KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.

Transcription

1 5.1 The Cell Cycle KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. Objective: Cells have distinct phases of growth, reproduction and normal functions. APK: Why do you always cut your hair?

2 5.1 The Cell Cycle Cells double their DNA in order to divide and create two nearly identical duplicates or copies. Divide to separate Duplicate an identical copy Double to increase twofold Copy a reproduction of an original

3 5.1 The Cell Cycle The cell cycle has four main stages. The main stages of the cell cycle are Gap 1 (G1): 2. cell growth and normal functions, double organelles DNA synthesis (S): 4. copies DNA, Replication Gap 2 (G2): 6. additional growth, normal functions

4 5.1 The Cell Cycle The cell cycle has four main stages. The main stages of the cell cycle Take out a textbook and turn to CH 5.1 page 134 Copy down the diagram (just like the one to the right ) and make sure to take detailed notes on what happens in each part of the cell cycle!

5 5.1 The Cell Cycle Cells divide at different rates. The rate of cell division varies with the need for those types of cells. Some cells are unlikely to divide (G0).

6 5.1 The Cell Cycle Cell size is limited. Volume increases faster than surface area.

7 5.1 The Cell Cycle Surface area must allow for adequate exchange of materials. Too small, not enough machinery Too big, nutrients and waste can t move in/out Cell growth is coordinated with division. Cells that must be large have unique shapes.

8 5.1 The Cell Cycle Interphase Mitosis (M): Cell division includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis) Prophase Metaphase Anaphase Telophase cytokinesis Mitosis occurs only if the cell is large enough and the DNA undamaged.

9 5.1 The Cell Cycle What are the four main parts of the cell cycle? What phase are cells in during the majority of their life span? Why would some cells have a shorter life cycle than others? Are there cells that rarely or never divide?

10 5.1 The Cell Cycle Generalization What is the purpose of the cell cycle?

11 5.1 The Cell Cycle Homework: Answer the following questions: 1. During which stage of the cell cycle is the DNA copied? 2. Which stages of the cell cycle generally require about the same amount of time in all human cells? 3. What limits the maximum size of a cell?

12 5.2 Mitosis and Cytokinesis KEY CONCEPT Cells divide during mitosis and cytokinesis. Objective: Describe the structure of a chromosome. APK: What would you do if you had to put a lot of clothes into a small suitcase?

13 5.2 Mitosis and Cytokinesis Chromosomes condense at the start of mitosis. DNA wraps around proteins (histones) that condense it. DNA double helix DNA and histones Chromatin Supercoiled DNA

14 5.2 Mitosis and Cytokinesis DNA plus proteins is called chromatin. chromatid One half of a duplicated chromosome is a chromatid. Sister chromatids are held together at the centromere. Telomeres protect DNA and do not include genes. telomere centromere telomere Condensed, duplicated chromosome

15 5.2 Mitosis and Cytokinesis Mitosis and cytokinesis produce two genetically identical daughter cells. Parent cell Interphase prepares the cell to divide. During interphase, the DNA is duplicated. centrioles spindle fibers centrosome nucleus with DNA

16 5.2 Mitosis and Cytokinesis Mitosis divides the cell s nucleus in four phases. During prophase, chromosomes condense and spindle fibers form.

17 5.2 Mitosis and Cytokinesis Mitosis divides the cell s nucleus in four phases. During metaphase, chromosomes line up in the middle of the cell.

18 5.2 Mitosis and Cytokinesis Mitosis divides the cell s nucleus in four phases. During anaphase, sister chromatids separate to opposite sides of the cell.

19 5.2 Mitosis and Cytokinesis Mitosis divides the cell s nucleus in four phases. During telophase, the new nuclei form and chromosomes begin to uncoil.

20 5.2 Mitosis and Cytokinesis Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed. In plant cells, a cell plate forms.

21 5.2 Mitosis and Cytokinesis Generalization: Cells have distinct phases of growth, reproduction and normal functions.

