210 likes | 360 Views
DNA. Structure Replication Functions (Stores and provides copies of genetic material- genes) Blueprint (genes) for Protein Synthesis (Enzymes and cell building blocks). Francis Crick. RNA (Ribonucleic Acid). Why do we need RNA? Why can’t DNA directly make proteins?
E N D
DNA • Structure • Replication • Functions (Stores and provides copies of genetic material- genes) • Blueprint (genes) for Protein Synthesis (Enzymes and cell building blocks)
RNA (Ribonucleic Acid) • Why do we need RNA? • Why can’t DNA directly make proteins? • Where is DNA located? Can it leave? Why does it stay there? • Where are proteins made? • Temporary copies of parts of the blueprint
Ribonucleic acid (RNA) • carries DNA’s instructions • acts as an link between DNA in the nucleus and protein synthesis in the cytoplasm. • plays several different roles in protein synthesis.
Similarities DNA and RNA • Both are nucleic acids • Both are made up of nucleotides (sugar, base, phosphate)
Differences between DNA and RNA DNA RNA
Types of RNA 1. Messenger RNA (mRNA) -formed in nucleus from DNA template -Carries copies of instructions for protein synthesis to the ribosomes in cytoplasm (nuclear membrane pores) 2. Ribosomal RNA (rRNA) -along with some proteins make up ribosomes (cytoplasm) 3. Transfer RNA (tRNA) - transport amino acids to ribosomes (cytoplasm) All types of RNA are formed in the nucleus.
Transcription • Messenger RNA (mRNA) is made from DNA • DNA is template • Complementary RNA is produced • Nucleus (eukaryotic cells) • RNA polymerase (unwinds the DNA and adds nucleotides to form RNA) • Uracil is paired with adenine
Transcription steps • RNA polymerase binds to promoter (“start”) region of gene • RNA polymerase unwinds and separates the two strands of DNA • RNA polymerase adds complementary RNA nucleotides • RNA polymerase reaches a sequence of nucleotides on the gene that signals “stop” • RNA polymerase detaches
http://www.fed.cuhk.edu.hk/~johnson/teaching/genetics/animations/transcription.htmhttp://www.fed.cuhk.edu.hk/~johnson/teaching/genetics/animations/transcription.htm • What does this remind you of? • Practice creating complementary mRNA
Post-transcription • Pre-mRNA molecule produced and undergoes processing and editing. (spliceosomes) • Introns – cut out and discarded • Exons – remaining pieces spliced back together to form mRNA • mRNA travels through nuclear membrane pore into cytoplasm