L1.pdf

Learning objectives Know the general structural features of the nucleic acids and their molecular components Be able to describe the basic structural features of the DNA double helix and its organization within the nucleus Know the components of the human genome and the stru...

Learning objectives Know the general structural features of the nucleic acids and their molecular components Be able to describe the basic structural features of the DNA double helix and its organization within the nucleus Know the components of the human genome and the structure of a gene Have knowledge about the processes of DNA replication, transcription and translation of mRNA  Nucleic Acids DNA: Deoxyribonucleic acid RNA: Ribonucleic acid Monomer molecules for the nucleic acids are called nucleotides  A human cell Cytosol  Structure of DNA It is a polymer of deoxynucleotides. Genetic information (inherited from parent cells) content of DNA is determined by the sequence of nucleotides.  Structure of a deoxynucleotide Is formed of: A nitrogenous base (purine or pyrimidine derivative) Deoxyribose A phosphate group Nucleotide → nucleic acid Sugar Bases in DNA Bases in RNA Nucleotide The DNA backbone has phosphodiester bonds  Polarity of a 5’end DNA strand A DNA strand has polarity because it has different chemical groups at it’s ends 5’ end; beginning of strand, has a free phosphate group at 5th carbon of the sugar 3’ end; end of strand, has a free OH group at 3rd carbon of the sugar 3’end  Complementary base-pairing in DNA DNA DNA double helix DNA strands have complementarity 5’ 3’ Sequence of one strand complements the opposite strand 5’-CTGACA-3’ 3’-GACTGT-5’ 3’ 5’  Main types of RNAs Messenger RNAs (mRNA) →codes for proteins Ribosomal RNAs (rRNA) →found in ribosomes, machinery for making proteins Transfer RNA (tRNA) →carries the amino acid for growing protein chain RNA is single stranded tRNA molecule