DNA profiling Flashcards
DNA profiling
the production of a visible pattern of fragments (bands) of DNA for comparing samples of DNA
Other name for DNA profiling
genetic fingerprinting
5 steps in preparing a DNA profile `
- collect tissue samples
- cells broken down and DNA extracted
- DNA is cut into fragments
- fragments separated
- profiles analysed
3 examples of suitable tissue samples
blood semen or saliva
how is the DNA cut into fragments
using restriction enzymes
what is restriction enzymes do?
cut DNA at a specific base sequence
how are the fragments of DNA separated
by gel electrophoresis
the basis upon which the DNA fragments are separated
on the basis of size
3 applications of DNA profiling
forensic science/crime
medical/paternity disputes
genetic screening
forensic science or crime as an application of DNA profiling
bodily material found at crime scene
used to identify a subject
medical/paternity disputes
used to identify the father or mother of a child
genetic screening
a test for the presence or absence of genes
genetic engineering
the artificial manipulation or alteration of genes or genotype or DNA
recombinant DNA
the combination of DNA from different organisms
5 processes in genetic engineering
isolation cutting ligation transformation/introduction of base sequence changes expression
isolation
human chromosome with the target gene is removed from a cell the plasmid (made of DNA) is removed from the bacterium
cutting
the human chromosome is cut to remove the target gene using a restriction enzyme
plasmid is cut using same enzyme
ligation
human target gene mixed with plasmid, the cut ends of the human DNA and the plasmid DNA are joined by an enzyme called ligase (ligation)
plasmid is now composed of recombinant DNA
transformation/introduction of base sequence changes
the uptake of DNA into a cell
bacteria are treated to take up the plasmids with the target gene from the surrounding solution
bacterial DNA now has a different base difference from before
expression
bacteria now cultured in bioreactor, reproduce asexually
the target gene is expressed (directs the formation of a protein eg. to make insulin)
extracted and purified
application of genetic engineering in plants
weedkiller - resistant crops
example of weedkiller - resistant crops
tomatoes with a long shelf life
application of genetic engineering in animals
production of a human-blood clotting factor in sheep, produced in their milk
(pharming)
these animals with human genes are said to be transgenic
application of genetic engineering in microorganisms
production of human insulin by bacteria
dangers of genetic engineering 2
release of GMOs into the environment may lead to the escape of foreign genes into the environment
as a food source - possible danger to health, toxic proteins, allergic reactions
genetic testing in humans
tests carried out after birth to detect diseases or genes early
mutation 2
change in genetic material
change in dna or gene or chromosome structure
how do mutations occur
at random in any gene or chromosome
number of mutations that survive
very low as cells can often repair damaged DNA
mutant genes in DNA
often recessive and don’t appear in the phenotype
harmful mutations
may increase the rate of mitosis forming tumors
can mutations be inherited
yes, may cause genetic defects in the child
genetic mutations give rise to
changes in the phenotype and variation
if a mutation is inheritable
it can play a part in evolution by allowing natural selection to occur
2 types of mutation
chromosome mutation
gene (or point) mutation
2 types of chromosome mutation
change in structure of chromosome
change in the number of chromosomes
2 examples of change in structure of chromosome
deletion
inversion
deletion
a piece of chromosome (DNA) is lost
inversion
a piece of chromosome breaks off and turns upside down before rejoining (may cause cancer in humans)
change in number of chromosomes
addition or loss of one or more chromosomes eg. Downs syndrome results from presence of an extra chromosome in zygote, i.e. every cell is 2n = 47
gene (or point) mutation
sequence of bases in part of a DNA strand is altered
4 examples of gene (or point) mutation
albinism
haemophilia
cystic fibrosis
sickle-cell anaemia
albinism
can’t produce melanin - skin pigment
haemophilia
blood won’t clot due to lack of clotting factor
cystic fibrosis
thick mucus secreted in lungs and gut
sickle-cell anaemia
abnormal red blood cells
sickle cell anaemia is caused by
a mutant recessive gene - only occurs in someone who is homozygous for the condition
sickle cells
have abnormal haemoglobin which makes the red blood cells change into a sickle shape, cells clump together and cause heart failure and damage to brain, kidney, liver etc
causes of mutation
mutagenic agents
3 examples of mutagens
radiation (X-rays, UV rays)
chemicals (tobacco smoke, benzene, asbestos, mercury)
viruses
if a mutagen causes cancer it is called
a carcinogen
