2. The diversity of cells
All eucaryotic cell, no matter what origin, size, function and shape, have basic principle of
structure, but shape and inner organization is for every type of cell characteristic, according to
heredity and function.
1. Observing of permanent sections
Material and methods: microscope, permanent sections (myocardium, brain, liver, kidney,
spleen, lungs, aorta).
2. Observing of differences between plant and animal cell
Material and methods: onion, frog’s skin epithelium, microscope, chlorine-zinc-iodine, 1%
methylene blue.
– we put the thin layer of onion cell and epithelium into drop of chlorine-zinc-iodine on
microscope slide. We observe under microscope.
3. The chemical composition of biological systems
The organic compounds (nucleic acids, proteins, lipids, sacharids) create the main element of
living matter. Quantitatively, they are not divided equally in all cells. The differences depend
on species, on type and age of cells.
1. The proof od proteins in egg white and in yeast – biuret reaction
Material and methods: 3 test tubes, test tube rack, pipettes, mortar and pestle, destilled water,
10% KOH, 5% CuSO4, yeast ( Saccharomyces cerevisiae ), egg white.
– cca 0,5g of yeast is crushed in mortar with couple of drops of water, mass is moved to the
test tube with 5cm3 of water. To the second test tube, we pipette 5cm3 of destilled water. To
the third test tube, 2 cm3 of egg white is diluted with saline (1:20) and filled with destilled
water to 5 cm3. Then we add 1 cm3 of KOH, mix, add few drops of CuSO4. We observe
changes of color.
2. The proof of amylum grains in potato cells and proof of sacharides in fruit
2.1. amylum-presence test
Material and methods: potato, filter paper, razor blade, Lugol‘s solution, microscope.
– piece of potate is rinsed with water, using the razor blade we cut thin slice and move it to
microscope slide, we add drop of water and cover it with cover slip. After short examination
we add Lugol’s solution.
2.2. sacharides-presence test
Material and methods: fruit juice, Ferhling’s reagent I. and II.
– we mix juice and Fehling’s reagent (1:1), we slowly heat the substance in water bath. We
observe the change of color.
3.The observation of animal fat in subcutaneous tissue – lipid-presence test
Material and methods: animal subcutaneous fat, sudan III solution, microscope
– we cut thin slice from frozen bacon, we put in on microscope slide with drop of sudan III
solution. We wait 5-10 minutes. After 10 minutes, we observe the slide under microscope.
4. Living cycle of cells
The cell division belongs to the basic life manifestations. Cells originate from mother cells by
division, there are three types of division: direct division – amitosis, indirect division –
mitosis, and reduction division – meiosis. The mitosis is the most common way of cell
division, in which the chromosomes are divided equally, which means that mitosis causes the
division of cell into daughter cells and also equal division of genetic material into them.
1. The mitotic cell division – observing of phases of mitosis
Material and methods: microscope, Petri dish, razor blade, fixation solution, maceration
solution, dye.
– we cut cca 0,5 cm long part of root apex and put it into fixation solution for 15 minutes.
Then we move it to maceration solution for 10 minutes, after that we rinse it in destilled water
for 10 minutes. We move it to microscope slide and cut 2 mm long part from apex, the rest of
root is trashed. We add drop of dye and cover with cover slip. We squash it with slight
pressure using a pencil. We observe under microscope.
2. The evolution processes after fertilization – the observing of stages of ontogenesis
using model of Psammechinus miliaris
The process of prenatal evolution of new specimen starts with fertilization of egg and first
mitotic division of zygote. This process is divided into two phases – blastogenesis (from
fertilization to the start of creation of organ systems) and organogenesis (creation of organ
systems). Blastogenesis is characterised by constant division of cells.
Material and methods: microscope, microscope slides of blastogenesis
5. The nucleic acids
The nucleic acid are basic elements of biological systems. They are the bearers of genetic
continuity. They are macromolecular polymers, which are composed of basic building
components – monomers – nucleotides. Single nucleotides are in molecule polymerized –
binded into long polynucleotide chains, in which H3PO4 of one nucleotide is binded with
pentose of another nucleotide. The representation of polynucleotides and their sequence in
polynucleotide chain is called primary structure.
1. The proof of deoxyribonucleic acid ( DNA ) in nucleus
Material and methods: onion, filter paper, Strassburger‘s mixture, microscope.
– we place onion skin into drop of Strassburger’s mixture and cover with cover slip. After
couple of minutes we observe under microscope.
2. Separation and detection od nucleic acids
Material and methods: isolated DNA or RNA, ELFO, agarose gel, ethidium bromide, loading
buffer, UV lamp, elektrolyte.
– to 5 μl of isolated nucleic acid we add 2μl 6x loading buffer and we centrifugate for 2
minutes. Prepared sampe is loaded into 2% agarose gel with ethidium bromid. We run the
electrophoresis. Single parts of nucleic acids run through gel according their molecular mass –
the quickest are the molecules with smallest molecular mass. The detection of nucleic acids is
done using UV lamp.
6. Basic questions of genetics
The basic method used in Mendel’s genetics is crossing – hybridization (sexual reproduction
of two individuals with different genotype). The offsprings are hybrids.
Very well described genetic object is Drosophila melanogaster, which has:
- short time of development (10 – 14 days )
- high reproductive ability
- minimal costs on laboratory breeding
- 4 pairs of chromosomes
- number of well-distinguished signs
- many signs following Mendel’s rules
In monohybrid crossing, we observe one property. The results of reciprocal crossing are in F1
generation the same. In F2 generation, which is created by crossing of F1 generation, the
offsprings are from 75% with dominant phenotype and from 25% with recessive phenotype.