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| Name | What are chromosomes | Biology | Extraclass.com |
| Video Uploader | Video From Extraclass Official |
| Upload Date | This Video Uploaded At 07-03-2020 12:45:00 |
| Video Discription | What are chromosomes? Have you ever wondered about how your eyes or hair came to be colour they are? Did your parents pick out the colour of your eyes? Not exactly, but they did play a big part in determining their colour. How? They passed along their chromosomes to you! In this video, we will learn about the structure and types of the chromosomes - Chromosomes are thread-like structures in which DNA is tightly packaged within the nucleus. The term chromosome was coined by Waldeyer in 1888. The chromosomes exhibit different structures as circular in bacteria and linear in eukaryotic organisms. A typical chromosome has similar structures called chromatids. The chromatids are connected to the centre part called the centromere. There are of two types of constrictions in chromosomes called primary and secondary constrictions. A primary constriction is made up of centromere and kinetochore. The centromeres vary in number in different chromosomes. A chromosome with only one centromere is called monocentric and the chromosome with many centromeres is called polycentric. A centromere consists of two kinetochores in it. Each kinetochore is made up of protein fibres and microtubules. The centromere is the one which allows the chromatids to move. Let’s move on to learn about the different types of chromosomes On the basis of the position of centromeres, chromosomes are of mainly four types - (1) Metacentric Chromosomes - They have the centromere in the centre, such that both sections are of equal length. Human chromosome 1 and 3 are metacentric. (2) Submetacentric Chromosomes - They have the centromere slightly offset from the centre leading to a slight asymmetry in the length of the two sections. Human chromosomes 4 through 12 are submetacentric. (3) Acrocentric Chromosomes - They have a centromere which is severely offset from the centre leading to one very long and one very short section. Human chromosomes 13,15, 21, and 22 are acrocentric. (4) Telocentric Chromosomes - They have the centromere at the very end of the chromosome. Humans do not possess telocentric chromosomes but they are found in other species such as mice. Besides this chromosomes are also classified into autosomes and sex chromosomes. The chromosomes that are found in all somatic cells of the body are called autosomes and they decide the somatic characters of the organism. While sex chromosomes are present in gametes or germinal cells and they decide the sex of an organism. For example- In humans, there are 23 pairs or 46 chromosomes out of which 22 pairs are autosomes and the remaining one pair is sex chromosomes. Download Extraclass.com app: - Play Store: http://bit.ly/extraclassapp Follow us on our social media handles to stay updated. Website – https://www.extraclass.com/ Facebook - https://www.facebook.com/extraclassofficial Instagram - https://www.instagram.com/extraclassofficial Youtube - https://www.youtube.com/extraclass Twitter - https://twitter.com/extraclass_com Happy Learning!! “Thanks for watching”. #Extraclass #Chromosomes #biology #class10 #cbse #neet #icse #aiims [2CEyBt1p0CE] |
| Category | Education |
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