Genes and Gene Technology Chapter 6 Genes and Gene Technology

Section 1 – What do genes look like? DNA – Deoxyribonucleic Acid; hereditary material that controls all the activities of the cell, contains the information to make new cells and provides instructions for making proteins Nucleotides – A subunit of DNA consisting of a sugar, a phosphate and one of four nitrogenous bases Adenine – One of the four bases that combine with sugar and phosphate to form a nucleotide subunit of DNA: adenine pairs with thymine Thymine – Thymine pairs with adenine Guanine – Pairs with cytosine Cytosine – Pairs with Guanine

The DNA molecule looks like a twisted ladder The DNA molecule looks like a twisted ladder. The rungs of the ladder are made of base pairs A, G, C, and T DNA carries genetic information in the order of the nucleotide bases DNA can be copied because one strand of the molecule serves as a template for the other side

Each skin cell contains 46 chromosomes: each chromosome is made of proteins (Proteins are made of long strings of amino acids) and DNA: each molecule of DNA contains two halves that are connected down the center (DNA is made of long strings of nucleotides) and twisted by a spiral staircase called a double helix (discovered by Watson and Crick)

Incomplete Dominance shows that sometimes one trait does not completely dominate another: each allele may have its own degree of influence (a red flower and a white flower make a pink flower) Many genes can influence a single trait (the hair color gene can influence the eye color gene)

Section 2 – How DNA Works Ribosome – A small organelle in cells where proteins are made from amino acids Mutation – A change in the order of the bases in an organism’s DNA: deletion, substitution, insertion Mutagen – Anything that can cause changes or damage DNA Pedigree – A diagram of family history used for tracing a trait through several generations

A gene is a set of instructions for assembling a protein Making a protein: 1. Copy the section of a strand of DNA with the gene 2. Messenger molecules take the genetic information from the nucleus to the cytoplasm 3. The copy of DNA is fed through ribosome 3 bases at a time Bases match up and the amino acids are strung together to form a protein

Mutations Mutations can be caused by X rays and ultraviolet radiation Insertion – extra base is added Deletion – base is left out Substitution – incorrect base replaces a correct base