+ 1.1 cell biology false-colour scanning electron micrograph (sem) of neurones (nerve cells) from...
TRANSCRIPT
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1.1 Cell Biology
False-colour scanning electron micrograph (SEM) of neurones (nerve cells) from the cerebral cortex - the outer, heavily folded, grey matter of the brain.
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Cell theory
Robert Hooke (1635 – 1703) was the first to
observe cells under the microscope which he
invented.
What common features do you think exist amongst all cells?
Membranes, genetic material, enzyme-catalyzed reactions, generate their own
energy
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+Use a light microscope to
investigate the structure of human cheek cell & onion
cell.
Draw diagrams of each cell type.
Drawing rules:
1.Use a sharp pencil2.Draw lines carefully3.Use a ruler for labeling lines
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Magnification = Size of image / Actual size of specimen
Practice questions page 6/7
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Prepare for test on 2.1 – 2.3. Test Thursday 11th September.
You will have a review Tuesday.
Homework
+ What is the magnification of the image when we view it down the compound microscope?
Multiply these values:
Eyepiece X Objective
10 x 40
= 400x magnification
+Standard international (si) units of measurement:
Unit Abbr. Metric equivalentKilometre km 1000m 103mMetre m 1m -Centimetre cm 0.1m 10-2mMillimetre mm 0.001m 10-3mMicrometre
m 0.000001m 10-6m
Nanometre nm 0.000000001m 10-9m
+Microscopy calculations
Use these calculations to find the magnifications or actual sizes of images.
Rule 1: Convert all units to make them the same (where appropriate)
Rule 2: Perform calculationsRule 3: Convert answers to appropriate
SI units, using scientific notation where needed.
+Calculations:
2 types:Actual Size of an imageMagnification of an image
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Magnification
Magnification = Measured length
____________________
Scale bar label
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Actual size
Actual Size =Measured Length
____________________
Magnification
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http://learn.genetics.utah.edu/content/cells/scale/
+What are the 7 ‘functions of life’?
1. Nutrition
2. Metabolism
3. Growth
4. Response
5. Excretion
6. Homeostasis
7. Reproduction
+A comparison
Unicellular Multicellular
Organism consisting of only one cell carry out all functions of life.
Some can move using cillia, some drift using currents/air etc.
Size limited. Surface to Volume ratio
Often live in colonies
Have properties that emerge from the interactions of their cellular components.
Specialized tissues result from cell differentiation
Humans have 220 specialized cells.
Differentiation involves in expressing some genes but not others from the whole genome.
Paramecium, Chalmydomas Caenorhabditis elegans
+Paramecium
1.Asexual reproduction
2.Food vacuoles
3.Waste excreted by diffusion through cell membrane
4.Contractile vesicles – regulate water content
5.Cilia in order to move
+Chlamydomonas
1.Asexual reproduction
2.Cell wall freely permeable, inner membrane is not.
3.Contractile vesicles
4.Chloroplasts for photosynthesis
5.Flagella for movement
+Volvox aureus
1.Algae colony
2.Ball made up of a protein gel
3.500 or more cells in a colony
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Caenorhabditis elegans
1.Worm
2.1mm (approx. adult length)
3.959 cells
4.Decomposer
5.Hermaphrodite
6.1/3 of cells are neurons
+Stem cells
The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development. It also makes stem cells suitable for therapeutic uses.
Ethics of therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new born baby and from an adult’s own tissue.