Cell cycle The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication (replicatio

Transcription

1 Cell Division

2 Cell cycle The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication (replication) that produces two daughter cells.

3 Chromosome 염색체 ( 染色體, chromosome) 는생물체 ( 엄밀히말하면진핵세포를지닌생물 ) 의세포분열과정에서만관측되며, 세포분열기에들어가면서유전물질을안전하게보호하고딸세포들에게형평성있게유전정보를분배하기위해염색사가꼬이고뭉쳐져응축되어 X 자형태를이룬구조물이다.

4 Chromosome

5 Mitosis

6 Interphase

7 Interphase a) Interphase: The period of a cell s growth and development. I. Before a cell can enter cell division, it needs to take in nutrients. All of the preparations are done during interphase. II. Interphase is a series of changes that takes place in a newly formed cell and its nucleus, before it becomes capable of division again. III. Typically interphase lasts for at least 90% of the total time required for the cell cycle.

8 Interphase

9 Mitotic Phase b) Mitotic phase: The period of a cell s reproduction. I. Mitosis is the process by which a cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei. II. Mitosis occurs exclusively in eukaryotic cells. Prokaryotic cells, which lack nucleus, divide by a process called binary fission. III. Mitotic phase is divided into phases, corresponding to the completion of one set of activities and the start of the next. These phases are sequentially known as: prophase metaphase anaphase telophase cytokinesis

10 Why do Cell divide? 1. Growth 2. Reproduction 3. Repair Some cells never divide (ex. Nerve cell)

11 DNA vs. Gene vs. Chromosome? DNA: A material which contains genetic information Gene: The genetic material inside the DNA Chromosome: Chromosomes contain DNA

12 Terms 1. Centromere: 중심립 2. Telomere: 말단소립 3. Kinetochore: 동원체 4. Centrosome: 중심체 5. Chromatid: 염색분체 6. Spindle: 방추사 7. Spindle pole: 방추체극 8. Chromosome: 염색체 9. Microtubule: 미소관 10. Nuclear envelope: 핵외피 11. Diploid: 2 배체 12. Autosome: 상염색체 13. Sex chromosome: 성염색체 14. Cleavage furrow: 분열구 15. Centriole: 중심체

13 Mitotic Phase

14 Animal cell vs. Plant cell

15 Cancer Cells: Growing out of Control

16 What is Cancer? Disease of the cell cycle. In all types of cancer, some of the body s cells begin to divide without stopping and spread into surrounding tissues.

17 Tumor and Metastasis Benign tumor: If the abnormal cells remain at the original site, the lump is called a benign tumor. Malignant tumor: One that has begun to spread into neighboring tissues and other parts of the body. Metastasis: the spread of a cancer or other disease from one organ or part to another not directly connected with it.

18 Cancer Staging Primary Tumor (T) TX: Primary tumor cannot be evaluated T0: No evidence of primary tumor Tis: Carcinoma in situ T1, T2, T3, T4: Size and/or extent of the primary tumor Regional Lymph Nodes (N) NX: Regional lymph nodes cannot be evaluated N0: No regional lymph node involvement N1, N2, N3: Degree of regional lymph node involvement (number and location of lymph nodes) Distant Metastasis (M) MX: Distant metastasis cannot be evaluated M0: No distant metastasis M1: Distant metastasis is present Stage Stage 0 Stage I, Stage II, and Stage III Stage IV Definition Carcinoma in situ Higher numbers indicate more extensive disease: La rger tumor size and/or spread of the cancer beyond t he organ in which it first developed to nearby lymph nodes and/or tissues or organs adjacent to the locati on of the primary tumor The cancer has spread to distant tissues or organs

19 Cancer Treatment Radiation Therapy: Parts of the body that have cancerous tumors are exposed to concentrated beams of high energy radiation, which can often harm cancer cells more than the normal cells of the body. Chemotherapy: The use of drugs to disrupt cell division.

20 Meiosis

21 Meiosis A specialized type of cell division which reduces the chromosome number by half. Occurs in all sexually reproducing single-celled and multi-celled eukaryotes. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells each with half the number of chromosomes as the original parent cell. In the case of animals, meiosis only happens in testis and ovary.

22 Meiosis I. Meiosis I: Homologous chromosomes pair at the metaphase plate, and then the homologues migrate to opposite poles. II. Meiosis II: Chromosomes spread across the metaphase plate and sister chromatids separate and migrate to opposite poles.

23 Meiosis I Meiosis II: Homologous chromosomes pair at the metaphase plate, and then the homologues migrate to opposite poles.

24 Crossing Over Genetic material from the homologous chromosomes is randomly swapped This creates four unique chromatids Since each chromatid is unique, the overall genetic diversity of the gametes is greatly increased

25 Meiosis II Meiosis II: Chromosomes split across the metaphase plate and sister chromatids separate and migrate to opposite poles.

26 Meiosis

27 Mitosis vs. Meiosis

28 Genetic Variation 1. Crossing over - During prophase I, nonsister chromatids of homologous chromosomes exchange pieces of genetic material. 1. Independent assortment of homologues - During metaphase I and anaphase I, tetrads of homologues chromosomes separate into chromosomes that go to o pposite poles. 2. Random joining of gametes - Which sperm fertilizes with which egg is a random event.

29 Regulation of the Cell Cycle 1. Surface to volume ratio (S/V) - When S/V is large, a cell can efficiently react with the outside environment. For instance, adequate amounts of oxygen can diffuse into the cell, and waste products can be rapidly eliminated. When S/V is small, the surface area might be unable to exchange enough substances with the outside environment. 2. Genome to volume ratio (G/V) - The genetic material in the nucleus, called its genome, controls the cell by producing substances that make enzymes and other biosynthetic substances. The capacity of the genome to do this is limited by its finite amount of genetic material. As the cell grows, its volume increases, but its genome size remains constant. As the G/V decreases, the cell s size exceeds the ability of its genome to produce sufficient amounts of materials for regulating cellular activities.

30 When Meiosis Goes Awry Nondisjunction: members of a chromosome pair fail to separate at anaphase.

31 Down Syndrome: An Extra Chromosome 21 Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.

32 Down Syndrome: An Extra Chromosome 21 - One in every 691 babies in the United States is born with Down syndrome, making Down syndrome the most common genetic condition.

33 Down Syndrome: An Extra Chromosome 21 - Down syndrome is usually identified at birth by the presence of certain physical traits: low muscle tone, a single deep crease across the palm of the hand, a slightly flattened facial profile and an upward slant to the eyes.

34 Abnormal Numbers of Sex Chromosomes Also known as 47,XXY or XXY, is the set of symptoms that result from two or more X chromosome in males.

35 Abnormal Numbers of Sex Chromosomes 45,X, is a condition in which a female is partly or completely missing an X chromosome.