+ 1.1 Cell Biology False-colour scanning electron micrograph (SEM) of neurones (nerve cells) from the cerebral cortex - the outer, heavily folded, grey.

+

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.

+

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

+

+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

+

Magnification = Size of image / Actual size of specimen

Practice questions page 6/7

+

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

+

Magnification

Magnification = Measured length

____________________

Scale bar label

+

Actual size

Actual Size =Measured Length

____________________

Magnification

+

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

+

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.