Presentation on theme: "Growth and Development!!"— Presentation transcript:
1Growth and Development!! 10-1 Cell GrowthGrowth and Development!!
2When Do New Cells Need to Form? A. Growth - More cellsB. Maintenance (repair and replacement)--> intestinal lining/RBC’s)C. Asexual reproductionD. Formation of sex cells (Meiosis)
3Limit of cell size?1. TOO SMALL - There will not be enough room for all the organelles to carry out the processes needed.
42. TOO BIG!: Cell membrane cannot control all movements of materials The larger a cell grows the more trouble it has…moving enough nutrients inMoving all the waste materials out
5Problem with Being Too Big!! The volume gets too big for the surface area.The cell membrane cannot control all the movement in and out when the volume is too large.Your cells cannot too large either. The surface area must be in the correct ratio of the volume.Neurons are very long and skinny so that ration is correct.
6S.A. = 4 (pi) r 2 Radius 1cm S.A. = _____ V = ______ Ratio SA:V = ___ S.A. = __13cm2___V = __4cm3____Ratio SA:V = _13:4 or 3.25:1__Radius 2cmS.A. = ___50cm2__V = __33cm3____Ratio SA:V = 50:33_or 1.51:1Radius 3cmS.A. = __113cm2_V = ___113cm3___Ratio SA:V = _113:113 or 1:1__Radius 3cmS.A. = _____V = ______Ratio SA:V = ___S.A. = 4 (pi) r 2As the spheres get larger what happens to the SA:V ratio?
83rd Problem - Too Big 3. DNA overload Your DNA controls all activities in the cell. When the cell gets too big then the DNA cannot control all activites.
9Cells Divide at Different Rates The rate of cell division is determined by the body’s need for that type of cell.Nerve cells do not divide because they do not die like our skin cells.A new layer of skin is replaced every 3 weeks. The lining of your intestines has to be replaced often because of the wear and tear. This is also skin cells.
11Cell Cycle – life of a cell The life of a cell. It has a pattern of cell growth, DNA replication, and cell division. Results in two new daughter cells.
12The Cell CycleThe sequence of growth and division of a cell.95% of cell cycle in interphase(growth)5% of cell cycle in mitosis(division)
133 Main Events of a Cell Cycle 1. InterphaseG1 - growthS – DNA replicationG2 – growth and prepare for division2. Mitosis Phase – nucleus dividingProphaseMetaphaseAnaphaseTelophase3. Cytokinesis – cell division
17The Cell Cycle - series of events that cells go through as they grow and divide The cell cycle is divided into two halfsInterphase - period of the cell cycle between cell divisionsMitosis phase and cytokinesis – period of time when mitosis and cell division occurs
19Some DefinitionsHistones: proteins that DNA will wrap around. This helps the DNA to fit.Telomeres: End of DNA molecules to prevent them from attaching to each other. They do not contain genes.Somatic Cells – body cellsProduced through mitosisHas 46 chromosomes (23 pairs)
20Chromatin - A complex of DNA and proteins in the cell nucleus that condenses to form chromosomes during cell division(loose DNA).Chromosomes – Condensed Chromatin(X)They are the same stuff, just in different formsCentromeres: Center point where chromatids are attached.Spindle Fibers - Fibers that pull part the chromosomes during mitosis.
21Chromatin condenses in chomosomes before mitosis begins Chromosomes
22Parts of Interphase G1 Phase(growth) Cell grows Synthesize new proteins and organellesDoing their jobsLongest phase of cell cycle
23S Phase S Phase(synthesis) Chromosomes(DNA) are replicated Key proteins associated with replication are made (centromeres
24Gap 2 Phase G2 Phase(growth) Shortest of the 3 phases of interphase Organelles and molecules for cell division are produced (centrioles)Check-up phase before mitosis
25G - 0 StageThis is a stage of interphase that SOME cells enter. Cells such as nerve and white blood do not divide often so they enter this stage of rest.
28What stops cell from growing? Proximity to neighbor cells.Cells in a petri dish will continue to grow until they come into contact with other cells.Similarily, skin around a woundAfter a cell has quit growing, it is time to divide!!!Mitosis
46CytokinesisCytoplasm dividesTwo new daughter cells are now separate
47Cytokinesis The cytoplasm pinches in half Animal - cleavage furrow CytokinesisThe cytoplasm pinches in halfAnimal - cleavage furrowPlants - cell plate
48In plant cells, a cell plate forms In plant cells, a cell plate forms. The cell plate is synthesized by the fusion of multiple membrane-bounded vesicles. Their fusion supplies new plasma membrane for each of the two daughter cells. Synthesis of a new cell wall between the daughter cells then occurs at the cell plate.
49ApoptosisCell death. Factors that signal genes to produce self destructive enzymes. Not sure why.EX: webbing of toes on an embryo.
50Cyclins Protein that controls cell division.. They can make cells grow in a petri dish.Doesn’t work on all cells.
52CancerClass of disease caused by uncontrolled cell division. Arises when the regulation of the cell cycle breaks down. The cells continue to divide with the absence of internal and external growth factors.Benign tumor: cancer cells remain in one mass and usually can be removed.Malignant: cancer cells break away from the cancer cells to other parts of the body.
53Why are cancer cells so dangerous? Cancer cells cannot perform the duties needed by the body. Too many cancer cells and the body cannot perform the processes needed to live. A large tumor can apply pressure to other organs and affect the processes of organ.
54What causes cells to form cancer? Cancer cells comes from regular cells that have damage in one of the two genes that makes the proteins for cell cycle regulation.Oncogene: gene that accelerates the cell cycle.Gene 2 : breaks cell cycle.A mutation in these 2 genes can be inherited or a carcinogen can cause a mutation in these genes.
55Causes of CancerCarcinogen: Substances known to cause the cell cycle genes to mutate and cell divide uncontollably.Various forms of cancer have many causesSmokingRadiationViral infectionsThe common thread in all cancers is that control over the cell cycle has broken down.Over 50% of cancer cells have a defect in the p53 gene.
56p53 antioncogenep53 is a tumor suppressor gene found mutated in about half of human cancers.It encodes a gene regulatory protein that is activated by damaged DNA and is involved in blocking further progression of the cell cycle.