Chapter 9
About this set
Created by:
kmcdaniel223 on July 25, 2011
Subjects:
Log in to favorite or report as inappropriate.
Order by
32 terms
Terms | Definitions |
|---|---|
 What was levene's tetranucleotide structure hypothesis? | -the hypothesis proposed that DNA was made up of equal amounts of adenine, guanine, cytosine, and thymine -tetranucleotides organized in a repeating manner--whether you have a large piece or a small piece its all the same -static molecule |
| If correct, would this structure be consistent with a hypothesized role of DNA as the genetic informational molecule? | -no, it would not -the reason being that levene proposed that DNA is a static molecule, with no variation in the nucleotide sequence |
| What are the three main components of a nucleic acid? | -phosphate group -sugar -base |
| What are the five nitrogenous bases? | -adenine -thymine -guanine -cytosine -uracil |
| What is the difference between a purine and a pyrimidine? | -purines have a double ring -pyramidines have a single ring |
| Which nitrogenous bases are purines? | -adenine -guanine |
| Which nitrogenous bases are pyrimadines? | -thymine -cytosine -uracil |
| In what way does RNA differ from DNA? | -the sugar used in RNA is oxyribose; the sugar used in DNA is deoxyribose -the base uracil is found in RNA instead of thymine |
| What is a nucleoside? | -a nitrogenous base plus a sugar (with no phosphate group) |
| Why, in the early 1900s, did many scientists believe that proteins, rather than DNA, were the carriers of genetic information? | -because proteins are biochemically more complex than nucleic acids -(there are 20 amino acids versus 4 nucleotides) -the idea prevailed that nucleic acids were "too simple" to be the genetic material |
| Describe the four components of the Fred Griffith experiments | -living S type bacteria injected into a mouse, mouse dies, type S bacteria isolated from dead mouse -living R type bacteria injected into a mouse, mouse lives, no living bacteria isolated from mouse -heat-killed S type bacteria injected into a mouse, mouse lives, no living bacteria isolated from the mouse -heat-killed S type bacteria + live type R bacteria injected into mouse, mouse dies, type S bacteria isolated from dead mouse |
| What were the critical and unexpected results of this experiment? | -when heat-killed S type bacteria + live type R bacteria were injected into a mouse, the mouse dies -extracts from tissues of the dead mouse were found to contain living type S bacteria |
| What can account for these results? | -something from the dead type S bacteria was transforming the type R bacteria into type S |
| What then did Griffith "discover"? | -bacterial transformation |
| What is bacterial transformation? | -the ability of living cells to take up DNA released from dead cells |
| What question did Avery, MacLeod, and McCarty attempt to answer? | -What substance is being transferred from the dead type S bacteria to the live type R? |
| What did they do to attempt to find an answer? | -used biochemical purification procedures and specific digestive enzymes to assess DNA, RNA, and proteins as possible genetic material |
| What was the first step of the experiment? | -DNA, RNA, and protein was extracted from the S strain streptococcus pneumoniae cells |
| What was the next step? | -DNA, RNA, and protein extracts were mixed with Type R cells |
| What was the key discovery? | -only one of the extracts-DNA-was able to convert the type R bacteria into type S |
| What were the implications of this? | -DNA is responsible for transformation -DNA therefore carries genetic information |
| What steps were taken to rule out possible contamination of DNA extract? | -type S DNA extract was combined with DNase, RNase, and protease (within 3 different tubes) |
| What were the results? | -transformation did not occur when type R cells were mixed with type S DNA extract that also contained DNase |
| What did these results indicate? | -that any remaining RNA or protein in the extract was not acting as the genetic material -the degradation of the DNA in the extract by DNase prevented conversion of type R to type S |
| What is Chargaff's rule? | -the amount of A in DNA equals the amount of T, and the amount of G equals C -total purines (A+G) equal total pyramidines (C+T) |
| What did the x-ray diffraction work of Franklin suggest? | -DNA has a helical structure -DNA is composed of 2 or more strands -DNA contains 10 bases per helical turn |
| What did Watson and Crick do? | -proposed the double-helix structure |
| What information did Watson and Crick use to develop the DNA double helix structure?/On hat lines of evidence was their structure based? | -chargaff's rules -x-ray diffraction data -3-D modeling -knowledge of nucleotide components |
| What are the key structural features of DNA? | -DNA Is composed of 2 strands -2 strands form a right-handed double-helix -2 strands run anti-parallele to each other (in regards to their 5' to 3' directionality) -Phosphate and sugars for DNA "backbone" -Bases protrude inward -Bases hydrogen bond according to AT-GC rule (which explains Chargaff's data) -There are 10 nucleotides in each strand per complete 360 degree turn of the helix -Linear distance of a complete turn is 3.4 nm -Each base pair traverses 0.34 nm -Major and minor grooves are present |
| What does the AT/GC rule imply? | -that we can predict the sequence in one strand if the sequence in the opposite strand is known |
| What is meant by complementary base pairing? | -A will always bind with T -G will always bind with C -allows us to predict the sequence in one DNA strand if the sequence in the opposite strand is known -allows DNA template to be used for RNA transcription -helps to determine the secondary structure of RNA |
| How does complementary base pairing help to determine the secondary structure of DNA? | -base pairing allows short segments of RNA to form double-stranded regions |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.