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Published byHomer Young Modified over 9 years ago
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DNA & RNA + PROTEIN SYNTHESIS
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DNA (Deoxyribonucleic acid) is the code inside all living organisms. The first model of DNA was built by Watson & Crick in 1953 and they won the Nobel Prize for it. DNA is a double helix or twisted ladder
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DNA is made up of nucleotides Nucleotides…. are made up of a sugar, a phosphate group, & a base attach to one another to form a ladder The sides of the DNA ladder are made up of phosphates & sugars The steps or rungs of the ladder are made up of 2 bases
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Nucleotide DNA
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The bases in DNA come in 4 types Adenine (A) Thymine (T) Cytosine (C) Guanine (G) So there are 4 different types of nucleotides
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A can ONLY go with T T can ONLY go with A C can ONLY go with G G can ONLY go with C The pattern of the bases actually makes up the code actually makes up the code in the DNA in the DNA One section of DNA code codes for one protein, which then controls one characteristic in an organism.
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How is DNA copied by a cell? DNA has to be copied every time a cell goes through the cell cycle ( to make more cells:mitosis) DNA is copied during the S phase of interphase It needs to be copied so each new cell has identical DNA
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1. An enzyme attaches to the DNA molecule and starts to unzip or unwind it. The bond between the bases is broken
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2.The bases are exposed! A new nucleotide attaches to the matching nucleotide on the open DNA strand. attaches to the matching nucleotide on the open DNA strand. 3. An enzyme proofreads the DNA & stops the process & fixes any mistakes that may occur. process & fixes any mistakes that may occur. 4. In the end, 2 identical pieces of DNA are made. Each is made of half old & half new DNA. Each is made of half old & half new DNA. Replication
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PART 3. DNA to RNA - Transcription A.DNA is the recipe which codes for how to make all the different types of proteins DNA can’t make the proteins (It is the recipe) DNA never leaves the nucleus, & proteins are made on the ribosomes
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B. Proteins are the building blocks of life Proteins are necessary to BUILD an organism Hair, muscle, bones = made of proteins Proteins are necessary to make an organism function & be alive Proteins are made of amino acids – the amino acids are like the ingredients to make the proteins
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C.RNA (Ribonucleic acid) is the molecule that will help build the proteins RNA makes the proteins on the ribosomes, using the instructions it gets from DNA (It is like a chef following a recipe) RNA is very similar to DNA -Both needed to build proteins -Both needed to build proteins - Both are nucleic acids - Both are nucleic acids -Both are made of nucleotides -Both are made of nucleotides -Both contain a code -Both contain a code But RNA is also very different than DNA
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DNARNA Sugar = Deoxyribose Job = Controls everything in a cell “recipe” Shape = double stranded Only 1 type Has Thymine as a base Sugar = Ribose Job = Helps to build proteins in a cell “chef” Shape = single stranded 3 types mRNA, tRNA & rRNA mRNA, tRNA & rRNA Has Uracil as a base
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RNA comes in 3 different types: 1.Messenger RNA (mRNA) Carries a message from DNA to the ribosome for how to build a protein Made in the nucleus & moves to the ribosomes 2. Ribosomal RNA (rRNA) Part of the ribosome Help to make proteins
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3. Transfer RNA (tRNA) Brings the ingredients (amino acids) needed to make proteins to the ribosome where they are made The 3 different types of RNA must all work together to must all work together to make proteins make proteins
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Making proteins involves 2 processes: Transcription & Translation 1. During Transcription: mRNA is made in the nucleus using DNA as a guide DNA has the recipe for how to make protein, but it is stuck in the nucleus. mRNA is a copy of the recipe that is brought to the ribosome (protein factory) to make the protein
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2. During Translation: The mRNA, which is now at the ribosome, is read & translated, so it knows what amino acids are needed to be put together to make the protein The tRNA brings the needed amino acids to the ribosome The ribosome, which is made of rRNA, attaches the amino acids into a chain following the directions in the mRNA A protein is formed Protein synthesis Protein synthesis Protein synthesis
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The chef (ribosome) now has the protein recipe (mRNA) The ingredients need to be brought to the chef. The tRNA brings the needed ingredients (amino acids) to the chef (ribosome) The chef (ribosome) now follows the recipe (mRNA) and attaches the amino acids into a chain. A protein is made!
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How can we read & translate the mRNA? 1.Every 3 letters in the mRNA codes for an amino acid This is called a codon 2. Use a chart to figure out which amino acid is needed DNA code: mRNA:Amino acids needed: DNA code: mRNA:Amino acids needed:ATTGCGGCCTAAATCCGA
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