DNA and RNA B.4.1

Nucleic acids there are two types -DNA- deoxyribose nucleic acids -RNA - ribose nucleic acids both are made of nucleotides that are made of three parts a nitrogenous base ( C) - cytosine(A) - adenine ( G) - guanine(T) - thymine --- DNA only ( U)- uracil ---- RNA only a simple (pentose) sugara phosphate group deoxyribose (DNA only) ribose (RNA only)

basic structure DNA- contains two single chains which spiral around an imaginary axis to form a double helix with nitrogenous bases from each strand of DNA chemically bonded through the axis of the helix ●complimentary bases bond together ○guanine to cytosine ○thymine to adenine RNA - consists of a single chain of nucleotides ●complimentary bases bond together ○guanine to cytosine ○uracil to adenine

DNA, Chromosomes, Genes

Protein Synthesis the DNA carries the code for all genes in the organism Genes are pieces of the DNA molecule that code for specific proteins The process of making genes into proteins is called protein synthesis. Protein assembly occurs in the ribosomes. 3 steps to protein synthesis: 1.DNA code of the gene segment is copied in the nucleus 2.the code is carried from nucleus into cytoplasm to ribosomes 3.the protein is then assembled and released from ribosome these steps are carried out by the RNA

Protein Synthesis - step 1- transcription mRNA is made -region of the DNA unwinds & separates (this segment is gene) -unattached nucleotides in the nucleus are used to form a mRNA strand -the base uracil (U) matches the base adenine (A) instead of thymine (T) - the mRNA leaves the nucleus, goes into the cytoplasm, settles on the ribosome surface narration.html transcription animation

protein synthesis- step 2- translation mRNA is decoded and corresponding polypeptide is formed (a polypeptide is made up amino acids) --- this happens at the ribosome mRNA is chain of nucleotides- AUG ACA UUG CCA for example *note that it is divided into 3’s- this is how the code is read and each group of 3 is called a codon each codon corresponds to a specific amino acid tRNA (transfer RNA) brings amino acids that compliment each mRNA codon to the surface of the ribosome where it is bound to the polypeptide chain that forms the protein a start codon signals the beginning of the polypeptide and when the stop codon is reached, the ribosome releases the polypeptide chain as a protein into the cell’s cytoplasm translation animationtranslation animation

REMEMBER! ●protein synthesis begins with the manufacture of mRNA ●Ribosomes are made of rRNA ●proteins are made of polypeptide chains which are made of amino acids ●transfer RNA (tRNA) carries amino acids to the ribosomes ●the last step of protein synthesis is when the stop codon binds to the ribosome and the polypeptide is released