Who discovered the basic principles of heredity by breeding garden peas?
Gregor Mendel in 1867
When did we know genes were encode by DNA?
1944 Griffith
Who came up with DNA structure?
1953 James Watson and Francis Crick
What is hybridization?
cross breeding
What are the results of Mendel’s experiments came the two fundamental principles of genetics?
- Law of Segregation
- Law of Independent Assortment 2
What is Mendel’s first conclusion?
What is Mendel’s first conclusion?
- They are alternative versions of ‘heritable units’ that can be passed on to progeny
-these are called alleles
-arise from mutations of the DNA sequence of a gene
-alters or eliminates the function of the encoded protein
What is Mendel’s second conclusion?
- For each character, an organism receives two copies (i.e two alleles) of any given gene, one from each parents
What is Mendel’s third conclusion?
If alleles differ at a locus, then one must be dominant
-dominant vs. recessive
What is Mendel’s fourth conclusion?
- The Law of Segregation: the two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes
a.) start with set of homologous chromosomes
b.) duplicate their DNA
c.) anaphase I separates the homologous chromosomes
d.) anaphase II separate the sister chromatids
e.) half the gametes get one allele of a gene, the other half gets the other
What is the phenotype?
the observed trait of a characteristic
What is the Genotype?
the genetic makeup that produces the phenotype
What is a homozygote or homozygous ?
organism has a pair of identical alleles for a gene
ex. PP or pp
What is a heterozygote or heterozygous?
if an organism has a pair of alleles for a gene that are different
ex. Pp and pP
What is a monohybrid cross? Dihybrid cross?
MONO: follows only one character
DI: follows two characters at once
What is the Law of Independent Assortment?
states that two or more genes will assort independently into gametes
-each pair of alleles segregates independently of any other pair of alleles during gamete formation
What was Mendel’s observed phenotypic ratio?
9:3:3:1
What happens if genes are realllllllly close on a chromosome?
they are linked
-alleles of these genes will be packaged into chromosomes together during meiosis
What happens if genes are reallllllly far apart on the same chromosome?
the odds of crossing over between them is very likely
-this makes it so that they’re no longer linked and the alleles can assort independently
What is pleiotropy?
occurs when one gene (or the alleles of one gene) affect multiple phenotypes
What is Co-dominance ?
results in the heterozygous having a unique phenotype that is different from the homozygous phenotypes
ex. albinism causes lack of melanin in skin, eyes, hair but can also cause light sensitivity and strabismus in eyes
What is Penetrance?
if a homozygous genotype doesn’t always produce a specific phenotype in all members of the group
