BIOLOGY - microscopia.info

Overhead Transparency Atlases
105
Replicating DNA molecule II. - IV. DNA and RNA - Differences between DNA and RNA - Fractionation of cell components
by centrifugation - Synthesizing ability of components - Function of ribosomes - Structure of ribosomes - Amino
acid-tRNA-complexes - Specifity of tRNA - Kinds of RNA in the cell - Experiments with artificial messengers - Polysomes
on bacterial DNA - Electron micrograph of RNA-phages - Coat protein-gene of an RNA-phage - Summary:
replication, transcription, translation - V. Genetic code and mutation - Colinearity between nucleotide- and amino-acid
sequence - Frame shift mutations - Triplet-binding test - The genetic code - Relations between codon and anticodon -
Begin of protein synthesis - Section of phage RNA - Chemical mutagenesis - Effect of mutations - VI. Synthesis,
structure, and function of proteins - Protein-synthesizing complex I - Protein-synthesizing complex II - Secondary structure
of proteins: a-helix - Secondary structure of proteins: b-pleated sheath - Tertiary structure of a protein: b-chain of
hemoglobin - Sickle cell anemia, erythrocytes - Molecular interpretation.
No. 8224 E Mitosis and Meiosis
Atlas of 25 OHP Transparencies size 22 x 28 cm, comprising over 95 color pictures. Specially selected and beautiful
multicolored photomicrographs are presented on this atlas. Sketch and work-sheets with semidiagrammatic designs
and texts - In strong plastic file with ring-mechanism.
Typical Cell Division in the Root Tip of the Hyacinth. - An unique series to illustrate the normal sequence of mitosis.
The photomicrographs show each stage in a high degree of magnification. The cell components are differentiated in
contrasting colors by a special staining technique. - Interphase, the resting nucleus shows the chromatin in the form of
a fine network, nuclear membrane and nucleoli are present - Early prophase, the chromosomes appear as fine threads
- Late prophase, the chromosome threads shorten by contraction - Early metaphase, duplicate daughter chromosomes
are formed - Metaphase, the chromosomes are arranged on the equatorial plate - Early anaphase, the daughter chromosomes
move away from the equator - Late anaphase, the chromosomes reach the opposite cell poles - Early telophase,
chromosomes become reorganized to form the daughter nuclei, primary cell wall - Late telophase, new cell wall
is formed and the nucleoli are reformed - Reconstruction. Complete separation of the daughter cells - Development of
the Microspore Mother Cells of Lilium (Anthers). - New combination of hereditary traits and reduction of the number
of chromosomes are the aim of meiotic division. - Young anther of lily. t.s. - Microspore mother cells, resting stage -
Leptotene, the chromosomes appear as fine threads - Zygotene, the homologous chromosomes associate in pairs -
Pachytene, complete pairing of the chromosomes - Diplotene, bivalent chromosomes split, chiasmata, interchange of
genetic material - Diakinesis, contraction of the bivalents - Metaphase of the first (heterotypic) division showing the
equatorial plate - Equatorial plate, surface view with duplicated chromosomes - Metaphase, side view, a spindle is
formed - Anaphase, two haploid sets of chromosomes are separated - Telophase, new cell wall between the daughter
cells - Prophase of the second (homeotypic) division - Metaphase of the second division - Pollen tetrads. Four nuclei are
formed after the second division - Uninuclear microspores - Prophase, metaphase, anaphase and telophase of the third
division - Mature two-nucleate pollen grain. Each pollen grain possesses a tube cell and a generative cell - Mature
pollen grain with surface structure - Growing pollen grain showing pollen tube - Growing pollen tube, l.s. showing the
division of the generative cell into two sperm nuclei - Development of the Megaspore Mother Cells of Lilium (Embryosac).
