amoebas get stuck in interphase Nutrient-deprived amoebas get stuck in interphase

The Spindle The Spindle  2 sets of microtubules that move chromosomes

Spindle Apparatus one spindle pole one of the condensed chromosomes spindle equator microtubules organized as a spindle apparatus one spindle pole

microtubule of bipolar spindle p.145 pole Maintaining Chromosome Number

a Two of the chromosomes (unduplicated) in a parent cell at interphase b The same two chromosomes, now duplicated, in that cell at interphase, prior to mitosis c Two chromosomes (unduplicated) in the parent cell’s daughter cells, which both start life in interphase Fig. 9-6b, p.145 Maintaining Chromosome Number

Interphase nuclear envelope pair of centrioles Early Prophase Late Prophase Prometaphase Stepped Art Fig. 9-7a, p.146

Metaphase AnaphaseTelophase Interphase Stepped Art Fig. 9-7b, p.146

Cytoplasmic Division  occurs at the end of mitosis  Two mechanisms Cell plate formation (plants) Cell plate formation (plants) Cleavage (animals) Cleavage (animals)

 A ring of microfilaments in the same plane as the spindle equator contracts, dividing the animal cell Animal Cell Division

Vesicles containing wall materials cluster at equator. Vesicle membranes fuse. Wall material sandwiched between 2 new membranes that lengthen along cell plate. Plant Cell Division

Cellulose deposited inside sandwich. These will form 2 cell walls. Others form the middle lamella between walls. A cell plate fuses with parent cell membrane. Plant Cell Division

Animal Cell Division

Cell Plate Formation Cell Plate Formation cell wall former spindle equator cell plate vesicles converging Stepped Art Fig. 9-8b, p.148

ring of microfilaments midway between the two spindle poles, in the same plane as the spindle equator Fig. 9-9, p.149 Cell Division

Fig. 9-10, p.149 Cell Division

Mitotic Control  Kinases  Growth factors  Checkpoint genes

Fig. 9-11a, p.150 Mitotic Control

Fig. 9-11b, p.150 Mitotic Control

Tumors uncontrollable division forms an abnormal mass called a tumor.  Neoplasms - an abnormal mass of cells

Fig. 9-12, p.150 Cancer

benign tumormalignant tumor 1 Cancer cells slip of out their home tissue 3 Cancer cells creep or tumble along inside blood vessels, then leave the bloodstream the same way they got in. They start new tumors in new tissues. 2 The metastasizing cells become attached to the wall of a blood or lymph vessel. They secrete digestive enzymes onto it. Then they cross the wall at the breach. Fig. 9-13, p.151Cancer

Fig. 9-14a, p.151 Cancer

Fig. 9-14b, p.151 Cancer

Fig. 9-14c, p.151 Cancer

Mitosis lab Onion Root Tip & Whitefish Blastula

Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis.

Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in.

Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in. Wednesday - Do procedure in class

Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in. Wednesday - Do procedure in class Friday – Turn in report (1 per group) including Methods, Data, and just your display of the % times as your conclusion