Transmission Genetics Flashcards
published his findings on the inheritance of 7 characteristics of pea plants
Gregor Mendel
Seed form:
Dominant = Round
Recessive = wrinkled
Seed color:
Dominant= Yellow
Recessive = green
Pod form:
Dominant= Inflated
Recessive= constricted
Pod color:
Dominant= Green
Recessive= yellow
Flower color:
Dominant= Purple
Recessive = white
Flower arrangement:
Dominant= Axial
Recessive= terminal
Stem:
Dominant= Tall
Recessive= short
comes from a Greek root which means appearance or observable characteristics
Phenotype
is the current term to replace Mendel’s “particles.”
Gene
= is the current term to replace Mendel’s “particles.”
Gene
is the basic unit of inheritance. It contains instructions for heredity
Gene
the set of genes manifested or expressed in the organism’s phenotype
Dominant allele
aka “hidden” trait, and is expressed only when the
individual carries 2 copies of the gene
Recessive allele
a cell that carries two copies of the gene; applicable in autosomes
or somatic cells
Diploid
a cell that carries one copy of the gene; applicable in sex
chromosome or gamete
Haploid
If the cell carries two copies of the same allele it is said to be
“HOMOZYGOUS”
If the cell carries one gene of different alleles, it is said to be
HETEROZYGOUS”
Genes separate randomly in the gametes so that each gamete will only receive haploid copies of the gene
2nd Mendel’s Law: Law of Segregation
Genes of different traits can segregate independently.
3rd Mendel’s Law: Law of Independent Assortment
The Chromosome Theory of Inheritance was First proposed by
Theodor Boveri and Walter Sutton in 1902.
observed that development in sea urchins does not happen without chromosomes
Theodor Boveri
observed chromosomes in meiosis among grasshoppers
Walter Sutton
observed chromosomes among fruitflies (Drosophila melanogaster)
Thomas Hunt Morgan
the eye color phenotype was sex-linked. It was transmitted along with sex in the experiments. Males were _______ for the X chromosome.
“HEMIZYGOUS”
Chromosome theory of inheritance:
- Genes have places or loci.
- Diploid organisms such as humans normally have 2 copies of all chromosomes except sex chromosomes
the allelic constitution of a gene
Genotype
The complete set of genes of an organism
Genome
the offspring appear to have a different allele not seen in the parents, and are therefore called
RECOMBINANTS.
How are recombinants produced?
By crossing-over during the pachytene stage of Prophase I.
Stages of Meiosis:
Meiosis I:
Prophase I:
Leptotene, Zygotene, Pacytene, Diplotene
the gene that occurs more frequently
Wild-type or Standard-type
the gene that is less present
Mutant
This finding was supported by _______ and made a mathematical relationship simply stated, that if the frequency of the recombination is 1%, it is equivalent by a map distance of 1 centimorgan (equivalent to 1 million basepairs in humans). This established the rationale of genetic mapping techniques still used today.
A. H. Sturtevant
provided a direct physical evidence of recombination in 1931. From their observation of maize chromosomes, they established a direct relationship between a region of the chromosomes and a gene.
Barbara McClintock and Harriet Creighton
Together with —-z they detected that recombination can be physically and genetically detected in both plants and animals.
Curt Stern
moveable genetic elements, were also discovered by McClintock.
Transposons,