- Thousands of sections had to be prepared in order to produce this series - Ovary of lily, t.s. low magnification
- Very young ovary before the formation of the megaspore mother cell. Abundant mitotic figures in the tissue - Developing
embryosac mother cell - Megaspore mother cell, pachytene stage of prophase - Anaphase and telophase of the first
(heterotypic) division. Spindle fibers - Two-nucleate embryosac, prophase of the second division - Anaphase and telophase
of the second (homeotypic) division. Two division figures - Primary or first four-nucleate stage - Primary fournucleate
stage, three nuclei migrate to the chalazal end of the embryosac, one nucleus remains in the micropylar end
- Prophase and metaphase of the third division after the three chalazal nuclei have fused - Telophase of the third
division - Second four-nucleate stage, consisting of two haploid and two triploid nuclei. A vacuole can be observed -
Metaphase and anaphase of the fourth division - Eight-nucleate stage, the mature embryosac. Egg nucleus, synergid
nuclei, polar nuclei, and antipodal nuclei - Double fertilization by the two sperm nuclei of the pollen tube - Formation of
the embryo, early and later stage. Many mitotic figures in the endosperm cells - Young embryo with suspensor cells, l.s.
- Older embryo, l.s. formation of cotyledons - Maturation and Cleavage of Ascaris megalocephala bivalens. - Due to
its low number of chromosomes (only four), Ascaris megalocephala bivalens is an ideal zoological example to demonstrate
the complex phenomena of reduction divisions, fertilization and early cleavage in animals - Primary germ cells -
Entrance of spermatozoon in the oocyte - Oocyte before the reduction divisions. The genetic substance appears in form
of two tetrads - First maturation division. Eight chromosomes and the spindle visible. The male pronucleus in the middle
of the oocyte - Formation of the first polar body - Second maturation division. Four chromosomes visible - Formation of
the second polar body. Only two chromosomes remain in the oocyte, subsequently they change to the female pronucleus
- Mature oocyte with male and female pronuclei, each nucleus contains two chromosomes - The nuclear membranes
of the pronuclei disappear, and the maternal and paternal chromosomes become visible (fertilization) - Metaphase of
the first cleavage. The somatic number of chromosomes is now restored - Metaphase, equatorial plate in side view
shows chromosomes, spindle fibers, centrioles - Anaphase, beginning movement of the daughter chromosomes towards
the poles - Early telophase, beginning constriction of the cell - Telophase, further division of the cell - Late
telophase, complete division of the cell - Second cleavage with two division figures - Later stage of fetal development
showing young embryo - Development of the Female Gametophyte of Pinus. - The ovules of pine mature within two
vegetation periods. In the first year pollination and growth of the female gametophytes. In the following spring the
formation of archegonia and the fertilization take place. - Young female cone, median l.s. for general view - Bract scale,
ovuliferous scale and ovule, median l.s. - Young ovule before pollination, l.s. with megaspore mother cell - Growing ovule
at free nuclear stage, after repeated division of the megaspore mother cell without formation of cell walls - Growing
ovule, later stage with young macroprothallium - Mature archegonium, median l.s. showing neck canal cells, ventral
canal cell, egg nucleus, layer of jacket cells, paranuclei - Fertilization of the archegonium by entrance of the pollen tube
- First division of fertilized egg nucleus, anaphase - Four-nucleate stage, all nuclei in the centre of the archegonium -
Four-nucleate stage, the nuclei migrate towards the base of the archegonium - Sixteen-nucleate stage, the nuclei lie in
four tiers of four. Rosette cells, suspensor cells, embryonic cells - Young proembryo with short suspensor cells - Older
proembryo with elongated suspensor cells and four young embryos - Mature embryo with endosperm, median l.s.
showing cotyledons, radicle, hypocotyl, plumule, and t.s. showing the eight cotyledons.
No. 8248 E Cytology and Genetics (Short Version TE)
Atlas of 10 Overhead-Transparencies size 22 x 28 cm, comprising 67 pictures (anatomical pictures, photomicro- and
macrographs, nature photographs, electron micrographs, drawings, diagrams, tables, scenes, test data and results).
With comprehensive interpretation text. - Sketch and work-sheets with semidiagrammatic designs and texts - In strong
plastic file with ring-mechanism. - Compilation and text: Dr. Dieter Gerlach and Johannes Lieder.
Animal Cells and Genetics: - Typical Animal Cell, showing all details visible by light and electron microscope in different
color - Squamous epithelium, isolated cells. Nuclei and cytoplasm are shown - Striated muscle l.s. showing nuclei,
striations, myofibrils - Compact bone, human t.s. showing cells and canaliculi - Hyaline cartilage, human t.s. - Nerve