Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
DNA
(deoxryibosenucleic acid) |
the molecule of heredity
-allows genetic information to be passed from one generation to the next |
|
|
Genes
|
-discrete packets in heritable information
-comprised of DNA -genes are located on specific areas of chromosomes=locus(loci) -geners are directions for protein synthesis |
|
|
Chromosome
|
structure made of DNA and protein(histones)
|
|
|
Uncondensed DNA
|
-long, thread-like structure
-DNA usually exists in this form in a cell nucleus |
|
|
Condensed DNA
|
-form that DNA takes prior to cell division
-DNA wraps around histones, forming a nucleosome -Nucleosomes are coiled by other proteins (like a slinky) -those coils are wrapped around proteins scaffolding to form a supercoil |
|
|
Frederick Griffith
|
1920s: while attempting to make a vaccine for bacterial pneumonia, discovered that genetic information could be transferred from one strain of bacteria to another (transformation)
|
|
|
Frederick Griffith's experiment
|
-used 2 strains of Streotococcus pneumoniae: R strain-harmless to mice; S strain-deadly to mice
-the heat killed S-strain was mixed with the R-strain(living) and injected into mice as a possible vaccine -mice died, Griffith examined the mice -Griffith found live S-strain bacteria, proving that the genetic material from dead S-strain becaterua moved into the live R-strain bacteria |
|
|
Avery, MacLeod, & McCarty
|
1940s: discovered that the molecule that changed the S-strain to the R-strain was DNA
-concluded that genes were made of DNA |
|
|
Hershey & Chase
|
1950s: proved that DNA, not protein, was the hereditary material
|
|
|
"Blender Experiment"
|
-Hersehy and Chase used:
radioactive S (sulfur)-found in protein, NOT in DNA radioactive P (phosphorus)-found in DNA, NOT in protein -traced where the radioactivity showed up using viruses(bacterophages) that attack bacteria and replicate inside them -radioactivity showed up inside bacteria (DNA) & not on outside of bacteria (protein coating) when using radioactive P *did experiment twie, once w/ S and once w/ P |
|
|
Nucleotides
|
-consist of three parts:
1. phosphate group(PO4) 2. sugar group(deoxyribose) 3. nitrogen-containing base: Adamine, Guanine-purines(double rings) Thymine, Cytosine-pyrimidines(single rings) |
|
|
Structure of DNA
|
-shaped like a twisted ladder:double helix
-"backbone" or sides of ladder are mad of alternating sugars & phosphates -"rungs' made of complementary base pairs A=T C=G - - '=': Hydrogen bonds |
|
|
X-ray diffraction
|
An analytical technique used to identify crystalline solids by measuring the characteristic spaces between layers of atoms or molecules in a crystal
|
|
|
Replication
|
*prior to cell division, DNA must make an exact copy of itself so that each new cell receives the correct genetic info
*occurs in nucleus *requires enzymes |
|
|
DNA helicase
|
breaks apart the DNA helix
|
|
|
DNA polymerase
|
moves along a single strand of DNA matching (pairing) a free nucleotide to one on the exposed strand
- base pairing - catalyzes covalent bonds of sugar and phosphate |
|
|
DNA ligase
|
joins the small DNA segments together into one long strand
|
|
|
Replication bubble
|
the unwound portion of the two parental DNA strands, separated by DNA helicase, in DNA replication
|
|
|
Replication forks
|
the place where enzymes synthesize two new DNA strands that are complemtary to the two parental strands
|
|
|
Free nucleotides
|
nucleotides that have not been joined together to form a DNA or RNA strand
|
|
|
Thymine pair
|
T=T
are present when there has been damage by UV rays |
|
|
How does a long, thread-like molecule of DNA condense into a chromosome?
|
-uncondensed DNA wraps around histones, forming a nucleosome
-nucleosomes are coiled by other proteins (like a slinky) -those coils are wrapped around a protein scaffolding to form a supercoil |
|
|
How did Hershey and Chase prove that DNA, not protein, was the hereditary material?
|
By doing the "Blender Experiment"
|
|
|
How are the component parts of DNA arranged to form a double helix?
|
-shaped like a twisted ladder
-"backbone" made of alternating sugars and phosphates -"rungs" made of complementary base pairs |
|
|
What are the steps of DNA replication?
|
1. DNA helicase breaks apart the H-bonds between A,T,C,G - forms replication bubble & 2 replication forks
2. DNA polymerase goest to replicatoin fork site, recognizes chemically nucleotide bases, and then apirs it up with a free nucleotide found floating in the nucleus; the polymerase helps build the "backbone" by bonding sugars to PO4; polymerase always moves to "free sugar" end 3. DNA ligase creates 2 long strands of DNA *replication rate is 100-700 nucleotides at the same time |
|
|
How is UV ray damage to DNA repaired in the cell?
|
enzyme removes "thymine pair" and replaces it by A=T; DNA ligase reattach to DNA strands
|
