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BIO 100 Exam 2 Study Guide - Santa Barbara City college

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BIO 100 Exam 2 Study Guide - Santa Barbara City college Bio 100 - Exam 2 Study Guide DNA DNA Structure • Building blocks of DNA are nucleotides, made up of 3 parts: a deoxyribose (5-carbon sugar), a phosphate group, and a nitrogenous base • The phosphate group of one nucleotide bonds covalently with the sugar molecule of the next nucleotide, and so on, forming a long polymer of nucleotide monomers Bonding Rules • Chargaff’s Rule - A only binds with T, G only binds with C in a DNA strand • GCAT Nucleotides • 4 kinds of monomers (nucleotides) in DNA • Adenine (A), Thymine (T), Guanine (G), Cytosine (C) • Named accordingly after the base it contains Codons • A sequence of 3 nucleotides (3 letter words, 4 possible letters) that form a unit of genetic code (AUG, ACG) Difference between DNA and RNA • In the case of RNA, the 5-carbon sugar is ribose ( [D]eoxyribose [N]ucleic [A]cid vs [R]ibose [N]ucleic [A]cid ) • Ribose has a hydroxyl group at the 2’ carbon • RNA does not contain Thymine, but Uracil (U), so its rule is GCAU Chromosomes • In eukaryotes, contains well defined nucleus • In prokaryotes, in cytoplasm in nucleoid • DNA Double Heilx, DNA wrapped around histone, nucleotides coiled into a chromatin fiber, condensation of chromatin, duplicated chromosome Number • Humans have 46 chromosomes (23 pairs) Autosomal vs Sex chromosomes • Sex chromosomes, only 1 pair (X and Y) • Autosomal are the other 22 pairs of chromosomes PCR • Polymerase Chain Reaction • Used to rapidly increase the number of copies in specific regions of DNA • Uses enzyme that replicates DNA, & other short nucleotide sequences DNA Fingerprinting • Uses hypervariable regions of DNA, only unique to an individual  Mitosis DNA Replication • Produce 2 genetically identical cells • Interphase - cell undergoes normal processes to prepare for cell division • Prophase (Prepare) - chromosomes condense, spindle fibers emerge, nuclear envelope breaks down, centrosome moves toward opposite poles - - - - - - - - - - - - - - Mutation and variation • A change in a DNA sequence of the gene • Mutation = a source of new alleles in a population, ULTIMATE source of genetic variation in all populations Requirements for Evolution by a Selection Pressure • More organisms are born than can survive • Organisms vary in their characteristics, even within a species • Variation is inherited Adaptation • Trait that makes an individual suited to its environment • A population adapts overtime by increasing the frequencies of individuals with an adaptations • Individuals do NOT evolve or adapt Evidence of Evolution • Fossils • Biogeography - pattern of distribution of species • Molecular Biology - commonality of DNA • Homologous structures - structures in organisms that share same basic form • Vestigial structures - unused structures without function Genetic Engineering Difference between traditional modes of creation of a crop vs genetic engineering • Genetic Engineering - using recombinant DNA technology to modify an organism’s DNA to achieve desirable traits How do we insert a trait into a prokaryote • DNA fragment is first inserted into a plasmid (small circular DNA molecule) then bacteria copy their own DNA (including plasmids)

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