Biology · IGCSE · Cambridge · Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) · Specification point · 17.1 · Inheritance
17.1 Chromosomes, genes and proteins
| Core | Supplement |
|---|---|
1 State that chromosomes are made of DNA, which contains genetic information in the form of genes | |
2 Define a gene as a length of DNA that codes for a protein | |
3 Define an allele as an alternative form of a gene | |
4 Describe the inheritance of sex in humans with reference to X and Y chromosomes | 5 State that the sequence of bases in a gene determines the sequence of amino acids used to make a specific protein (knowledge of the details of nucleotide structure is not required) 6 Explain that different sequences of amino acids give different shapes to protein molecules |
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7 Explain that DNA controls cell function by controlling the production of proteins, including enzymes, membrane carriers and receptors for neurotransmitters 8 Explain how a protein is made, limited to: • the gene coding for the protein remains in the nucleus • messenger RNA (mRNA) is a copy of a gene • mRNA molecules are made in the nucleus and move to the cytoplasm • the mRNA passes through ribosomes • the ribosome assembles amino acids into protein molecules • the specific sequence of amino acids is determined by the sequence of bases in the mRNA (knowledge of the details of transcription or translation is not required) 9 Explain that most body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs 10 Describe a haploid nucleus as a nucleus containing a single set of chromosomes 11 Describe a diploid nucleus as a nucleus containing two sets of chromosomes 12 State that in a diploid cell, there is a pair of each type of chromosome and in a human diploid cell there are 23 pairs |