Upload
peter-webb
View
220
Download
2
Tags:
Embed Size (px)
Citation preview
Cell Growth and ReproductionCell Growth and Reproduction
Chapter 9
Chapter Objective
Describe the processes of cell growth and cell reproduction (SPI 3210.1.6.)
Section 9.1
The cell cycle multiplies cells
Section Objectives
1. Describe the structure and function of a chromosome.
2. Given a diagram or picture of a cell, identify whether the cell is in the interphase or mitotic phase of the cell cycle and explain what happens during each phase.
Key Terms
• chromatin• chromosome• sister chromatid• centromere• cell cycle
• interphase• mitotic phase• mitosis• cytokinesis
Large Cells Can Have Problems!
As cells grow, their volume increases much more rapidly than their surface area!
Large cells may have difficulty supplying nutrients and expelling enough waste products.
Why is size a problem?
Transport of Substances
Substances move by diffusion or by motor proteins.
Diffusion over large distances is slow and inefficient.
Small cells maintain more efficient transport systems.
Cellular Communications
The need for signaling proteins to move throughout the cell also limits cell size.
Cell size affects the ability of the cell to communicate instructions for cellular functions.
• How often a cell divides depends on the type of cell (its functionfunction).
• Eukaryotic cells that do divide undergo an orderly sequence of events known as the cell cycle.
Cells Divide at Different Rates
The Cell Cycle
Cell division prevents the cell from becoming too large.
It also is the way the cell reproduces so that you grow and heal certain injuries.
Cells reproduce by a cycle of growing and dividing called the cell cycle.
Interphase - the cell grows, carries out cellular functions, and replicates.
Mitosis - the cell’s nucleus and nuclear material divide.
Cytokinesis - a cell’s cytoplasm divides.
The Cell CycleThe Cell Cycle
Phases of The Cell CyclePhases of The Cell Cycle
• Interphase–G1 (Gap1)–S (DNA Synthesis)–G2 (Gap2)
• Mitotic (M) Phase• Cytokinesis
The Cell Cycle
The Stages of Interphase
1st stage - G1
The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.
2nd Stage – S The cell copies its DNA in preparation for
cell division.
The Stages of Interphase
S phaseGenetic material (chromosomes) duplicate)
3rd Stage - G2
Cell prepares for division of nucleus (mitosis).
The Stages of Interphase
Mitosis and CytokinesisMitosis and Cytokinesis
Concept 9.2
Cells divide during the mitotic phaseCells divide during the mitotic phase
Section Objectives
Given diagrams or pictures of cells in various stages of the mitotic phase of the cell cycle, identify and name the stages and explain what happens during each stage.
Key TermsKey Terms
• prophaseprophase• sister chromatidsister chromatid• centromerecentromere• spindle apparatusspindle apparatus
• metaphasemetaphase• anaphaseanaphase• telophase telophase
Mitotic PhaseMitotic Phase
• Unique to eukaryotes• Very accurate (error rate 1/100,000
cell divisions)
CentromereCentromere
Chromosomeduplication
Sister chromatidsSister chromatids
Chromosome distributionto daughter cells
ChromosomePrior to S phase
Mitosis Duplicates the Nucleus (Chromosomes)
The Mitotic Phase
Stages of Mitosis
Prison (Prophase)
Men (Metaphase)
Are (Anaphase)
Thin (Telophase)
Prophase
The cell’s chromatin tightens.
Sister chromatids are attached at the centromere.
Spindle fibers form in the cytoplasm.
The nuclear envelope seems to disappear.
Spindle fibers attach to the sister chromatids.
Metaphase
Sister chromatids line up in the middle of the cell.
Anaphase
Microtubules of the spindle apparatus begin to shorten.
Sister chromatids separate.
Chromosomes move toward the poles of the cell.
Telophase
The chromosomes arrive at the poles and begin to relax.
Two new nuclear membranes begin to form and the nucleoli reappear.
The spindle apparatus disassembles.
Process by which the cytoplasm of a Process by which the cytoplasm of a cell is divided in two; usually follows cell is divided in two; usually follows mitosis and meiosis.mitosis and meiosis.
CytokinesisCytokinesis
Microfilaments constrict, or pinch, the cytoplasm to create a cleavage furrow
Cytokinesis in Animal Cells
Cell wall too rigid for microfilaments to constrict cell.
Cell plate created.
Cytokinesis in Plant Cells
How Cytokinesis Differs in PlantsHow Cytokinesis Differs in Plants
Section 9.3
Cell Cycle Regulation
Terms to knowTerms to know
• cyclincyclin• cyclin-dependent kinasecyclin-dependent kinase• cancercancer• carcinogencarcinogen• apoptosisapoptosis• stem cellstem cell• benign tumorbenign tumor• malignant tumormalignant tumor• metastasismetastasis
Normal Cell Cycle
Different cyclin/CDK combinations signal other activities, including DNA replication, protein synthesis, and nuclear division throughout the cell cycle.
Quality Control Checkpoints
Checkpoints in the cell cycle can stop the cycle if something goes wrong.
Apoptosis
Programmed cell death
Cells going through apoptosis actually shrink and shrivel in a controlled process.
Signals from the checkpoints can start apoptosis.
A disease caused by severe A disease caused by severe disruption of the mechanisms disruption of the mechanisms that normally control the cell that normally control the cell cycle.cycle.
Cancer
Abnormal Cell Cycle: Cancer
Cancer is the uncontrolled growth and division of cells.
Cancer cells can kill an organism by crowding out normal cells, resulting in the loss of tissue function.
Cancerous cells reproduce at an abnormally fast rate!
Benign:Benign: An abnormal mass of normal An abnormal mass of normal cells.cells.
Types of Tumors
Malignant: A mass of abnormal cells resulting from uncontrolled cell division.
The spread of cancer cells The spread of cancer cells beyond their original site beyond their original site
Metastasis
Causes of cancerCauses of cancer
• Genetic mutationsGenetic mutations• FoodFood• HormonesHormones• RadiationRadiation• TobaccoTobacco• Weight & physical activityWeight & physical activity• Workplace environmentWorkplace environment
Cancer TreatmentsCancer Treatments
• SurgerySurgery• Radiation therapyRadiation therapy• ChemotherapyChemotherapy• A mix of the threeA mix of the three
Stem Cells
Unspecialized cells that can develop into specialized cells when under the right conditions
Embryonic Stem Cells
After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. These cells have not become specialized.
Adult Stem Cells
Found in various tissues in the body and might be used to maintain and repair the same kind of tissue
Less controversial because the adult stem cells can be obtained with the consent of their donor
chromatin: combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell.
chromosome: condensed threads of genetic material formed from chromatin as a cell prepares to divide.
sister chromatid: one of a pair of identical chromosomes created during the S phase before a cell actually divides.
Vocabulary Review
centromere: region where two sister chromatids are joined tightly together.
Vocabulary Review (contd’)
cell cycle: sequence of events from the production of a eukaryotic cell to the time the cell itself reproduces.
interphase: stage of the cell cycle during which a cell carries out its metabolic processes and performs its functions in the body.
mitotic phase: stage of the cell cycle when a cell is actively dividing.
mitosis: process by which the nucleus and duplicated chromosomes of a cell divide and are evenly distributed, forming two daughter nuclei.
cytokinesis: process by which the cytoplasm of a cell is divided in two; usually follows mitosis and meiosis.
Vocabulary Review (contd’)