RNA and Protein Synthesis
I. RNA Formed from nucleotides Single stranded Uracil instead of thymine (A – U) Sugar Ribose Copies the DNA info for protein synthesis Central Dogma= DNARNA RNA is very similar to DNA with a few exceptions Single stranded (DNA is double stranded) Thymine is a DNA nucleotide that bonds with Adenine (in RNA Uracil bonds with Adenine) The sugar is ribose sugar (DNA = deoxyribose) RNA copes DNA information to make proteins
3 Types of RNA: rRNA (ribosomal): help make up ribosome mRNA (messenger): carries the DNA info from nucleus to ribosome tRNA (transfer): brings amino acids to ribosomes to build proteins mRNA- DNA cannot move, mRNA is needed to move the information
RNA vs DNA
Students do not need to be able to recognize what the different types of RNA look like http://images.encarta.msn.com/xrefmedia/zencmed/targets/illus/ilt/T068340A.gif
II. Protein Synthesis A. Transcription: The DNA code is transcribed (copied) into mRNA in the nucleus mRNA bases pair with one strand of DNA. Just like when DNA replicates except that Thymine is replaced with Uracil
B. mRNA moves into the cytoplasm, attaching to a ribosome DNA is too large to move, it remains in the nucleus At this point, both the DNA and RNA contain genetic information
Ribosome reads the mRNA and joins amino acids to form a protein Translation: Each codon of mRNA selects a tRNA with a specific amino acid Ribosome reads the mRNA and joins amino acids to form a protein (polypeptide chain) Codon – a 3 base pair sequence of mRNA (pass out Amino acid table). The Amino acid tables show all the different codons (ex: UCU) and the amino acid associated with it (Serine). There are 20 different amino acids but many more codons. Several codons may be associated with the same amino acid (Serine is coded for by UCU UCC UCA UCG AGU AGC)
E. After delivering its amino acid, tRNA picks up another amino acid tRNA picks up the next amino acid, these hook together creating an amino acid chain. The tRNA has the complementary/opposite RNA sequence as the codon. This is called the anticodon.
Chapter 12.3
From Gene to Protein
A Review of Protein Synthesis http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302 May be helpful to show again tomorrow as revew