List five ways in which scientists study and manipulate DNA.
1) restriction enzymes, 2) gel electrophoresis, 3) restriction maps, 4) recombination, 5) Polymerase chain reaction
Restriction Enzyme
enzymes that cut DNA molecules at specific nucleotide sequences
Restriction Sites
the nucleotide sequence at which a restriction enzyme cuts DNA
Blunt Ends
cuts made by restriction enzymes that are straight across
Sticky Ends
cuts made by restriction enzymes that leave tails of free DNA bases
After DNA is cut with a restriction enzyme, how is the mixture of DNA fragments sorted?
sorted by size through the process *
Gel Electrophoresis
*
Gel Electrophoresis
after sitting in a electric bowl of water, DNA spreads out on the gel with long pieces of DNA at the top and short pieces on the bottom; electricity carries DNA down the gel (DNA is negatively charged, negative repels negative, shorter DNA fragments w/mor
How do different fragments of DNA show up on a gel?
long DNA fragments at the top short at the bottom
Restriction Map
show the lengths of DNA fragments between restriction sites in a strand of DNA, doesn't show order of nucleotides
Polymerase chain reaction (PCR)
technique that produces copies of specific DNA sequences *
makes millions of copies of DNA
*
Why is PCR useful?
it amplifies DNA samples
What is the process of PCR?
separating, binding, and copying
What four materials are needed for PCR?
(1) DNA to be copied,
(2) DNA polymerase
(3) A & T, C & G nucleotides
(4) two primers
Why are primers needed in the PCR process?
they bind to each DNA strand on opposite ends of the sequence for the segment to be copied
DNA fingerprint
a type of restriction map; a representation of part of an individual's DNA that can be used to identify a person at a molecular level
What does a DNA fingerprint show?
focuses on non-coded regions of DNA sequences outsides genes
How is a DNA fingerprint made?
it is made by imprinting the banding pattern on a gel
What is a DNA fingerprint based on?
based on noncoding regions of DNA
How is a DNA fingerprint a specific type of restriction map?
because numbers of repeated noncoding regions differ between people
How does identification through DNA fingerprinting depend on probability?
because the specific nucleotide sequences that are repeated can be found in everyone; usually DNA compares 5 regions to decrease likelihood of two people with same DNA
List two ways in which DNA fingerprinting is used for identification.
(1) evidence in criminal cases
(2) paternity tests
(3) immigration requests
(4) study of biodiversity
(5) tracking genetically
(6) GMOs
Clone
a genetically identical copy of a gene or of an organism
Cloning in nature
plants clone themselves, have stem cell tissues, regeneration
Cloning in mammals
nuclear transfer: an unfertilized egg is taken from an animal and the nucleus is removed, nucleus of a cell from the animal to be cloned is implanted into egg, egg is stimulated, egg will begin dividing, transferred into a female
gene expression in clones
clone may not look like the original or behave like the original because many factors, including environment, affect gene expression
Cloning benefits
studying how to use organs from cloned mammals for transplant into humans, can save endangered species
Cloning concerns
success rate in mammals is very low, health problems, reduces biodiversity
Genetic engineering
the changing of an organism's DNA to give the organism new traits, possible because the genetic code is shared by all organisms
Recombinant DNA
DNA that contains genes from more than one organism,
(1) A plasmid and the foreign DNA with the gene are cut with the same restriction enzyme
(2) The sticky ends of the plasmid and the foreign gene match
(3) The plasmid and the foreign gene are bonded tog
Plasmids
closed loops of DNA that are separate from the bacterial chromosome and that replicate on their own within the cell
Transgenic organism
has one or more genes from another organism inserted into its genome
Transgenic plants
gene is inserted into a plasmid and the plasmid is inserted into bacteria, bacteria infects the plant and becomes part of DNA (GM foods)
Transgenic animals
get fertilized egg cell, foreign DNA inserted into the nucleus and the egg is implanted back into a female, only a portion mature normally and of that only a portion will be transgenic, passed on to offspring (MICE)
Genomics
the study of genomes, which can include the sequencing of all of an organism's DNA, compared to find similarities and differences among DNA sequences
DNA sequencing
determining the order of DNA nucleotides in genes or in genomes
Bioinformatics
the use of computer databases to organize and analyze biological data, give scientists a way to store, share, and find data, lets researchers predict and model functions of genes and proteins
DNA microarrays
tools that allow scientist to study many new genes, and their expression ,at once; a microarray is a small chip that is dotted with all of the genes being studied, laid out in a grid pattern, cDNA (single-stranded DNA molecule, complementary to mRNA) labe
How can DNA microarrays compare gene expression in different cells?
anywhere cDNA binds to DNA in microarray shows up as a glowing dot, shows which genes are expressed and how much they are expressed
Proteomics
study and comparison of all the proteins produced by an organism's genome, study of functions and interactions of proteins, allows scientists to learn about proteins involved in human diseases
Genetic screening
the process of testing DNA to determine a person's risk of having or passing on a genetic disorder (pedigree analysis)
Gene therapy
the replacement of a defective of missing gene, or the addition of a new gene, into a person's genome (to treat a disease)
Gene therapy (example)
inserting a suicide gene into a cancer cell
Technical challenges of gene therapy
(1) correct gene has to be added to correct cells
(2) must determine if new gene will affect other genes
Gene knockout
disruption the function of the gene, genes are purposely "turned off" and used for studying gene function and genetic diseases
Concerns of genetic engineering
human health and environment (GM), decrease in genetic diversity
Gene sequencing
determining the order of DNA nucleotides in genes or in genomes
Importance of bioinformatics
give scientists a way to store, share, find data, and predict the functions of genes and proteins