Presentation on theme: "REVIEW QUESTIONS on your own paper- Use your notes- Turn into pink basket. 1. How is a cancer cell affected by the cell cycle? 2. Compare an internal."— Presentation transcript:
REVIEW QUESTIONS on your own paper- Use your notes- Turn into pink basket. 1. How is a cancer cell affected by the cell cycle? 2. Compare an internal regulator from an external regulator. Include examples. 3. Which is worse, a benign tumor or a malignant one and why? 4. Describe how a stem cell can become any other cell. 5. What are the two sources for stem cells and how are they
Standards B-2.4 Explain the process of cell differentiation as the basis for the hierarchical organization of organisms (including cells, tissues, organs, and organ systems). B-2.6 Summarize the characteristics of the cell cycle: interphase (called G1, S, G2); the phases of mitosis (called prophase, metaphase, anaphase, and telophase); and plant and animal cytokinesis. B-2.7 Summarize how cell regulation controls and coordinates cell growth and division and allows cells to respond to the environment, and recognize the consequences of uncontrolled cell division. B-4.2 Summarize the relationship among DNA, genes, and chromosomes.
1. DNA, genes, and chromosomes compose the molecular basis of heredity. a. A chromosome is a structure in the nucleus of a cell consisting of one long thread of DNA that is tightly coiled. DNA double helix DNA and histones Chromatin Supercoiled DNA
b. DNA is composed of nucleotides and provides the blueprint for the synthesis of proteins by the arrangement of the nitrogenous bases
c. A gene is a specific location on a chromosome, consisting of a segment of DNA, that codes for a particular protein. i. The particular proteins coded by the DNA on the genes determine the characteristics of an organism ii. Each chromosome consists of hundreds of genes determining the many proteins for an individual organism.
1. The cell cycle is a repeated pattern of growth and division that occurs in eukaryotic cells. 2. It consists of three main stages:
a. Interphase – Cells spend most of their time in interphase. During this time the DNA in the nucleus is loosely organized and looks like spaghetti. i. G1 (gap 1) phase – The cell carries out its normal functions including growth and synthesizing proteins ii. S (synthesis) phase – Chromosomes copy themselves to form identical sister chromatids that are held together by a centromere. iii. G2 (gap 2) phase – Cells continue to grow and produce proteins needed for cell division
Interphase Parent cell centrioles spindle fibers centrosome nucleus with DNA
1. Mitosis – The DNA that was replicated (sister chromatids) in Interphase has to be broken apart during mitosis so that each new cell has only one double- stranded chromosome. 2. Mitosis is divided into four phases:
a. Prophase i. Chromosomes condense and are more visible ii. The nuclear membrane (envelope) disappears. iii. Centrioles (organelles that make spindle fibers) travel to opposite poles of the cell. iv. Spindle fibers form and begin to radiate toward the center of the cell.
c. Anaphase i. The centromeres that join the sister chromatids split ii. The sister chromatids are now individual chromosomes iii. The spindle fibers shorten to pull the separated chromatids to opposite poles of the cell.
1. Cell Cycle Control a. The cell cycle is driven by a chemical control system that triggers and coordinates key events in the cell cycle. b. Internal Signals – involve sensing the presence of enzymes which are produced inside the cell.
c. External signals – sensing of a chemical outside of cell that tells it to grow i. Ex: Growth factors – proteins stimulate cell division. ii. Ex: Cell – Cell Contact: When cells meet and touch, they stop dividing. When cells are not touching, mitosis occurs until they do
d. Checkpoints – are critical control points where stop and go signals can regulate the cycle. G1- DNA is checked for mistakes. If a mistake is present, cell stops dividing G2 (beginning of G2) Rechecks replicated DNA (after S) for mistakes M - checks to make sure all chromosomes are lined up exactly in middle before anaphase G 0 Resting Cell stops dividing
2. Cancer Cells a. Cancer cells ignore the normal signals to stop dividing. Uncontrolled cell division b. Starts when one cell is transformed into a cancer cell. i. The immune system will normally destroy this cell. ii. If it is not destroyed the cell divides and each daughter cell will be a cancer cell. These daughter cells continue to divide until a tumor forms.
iii. Malignant Tumors 1. When cancer cells invade and hurts the function of one or more organs. 2. The cancer cells can break away from the tumor and be carried through the bloodstream or lymph system to other parts of the body where they form more tumors. iv. Benign Tumors 1. A mass of abnormal cells that remains at the original site.
1. Homeostasis – the maintenance of a stable internal environment a. In multicellular organisms cells communicate and work together to maintain homeostasis. b. A single fertilized egg gives rise to many different types of cells that all have different structures and functions.
2. Cell Differentiation a. Cell division by itself makes all identical cells. b. Cell differentiation- takes unspecialized cells (stem cells)and develops them into their mature forms and functions.
c. In a multicellular organism, all cells have the same chromosomes and DNA. i. During differentiation, only specific parts of the DNA are activated. The part activated determines the function of the cell. ii. All cells have the potential to become any type of cell. iii. Once a cell differentiates, it cannot be reversed.
3. Stem Cells a. Are unspecialized cells that continually reproduce themselves and have the ability to differentiate into one or more types of cells. b. There are two types of stem cells: i. Embryonic Stem Cells 1. Embryonic cells that have not differentiated yet. ii. Adult Stem Cells 1. Found in adults such as in the bone marrow.
Embryonic stem cells Can become any type of cell
Adult stem cells from bone marrow Can only become a few types of cells.
c. Scientists have discovered that with the right laboratory conditions, both embryonic and adult stem cells can be differentiated into specialized cells.
*Benefits of Stem Cells – Stem cells are used to treat leukemia and lymphoma. – Stem cells may cure disease or replace damaged organs. – Stem cells may revolutionize the drug development process.