DNA & RNA + PROTEIN SYNTHESIS

 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

 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

Nucleotide DNA

The bases in DNA come in 4 types  Adenine (A)  Thymine (T)  Cytosine (C)  Guanine (G) So there are 4 different types of nucleotides

 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.

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

1. An enzyme attaches to the DNA molecule and starts to unzip or unwind it.  The bond between the bases is broken

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

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

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

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

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

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

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

 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

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

 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!

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