DNA Flashcards
DNA markers?
specific DNA sequences that can be used to identify individual people or characterize human populations, or to identify and study non-human species
DNA in criminal cases?
DNA left behind can imply the presence of a specific person at that crime scene
What is DNA useful for?
parentage, tracking in migrations of people, ancestry, and disease susceptibility
What are the monomers for DNA?
nucleotides
What are nucleotides composed of?
one or more phosophate grous, a sugar, and a nitregenous base
What are the 4 DNA nucleotides?
adenine (purine)
guanine (purine)
cytosine (pyrimindines)
thymine (pyramindine)
polynucleotide strand? features?
how nucleotides are hooked together
sugar-phosophate backbone, with 5’ end and a 3’ end
nitrogenous base sequence
what are the complementary base pairings
adenine-thymine
cytosine-guanine
Why in a helical shape?
most stable (lowest energy) conformation
What bonds hold DNA together?
hydrogen bonds
What causes DNA denaturation?
heat- breaks the bonds
polyelectrolyte theory?
negative charges on the backbone are spread out to allow for easier access for machinery to read and copy base sequences
DNA polymerization reactions
the process in which DNA molecules can be copied. Catalyzed by enzymes
Why semiconservative in coping DNA?
only have of the orginal strand is kept, the other half is synthesized
DNA polymerase
enzyme responsible for DNA replication
Source of mutation?
errors in DNA replication
In order to replicate DNA, what do you need?
DNA polymerase, free nucleotides and DNA template
ethidium bromide
a fluorescent molecule that is flat and can slide between the stacked base pairs of DNA
how can you visualize DNA with ethidium bromide?
if ultraviolet light is shown on the DNA-ethidium compex, the ethidium bromide absorbs the light and re-emits some of the energy as green light
Agrose
a carb from seaweed that is used to make a jelly with tiny holes
how is agrose used with DNA
determines sizes of DNA when in contact with electrical current and the negatve DNA will migrate down toward the cathode
whats that process called?
electrophoresis
PCR
polymerase chain reaction. used to amplify DNA
What do you need for PCR?
DNA template, DNA primer, free nucleotides, taq polymerase, a thermal cycler
what happens in PCR
heating and cooling repeated, resulting in a the seperation then reformation of the DNA hrough a primer binding followed by taq making a new strand with the free nucleotides then repeated
gene
a segment of DNA molecule in a cell that has the information necessary to construct a specific protein
chromosome
a very long piece of DNA and associated proteins
genome
collectively all the genes in an organism
alleles and homologues
alleles, two different version of genes in a cell
homologues, chromosomes the genes are arranged of each chromsome
meisos
cell division leading to the formation of gametes
reductional division
the daughter cells resulting from meiosis have half the chromosome of the mother cell
zygote
at fertilization, the contribution of egg and sperm chromosomes creating a fertilized egg
what determines maleness in people?
the Y chromosome, only passed down from father to son
maternal inheritiance
mitochondrial DNA
polymorphism
an inheritied character for which different values (traurs) are present in a population
ex. hair colour, blood type
DNA polymorphism
located on a specific chromosome that has appreciable variation in a population
SNP
single nucleotide polymorphisms. A type of DNA polymorphism, where differnt base pairs are found in different individuals
VNTR
variable number of tandem repeats. type of DNA polymorphism, short (15-100 bp) DNA sequences over a distances of 1000-20000 base pairs are repeated
STR
short tandem repeats. type of DNA polymorphism, similar to VNTR but 2-9 basepairs long and repeated 7-40 times
VNTR and STR inheritance
you inherit one pattern of a chromosome from your mother and a different pattern of the same chromosome from your father
Sources of DNA
blood, semen, hair, bits of tissue, saliva, bone
If a lot of DNA is found, what DNA polymorphism is used?
VNTR loci. too big for PCR. But restriction enzymes are used to cut into fragments
If small amount of DNA is recovered =, what DNA polymorphism is used?
STR loci. PCR amplification using flanking sequences as primers, and direct detection of the amplified DNA on a gel
Southern Blot
1) desired DNA is cut into fragments by restriction enzymes
2) The fragments are seperated using electrophroesis
3) The fragments are transferred onto a nitrocellolose filter paper via blotting
4) produces the exact posistion the DNA was on the filter nitrocellulose paper
5) The genes are treated with a radioactive prob that binds to the STR in a gene
6) the film undergoes a X ray treatment to expose the desired gene
proability of a DNA match between two unrelated people?
use the Hardy-Weinberg equilibrium equation. p2 + q2 + pq2=1. assuming no natural selection, migration
What can go wrong with DNA evidence?
too degraded, contamination of DNA at crime scene (planted, accidental, or was already present previously), multiple comclusions can be drawn by experts
prosecutors fallacy
having blinders in regards to DNA evidence and not paying attention to other facts or evidence in regards to the case
pitchfork case
first time DNA was used to solve a crime. proved someones innocence. They did DNA dragnet but the actual guy didnt attend then he was busted by someone overhearing a conversation at a bar
Roy Brown Case
DNA evidence can trump other evidence. He was accused based off of bite marks but the DNA evidence proved his innocence
OJ simpson
how you can accuse the handling DNA and it can prove evidence to be false. The DNA was said to be put on ice but it actually wasnt. Quality was disregarded and the case had no back up so he was let free
John Sneeberger case
he was accused for raping and drugging but multiple DNA tested proved him to be innocent. They attained illegal evidence and found that he was guilty. But he did it again to a step daughter and he was then proved guilty. He got away with it originally by putting a tube into his forearm so he was home free!
Thomas Jefferson and Sally Hemings
Jeffereson was long suspected for being the father of one or more childs of his slave Sally. Y chromosome test on the remaining descedent (nephew) proves he is a match to being related
jack the ripper
blood from one of his murders matched the blood on the murder victims shawl
what does isolation cause?
specific DNA sequences to become common or universal to a certain population
nesting effect
one group gives rise to another group and things change slightly between each nesting. The christmas carole example
Out-of-Africa model
we started out in africa and we migrated out from there and there was founder effects occur resulting in different populations
what are the most frequent DNA markers used?
Y chromosome and mitochondrial genome
What is an example of a disease that can be predicted by gene anlysis>
huntingtons disease- if you have more than 40 repeats of CAG you will unfortunately get the disease
Herceptin therapy
bind herceptin to the HER-2 receptors to prevent further cell division in breast cancer cells.
DNA barcode project
an attempt to derive a set of unique DNA markers for wild animal and plant species. Can help fight the illegal trade in endangered organisms
where were dogs first domesticated?
central asia (perhaps mongolia or nepal)
