Analyze morphological features such as chromosome number, size, position of the mitotic grain and follower in plant cells at mid-mitosis, and learn the methods of chromosome histotyping. Provide a basis for the origin and evolution of species, and provide cytological evidence for genetic breeding studies.
Operation method
Chromosome typing experiment
Principle
The morphology, structure and number of chromosomes in various organisms are relatively stable. The specific composition of chromosomes in each biological cell is called karyotype. Karyotype analysis is also called karyotype analysis. Chromosome slide specimens of mitosis are made by certain methods, and chromosome photographs are obtained through microphotography, processing and magnification. From the comparative analysis of chromosome slide specimens and chromosome photos, chromosomes are grouped, and morphological features such as length, location of mitotic sites, arm ratio, and presence or absence of follower are observed and described, so as to elucidate the chromosome composition of living organisms and to determine their chromosome groups, which is called chromosome grouping analysis.
Materials and Instruments
Fava beans, onions, barley, jute. Move I. Production of chromosome specimen slides For more product details, please visit Aladdin Scientific website.
Mithril Sodium sulfite anhydrous Sodium guarani Sodium carbonate anhydrous Potassium bromide Sodium thiosulfate Boric acid Potassium alum Acetic acid
Microscopes Micrographic systems Photo development and magnification equipment Eyepiece micrometer Stage micrometer 4# magnifying paper 135 black and white film Calculator Transparent ruler Scissors Coordinate paper Glue
Chromosome histotype analysis is generally used in the mid-mitotic division cells, usually using plant root tip cells. The chromosomes in the middle of mitosis have typical morphological characteristics, which is convenient for analysis, the specific production method is shown in experiment one.
II. Microscopic examination and measurement
When the chromosome slide is ready, put it under the microscope to observe and select the cells that meet the requirements of chromosome group type analysis, these cells are in the mid-mitotic division, the chromosomes are well dispersed, there is no overlap, the number is complete, the follower and the filamentation point are obvious, there is no break, the coloring is sharp, the morphology is clear, and the chromosomes are on the same plane.
Select one or more of the chromosomes that are relatively straight and measure their length with an ocular micrometer (eyepiece micrometer).
Third, micrographs, developing and magnifying
Will be selected under the microscope to meet the requirements of the cell micrograph (available 10 × 100 times the oil mirror), and then rinsed, select a clear image of the negative, enlargement, washing and printing of the chromosome morphology clear photographs. At the same time of microphotography, the same magnification (oil lens 10×100x) was taken on the microscope stage micrometer, enlarged, and then the magnification was calculated according to the actual length on the photograph.
IV. Measuring and calculating the photographic length of chromosomes
1. Measurement
Measure accurately the total length of each chromosome and the length of the two arms of each chromosome with a transparent ruler on the enlarged photographs (respectively, to the middle of the node) and fill in the results in Table 15.The length of the follower can be counted or excluded from the length of the chromosome, but it should be indicated. When the bend of the chromosome cannot be measured with a straightedge, measure an equal length of the chromosome with a fine line, and then measure the corresponding length of the fine line with a ruler.
2. Calculation:
(1) Calculation of magnification: Calculation of magnification is done by using the actual length (μ) of a flat chromosome measured directly under the microscope, divided by the photographic length (μ) of the corresponding chromosome on the magnified photograph. 
V. Chromosome Morphometry Data Sheet 
VI. Cut and Paste and Matching
Each chromosome on the enlarged photograph was cut out and homologous chromosomes were paired based on visual inspection and characteristics such as relative length of chromosomes, arm ratio, position of the mitre, presence or absence and position of secondary constrictions, presence or absence of follower and morphological size.
VII. Arrangement and Pasting
Arrange the paired chromosomes in order from the largest to the smallest. Arrange the chromosomes in a straight line, and make the short arm on the top and the long arm on the bottom. For chromosomes of equal length, place the chromosome with the longer short arm in front. The follower chromosomes are arranged last, and the sex chromosomes and extra chromosomes are arranged separately.
The arranged homologous chromosomes are pasted onto graph paper in order of chromosome numbering, with the mitoses in the same straight line.
Classification
According to the position of the mitotic site, to determine the morphological type of chromosome, arm ratio is to reflect the position of the mitotic site on the chromosome. 
Chromosomes with follower (sat) are labeled with.
IX. Plotting and Turning
The cut-and-paste arrangement of the chromosome histotypes was plotted on coordinate paper as a chromosome pattern map and tipped.