Cell Theory In biology‚ cell theory is a scientific theory that describes the properties of cells‚ the basic unit of structure in every living thing. The initial development of the theory‚ during the mid-17th century‚ was made possible by advances in microscopy; the study of cells is called cell biology. Cell theory states that new cells are formed from pre-existing cells‚ and that the cell is a fundamental unit of structure‚ function and organization in all living organisms. It is one of the
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mark) 3. The lengths of a sample of tiger canines were measured. 68% of the lengths fell within a range between 15 mm and 45 mm. The mean was 30 mm. What is the standard deviation of this sample? A. 5 mm B. 15 mm C. 7.5 mm D. 30 mm (Total 1 mark) 4. What does the following scatter graph show? A. No correlation between these variables B. Strong positive correlation between these variables C. Strong negative correlation between these variables D. Weak negative correlation between these variables
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Cell Structure and Function Chapter Outline Cell theory Properties common to all cells Cell size and shape – why are cells so small? Prokaryotic cells Eukaryotic cells Organelles and structure in all eukaryotic cell Organelles in plant cells but not animal Cell junctions History of Cell Theory mid 1600s – Anton van Leeuwenhoek Improved microscope‚ observed many living cells mid 1600s – Robert Hooke Observed many cells including cork cells 1850 – Rudolf Virchow
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Cell: The cell is the basic structural‚ functional and biological unit of all known living organisms. Cells are the smallest unit of life that is classified as a living thing‚ and are often called the "building blocks of life". Discoverer: The cell was discovered by Robert Hooke in 1665. The cell theory‚ first developed in 1839 by Matthias Jakob Schleiden andTheodor Schwann‚ states that all organisms are composed of one or more cells‚ that all cells come from preexisting cells‚ that vital functions
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The studies of Robert Hooke 1665 into a plant material would allow the determination of a pore like regular structure surrounded by a wall of which he called cells’ this in itself unbeknownst to him‚ was the discovery of the fundamental unit of all living things. In 1838 a botanist called Schleiden derived the theory The basic unit of structure and function of all living organisms is the cell.’ Over 150 years later this can be regarded as one of the most familiar and important facts within the
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October 2014 Cell Division Mitosis Abstract Mitosis and Meiosis: Cells can be divided in unicellular organisms or in multi-cellular organisms. DNA controls the cell division. Bacteria reproduce by a process called binary fission. Bacteria have one chromosome that’s attached to the cell membrane. The chromosome replicates and the two copies separate as the cell grows. Over a period of time this one cell makes two cells. Eukaryotes do the process of mitosis. In mitosis‚ each daughter cell gets about
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roles of mitotic cell division‚ meiosis‚ and fertilization in the human life cycle. Mitosis allows for growth and repair from the fertilized egg to the adult. In reproductively mature individuals‚ meiosis creates gametes with half the genetic material. The male gamete then fertilizes the female gamete during sexual reproduction‚ forming a zygote with a full set of genetic material. 2. Why are both cell division and apoptosis necessary for the development of an organism? Cell division is needed
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Cell Fractionation * Cell Fractionation: takes cells apart and separates the major organelles and other subcellular structures from one another. * Tissue cells are the first one to be homogenate or broken apart. * Plasma membranes are broken up so that there internal contents spill out and mix together and this is called homogenate. * Homogenate is in spun in a higher rate of speed in a process called centrifugation. And that speed can vary that why it’s called differential
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Cell Structure - Cell Organelles 1. What is cell theory? Cell theory asserts that the cell is the constituent unit of living beings. Before the discovery of the cell‚ it was not recognized that living beings were made of building blocks like cells. The cell theory is one of the basic theories of Biology. 2. Are there living beings without cells? Viruses are considered the only living beings that do not have cells. Viruses are constituted by genetic material (DNA or RNA) enwrapped by a protein
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noticed some “pores” or “cells”. 1674= Anton Van Leeuwenhoek built a simple microscope with only one lens to examine blood‚ yeast‚ insects‚ and many other tiny objects. 18th Century= technical innovations improved microscope leading to microscopy becoming popular among scientists. 1830= Jospeh Jackson Lister reduces spherical aberration of the chromatic effect. 1931= Ernst Ruska co-invented the electron microscope for which he won the Nobel prize in physics in 1986. 4 kinds of microscope Compound
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