Ch 12 DNA and RNA

12-1 DNA Transformation- one strain of bacteria permanently changes into another strain.

12-1 DNA Avery and other scientists discovered that DNA stores and transmits the genetic information from one generation to the next.

12-1 DNA Bacteriophage- type of virus that infects bacteria. Hershey and Chase concluded that the genetic material of the bacteriophage was DNA, not protein.

12-1 DNA Nucleotides- units that make up DNA, composed of: 1) 5-carbon sugar (deoxyribose) 2) phosphate group 3) nitrogenous base (adenine, cytosine, guanine, or thymine).

12-1 DNA Watson and Crick’s model of DNA was a double helix, in which two strands were wound around each other.

12-1 DNA Base pairing- hydrogen bonds can only form between certain base pairs. adenine=thymine guanine=cytosine.

12-2 Chromosomes and DNA Replication Chromatin- substance containing DNA and protein that makes up chromosomes. Histones- protein that DNA wraps around.

12-2 Chromosomes and DNA Replication Replication- the copying of DNA before a cell divides.

12-2 Chromosomes and DNA Replication During DNA replication: 1) the DNA molecule separates into two strands. 2) two new complementary strands are formed following base pairing rules. 3) Each original strand of DNA serves as a template for a new strand.

12-2 Chromosomes and DNA Replication DNA polymerase- principle enzyme involved in DNA replication. Joins individual nucleotides together to produce a DNA molecule.

12-3 RNA and Protein Synthesis Genes- coded DNA instructions that control protein production within a cell.

12-3 RNA and Protein Synthesis RNA is similar to DNA with three major differences: 1) single stranded (instead of double stranded) 2) ribose sugar (instead of deoxyribose) 3) Uracil instead of Thymine (U replaces T) There are three main types of RNA: 1) messenger RNA (mRNA) 2) ribosomal RNA (rRNA) 3) transfer RNA (tRNA)

12-3 RNA and Protein Synthesis Messenger RNA- carry copies of DNA instructions to the rest of the cell.

12-3 RNA and Protein Synthesis Ribosomal RNA- help ribosomes assemble proteins.

12-3 RNA and Protein Synthesis Transfer RNA- transfers the appropriate amino acids to the ribosome as a protein is made.

12-3 RNA and Protein Synthesis Transcription- copying part of a DNA sequence into a complementary RNA sequence.

12-3 RNA and Protein Synthesis During transcription, RNA polymerase: 1) binds to DNA. 2) separates the DNA strands. 3) uses one DNA strand as a template to create an RNA strand.

12-3 RNA and Protein Synthesis Promoters- Specific regions of DNA where RNA polymerase will bind.

12-3 RNA and Protein Synthesis Introns- “junk” DNA sequences that do not code for proteins. Exons- DNA sequences that code for proteins.

12-3 RNA and Protein Synthesis Codon- three consecutive nucleotides that specify a single amino acid. *The genetic code is universal*

12-3 RNA and Protein Synthesis Translation- the process of using the mRNA sequence to produce proteins. Anticodon- carried on tRNA molecules, complementary to a codon in mRNA.

12-4 Mutations Mutations- changes in the genetic code. Point mutation- mutation involving one or a few nucleotides. Frameshift mutation- mutations that shift the “reading frame” of a genetic sequence.

12-4 Mutations Causes of mutations: 1) Spontaneous 2) Chemicals and radiation 3) High energy radiation (x-rays, gamma rays)

12-5 Gene Regulation Operon- a group of genes that operate together. The lac genes are turned off by repressors and turned on by the presence of lactose.

12-5 Gene Regulation Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex than those of the lac operon.

12-5 Gene Regulation Differentiation- during embryonic development, cells become specialized in structure and function. hox genes- a series of genes that control the body plan of many organisms.