Cell Division - Nucleus and Chromosomes (GCSE Biology)
Nucleus and Chromosomes
Chromosomes
Chromosomes in Nucleus
- The nucleus contains genetic information. Most cells have a nucleus, which contains the genetic information of the cell. This information affects the make up of the cell, and determines which proteins are made.
- DNA is packaged in chromosomes. A chromosome is a molecule made up of many coiled up sections of DNA. It is important that the DNA does not become tangled.
- DNA makes up genes. Genes are sequences of DNA that code for certain characteristics. Each chromosome therefore contains many genes.
Chromosome Pairs
- Chromosomes come from biological parents. Each cell has 23 pairs of chromosomes. Each set of chromosomes gets one copy from the father and the other from the mother. Therefore, the chromosomes are
found paired. - If chromosomes are not paired, it could lead to genetic disease. Many genetic conditions occur due to problems in chromosome pairing. A common example is Down’s Syndrome, in which patients suffer from an extra 21st chromosome.
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