Đang tải... (xem toàn văn)
This chapter explain the chromosomal theory of inheritance and its discovery, explain why sexlinked diseases are more common in human males than females, distinguish between sexlinked genes and linked genes, explain how meiosis accounts for recombinant phenotypes, explain how linkage maps are constructed.
Ch 16 Warm-Up Draw and label a nucleotide Why is DNA a double helix? What is the complementary DNA strand to: DNA: A T C C G T A T G A A C Ch 16 Warm-Up What was the contribution made to science by these people: A.Hershey and Chase B.Franklin C.Watson and Crick Chargaff’s Rules: If cytosine makes up 22% of the nucleotides, then adenine would make up _ % ? Explain the semiconservative model of DNA replication Ch 16 Warm-Up What is the function of the following: A Helicase B DNA Ligase C DNA Polymerase (I and III) D Primase E Nuclease How does DNA solve the problem of slow replication on the lagging strand? Code the complementary DNA strand: 3’ T A G C T A A G C T A C 5’ What is the function of telomeres? THE MOLECULAR BASIS OF INHERITANCE Chapter 16 What you must know The structure of DNA The major steps to replication The difference between replication, transcription, and translation The general differences between the bacterial chromosome and eukaryotic chromosomes How DNA is packaged into a chromosome Problem: Is the genetic material of organisms made of DNA or proteins? Frederick Griffith (1928) Frederick Griffith (1928) Conclusion: living R bacteria transformed into deadly S bacteria by unknown, heritable substance Os wald Ave ry, e t al (1944) Discovered that the transforming agent was DNA Hershey and Chase (1952) Bacteriophages: virus that infects bacteria; composed of DNA and protein Protein = radiolabel S DNA = radiolabel P Hershey and Chase (1952) Co nc lus io n: DNA entered infected bacteria DNA must be the genetic material! Major Steps of Replication: He lic as e : unwinds DNA at origins of re plication Initiation proteins separate strands forms re plication bubble Primas e : puts down RNA primer to start replication DNA po lyme ras e III: adds complimentary bases to le ading s trand (new DNA is made 5’ 3’) Lagging s trand grows in 3’5’ direction by the addition of Okaz aki fragm e nts DNA po lyme ras e I: replaces RNA primers with DNA DNA lig as e : seals fragments together Helicase unwinds DNA at origins of re plication and creates re plication forks Primase adds R NA prim e r DNA polymerase III adds nucleotides in 5’3’ direction on le ading s trand Replication on leading strand Le ad ing s trand vs Lag g ing s trand Okazaki Fragments: Short segments of DNA that grow 5’3’ that are added onto the Lagging Strand DNA Ligase: seals together fragments Proofreading and Repair DNA polymerases proofread as bases added Mismatch repair: special enzymes fix incorrect pairings Nucleotide excision repair: cut damaged DNA DNA poly and ligase fill in gaps Nuc le as e s Nuc le o tide Exc is io n Re pair Errors: Pairing errors: in 100,000 nucleotides Complete DNA: in 10 billion nucleotides Pro ble m at the 5’ End DNA poly only adds nucleotides to 3’ end No way to complete 5’ ends of daughter strands Over many replications, DNA strands will grow shorter and shorter Te lo me re s : repeated units of short nucleotide sequences (TTAGGG) at ends of DNA Telomeres “cap” ends of DNA to postpone erosion of genes at ends (TTAGGG) Te lo me ras e : enzyme that adds to telomeres Eukaryotic germ cells, cancer cells Telomeres stained orange at the ends of mouse chromosomes Telomeres & Telomerase BioFlix: DNA Replication http://media.pearsoncmg.com/bc/bc_0media_ bio/bioflix/bioflix.htm?8apdnarep ... G C T A A G C T A C 5’ What is the function of telomeres? THE MOLECULAR BASIS OF INHERITANCE Chapter 16 What you must know The structure of DNA The major steps to replication The difference... model of DNA replication Ch 16 Warm-Up What is the function of the following: A Helicase B DNA Ligase C DNA Polymerase (I and III) D Primase E Nuclease How does DNA solve the problem of slow... X-ray crystallography =images of DNA Provided measurements on chemistry of DNA J ames Watson & Francis Crick (1953) Discovered the double helix by building models to conform to Franklin’s X-ray