Genes in Science 7 - PDF

Genes Miss Amilicia Science 7  Genes ▪ most of your characteristics (hair color, height, etc.) depend on the kinds of proteins your cells make ▪ DNA stores the instructions for making proteins ▪ the instructions for making a SPECIFIC protein are found in a GENE ▪ A Gen...

Genes Miss Amilicia Science 7  Genes ▪ most of your characteristics (hair color, height, etc.) depend on the kinds of proteins your cells make ▪ DNA stores the instructions for making proteins ▪ the instructions for making a SPECIFIC protein are found in a GENE ▪ A Gene is a section of DNA on a chromosome Genes on a Chromosome  Proteins ▪ made of chains of hundreds or thousands of amino acids ( gene determines the order of aa’s) > Proteins build cells and tissues or work as enzymes  Making Proteins ▪ proteins are made on ribosomes in cytoplasm ▪ the codes are carried from nucleus--> ribosomes by the nucleic acid… RNA  RNA= Ribonucleic Acid ▪ RNA is made in the nucleus on a DNA pattern ▪ RNA is DIFFERENT from DNA ▪ RNA is like a ladder that has all its rungs sawed in half ▪ RNA has the bases A, G, C, & U(uracil) (no thymine)  DNA to RNA ▪ DNA in the nucleus is used to make RNA ▪ RNA carries the code for a protein from the nucleus to the ribosome ▪ At the ribosome, the RNA’s message is translated into a specific protein  Controlling Genes ▪ cells have exactly the same chromosomes and the same genes ▪ they DO NOT make the same proteins ▪ each cell uses only SOME of the thousands of genes that is has to make proteins ----->  How do the cells do this? ▪ sometimes the DNA is twisted so tightly that no RNA can be made ▪ other times, chemicals bind to the DNA so that it cannot be used ▪ If the incorrect proteins are produced, the organism cannot function  Mutations ▪ sometimes mistakes happen ▪ If DNA is not copied exactly, the proteins made from the instructions might not be made correctly ▪ these mistakes are ----> Mutations Mutation= any permanent change in the DNA sequence of a gene or chromosome of a cell  Mutation Factors OUTSIDE FACTORS > x rays, sunlight, and some chemicals have been known to cause mutations ** Mutations can be positive and negative > negative= cells maybe receive an extra chromosome of a cell > positive= mutations add variety to species and also help some plants produce chemicals to keep insects away