The flow of genetic info.
If one letter is different from what it should be
The protein may not fold correctly
Causing a mutation
A random change in the DNA sequence
DNA replication
The process through which the amount of DNA is doubled after separating the sister chromatids
The strands separate with the help of the enzyme helicase
DNA polymerase synthesizes the new strand by joining the nucleotides together depending on complementarity in the sequence
For this process all DNA is replicated. While for transcription only the gene that needs to be expressed in transcribed.
Most times the mistake is repaired by the DNA polymerase.
Types of mutations
Substitution
Insertion
Deletion
One nucleotide is changed by another one.
One or more nucleotides are inserted into the DNA sequence.
One or more nucleotides are deleted from the DNA sequence.
Genetic modification
Genetic engineering transfers the genes from a species to another thanks to the universality of the genetic code.
GMOs / Transgenics
Plasmids
They are small circular molecules of DNA in bacteria
The plasmids are cut and restriction enzymes are used as catalysts, cutting DNA molecules.
There is DNA from humans that was cut by the same enzymes and so a gene is removed with molecular scissors.
The plasmid and human gene are binded by the ligase enzyme
Recombinant DNA
For example
Rice genetically engineered with the Sub 1 gene survived flooding
Papaya resistant to a certain virus
Golden rice
B carotene, precursor of vitamin A
Reduce malnutrition
To be freely distributed
They contain a specific gene that wasn't there before
Because science is an evidence system
Glysophates
are used to spay on plants, and they are not so toxic
only the weeds die
instead of using herbicides
The ethical debate on GM crops
GM: Golden rice, which contains the beta carotene gene
Concern: golden rice does not solve the real problem: poverty
Answer to concern: we can still help people who have deficency in vitamin A
GM: Herbicide resistant crops
Concern: pollen from resistant crops may fertilize unrelated species producing superweeds.
Answer to concern: Highly unlikely to happen, biologically and no evidence of that happening in the past decades.
Answer to concern: Extra benefit, which is that reduces the number of times that herbicides are sprayed on corps.
GM: pest resistant crops
Concern: Development of pesticide resistant pests by natural selection.
Concern: Unrelated species could be affected by the pesticide.
Answer to concern: Possible solution suggested in the book.
Answer to concern: Pesticide is very specific, no evidence for this happening, less chemicals sprayed so better for biodiversity.
Inheritance
Homologous chromosomes have the same genes but no necessarily the same alleles.
The allele is dominant over the other determines the trait
Genotype: the possible combination of alleles for a certain gene.
3 combinations
AA or aa: homozygous
Aa: heterozygous
Phenotype: expression of the genotype
The dominant allele will always be expressed whether it is in the homozygous or the heterozygous form
The recessive allele will only be expressed in the recessive homozygous.
Gregor Mendel
founding father of genetics
Crossbreeding is more favourable
Experiment with pea plants
C=yellow
c=green
Yellow pods and green pods: the parental generation
CCxcc
All yellow heterozygous pods--> F1
CcxCc
Most yellow and some green according to probabilities--> F2
Pedigree chart or punnet charts
Blood types: ABO
1 gene
3 possible alleles
I(A) and I(B), codominant
i, recessive
Genotype is the alleles: I(A), I(B) and i
Phenotype is the bloodtype: ABO
Proteins expressed in the surface of blood cells
O is for no antigen
The RH factor determines if it is negative or positive
O-
Universal donor
AB
Universal recipient
The immune system produces antibodies against the antigens on the surface of the red blood cells that are foreign to your body
AGGLUTINATION
Blood type determination
One drop of anti A antibodies and one of anti B antibodies
Then add a drop of blood to each.
The result depends on whether the is a reaction.
Sex chromosomes X Y have gene for sex linked traits
X is bigger and essential for human survival
X(A/a) and X(A/a)/Y