Difference between revisions of "Foundations-Cells-1"

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A micron or micrometre is one millionth of a metre. (1 x 10<sup>-6</sup>)
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The SI unit of one micron or micrometre is one millionth of a metre. (1 x 10<sup>-6</sup>)
 
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Revision as of 15:04, 12 February 2018

Introduction to Cells and Sizes

This lecture is also an introduction to cell compartments and describes the structure of membranes forming these compartments.


Draft - this online lecture is currently in 2020 draft status. This notice removed when completed.
Cells and Membranes: 1 Cells and sizes | 2 Prokaryotes | 3 Viruses and prions | 4 Plasma membrane | 5 Compartments | 6 Membrane structure | 7 Membrane specialisations | Foundations - Moodle

Terms

  • Archaea - prokaryote single-celled microorganism with no cell nucleus or any other membrane-bound organelles. Archaea were initially classified as bacteria.
  • Bacteria - Prokaryotes.
  • Commensal bacteria - (normal microflora, indigenous microbiota) micro-organisms present on body surfaces covered by epithelial cells exposed to the external environment (gastrointestinal and respiratory tract, vagina, skin, etc.).
  • Compartments - separate sections or part of a structure either as a physical compartment (membrane bound) or functional compartment (no membrane).
  • Eukaryote - cells containing a nucleus.
  • Flora - (microflora) bacteria and microscopic algae and fungi living in a particular anatomical site or habitat.
  • Fungi - eukaryotic organisms that include yeasts.
  • Gut - (intestine)
  • Micron - (micrometre) is one millionth of a metre. (1 x 10-6)
  • Nucleus - the double membrane compartment containing chromosomes within all eukaryotic cells.
  • Plasma membrane - (cell membrane) the lipid bilayer containing proteins and cholesterol that encloses each cell.
  • Prokaryote - single-celled microorganism with no cell nucleus or any other membrane-bound organelles.
  • Red blood cell - (RBC, erythrocyte) the blood cell containing haemoglobin for delivering oxygen and removing carbon dioxide from tissues.
  • White blood cell - (WBC, leukocyte) the blood cell of the immune system that protect the body against both infectious disease and foreign invaders.

About Human Body

Human Cells

  • 210+ cell types in body
  • total number of estimated cells in the body - 1013 (American Ten trillion/British Ten billion)

Flora

  • bacteria, fungi and archaea
  • found on all surfaces exposed to the environment
    • skin and eyes, in the mouth, nose, small intestine
  • most bacteria live in the large intestine
  • 500 to 1000 species of bacteria live in the human gut
  • total number of estimated flora ten times as many bacteria 1014 (American One hundred trillion/British One hundred billion)


Cell Sizes

  • 1000 micron (1mm) diameter - frog or fish egg are the largest individual cells easily visible,
  • 100 micron diameter - human or sea urchin egg
  • 30 x 20 micron - plant cells
  • 20 micron diameter - typical somatic cell
  • 2 x 1 micron - bacteria


The SI unit of one micron or micrometre is one millionth of a metre. (1 x 10-6)

Red White Blood cells 01.jpg

Human white blood cell (neutrophil, polymorphonuclear leukocyte) crawling among red blood cells (erythrocytes). The neutrophil is "chasing" bacteria (Staphylococcus aureus) that have been added to the film.

Cells.jpg


  • blue ring - bacteria
  • white ring - white blood cell
  • red ring - red blood cell
Cell History  
Cork Bark by Robert Hooke 1665

Background only, you do not need to know the details.


Robert Hooke (1635-1703)

  • used early microscopes to view cork tree bark, first to use the term CELL.

Robert Brown 1825

  • identified nuclei in plant cells.


Theodor Schwann (1810 - 1882) - together with Matthias Schleiden (plants) developed the cell theory in 1839

  • All organisms consist of one or more cells.
  • The cell is the basic unit of structure for all cells.
  • All cells arise only from preexisting cells.
Quiz 1 - Cells and Sizes   (click Expand to open)   
Select your choice for each correct answer to the quiz questions below. When you have answered all questions and finished, click submit button and then reopen the collapsed table to see your result.


1

The multicellular human body consists of many different tissues and organs composed of individual cells. In addition, located on the body surfaces are the microflora. Which cell type is generally more abundant?

  human cells
  microflora

2

Which of the following is the best common unit to measure our cell sizes?

  metres
  centimetres
  millimetres
  micrometres
  nanometres
  picometres
  inches

3

All prokaryotic bacteria are "bad" and best treated immediately with antibiotics.

  True
  False

4

All bacteria lack nuclei and are prokaryotes, therefore all prokaryotes are bacteria?

  True
  False

5

Which if the following statements about red blood cells (RBCs) is incorrect?

  Circulating human red blood cells are typically 6-7 microns in diameter.
  Circulating human red blood cells contain no nucleus and by definition are prokaryotic cells.
  Circulating human red blood cells use haemoglobin to carry oxygen and carbon dioxide.
  Circulating human red blood cells are "donut" shaped cells.


Draft - this online lecture is currently in 2020 draft status. This notice removed when completed.
Cells and Membranes: 1 Cells and sizes | 2 Prokaryotes | 3 Viruses and prions | 4 Plasma membrane | 5 Compartments | 6 Membrane structure | 7 Membrane specialisations | Foundations - Moodle