NUCLEIC ACIDS PROTEIN SYNTHESIS DNA Deoxyribo Nucleic Acid
NUCLEIC ACIDS & PROTEIN SYNTHESIS
DNA • Deoxyribo Nucleic Acid • Found in the nucleus of eukaryotic cells. • It is a template (pattern) for protein synthesis. • “Double helix” shaped thanks to the discovery of James Watson and Francis Crick
DNA is made up of repeating chains of NUCLEOTIDES • NUCLEOTIDES are composed of: – SUGAR (deoxyribose) – PHOSPHATE – NITROGENOUS BASE • • Adenine (A) Thymine (T) Guanine (G) Cytosine (C)
• How many nucleotides do you see?
BASE PAIRING RULE • C (cytosine) always bond to G (guanine) • A (adenine) always bonds to T (thymine) • This bonding allows for the distinctive twisted ladder or double helix shape of DNA
DNA REPLICATION Replication: chromosomes making exact copies of themselves which get passed on during cell division • In order to do this: – The DNA double helix unzips, separating at the nitrogenous bases – Each strand is a template for the new nucleotide strand – Free nucleotides present in the cytoplasm pair with the free nitrogen bases of both strands according to base pairing rules. – Two identical DNA molecules are produced.
COMPLEMENTARY DNA C DNA G G C T A A T G C C T G A T A A T
RNA • Ribo Nucleic Acid • Single stranded • The sugar is Ribose instead of Deoxyribose • Does NOT contain Thymine • Instead contains URACIL (A – U)
Three Types of RNA • m. RNA – messenger RNA • t. RNA – transfer RNA • r. RNA – ribosomal RNA
PROTEIN SYNTHESIS 1. DNA holds the code or blue print for making all of the proteins in the body.
TRANSCRIPTION • Double stranded DNA unzips • One strand of the doublestranded DNA is used as a template to make m. RNA (single strand)
Once the m. RNA molecule is made through transcription: • It travels out to the cytoplasm in search of the correct amino acid that it is “coding” for. • Each triplet of m. RNA nitrogen bases is called a CODON and it holds the code for a which amino acid comes next for a particular protein. • Ex: CODON = base triplet = AGC, AAU
The Genetic Code • Use the chart for the genetic code to figure out which amino acid the m. RNA codon (triplet) is coding for.
TRANSLATION • Now that we know what amino acids we are looking for, the m. RNA goes out in to the cytoplasm to find them (translates the code into amino acids. )
• Once the t. RNA hooks up with the correct amino acid, it goes to the RIBOSOME where the amino acids are connected to make a POLYPEPTIDE.
Protein Synthesis - long
- Slides: 20