how tightly hormone and receptor bind to each other small variations in specific amino acids of either molecule can change binding interaction DNA contains gene encoding protein called growth hormone produced by pituitary gland travels to other tissues and delivers signal for cells to grow and divide changes in amount or amino acid sequences can affect function variation in ht result from the following amount of signaling protein produced amount of receptor produced in different tissues a person who inherits a tall gene will not necessarily grow very tall Nucleic acids storage of genetic info synthesis of proteins DNA and RNA specialize in these functions DNA in prokaryotes in cytoplasm regardless of location DNA contains instructions for building proteins For protein synthesis genetic info in DNA must be copied into RNA RNA transported to cytoplasm where protein synthesis takes place DNA contains bases G A C T sequence of bases provide instructions needed to build any living organism human genome all DNA of organism has about 3 billion nucleotides divided up btw 23 DNA molecules or chromosomes info must be translated expressed in order for it to be useful cells need to access instructions A pairs with T C pairs with G because of molecular recognition due to specific H bonds and their perfect alignments with their atoms STRUCTURE bases point inward sugar deoxyribose with phosphate group forms backbone complimentary bases form H bonds with each other within double helix bigger bases purines A G pair with smaller pyrimidines C T keeps width of double helix constant two strands run antiparallel one from 5 to 3 other 3 to 5 new bases always added to the 3 end of newly synthesized DNA strand DNA replication catalyzed by DNA polymerase an enzyme that attaches many pieces of DNA 1 double helix of original DNA molecule separates 2 new strands made to match the separated original strands semiconservative half the original molecule is conserved in new molecule original strange is referred to as template strand provides info or template for newly synthesized strand primer anchor for DNA polymerase short sequence of DNA or RNA that is complementary to template strand will work to provide a free 3 end helicase enzyme that helps unwind and separate DNA helices DNA polymerase only works in one direction 5 to 3 but strands are oriented in opposite directions 2 strands synthesized slightly differently one new strand grows continually other in bits and pieces short RNA fragments are used as primers for SNA polymerase 1 genetic info copied to RNA preserving order of nucleotide bases genes with instructions for making proteins converted to mRNA 2 Polymerase Chain Reaction PCR Kary Mullins in 1983 uses repeated cycles of DNA polymerase activity to make copies of a small segment of DNA knows as the target DNA target DNA resides in larger DNA molecule that acts as template PCR product amplified DNA can also serve as template leading to chain reaction that double PCR product amy after each cycle used to amplify small DNA samples from forensic samples or historical artifacts when they have larger DNA sample they can determine base sequence and compare that to individuals figure out murderer or dad how it works essentially like DNA replication scientists must design primers to provide starting point for DNA polymerase usually made of RNA but with PCR short DNA molecules consisting of specific sequence that flanks right and left ends of target DNA PCR product will contain DNA sequences of primers and DNA between primers STEPS 1 Heat DNA so DNA template and primers convert to single strang DNA 2 Reaction is cooled so the H bonds between the primer and target DNA sequence form 4 Temperature raised again and new cycle begins at end of each cycle sample contains double amount of DNA template 3 Temperature raised activating DNA polymerase and stimulated copying of DNA polymerase starts at primer and copies DNA to end of template Repeats of DNA segments variations in of tandem repeats detected by polymerase chain reaction using primers that bind to unique sequences on edges of the repeat if 2 DNA samples show diff of repeats samples are 2 diff ppl if repeats are the same CHANCE that they are the same person not very reliable since 5 20 have same of repeats at same location to increase reliability 13 locations surveyed 99 99