GCSE Biology OCR B1 You and your genes

annaryann's version from 2016-05-16 19:22


Question Answer
What do genes do?Carry the instructions that control how you develop and function by telling the cells to make proteins you need.
What is each gene a section of?A very long molecule of DNA.
What are chromosomes?Lengths of DNA that are coiled anf packed into structures.
Where are chromosomes found?In the nuclei of the body cells.
What are bases?Strands of DNA that are made up of four chemicals.
What do the order of bases in a DNA strand determine?The order of amino acids in a protein.
What is a functional protein?Enables the body to function- enzymes, hormones, antibodies.
What is a structural protein?Gives the body structure, rigidity, and strength- collagen and keratin.
What do differences in genes produce?Variation in offspring.
What is a genotype?Genetic make up- genes for a particular characteristic. Usually written as two letters.
What is a phenotype?Observable features- depends on genes but can be affected by environment.
When is a zygote produced?At fertilisation when an egg and sperm join together.
What causes a mutation?Changes to our DNA which sometimes occur when sex cells are being made or after fertilisation.
What are alleles?The different forms in which the genes controlling a character istic can occur.
What does homozygous mean?If the two alleles of a gene are identical, the person is homozygous.
What does heterozygous mean?If the two alleles of a gene are different, the person is heterozygous.

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