DNA, RNA and Protein Synthesis Biology 11 – 2017/18 Mrs. Day
DNA - Review What is DNA made of? How is DNA put together? Just remember – SPBHSL S = sugar (deoxyribose) P = phosphate group B = base (nitrogenous base) H = helix (spiral staircase) S = strands (2) L = location (nucleus)
DNA - Review What is DNA’s function? DNA:
DNA and Genes How are DNA and genes related? Chromosomes is tightly wound up strands of DNA.
DNA and Genes How are DNA and genes related? Genes are a section of DNA. The sequence of DNA that codes for a protein = a gene. Proteins have many functions, one is to determine the traits of an organism.
How does DNA make proteins? DNA, a double stranded molecule is TOO BIG to leave the nucleus. Ribosomes make proteins - in the cytoplasm of the cell. So … how does DNA and genes make proteins? The protein message must be carried from the nucleus -> cytoplasm -> ribosomes
Step 1 - Transcription: What is mRNA? Copy the gene information on the DNA onto a molecule that can leave the nucleus – messenger RNA Messenger RNA (or mRNA) contains the genetic code for the gene What is mRNA? It is like a disposable copy of a segment of DNA It usually is a copy of a single gene
How does mRNA work? mRNA is made in nucleus, but functions outside of the nucleus It aids in protein synthesis It uses the DNA strand as the template to make it strand using complimentary base pairing
Step 2 - Translation: This process is complicated. Messenger RNA is a smaller molecule than DNA – so it can leave the nucleus and go into the cytoplasm Once in the cytoplasm, a ribosome will bind with the RNA molecule. The ribosome reads the mRNA code. The mRNA code tells the cell what amino acids to bring to the ribosome. Amino acids are the building blocks to make proteins. Remember – the RNA code has all the information to make a single gene. And, a gene is the code for a specific protein. This process is complicated. For more detailed information, read chap 12.3 in your textbook or take biology 12.
In Summary - Protein synthesis is a 2 step process: Step 1 – Transcription Step 2 - Translation:
In Summary Genes are a section of DNA. The sequence of DNA that codes for a protein = a gene. Transcription: RNA makes a copy of the gene in the nucleus RNA takes the information to the cytoplasm Translation: In the cytoplasm, RNA binds to a ribosome. The ribosome reads the RNA code and the cell brings the required amino acids to build the specific protein (or gene). Proteins and genes determine the traits of an organism.