Genetics Flashcards
T.H. Morgan 1908
Concluded genes are chromosomes.
Frederick Griffith 1928
Worked with mice. Realized a transforming factor can change phenotype.
Avery McCarthy and Macleod 1944
Purified DNA and proteins separately. Infected protien in bacteria had no effect but infected DNA did. So the transforming factor is DNA
Who had first evidence that DNA was genetic material?
Avery McCarthy and Macleod
Hershey and chase 1952
Worked with bacteriophage and put S35 in protien and P32 in DNA. Confirmed DNA is genetic material
Chargaff 1947
Made rules. A=T
C=G.
Watson and crick 1953
Developed double helix model of DNA
Meselson and stahl 1958
Semi conservative replication
Define central dogma
Flow of genetic material on cell
Course of action of central dogma (protien synthesis order)
DNA replication is transcribed to RNA and translated to protien
Purpose of DNA replication
Create a second copy of genetic material to be used in mitotic cell division
Steps in DNA replication
Unwind the DNA molecule. Make new DNA strand. Rewind the DNA molecule
Helicase
Splits H bonds between bases and unwinds them
DNA polymerase 1
Digests rna primers and replaces them with DNA (lagging strand)
DNA polymerase 3
Creates complimentary DNA strands in 5-3 direction. Adds dNTP’s to the 3’ end
Ligase
Joins Okazaki fragments together
How is the leading strand synthesized
Continuously in the 5’ to 3’ direction by DNA poly 3. Towards fork
RNA primase
This enzymes adds NTP’s (rna primers) to be eaten up by DNA polymerase 1.
Gyrase
Travels along DNA in front of fork relieving tension. Untangles DNA molecules before chromosomes can be replicated
Okazaki fragments
This is what the lagging strand is made of. They are fragments between 1000 and 2000 nucleotides long. Grown in 5 to 3 direction away from the fork
Leading strand
Grown continuously towards the replication fork in the 5 to 3 direction. DNA polymerase 3 is adding the dNTP’s
Lagging strand
Replicating away from the replication fork in 5 to 3 direction. Grown discontinuously
Purine
Class of bases that have a double ring structure ex guanine and and adenine
Pyrimidine
Class of base with single ring structure. Thymine and cytosine are examples
Gel electrophoresis
Method of separating DNA using an electric field
How gel electrophoresis works
DNA is negative so it moves towards the positive end. Smaller pieces travel faster therefore go farther
What is gel electrophoresis used for?
Used in forensics and paternity testing
Using gel electrophoresis in forensics
Must be 13 enzymes that match the suspect to convict someone. Add enzymes to DNA and cuts in the same spots so we can match it
Polymerase chain reaction
Method for making many copies of specific segment of DNA
What do you need for pcr?
Template strand. Taq polymerase. dNTP’s. Primer. And thermonuclear
What happens in pcr
Denature DNA at high temp then anneal to cool and hybridize primers and build the DNA
Taq polymerase
Used in pcr. It’s it found in hot springs. And can stand the high heat without firing
Plasmid
Small circular section of DNA found in cytosol of bacteria. Replicates independently of chromosomal DNA
Vectors
DNA molecule used as a vehicle to transfer foreign genetic material into a cell
Why are vectors used?
It is put in a cell to use it to reproduce the substance multiple times bc it can reproduce without using the chromosomal DNA
Complementary base pairing
Chemical tendency of adenine to pair with thymine and cytosine to pair with guanine.
How many h bonds when a bonds with t
2
How many h bonds when c bonds with g?
3
Cell cenescence
Period in cells lifespan when it loses the ability to divide and grow. Referred to as cell aging
Hayflick limit
Total number of times a cell can divide
Telomerase
Enzyme that adds telomere sequences to the end of chromosomes
Roles of telomeres 4
1 help prevent chromosome ends from fusing to eachother. 2 percent DNA degradation from nucleases 3 help DNA repair and distinguishes between DNA breaks and chromosomal ends. 4 plays a role in knowing how many times a cell will divide.
Telomere
Repeated sequence of nucleotides
Why do we need telomeres
Bc DNA poly 1 can’t replace the final rna primer on the stand and this would result in lost DNA but instead it breaks off the telomeres
How many times can a human cell divide
50 before hitting hayflick limit
Cells containing telomerase
Germ cells(gametes), stem cells, white blood cells and cancer cells
Cancer drugs are being developed to do what?
Inhibit binding site of telomerase. Or causes telomeres to fall offf the DNA
How many times is a telomere sequence repeated
500-5000 times
What does an operon consist of?
Structural genes. Promoter region. Operator region and regulatory gene. Y