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9 Ιουλ 2024 · Chromatin is the combination of DNA, histone, and other proteins that make up chromosomes. It is found inside the nuclear envelope of eukaryotic cells. It is divided between heterochromatin (condensed) and euchromatin (extended) forms.
15 Αυγ 2020 · Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. The term chromosome comes from the Greek ...
15 Μαΐ 2022 · The complete set of chromosomes in the cells of an organism is its karyotype. It is most often studied when the cell is at metaphase of mitosis when all the chromosomes are present as dyads. The karyotype of the human female contains 23 pairs of homologous chromosomes: 22 pairs of autosomes and an additional 1 pair of X chromosomes.
A very long chain of DNA can form a chromosome. In these chromosomes are areas called genes that code for specific proteins. All the different chromosomes of an organism make up that organism's genome. In other words: DNA makes up genes, genes make up chromosomes, and chromosomes make up a genome.
About 95% of the DNA in polytene chromosomes is in bands, and 5% is in interbands. The chromatin in each band appears dark, either because it is much more condensed than the chromatin in the interbands, or because it contains a higher proportion of proteins, or both (Figure 4-40).
Each chromosome in one set is matched by a chromosome of the same type in the other set, so there are actually 23 pairs of chromosomes per cell. Each pair consists of chromosomes of the same size and shape, and they also contain the same genes. The chromosomes in a pair are known as homologous chromosomes.
Chromosomes are found in the nucleus of every cell of our body and are made up of DNA, tightly coiled around proteins. We have 23 pairs of chromosomes altogether, and they can only be easily observed during cell division.
