DNA purposes and methods Human Variation Rowan University Diane L Markowitz DMD Ph D 02 01 23 1 DNA has at least 3 major functions Acts as a set of instructions for producing proteins Directs the production of new cells Reduces the diploid number of chromatids to the haploid number in order to form sex cells 02 01 23 2 DNA has three purposes The first of these is Protein production 02 01 23 3 Purposes of protein production Proteins are the building blocks of cells as well as parts of specific cell products such as enzymes You need to produce protein in order to produce new cells in order to drive biochemical reactions in your body enzymes in order to produce specific cell products necessary for you to function e g insulin 02 01 23 4 DNA its composition The DNA molecule is composed of two strands of DNA wound around each other in a double helix Each strand is composed of combinations of four nucleotides Here is an illustration of one nucleotide pair a nucleotide on one strand bonded to its complement on the other strand S S U U G G A A R R S U G A R A T hydrogen bond 5 02 01 23 DNA unwound There are four different bases adenine thymine cytosine and guanine A always bonds with T and G always bonds with C 02 01 23 S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R A T G C T A S U G A R C G S U G A R S U G A R S U G A R S U G A R S U G A R 6 DNA is found in the nucleus S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R A T G C T A S U G A R C G S U G A R S U G A R S U G A R S U G A R S U G A R 02 01 23 7 RNA is found in the cytoplasm different sugar S U A G different A R base uracil instead of S thymine U T G A R S G U G A single strand R C S U G A R S U G A R S U G A R U A S U G A R C G S U G A R S U G A R S U G A R S U G A R R N A 8 S U G A R 02 01 23 Transcription 1 Bonds break between the double strands of DNA For the cell to produce protein the DNA message must be transcribed by the RNA 3 RNA binds to single S strand of U G A R S U DNA G A R 2 RNA enters the nucleus 02 01 23 9 S U G A R S U G A R S U G A R 1 Messenger RNA is created from the DNA S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R A T G C U A S U G A R C G S U G A R S U G A R S U G A R S U G A R S U G A R 02 01 23 Free RNA 10 1 Messenger RNA is created from the DNA 2 Bonds between DNA and RNA then break S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R A T G C U A S U G A R C G S U G A R S U G A R S U G A R S U G A R S U G A R 02 01 23 RNA 11 Messenger RNA breaks off and leaves A DNA bonds re form S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R T mRNA leaves the G nucleus and travels to the ribosomes C U A S U G A R C G S U G A R S U G A R S U G A R S U G A R S U G A R 12 02 01 23 Ribosome with tRNA inside mRNA bonds to tRNA mRNA travels to the ribosomes where it translates its message to tRNA 02 01 23 S U G A R S U G A R S U G A R S U G A R U A C G A U G S U G A R C S U G A R S U G A R S U G A R S U G A R S U G A R a m i n o a c i d 13 The mRNA assembles a comple mentary strand of tRNA S U G A R S U G A R S U G A R S U G A R S U G A R U A C G G One of 20 amino acids is bonded to each group of 3 tRNA bases A U G S U G A R C C S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R a m i n o a c i d a m i n o a 02 01 23 14 mRNA breaks off from tRNA and the mRNA nucleotides go back to the cytoplasm to await further instructions S U G A R S U G A R S U G A R S U G A R S U G A R U A C G G One of 20 amino acids is bonded to each group of 3 tRNA bases A U G S U G A R C C S U G A R S U G A R S U G A R S U G A R S U G A R S U G A R a m i n o a c i d a m i n o a 02 01 23 15 The tRNA breaks off from the amino acids and nucleotides stay in the ribosomes until needed again A U S U G A R S U G A RG C C S U G A R S U G A R S U G A R S U G A R S U G A R a m i n o a c i d a m i n o a c …