Unit 3 Genetics Flashcards
When does DNA replication occurs during the cell cycle?
S phase (synthesis)
What are the three hypothetical ways of daughter stands are being arranged?
- Conservative
- Semiconservative
- Dispersive
Which experiment proves how DNA replicates? Briefly explain the experiment and state which ways does DNA replicate?
Meselson-Stahl Experiment:
1. They first grew bacteria in a medium containing heavy 15N, causing the bacteria’s DNA to become labeled with the heavy isotope.
2. Then, they switched the bacteria to a medium containing light 14N and allowed them to replicate several times.
3. After each generation, they extracted the DNA and used density gradient centrifugation to separate the DNA based on its weight (heavy vs. light).
First generation: 15N, 15N&14N
Second generation: 15N& 14N, 14N
Semiconservative model
Where does DNA replication starts and what forms when DNA is unwound?
origin, replication bubbles (replication fork after unwound)
How many hours does DNA replication take place?
8 hr
What is the name of the enzymes that separates the nucleic acid strands?
DNA helicase
What is the name of the enzymes that works ahead of DNA helicase to prevent tangling and supercoiling of DNA ?
Topoisomerase (DNA gyrase)
What is the name of the enzymes that prevent the unzipped DNA from tangling and reannealing ?
SSBs- Single Stranded DNA Binding Proteins
What is the name of the enzymes that synthesis the daughter DNA strands? Which direction of the strand does it read?
DNA polymerase (read from 3’ to 5’, producing daughter strands of 5’ to 3’)
What are the two strands of unzipped DNA called?
leading strand, lagging strand
What is the name of the enzymes that synthesis RNA primer for DNA polymerase to start synthesizing ?
RNA primase
What is the name of the enzymes that replace the RNA primer with DNA nucleotide ?
DNA polymerase
How are DNA in the lagging strand synthesized? And what is short sections in this part called?
discontinuous and synthesized backwards, Okazaki fragments
What is the name of the enzymes that attaches Okazaki fragments together?
DNA ligase
What is the name of the enzymes that proofreads and cleave the incorrect nucleotides?
exonuclease (one type of DNA polymerase): run from 3’ to 5’
What is a long strands of repeated DNA sequence at the end of each chromosomes called (does not code for anything)? And why we have them?
telomere, DNA polymerase unable to add nucleotides at the very end of a sequence
Who is the first person to discover the “molecule of heredity”?
Gregor Mendel (pea plant experiment)
Who discover the inherited of “transform principle” that convert R cells into S cells bateria?
Frederick Griffith
What experiment discover that the genetic information is stored in the nucleus?
The Hammerling Experiment: The genetic material in the cap is stored in the foot (nucleus) of an algae
Which experiment determine the transform principle is DNA?
Avery-MacLeod-McCarty Experiment: Heat killed S cells in Deoxyribonuclease dose one transform R cells into S cells
Which experiment determines the transform factor of virus?
Hershey-Chase Experiment: P32 makes DNA in virus radioactive, and the bacteria is radioactive after infected
S35 make the proteins radioactive, and bacteria is not radioactive after infected
Who discover that an acidic substance with larger amount of phosphorous from white blood cells in used bandage?
What is the substance called?
F. Miescher, nuclein
Who discover the 3 major components of a nucleotide (phosphate group, pentose ring, nucleobase) ?
P. Levene
Who figures out that A-T and C-G are paired by looking at the amount of adenine and thymine in DNA of different species?
E. Chargaff
