Cellular Reproduction Chapter 8

Transcription

1 Cellular Reproduction Chapter 8 1. Importance of Cell Division 2. Eukaryotic Cell Cycle 3. Eukaryotic Chromosomes 4. Mitosis 5. Cytokinesis in animal and plant cells 6. Sexual Iife cycle 7. Meiosis 8. Cancer 9. Aneuploidy

2 Importance of Cell Division Growth and Development Zygote Embryo Fetus Adult 1 Cell 100 cells millions cells 100 trillion cells Asexual Reproduction

3 Figure 8.3 Chromosomes

4 Figure 8.4 TEM TEM DNA double helix Beads on a string Histones Nucleosome Tight helical fiber Thick supercoil Duplicated chromosomes (sister chromatids) Centromere

5 Organization of DNA in Cell Monad Interphase Chromatin Dyad Monad Mitotic Chromatin

6 Chromosome Number Humans 23 pair of chromosomes Diploid cells total of 46 chromosomes 44 Autosomes 2 Sex Chromosomes Haploid cells total of 23 chromosomes 22 Autosomes 1 Sex Chromosomes Other species have different # of chromosome. Haploid corn cells 10 Dog s 39

7 Figure 8.2 Species Number of chromosomes in body cells Indian muntjac deer Koala Opossum Giraffe Mouse Human Duck-billed platypus Buffalo Dog Red viscacha rat 102

8 Chromosomes Karyotype number and type of chromosomes Diploid Cells two matched sets of chromosomes Homologous Chromosomes matched pair of chromosomes Sex chromosomes set of chromosomes that differ in two sexes Autosomes any chromosome that is not a sex chromosomes Haploid Cells cells with only one set of chromosomes - gametes

9 Eukaryotic Cell Cycle Grow Grow Divide Grow Grow Divide

10 Eukaryotic Cell cycle Divide M phase Grow Interphase Interphase Interphase M Phase Interphase

11 Eukaryotic Cell Cycle Mitosis G 2 G 1 S - Phase

12

13 Mitosis

14 Cytokinesis Cleavage Furrow Cell Plate

15 Cell Division Highly Regulated

16 Regulation of Cell Cycle Cell Cycle Check Points - Brakes of cell cycle Check Points monitor internal conditions Examples of monitored conditions Is the cell large enough Has the DNA been replicated Has every chromosome attached to spindle fiber Cell Cycle Stimulators - Accelerator of cell cycle Cell Growth Stimulators external factors that stimulate cell growth and the cell machinery that detects and response to these factors Examples of Stimulators Growth factor hormones Hormone Receptors

17 Cancer broken regulation of cell cycle Lymph vessels Tumor Blood vessel A tumor grows from a single cancer cell. Glandular tissue Cancer cells invade neighboring tissue. Metastasis: Cancer cells spread through lymph and blood vessels to other parts of the body.

18 Cell Cycle Genes 1. Tumor Suppressor Genes encode Cell Cycle Check Points 2. Proto-Oncogenes Genes encode Cell Cycle Stimulators

19 Cancer Caused By Mutations Tumor Suppressor genes mutated to lose function (Like a non-functioning brake) Proto-oncogenes mutated to change function and become Oncogenes (like a stuck accelerator) What Causes the Mutations Spontaneous mutations errors in DNA Replication Induced mutations caused by environmental factors called mutagens

20 Carcinogens

21 Multistep Nature of Cancer Chromosomes 1 mutation 2 mutations 3 mutations 4 mutations Normal cell Malignant cell

22 Multistep Nature of Cancer Cellular changes: Increased cell division Cellular changes: Growth of benign tumor Cellular changes: Growth of malignant tumor Colon wall Colon wall DNA changes: Oncogene activated DNA changes: Tumor-suppressor gene inactivated DNA changes: Second tumor-suppressor gene inactivated

23 1.Surgery Cancer Treatments Slash, Burn, Poison 2.Radiation 3.Chemotherapy

24 Human Life Cycle Mitotic Cell Cycle generates daughter cells identical to mother cell Meiosis generates daughter cells with ½ the genetic material of mother cell Fertilization (fusion of gametes) doubles the genetic material in the zygote

25 Figure 8.UN04 Human Life Cycle Haploid gametes (n 23) Key Haploid (n) Diploid (2n) n Egg cell n Sperm cell MEIOSIS FERTILIZATION Male and female diploid adults (2n 46) MITOSIS and development 2n Diploid zygote (2n 46)

26 Figure Chromosomes 2 Homologous 3 duplicate. chromosomes separate. Sister chromatids separate. Pair of homologous chromosomes in diploid parent cell Duplicated pair of homologous chromosomes Sister chromatids INTERPHASE BEFORE MEIOSIS MEIOSIS I MEIOSIS II

27

28 Figure 8.14a MEIOSIS I: HOMOLOGOUS CHROMOSOMES SEPARATE INTERPHASE PROPHASE I METAPHASE I ANAPHASE I Centrosomes (with centriole pairs) Sites of crossing over Spindle Microtubules attached to chromosome Sister chromatids remain attached Sister Nuclear chromatids Pair of envelope Chromatin Centromere homologous chromosomes Chromosomes duplicate. Homologous chromosomes pair up and exchange segments. Pairs of homologous chromosomes line up. Pairs of homologous chromosomes split up.

29 Figure 8.14b MEIOSIS II: SISTER CHROMATIDS SEPARATE TELOPHASE I AND CYTOKINESIS PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II AND CYTOKINESIS Cleavage furrow Sister chromatids separate Haploid daughter cells forming Two haploid cells form; chromosomes are still doubled. During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosomes.

30 Figure 8.15 MITOSIS MEIOSIS Prophase Duplicated chromosome Metaphase Chromosomes align. Parent cell Prophase I Metaphase I Homologous pairs align. MEIOSIS I Site of crossing over Anaphase Telophase Sister chromatids separate. 2n 2n Anaphase I Telophase I Homologous chromosomes separate. Sister chromatids separate. n n n n MEIOSIS I Haploid n 2 MEIOSIS II

31 Meiosis and Genetic Variation 1. Independent Assortment of Chromosomes 2. Random Fertilization 3. Genetic Recombination

32 Meiosis and Genetic Variation 1. Independent Assortment of Chromosomes 2. Random Fertilization 3. Genetic Recombination

33 Errors in Meiosis Non-disjunction

34 Aneuploidy Abnormal egg cell with extra chromosome n 1 Normal sperm cell n (normal) Abnormal zygote with extra chromosome 2n 1

35 LM Trisomy 21 Downs Syndrome Trisomy 21

36 Sex Chromosome Aneuploids Turners Syndrome (XO) Trisomy X (XXX) Klinefelters XXY Jacob Syndrome XYY