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Scientific study of heredity Gene… Study of genes
refers to the letter (TT or Tt or tt)
The outward expression of the trait (Tall or Short)
Pure (TT or tt)
The ones that cover
The ones that is dormant
- Father of genetics
- Peas Experiments
- 3 Laws of generics.
- Born in Austria in 1822
- University of Vienna (1854 graduated) became teacher
- Perform plain old garden PEAS
- 3 Laws of generics.
- 1865 he published his work
- Nobody paid attention
- 1900 his work was re-discovered by 3 different scientist.
Gregor Mendel was successful because:
- Careful, meticulous scientist.
- His choice of the garden pea was absolutely perfect on what he wanted to do.
- 7 different variations
- Concentrated on one characteristic at a time
- He kept accurate records
Same genes (Chromosomes)
Different forms of the same gene
1st LAW: Law of Dominance
- Some genes cover the effect of others.
- Tall allele and Short allele.
- P Generation: 1st Generation
- F1 generation: Filio (Children)
- F2 generation: Filio 2 (Grandchildren)
- Genotype ratio: (1TT:2Tt:1tt) or (1:2:1
- Phenotype Ratio: 3 Tall and 1 Short (3:1)
Identical heterozygous for one gene are crossed. (Pp) x (Pp) = Ratio 3:1
Expected Phenotype ratio of a monohybrid is 3:1
2nd Law: Law of Segregation
- When gametes are produce, gametes separate from each other. Big T and little t
- The two genes of each pair are separated from each other durig meiosis, so they endup in different gametes
Method of determining genotype in which an individual of unknown genotype is crossed with one that is known to be homozygous recessive. (pp) or (tt)
3rd Law: Independent assortment:
During meiosis, members of a pair of genes on homologus chromosmes get distributed into gametes independently of other gene pairs.
- are sections of chromosomes.
- Genes contain hereditary information or instructions about hereditary traits.
- Di -2 different traits.
- Both parents are heterozygous.
- Phenotypic ration is 9:3:3:1
- Breeding experiment in which individual identically heterozygous for two genes are crossed. The frequency of traits among the offspring offers information about the dominance relationships between the paired alleles.
- Genes change as a result of mutation
- Mutations do occur and they are the source of new variations
- He proposed that when we get a new alleles is because of mutation. The source of new alleles is mutations
- Discovered that they are not dominant but they both contribute. When neither aredominant (alleles)
- Incomplete Dominance: 1:2:1
- Recognized that within a species there were a lot of variations
- Natural selection picks the best suited selection to survived
- Nature selects that variant that has the greatest advantage for that species
- Could not explain where the variations came from
- How they were passed from Parent to Child
- Hugo Devris: Variants come by way of mutation.
- Gregor Mendel: How the traits are mended.
- Discovered that they are not dominant but they both contribute. When neither are dominant (alleles).
- Ratio 1:2:1 (Red and White) = 1 Red, 2 Pink, 1 White
- 1st letter of each trait
- Little letters
- (rr) (ww) pink = rw
- Is a case when you have at least 3 different alleles.
- 2 are dominant over the 3rd recessive allele.
- Blood Type is a good example. ABO.
- One single gene affects several different traits.
- Cystic fibrosis - thickened mucus affects the entire body, not just the respiratory tract
This is when one trait is affected by multiple genes. Eye color, skin color… 150 genes that can cause deafness. Fur color (retriever)
Ways that the an environment can affect a genotype
- Simple example is when you get a Sun Tan.
- Change in skin done by an environment
- Water buttercup.
Himalayan Rabbit: turn black until he heats up. WhiteArtic Hare: Produce white fur in the winter. Himalayan rabbit: Produces black fur
He discovered Chromosomes through a microscope.
Locus location singular loci
Each gene has a particular location on a particular/specific chromosome.
One per parent
Most advance species chromosomes come in pairs.
Have the same length, shape and gene sequence as its partner
Genes with identical loci
- Carry the same instructions or slightly different instructions
- The different forms of the same gene are called alleles
- Alleles arise through mutation
The pattern, on which homologous chromosomes separate during meiosis I
is totally random so the resulting gametes receive a mixture of maternal and paternal chromosomes.
The combination of genes along the length of the chromosome may change due to the process of crossing over. The further the genes are from each other, the more lightly re-combination (crossing over) will occur.
The structure of a chromosome
May change because of a variety of mistakes that may occur either during meiosis ormitosis.
Because of other mistakes
The number of chromosomes ending up in the gametes or the offspring may change
For any given trait
A particular combination of alleles inherited may be neutral, beneficial orharmful.