22 5.2 Mitosis and Cytokinesis 5.2 Homework Check 1. Draw what a chromosome looks like during metaphase. Identify the chromatids and the centromere. 2. Briefly explain why the daughter cells resulting from mitosis are genetically identical to each other and to the original cell. The independent variable is temperature and the dependent variable is the number of daily doublings. 3. How do prophase and telophase differ? Prophase and telophase are opposites. The nuclear envelope fragments, chromosomes condense, and spindle fibers start to assemble in prophase. In telophase, the reverse occurs: the nuclear envelope reforms, chromosome uncoil, and spindle fibers disassemble. 4. Using a light microscope you observe a cell that has no nucleus. What features would you look for to determine whether it is a eukaryotic cell undergoing mitosis or a prokaryotic cell? Other organelles should be visible in a eukaryotic cell along with (condensed) chromosomes and spindle fibers if it were undergoing mitosis.

23 5.2 Mitosis and Cytokinesis Homework for tomorrow: Read pages and answer questions 1-3 on page 147

24 5.3 Regulation of the Cell Cycle KEY CONCEPT Cell cycle regulation is necessary for healthy growth. Objective: Identify internal and external factors that regulate cell division. APK: What is cancer?

25 5.3 Regulation of the Cell Cycle Internal and external factors regulate cell division. External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

26 5.3 Regulation of the Cell Cycle Two of the most important internal factors are kinases and cyclins. Cyclin: group of proteins that triggers action of kinases Kinase: enzymes that affect molecule s activity - kin = Kinetics, kinein = to move - ase = enzyme Together these both help a cell advance to different External stages of the cell cycle growth External factors trigger internal factors, which affect the cell cycle. factors Triggered cell cycle activities Cyclins Kinases

27 5.3 Regulation of the Cell Cycle Apoptosis is programmed cell death. a normal feature of healthy organisms caused by a cell s production of self-destructive enzymes occurs in webbed fingers development of infants

28 5.3 Regulation of the Cell Cycle Cell division is uncontrolled in cancer. Cancer cells form disorganized clumps called tumors. Benign tumors remain clustered and can be removed. Malignant tumors metastasize, or break away, and can form more tumors. (noun = metastasis) normal cell cancer cell bloodstre am

29 5.3 Regulation of the Cell Cycle Different growth patterns of tumors

30 5.3 Regulation of the Cell Cycle Cancer cells do not carry out necessary functions. Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

31 5.3 Regulation of the Cell Cycle Carcinogens are substances known to promote cancer. UV radiation Smoking Other forms of radiation (nuclear radiation, x-rays, etc.) Standard cancer treatments typically kill both cancerous and healthy cells.

32 5.3 Regulation of the Cell Cycle Viruses can also cause cancer!

33 5.3 Regulation of the Cell Cycle How are cancers named? Type of tissue of origin: Carcinoma: tumor of the internal or external lining of the body (skin & covering and lining of organs and internal passageways). Sarcoma: cancer that originates in supportive and connective tissues such as bones, tendons, cartilage, muscle, and fat. Leukemias ("liquid cancers" or "blood cancers") are cancers of the bone marrow (the site of blood cell production). Lymphomas develop in the glands or nodes of the lymphatic system, a network of vessels, nodes, and organs.

34 5.3 Regulation of the Cell Cycle How are cancers named? First site of origin:

35 5.3 Regulation of the Cell Cycle APPLICATION 1. Explain the process of how cancer begins and causes metastasis. 2. What are some external and internal factors that cause the cell cycle to go wrong?

36 5.3 Regulation of the Cell Cycle Generalization: Why is cell cycle regulation necessary for healthy growth?

37 5.3 Regulation of the Cell Cycle Homework Check 1. Describe what a growth factor is and how it influences the cell cycle. A growth factor is an external signal that stimulates growth and division of cells. 2. Explain how cancer cells differ from healthy cells. Cancer cells have uncontrolled division, grow rapidly without many growth factors, can form tumors, can metastasize and do not contribute to the body s functions. 3. How do benign and malignant tumors differ? Benign tumors, cancer cells clustered together and relatively harmless. Malignant tumors, cancer cells can metastasize and form more tumors.

