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Cell Differentiation. Mrs. Harlin. 1.1.3. Explain how instructions in DNA lead to cell differentiation and result in cells specialized to perform specific functions in multicellular organisms. . Specialized Cells.
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Cell Differentiation Mrs. Harlin
1.1.3 • Explain how instructions in DNA lead to cell differentiation and result in cells specialized to perform specific functions in multicellular organisms.
Specialized Cells • Multicellular organisms begin as undifferentiated masses of cells and variation in DNA expression and gene activity determines the differentiation of cells and ultimately their specialization.
Differentiation • Only specific parts of the DNA are activated; the parts of the DNA that are activated determine the function and specialized structure of a cell. • Because all cells contain the same DNA, all cells initially have the potential to become any type of cell; however; once a cell differentiates, the process cannot be reversed.
DNA • Nearly all the cells in an organism contain the same chromosomes and DNA. • Different parts of the genetic instructions are used in different types of cells, influenced by the cell’s environment and past history.
Hormones • Hormones are chemical signals that are released by cells that influence the development and activity of other cells.
Stem Cells • Unspecialized cells that continually reproduce themselves and have, under appropriate conditions, the ability to differentiate into one or more types of specialized cells.
Types of Stem Cells • Embryonic stem cells • Adult stem cells- found in bone marrow • Research has demonstrated both types of stem cells can be differentiated into specialized cells.
Specialized cells in Animals • Nerve cells- eukaryotic, but have dendrites and axons for electrochemical communication in the body. • They are never replaced when they die.
Specialized cells in Animals • Muscle cells- eukaryotic; used for movement. • Skeletal muscles contain many nuclei and are striated- voluntary movement. • Smooth muscles only have 1 nucleus- involuntary movement
Specialized cells in Animals • Blood cells • Red blood cells- the hemoglobin protein transports oxygen and carbon dioxide (influenced by temperature and pH) • Do not divide • No mitochondria or nucleus • Plasma- transports materials • Insulin regulates glucose levels • Lipids, amino acids, and other ions also transported from digestive system. • White blood cells- protects the body from infection • Has a nucleus
Specialized cells in Animals • Gametes- Sperm and egg cell • Used in sexual reproduction • Only contain half the DNA as the rest of the cells in an organisms. • Haploid number for humans= 23 chromosomes
Specialized Cells in Plants • Xylem- transports water from roots • Phloem- transports water and sugars
References • http://www.sciencedaily.com/releases/2007/12/071220123837.htm • heal-thyself.us • http://faculty.washington.edu/chudler/cells.html • http://www.kidsbiology.com/human_biology/muscles2.php • health-niche.com • http://www.mcatzone.com/glosslet.php?letter=g • ap-bio-patrick-steed.wikispaces.com