chapter 13: gene technology

Página 1

DNA technology

DNA identification can be needed for multiple reasons like finding a person's paternity, identifying remains,tracing human origins, and providing evidence for crime scenes.

noncoding DNA- regions of DNA that dont code for any proteins

contains many length polymorphisms

come from short repeating sequences of DNA

length polymorphisms- variations in the length of DNA molecule between known genes.

variable number tandem repeats- sequences that repeat a few or many times in tandem (one right behind other)

the number of tandem repeats at specific places depends on DNA

main steps in DNA identification

isolate the DNA; make copies if needed

cut DNA into shorter pieces that contain VNTR areas

sort the DNA by size

compare the size fragments of the unknown to the known. if a match occurs then a person's identity can be found

polymerase chain reaction- technique that quickly produces many copies of a DNA fragment

used in crime scene investigations

steps of PCR *see page 256*

PCR requires a template to copy, a supply of all 4 nucleotides , heat tolerant DNA polymerase, and pimers ( artificially made pieces of single stranded DNA)

primers can bond to original strands after they cool

DNA polymerase adds free nucleotides to complete the strands

heat again to repeat

restriction enzymes- bacterial proteins that cut long DNA molecules into shorter pieces

recognize specific DNA short sequences and cut them near or in the sequence

sticky end- single stranded end of double stranded DNA fragment that combine to complimentary ends of others

gel electrophoresis- techniques that studies DNA fragments by using an electric field and gel

separates proteins or nucleic acids by size and charge

steps of gel electrohoresis

DNA samples cut with restriction enzyme and is places in wells with a tick gel

electric current runs through the gel. negatively charged DNA move towards positively charged end of the gel, smaller fragments are faster

DNA is transfered to nylon membrane and radioactive probes are added and bind to complimentary DNA

x-ray film is exposed to the radiolabeled membrane and show a pattern of bands called a DNA fingerprint

DNA fingerprints are powerful identification tools

restriction fragment length polymorphism (rflp) helps prepare a DNA fingerprint

plasmid- ring of DNA found in bacterium with its main chromosome

cloning vector- carrier used to clone a gene

donor gene- genes that get transferred depending on where the phage genome is on the chromosome

gene clones- the exact copy of a DNA segment, a whole cell, or a complete organism

plasmids can be used to produce insuline

recombinant DNA- DNA from at least two different organisms

probe- a strand of RNA or single stranded DNA that is labeled with a radioactive element that can base pair to specific DNA

​​​​​​​

Página 2

the human genome project

human genome project- research effort undertaken to sequence all of our DNA and locate within it all of the genes

wants to locate every gene on every chromosome in the human genome

discoveries the scientists made on the human genome project

2% of the human genome codes for proteins

chromosomes have unequal distribution of exons

the human genome is smaller than estimated

exons in the genome are spliced in many ways to encode different versions of a protein

half the human genome is from the shuffling of transpsons (pieces of DNA that that move from one chromosome location to another)

there are about 8 million single nucleotide polymorphisms (snp), unique spots where individuals differ by a single nucleotide. they are important for mapping out the genome in more detail.

model species help scientists

genetic engineering- process of manipulating genes for practical purposes

gene cloning- process by which many copies of a specific gene are made each time the host reproduces

dolly the sheep

cloning- the process of somatic cell nucleic transfer into a enucleated oocyt (egg with no nucleous)

basic steps

get an egg from a suitable donor

remove the genetic material from the egg

take a somatic cell from the individual to be cloned

remove genetic material from the somatic cell

microinject nuclear material from the somatic cell into the egg

activate the egg

implant the egg back into egg donor's reproductive track

vaccine- solution that contains a harmless version of a virus, bacterium, or toxin and that causes an immune response when introduced into the body

first was for small pox, the version was "cow pox"

pathogen- something that causes disease

viruses and bacteria