Transcription Mrs. Harper 2/15/18 Biology

February 15, 2015 Begin working on Do Now Have homework (DNA Replication WS) out

Do Now 12/2/15 Which nitrogen base pairs with which other? What is the difference between purines and pyrimidines? What type of bonds hold the nitrogen bases together? What type of bonds hold the sugar and phosphates together? What does helicase do? What is the function of DNA ligase? What are the segments in the lagging strand called?

Process following DNA Replication, Converts DNA into RNA Transcription Process following DNA Replication, Converts DNA into RNA

The Central Dogma DNA RNA  Proteins Transcription Translation

Transcription Transcription is the synthesis of an RNA strand from a DNA template. DNA transcribed to messenger RNA (mRNA). mRNA carries the code from DNA to the ribosomes where translation occurs

DNA vs RNA Double stranded Deoxyribose sugar Contains thymine Single stranded Ribose sugar Contains uracil (NOT thymine) COMMON TRAITS (place these in the middle) -Both have bases A, G, C -Both are nucleic acids

3 Types of RNA: Messenger RNA: (mRNA) carries nucleotide sequence from nucleus to ribosome Transfer RNA: (tRNA) picks up amino acid in cytoplasm and carries them to ribosome Ribosomal RNA: (rRNA)found in ribosome, joins mRNA and tRNA; forms protein

Synthesis of an RNA Transcript The three stages of transcription are: Initiation Elongation Termination

Initiation RNA polymerase binds to DNA at a specific sequence of nucleotides called the promoter. The promoter contains an initiation site where transcription of the gene begins. RNA polymerase then unwinds DNA at the beginning of the gene.

Elongation RNA polymerase synthesizes a single strand of RNA complementary to the DNA template strand adding to the 3’ end of the RNA chain As RNA polymerase moves along the DNA it continues to untwist the double helix. Elongation RNA polymerase Non-template strand of DNA RNA nucleotides 3 end C A E G U T 3 5 Newly made Direction of transcription (“downstream”) Template

Termination RNA polymerase continues to elongate until it reaches the terminator, a specific sequence of nucleotides that signals the end of transcription. Transcription stops and RNA polymerase and the new mRNA transcript are released from DNA. The DNA double helix reforms.

Transcription Overview

Practice Transcribing Create the complementary mRNA strand for each DNA strand (remember use U instead of T when pairing A) DNA strand 5’ ACTAGCTA 3’ mRNA strand DNA strand 5’ TTCCAGCA 3’

Assignment Complete the Transcription Homework independently on Code Red Unfinished classwork will become homework