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52 terms

Inside Genetics

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molecular biology
DNA is the molecular basis of heredity, exploring the structure of DNA and how it replicates
bacteriophages (phages)
bacterial viruses, structure consists of of DNA and protein, DNA containing head, tail and tail fibers that attach to surfaces susceptible to bacteria.
Hershey and Chase experiment
knew that phages held genetic information, made only of only proteins (20 different monomers) and DNA (4 monomers) one goes into the host cell, 1. they mixed radioactively labelled phages with bacteria, the phages infect bacteria, they wanted to track where the DNA went and where the Protein goes. Put it in centrifuge and tested for radioactivity. the protein caused radioactivity outside the cell, DNA radioactivity was found inside the pellet. discovered DNA was the genetic info of phages.
nucleic acids
DNA and RNA are _______ ____
nucleotides
chemical units of of polymers (long chains)
polynucleotide
polymer built of nucleic acids, example is the structure of DNA with the arrangement of the nucleotides A, T, C, and G
sugar-phosphate backbone
the nucleotides are joined to one another by covalent bonds between the sugar of one nucleotide and the phosphate of the next, ________________ a repeating pattern of sugar-phosphate, nitrogenous bases are arranged along this backbone
chemical structure of a single nucleotide
Phosphate Group, Sugar, and Nitrogenous base
four nucleotides found in DNA
Thymine (T), Cytosine (C), Adenine (A), guanine (G),
T and C are single ringed structures, A and G are double ring structures
uracil (U)
RNA has a nitrogenous base of this instead of thymine.
Watson and Crick experiment
used copy of Photo 51, and knowledge to gather that 1. DNA is a double helix, 2. helix diameter is uniform, 3. Phosphate on outside of helix is negatively charged.
double helix
two strands of DNA held together by hydrogen bonds
pellet
inside the cell
Chargaffs rule
A=T, C=G relative proportions of basis of DNA in every species, later changed to Base pair rule
Rosalind Franklin
X ray crystalography, found structure of a model of DNA, photo 51, didn't share it.
Photo 51
Found by Franklin, Wilkins stole Photo 51, copied it on newspaper with W and C, returned photo and Franklin never knew, shows X which means double helix, horizontal line through X (at the angel it is rotated) tells how tight the helix is.
PCR
Polymerase Chain Reaction, the process of copying DNA, DNA replication
anti parallel
the orietnation of DNA strands, running in opposite directions, copmliment, 3 prime to 5 prime then opposite would run 5 prime to 3 prime
number of carbons
______________ __ ________ only go from 5 prime to 3 prime and 3 prime to 5 prime, one direction
The three theories of DNA replication
1. conservative model: whole DNA molecule would be consumed 1rst gen: 1 exact parent replication and 1 new, 2nd gen: 1 original 3 new
2. semiconservative: produces DNA molecules 1 strand old and 1 strand new.
3. Disperative model: each strand of both daughter molecules contain a mixture of old and newly synthesized parts
Meselon- Stahl
density experiment to find the way DNA replicates, Nitrogen 15( number of neutrons, does not change property of atom, all DNA made of nitrogen, then bacteria grows and divides)they tracked old heavy DNA, with new lighter DNA, used a centrifuge and gel electrophysis to separate molecules on size- grows and divide in 20 minutes, just once, centrifuged it then found medium Density DNA so no to the conservative method, found that DNA replicates semi-conservatively.
replication fork
split the two strands of DNA, 2 strands separate and separate the two nucleotide strips that are complementary to each other (a and T, c and G)
helicase
the enzyme that unzips the double helix and holds them apart
SSBP
single strand binding protein, bind to DNA strands and holds them apart
DNA polymerase
reads the genetic code of A's, T's, C's, and G's, can only build 5 to 3
DNA polymerase on leading strand
travels down reading each of the sequences on the parental strips and putting the complementary nucleotide on the leading strand, DNA polymerase build 5 to 3, leading strands run in opposite direction 3 to 5 so it works
DNA polymerase on lagging strand
cannot build because both are going from 5 to 3 so needs to build in fragments, builds away from the replication fork, goes in opposite direction.
Okazaki fragments
fragments that are built on the lagging strand
primase
enzyme that can start from scratch to build DNA primer, which allows DNA polymerase to add nucleotides
RNA primer
built by primase then DNA polymerase can add more nucleotides to them
DNA ligase
forms a covalent bond from one fragment to the next
replication bubble
where the DNA strands split apart- splits in more than one place
radioactive probe
short radioactive DNA piece, once separated and treat gel, have specific code
restriction enzymes
enzyme that cuts DNA at a specific sequence of nucleotides
Parental DNA
strand of DNA before it splits
Leading strand
built continously, DNA polymerase
lagging strand
built in pieces, RNA clamp attaches to DNA polymerase, joined together removes RNA replaces DNA
RNA segments
built by primase, then DNA polymerase can add more nucleotides to them
DNA polymerase
builds new strand by adding new nucleotides
DNA ligase
joins pieces together
heating and cooling
______________ DNA breaks the bonds like helicase and __________ puts DNA back together like DNA ligase
lytic cycle
a cycle that leads to the lysis (breaking open) of the host cell
lysogenic cyle
viral DNA replication occurs without phage production or death of the host cell
prophage
the phage of DNA once inserted into the bacterial chromosome
DNA microarrays
makes it easy to determine exactly what genes are active in particular cells at particular times
gel electrophoresis
a method for physically sorting macromolecules proteins or nucleic acids- primarily on the basis of their electrical charge and size
genetic marker
a chromosomal landmark whose inheritance can be studied
restriction fragments
extract DNA from some of cells and treat it with a restriction enzyme, mixture of DNA pieces, the number of these and their sizes reflect the specific sequence of nucleotides in your DNA
repetitive DNA
nucleotide sequences present between genes, in many copies of the genome
telomeres
type of repetitive DNA at each end of a eukaryotic chromosome
transposons
"jumping genes", a segment of DNA that can move from one site to another within a cell and serve as an agent of genetic change
HGP
HUman Genome Project, map the entire human genome, determining the complete nucleotide sequence of human DNA