Chromosomes are thin strands of DNA (deoxyribonucleic acid). They are subdivided into genes . In most cells, chromosomes are located in functional pairs in the nucleus . Humans have 46 chromosomes arranged in 23 pairs.
Why are chromosomes in pairs BBC Bitesize?
One chromosome of each pair is inherited from the mother and the other one is inherited from the father. The chromosome in each pair carries the same gene in the same location. These genes could be the same, or different versions: Alleles are different versions of the same gene.
What are the 24 chromosomes?
The autosomes are normally present in pairs. The sperm contributes one sex chromosome (X or Y) and 22 autosomes . The egg contributes one sex chromosome (X only) and 22 autosomes . Sometimes microarray is referred to as 24-chromosome microarray : 22 chromosomes, and X and Y are counted as one each, for a total of 24.
Is DNA bigger than a chromosome?
If we talk about the uncoiled DNA, then DNA is larger than the chromosome. And if we talk about the coiled DNA, then DNA is smaller than the chromosome. When DNA gets coiled, it becomes smaller in size just in order to fit the nucleus of the cell.
Is an allele bigger than a chromosome?
An allele is found at a fixed spot on a chromosome. Chromosomes occur in pairs so organisms have two alleles for each gene — one allele in each chromosome in the pair.
|Refers to||A specific variation of a gene.||A section of DNA that controls a certain trait.|
What is genetic diagram?
Genetic diagrams show how characteristics are inherited. Alleles can be recessive, dominant or codominant genes. Pedigree analysis is used to show how genetic disorders are inherited.