38 5.3 Regulation of the Cell Cycle Homework for Friday October 30th Read pages and answer questions 1-3 on page 150.

39 5.4 Asexual Reproduction Many organisms reproduce by cell division. GOAL: Compare and contrast binary fission and mitosis. Describe how some eukaryotes reproduce through mitosis. APK: What is asexual reproduction?

40 5.4 Asexual Reproduction Sexual Reproduction- joining of an egg and sperm cell, one from each of two parents. Offspring are genetically unique Have a mixture of genes from both parents Asexual Reproduction- creation of offspring from a single parent and does not involve the joining of gametes. Offspring are genetically identical to each other and the single parent.

41 5.4 Asexual Reproduction Most prokaryotes reproduce through binary fission. Binary fission- asexual reproduction of a single celled organism by division into two daughter cells genetically identical to the parent cell. parent cell DNA duplicates cell begins to divide daughter cells

42 5.4 Asexual Reproduction Mitotic Reproduction Some eukaryotes reproduce through mitosis. - Usually simple plants and animals There are three types: Budding Fragmentation Vegetative Reproduction

43 5.4 Asexual Reproduction Budding forms a new organism from a small projection growing on the surface of the parent. Hydra bud Yeast

44 5.4 Asexual Reproduction Fragmentation is the splitting of the parent into pieces that each grow into a new organism.

45 5.4 Asexual Reproduction Vegetative Reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.

46 5.4 Asexual Reproduction What are other advantages for asexual reproduction? All organisms can potentially reproduce. - Male and female have offspring Don t have to look for a mate. - takes time, energy - need specific structures, signals, and behaviors

47 5.4 Asexual Reproduction APPLICATION Record in a t-chart the advantages and disadvantages of asexual reproduction

48 5.4 Asexual Reproduction GENERALIZATION Why do some organisms reproduce asexually?

49 5.4 Asexual Reproduction HOMEWORK 1. Explain how mitosis differ from binary fission. 2. Briefly explain why cutting s flatworm into pieces would not kill it.

50 5.5 Multicellular Life Objective: Identify the importance of stem cells. APK: What do you know about stem cells?

51 5.5 Multicellular Life Multicellular organisms depend on interactions among different cell types Tissues are groups of cells that perform a similar function. Organs are groups of tissues that perform a specific or related function. Organ systems are groups of organs that carry out similar functions. Organ systems work together to help organisms maintain homeostasis.

52 5.5 Multicellular Life Specialized cells perform specific functions. Cell differentiation- Process where cells develop into their mature forms. Cells differ because different combinations of genes are expressed. A cell s location in an embryo helps determine how it will differentiate. Outer: skin cells Prevent infection, dehydration Middle: bone cells Support, protect organs Inner: intestines Increase absorption

53 5.5 Multicellular Life Stem cells are unique body cells. Stem cells have the ability to divide and renew themselves remain undifferentiated in form develop into a variety of specialized cell types

54 5.5 Multicellular Life Stem cells are classified into three types Totipotent- can grow into any other cell type Pluripotent- can grow into any cell type but a totipotent cell Multipotent- can grow into cells of a closely related cell family

55 5.5 Multicellular Life Stem cells come from adults and embryos Adult stem cells can be hard to isolate and grow. may prevent transplant rejection. Limited cell type potential Embryonic stem cells Raise ethical issues are pluripotent and can be grown indefinitely in culture May be rejected by a patients body First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

56 5.5 Multicellular Life The use of stem cells offers many currently realized and potential benefits. used to treat leukemia and lymphoma. may cure disease or replace damaged organs. may revolutionize the drug development process.

57 5.5 Multicellular Life APPLICATION 1. List treatment benefits and risks of both types of stem cells. 2.What are the defining charactertics of stem cells?

58 5.5 Multicellular Life GENERALIZATION Cells work together to carry out complex functions