Chapter 2 Vocabulary List 1. Biology – the study of life 2. Organism – a living thing 3. DNA – Deoxyribonucleic Acid; carries the genetic code 4. Nucleotide – monomer of DNA or RNA composed of phosphoric acid, sugar (deoxyribose for DNA and ribose for RNA) and a nitrogen base (A,T,C,G for DNA and A,U,C,G for RNA). 5. Nitrogenous Bases – the parts of DNA and RNA that pair (A,T,C,G for DNA and A,U,C,G for RNA). 6. DNA Replication – the process of making another copy of the genetic code by a semi-conservative process. Occurs within the nucleus 7. DNA Polymerase – enzyme that links DNA nucleotides together during DNA replication using a DNA strand as a template. This enzyme also proofreads the new DNA strand and corrects any base pairing errors. 8. DNA Helicase – 9. Telomere – repetitive DNA at the end of a eukaryotic chromosome. This DNA is commonly lost during DNA replication but is replaced by the enzyme DNA Telomerase. 10. RNA – Ribonucleic Acid 11. mRNA – messenger RNA (Messenger Ribonucleic Acid); single stranded molecule that carries the genetic message from DNA within the nucleus to ribosomesoutside the nucleus 12. tRNA – transfer RNA (transfer Ribonucleic Acid); molecule the carries amino acids to ribosomes 13. rRNA – ribosomal RNA (Ribosomal Ribonucleic Acid); RNA that makes up ribosomes 14. Transcription – making mRNA from DNA; occurs within the nucleus 15. RNA Polymerase – enzyme that links RNA nucleotides together during transcription using a DNA strand as a template. 16. Promoter – specific region of a gene where RNA polymerase can bind and begin transcription 17. Translation/Protein Synthesis – reading the mRNA codons to make proteins; occurs on the ribosomes 18. Amino Acids – the monomers of proteins 19. Proteins – molecules that make up parts of cells and sometimes act as enzymes 20. Ribosomes – small organelles within cells where translation/protein synthesis takes place 21. Intron – a sequence of DNA that is not involved in coding for a protein (90% of DNA is composed of introns). 22. Exon – a sequence of DNA that is “expressed” and therefore codes for a protein (only 10% of DNA consists of exons). 23. Codon – a group of three nucleotide bases in mRNA that code for a specific amino acid 24. Anitcodon – a group of three nucleotide bases on a tRNA molecule complimentary to the three nucleotide bases on a mRNA codon. Each anticodon carries a specific amino acid. 25. Polyploidy – condition in which an organism has an extra set of chromosomes.