Dna and Amino Acids Essay

Submitted By Babygoats
Words: 2532
Pages: 11

Nucleotides – DNA and RNA are made up of nucleotides – Nucleotides are made up of 1) Pentose Sugar 2) Nitrogenous Base 3) Phosphate GROUP – The bases may be purines (2 rings; adenine and guanine) or pyrimidines (1 ring; cytosine and thymine or uracil) – Bases bond using hydrogen bonds – The sugar-phosphate backbone may be generalized by 5' (five prime) and 3' (three prime); ensures nucleotides are connected and read in the correct way DNA – Controls cellular activities; carries a genetic code – encoded in sequence of bases strung together – instructions used in building proteins – DNA replicates and makes copies of itself to pass onto other cells – Mutates: Genetic Diversity – Replication of DNA, Transcription mRNA, Translation Protein DNA Replication 1) 2 strands of DNA become “ladder like” 2) Enzyme hilicase breaks H-Bonds and unzips – DNA is opened at “Replication origin” 3) Free floating nucleotides in the nucleoplasm move to appropriate position via complementary base pairing – The enzyme DNA polymerase facilitates base pairing between S.S. DNA and nucleotides 4) Adjacent nucleotides become joined through sugar phosphate bonds 5) Once complete, 2 DNA molecules wind up. Two new DNA molecules are identical to each other – Semiconservative replication because each DNA molecule contains on new and one original strand – Complimentary base paring is crucial to replication beach each strand is acting as a template for a new strand – It takes 8 hours for the entire genome Enzymes involved in DNA Replication – Helicase: causes DNA to unzip – Topoisomerase: holds strands apart – DNA Polymerase: At heart of replication machine – Synthesizes new DNA strand using old strand as a template – Catalyses the addition of nucleotides to the growing DNA strand, linking them with phosphodiester bonds – Proof Reads: checks pairing as soon as it happens before making phosphodiester bonds

Ribonucleic Acid – RNA – Three types of RNA, but all involved in protein synthesis 1) Messenger RNA (mRNA) 2) Ribosomal RNA (rRNA) 3) Transfer RNA (tRNA) – Messenger RNA (mRNA) is a copy of the genetic code contained in the sequences of bases in the cell's DNA – Acts as a “go-between” for DNA in the nucleus and the ribosomes of the cytoplasm – Ribosomal RNA (rRNA) is a structural part of the ribosomes – Associates with proteins to form ribosomes – Ribosomes are the site of protein synthesis – Majority of cell's RNA – Transfer RNA (tRNA) delivers amino acids from the cytoplasm to the ribosome – Different tRNA for each amino acid Protein Synthesis – DNA info → mRNA info → Protein – DNA Transcription (DNA → RNA): Synthesis of mRNA – Photocopying stage – DNA doesn't leave nucleus and protein is made in the cytoplasm – Transcription Steps: 1) Two DNA strands separate 2) One strand acts as a template and complementary RNA bases are brought in 3) RNA Polymerase catalyses the addition of ribonucleotidesby forming sugarphosphate bonds between adjacent RNA nucleotides. New RNA strand grows as bases on DNA strand form H-bond with RNA bases one at a time, forming a chain 4) mRNA is released from DNA 5) DNA rewinds and returns to double helix 6) mRNA strand moves to cytoplasm from the nucleus vis a nuclear pore – RNA Translation (RNA → Proteins) process that changes RNA into protein; occurs at a ribosome – The order of the bases in DNA, and subsequently the mRNA, determines the order of amino acids in the protein being made – RNA is like a sentence made of words – RNA's words are called codons which are a set of 3 nucleotides – Each amino acid is coded for by a set of 3 nucleotides – a codon; this is called the triplet code – Codes tells when to start reading the gene and when to stop for a particular protein – Each codon corresponds to an amino acid – Translation Steps: i. Initiation: Proteins called “initiation factors” bring together: 1) mRNA, 2 Ribosomal subunits, tRNA (with an amino acid) 2) rRNA makes up large and small subunits of the ribosome 3) tRNA brings