Which is the largest chromosome?

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Is chromosome 21 the largest?

Two copies of chromosome 21, one copy inherited from each parent, form one of the pairs. Chromosome 21 is the smallest human chromosome, spanning about 48 million base pairs (the building blocks of DNA) and representing 1.5 to 2 percent of the total DNA in cells.

What is the second largest chromosome?

Chromosome 2 is the second largest human chromosome, spanning about 243 million building blocks of DNA (base pairs) and representing almost 8 percent of the total DNA in cells.

Which is the largest gene?

The largest known gene is the human dystrophin gene, which has 79 exons spanning at least 2,300 kilobases (kb).

What is chromosome 21 called?

Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. A medical term for having an extra copy of a chromosome is ‘trisomy. ‘ Down syndrome is also referred to as Trisomy 21.

What is chromosome 23?

The first 22 pairs of chromosomes are called autosomes. The 23rd pair of chromosomes are known as the sex chromosomes, because they decide if you will be born male or female. Females have two X chromosomes, while males have one X and one Y chromosome.

What is chromosome 15 called?

They’re made up of DNA and packaged into strands called chromosomes. A person has 2 copies of all their genes, which means chromosomes come in pairs. Humans have 46 chromosomes (23 pairs). One of the chromosomes that belongs to pair number 15 is abnormal in Prader-Willi syndrome.

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What is Nondisjunction?

1 NONDISJUNCTION

Nondisjunction means that a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell. This probably occurs most commonly in meiosis, but it may occur in mitosis to produce a mosaic individual.

Can you have 48 chromosomes?

Males with XXYY syndrome have 48 chromosomes instead of the typical 46. This is why XXYY syndrome is sometimes written as 48,XXYY syndrome or 48,XXYY. It affects an estimated one in every 18,000–40,000 male births.

Did Humans have 48 chromosomes?

Some 60 years ago, two researchers, Joe Hin Tjio and Albert Levan, discovered that the number of chromosomes (karyotype) in humans was 46 chromosomes, that is, 23 pairs and not 48 as was thought previously (1).

What happens when you have 47 chromosomes?

Humans have 23 pairs of chromosomes. A trisomy is a chromosomal condition characterised by an additional chromosome. A person with a trisomy has 47 chromosomes instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy.