Presentation on theme: "DNA Biology Lab 11. Nucleic Acids DNA and RNA both built of nucleotides containing Sugar (deoxyribose or ribose) Nitrogenous base (ATCG or AUCG) Phosphate."— Presentation transcript:
Nucleic Acids DNA and RNA both built of nucleotides containing Sugar (deoxyribose or ribose) Nitrogenous base (ATCG or AUCG) Phosphate group
Nitrogenous Bases Nitrogenous bases can be double ringed purines or single ringed pyrimidines.
Nitrogenous Bases A purine will always pair with a pyrimidine.
DNA The phosphate group and sugar make up the backbone of the DNA molecule.
DNA The DNA backbone Phosphate groups and pentose sugars The 5' end of each strand has a free phosphate group attached to the 5' carbon of the pentose sugar. The 3' end has a free hydroxyl group attached to the 3' carbon of the pentose sugar.
DNA DNA consists of two complementary chains connected by hydrogen bonds. A=T C=G
DNA DNA synthesis occurs in the 5' to 3' direction in both strands. The DNA strands are antiparallel 5' end of one is associated with the 3' end of the other. The DNA ladder is twisted into a double helix Ten base pairs occur per turn.
RNA RNA exists as a single polynucleotide chain. Ribose Uracil
DNA Replication DNA must replicate itself prior to cell division. Enzymes are responsible for each step of replication, including proofreading. The helix unwinds, separates, and each half acts as a template for the formation of a new complementary strand. Reaction catalyzed by DNA polymerase.
Gene Expression Gene expression – the use of information in DNA to direct the production of particular proteins. Transcription – first stage of gene expression. A messenger RNA (mRNA) is synthesized from a gene within DNA. Translation – second stage – mRNA is used to direct production of a protein.
DNA Coding DNA codes for the sequence of amino acids in a protein. A codon is three base- pairs long and is a segment of mRNA that codes for an amino acid.
Transcription Messenger RNA (mRNA) transcribes the DNA and transports it out of the nucleus.
Transcription Before leaving the nucleus, segments of mRNA called introns are removed and the exons are spliced together. Exons contain the information coding for the protein that will be synthesized.
Translation Translation occurs on ribosomes outside the nucleus. mRNA attaches to a ribosome and protein synthesis begins.
Translation Transfer RNA (tRNA) collects free amino acids from the cytoplasm and delivers them to the polysome (mRNA- ribosome complex) where they are assembled into a polypeptide. tRNA has a triplet – the anticodon – that is complementary to the codon of mRNA.