BELLRINGER Put this in the second box of your Bellringer Page 1.What does “replicate” mean? 2.What is the end result of DNA replication? 3.Why does this process occur?

The other type of NUCLEIC ACID

DNA holds the instructions to make proteins, but can NOT leave the nucleus. Proteins are made outside of the nucleus on the tiny organelles called ribosomes. The DNA needs a messenger to take a copy of the instructions to the ribosomes so the proteins can be made. What’s the problem?

Section 11.2 Summary – pages Other than DNA, what is another type of nucleic acid? There are 3 types of RNA, but today we will only focus on one- mRNA. Messenger RNA (mRNA) delivers a copy of DNA’s instructions from the nucleus to the ribosomes.

Section 11.2 Summary – pages mRNA structure differs from DNA structure in three ways. # 1 RNA is single stranded—it looks like one-half of a zipper—whereas DNA is double stranded.

Section 11.2 Summary – pages The sugar in RNA is ribose; REMEMBER: DNA’s sugar is deoxyribose. Ribose # 2

Section 11.2 Summary – pages Finally, both DNA and RNA can contain four nitrogenous bases, BUT RNA does not have Thymine. Thymine is replaced by a similar base called uracil (U). Uracil forms a base pair with adenine in RNA. # 3 What do you notice instead?

This picture is on the back of your notes. Talk to your neighbor about the differences? I will call on people at random.

Section 11.2 Summary – pages DNA provides mRNA with the instructions for making the proteins. mRNA takes the copy of instructions to the ribosome The instructions are a code for how the protein should be assembled (amino acid by amino acid) What is the Role of mRNA in a cell? DNA - boss with instructions mRNA - workers that take the instructions from the boss to the site to carry out the job.

The process of: TRANSCRIPTION

mRNA is made in a process called transcription. This occurs IN THE NUCLEUS Transcribe means “to copy” Steps of Transcription 1.DNA uncoils and unzips, just as it does in DNA replication.

Steps of Transcription 2.Free RNA nucleotides, containing A,U, C, and G float up and attach to one side of the DNA strand. Unzipped DNA Newly constructed mRNA

Steps of Transcription 3.Once the mRNA strand is made, it’s hydrogen bonds break. 4. Then it leaves the nucleus and goes to a ribosome in the cytoplasm. Once the mRNA is detached, the DNA strand goes back together.

TRANSCRIPTION

Section 11.2 Summary – pages Transcription results in the formation of one single- stranded RNA molecule DNA replication results in two double-stranded DNA molecules What is the difference between DNA Replication and Transcription? Talk to your neighbor!

What do DNA Replication and Transcription have IN COMMON? Talk to your neighbor! They both take place in the nucleus (if it involves DNA in a eukaryotic cell- it’s happening in the nucleus) They both have to do with making a copy of DNA (except DNA replication is making a full EXACT copy)

Below is a nitrogenous base sequence on one side of a DNA strand. 1. What is the sequence on the mRNA strand after Transcription? T A C C C G T A T T C G A A G G C T A U G G G C A U A A G C U U C C G A