1 REMEMBER 4 Basic Macromolecules Proteins-amino acids Nucleotides-DNA strands Carbohydrates-Monosacchrides Lipids-Fatty Acids DNA stands for deoxyribose nucleic acid Located: in the nucleus and MITOCHONDRIA Function: to direct the synthesis of proteins for the life of the organism The kind of organism which is produced (buttercup, giraffe, herring, human etc) is controlled by DNA DNA 2 DNA is a very large molecule made up of a long chain of sub-units of nucleotides. SUBUNIT: nucleotides DNA molecule 3 Each nucleotide is made up of a sugar called deoxyribose a phosphate group -PO 4 and an organic base DNA molecule 3 Ribose is a sugar, like glucose, but with only five carbon atoms in its molecule Examples:mRNA, tRNA, and rRNA Deoxyribose is almost the same but lacks one oxygen atom Example:DNA Both molecules may be represented by the symbol Ribose & deoxyribose 4 The most common organic bases are Adenine(A) Thymine(T) Cytosine(C) Guanine (G) The bases 5 The deoxyribose,the phosphateand one of the bases adenine deoxyribose PO 4 Combine to form a nucleotide Nucleotides 6 A molecule of DNA is formed by millions of nucleotides joined together in a long chain PO 4 sugar-phosphate backbone + bases Joined nucleotides 7 DNA usually consists of a double strand of nucleotides The sugar-phosphate chains are on the outside and the strands are held together by chemical bonds between the bases 8 PO 4 2-stranded DNA 9 The bases always pair up in the same way Adenine forms a bond with Thymine and Cytosine bonds with Guanine Bonding 1 10 AdenineThymine Cytosine Guanine PO 4 thymine PO 4 adenine cytosine PO 4 guanine Bonding 2 11 PO 4 Pairing up 12 The paired strands are coiled into a spiral called A DOUBLE HELIX 13 sugar-phosphate chain bases THE DOUBLE HELIX 14 A DIY model of part of a DNA molecule 15 Before a cell divides (mitosis and meiosis), 1. the DNA strands unwind and separate 2.Each strand makes a new partner by adding the appropriate nucleotides 3.there are now two double-stranded DNA molecules in the nucleus 4.when the cell divides, each nucleus contains identical DNA This process is called replication replication 16 PO 4 The strands separate 17 PO 4 Each strand builds up its partner by adding the appropriate nucleotides 18 We need more proteins DNA instruction copied by TRANSCRIPTION ( on to mRNA) and then instruction TRANSLATION to make PROTEINS (enzymes) to breakdown and build: carbohydrates, lipids and proteins. Transcription: process to make more proteins STEPS RNA polymerase binds to DNA to unwind the sequence. Synthesize a strand of DNA (A-U and G-C) DNA is stretched and exposed and templates read in groups of 3 codon AUG stop codon is synthesize the process stops Adenosine binds to Uracil Transcription :DNA to mRNA Transcription Adenosine binds with uracil A to U U to A Cytosine binds to Guanine G to C C to G TRANSLATION: where celluar ribosomes create proteins mRNA created in transcription Messenger RNA created in transcription is decoded by ribosomes complex to create more proteins This is known as the triplet code Each triplet codes for a specific amino acid CGA - CAA - CCA - CCA - GCT - GGG - GAG - CCA - AlaValGly ArgProLeuGly AlaValGly ArgProLeuGly The amino acids are joined together in the correct sequence to make part of a protein Triplet code 22 For example Cytosine Adenine Codes for Valine Cytosine (C) Guanine (G) Adenine (A) Codes for Alanine Thymine Coding 21 A sequence of triplets in the DNA molecule may code for a complete protein sequence forms a gene Genes 24 Question 1 Which of the following are components of nucleotides? (a) deoxyribose (b) amino acids (c) phosphate (d) enzymes (e) organic bases Question 2 Which of the following represent a correct pairing of bases? (a) adenine with thymine (b) adenine with guanine (c) thymine with adenine (d) guanine with cytosine (e) thymine with thymine Question 3 DNA molecules are formed from (a) organic bases (b) amino acids (c) deoxyribose (d) nucleotides Question 4 Which of the following are organic bases? (a) Valine (b) Guanine (c) Thymine (d) Serine Question 5 Replication of DNA occurs (a) During cell division (b) before cell division (c) at any time Question 6 A nucleotide triplet codes for (a) a protein (b) an amino acid (c) an enzyme (d) an organic base Answer CORRECT Answer INCORRECT