Biology Chap11 Dna Notes

Destiny Cobb Biology Chapter 11: DNA and Genes pgs.286-313

Main Idea Section 11.1 DNA: The Molecule of Heredity

Section 11.2 From DNA to Protein

Notes/Vocabulary • DNA, the genetic material for organisms, is composed of 4 kinds of nucleotides. A DNA molecule consists of 2 strands of nucleotides with sugars and phosphates on the outside and bases paired by hydrogen bonding on the inside. The paired stands form a twisted zipper shape called a double helix • Because adenine can only pair with thymine, and guanine can only pair with cytosine, DNA can replicate itself with great accuracy. This process keeps the genetic information constant through cell division and during reproduction. Nitrogen Base- carbon ring structure found in DNA or RNA that contain one or more atoms of nitrogen; includes andenine, guanine, cytosine, thymine, and uracil Double Helix- shape of a DNA molecule formed when 2 twisted DNA strands are coiled into a spring like structure held together by hydrogen bonds between the bases DNA replication- process in which chromosomal DNA is copied before mitosis and meiosis • Genes are small sections of DNA. Most sequences of 3 bases in the DNA of a gene code for a single amino acid in a protein. • The order of nucleotides in DNA determines the order of nucleotides in messenger RNA in a process called transcription. • Translation is a process through which the order of the bases in messenger RNA codes for the order of amino acids in a protein. Messenger RNA- RNA that transports information from DNA in the nucleus to the cells cytoplasm Ribosomal RNA- RNA that makes up the ribosomes; clamps onto mRNA and uses its information to assemble amino acids in the correct order Transfer RNA- RNA that transports amino acids to the ribosomes to be assembled into proteins Transcription- process in the cell nucleus where enzymes make an RNA copy of a DNA strand Codon- set of 3 nitrogen bases that represents an amino acid; order of nitrogen bases in mRNA determines the type and order of amino acids in a

Destiny Cobb Biology Chapter 11: DNA and Genes pgs.286-313

Section 11.3 Genetic Changes

protein Translation- process of converting information in mRNA into a sequence of amino acids in a protein • A mutation is a change in the base sequence of DNA. Mutations may effect only one gene, or they may affect the whole chromosomes. • Mutations in eggs or sperm affect future generations by producing offspring with new characteristics. Mutations in body cells affect only the individual and may result in cancer. Mutation- any change or random error in a DNA sequence Point Mutation- mutation in a DNA sequence; occurs from a change in a single base pair Chromosomal Mutation- mutation that occurs at the chromosome level resulting in changes in the gene distribution to gametes during meiosis; caused when parts of chromosomes break off or rejoin incorrectly Mutagen- any agent that can cause a change in DNA; includes high-energy radiation, chemicals, or high temperatures