Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
Ancient Ideas |
Hippocrates - pangenesis (whole of parental organisms participate in heredity) Aristotle: Form + potentially = actuality Bible: Experiences of a pregnant mother affects her offspring directly. (Jacob and striped/spotted sticks and mating sheet and goats) |
|
|
Hybridization |
Hybridization between two quite different animals yields an offspring species that are intermediate in appearance |
|
|
Genetic purity |
A concept that derives from essentialism Used today in science: Purity is the lack of genetic modification |
|
|
Inheritance from pre-existing forms |
Inheritance the transmission of pre-existing form (preformationism) -> Sperm are little people (Homunculus) |
|
|
Blending Inheritance |
Hereditary nature was fluid in nature (Example red and white flowers produce pink flowers) |
|
|
Gregor Mendel |
(1822-1884) - Born into poor peasant life - Studied at University but ran out of money so joined the Augustinian order in Brno (Monk) = worked as a substitute teacher in local grammar school |
|
|
Why did Mendel's work take a while to be accepted? |
1. Work was not getting recognition 2. Tried using another plant but could not gain the same result |
|
|
Mendel in 1950s and early 1960s |
Published a paper that detailed his pea hybridization experiment - When published it made no impact however did interest Karl Nageli -Paper could not be understood by everyone - After his death most of his personal papers were burned |
|
|
Mendel's Work |
Hybridization of pea lines w/ different traits - Observed segregation of traits - Tried to derive an abstract model to explain the numbers = implied particulate inheritable factors behaved as distinct, indivisible entitles/atoms of inheritance not as fluids - Observed (but did not name ) independent assortment |
|
|
Karl Nageli |
- Took interest in Mendel's paper - Botanist = stidoes cells is algae - Suggested Mendel try to repeat his work with another plant, hawkweed - Hawkweedis an apomiet = seems sexual but is not = offspring genetically identical to parent |
|
|
Darwin's Pangenesis |
- Other model of inheritance in the late 19th century - Gemmules (Internal buds found in sponges and are involved in asexual reproduction) - Also a particulate model - BUT Darwin's gemmules change over an individuals life, which was unlike Mendel's particles |
|
|
August Weismann |
(1834-1914) Germplasm Theory - Involves hereditary particles rather than fluids (thought particles were on chromosomes) - A single germ cells has hundreds of complete sets of hereditary particles passed from previous generations - Distinguished between two types of cells... 1. Germplasm: Pre-cursor cells of sex cells (gametes) = responsible for generation continuity 2. Somatoplasm: The rest of the cells of the body = Genetic dead ends, inheritable factors that are not passed on |
|
|
Sir Francis Galton |
(1822 - 1911) Biometrical Approach - Application of statistics to biological problems - Charles Darwin's cousin - School founded by him - Discovered the individuality of finger prints - Question if prayers worked - Mendel studied discrete (discontinuous) whereas, Galton studies quantitative (continuous) variation - Thought it was important in studying practical problems of genetics (milk production of cattle/ yields of crops) |
|
|
Galton's Law of Ancestral Heredity |
- Receive 1/2 of your hereditary materials from each parent and 1/4 from each grandparent - Pertains to your genome as whole - Does not distinguish between genomes and genes - There are no atoms of inheritance in this model |
|
|
What is Galton known for? |
- Considered the founder of eugenics, the science/pseudoscience of improving the human race heritably by selective reproduction
|
|
|
Hugo de Vries (Rediscoverer #1) |
(1848-1935) - Dutch botanist - Bread poppies as his explanatory model - Independently derived all of Mendel's observations - Dominance/ recessiveness in F2 generation - 3:1 ratio in F2 generation - Believed in atoms of inheritance (not mixing/blending) - Able to show his observations in 15 plant species - Read Mendel's paper but gave him no credit on his paper |
|
|
Carl Correns (Rediscoverer #2) |
(1864-1935) - Student of Karl Negeli - Studied paired traits in pea plants and maize - Read Hugo de Vries paper and forced de Vries to mention Mendel in a later paper |
|
|
Erik von Tschermak (Rediscoverer #3) |
- Bred peas using yellow/green cotyledons and round/wrinkled seeds
- Derived the same 3:1 ration in F2 generation |
|
|
William Bateson |
(1861-1926) - Became a lifelong defender of Mendel's approach on heredity - Train man (took a train and read Mendel's paper and decided to discuss his work instead - "Mendel's Principles of Heredity: A Defence" (1902) |
|
|
Origins of terms 1. Genetics 2. Gene 3. Genotype, phenotype |
1. Bateson, 1906 2. Wilhelm Johannsen (Danish Botanist), 1909 3. Wilhelm Johannsen, 1911 |
|
|
Objections to Mendelism (1900-1910) |
` |
|
|
Thomas Hunt Morgan |
(1866-1945) - American biologist - Critic and objected Mendelism 1. Mendel's laws cannot be demonstrated in all organisms, particularly animals 2. Dominance/ recessiveness cannot explain the 1:1 sex ratio 3. Progeny/offspring are intermediate in appearance = rather than resembling one of the parents are grandparents 4. No physical basis for Mendel's Hereditary determinants had been found |
|
|
The ghost of preformationist rides again? |
Mendel's work seemed to imply that embryonic offspring are miniature versions of their parents from the earliest stages of development, thus supporting the discredited preformationist theory of heredity. |
|
|
Walter Sutton |
(1903) - Observed chromosomes in meiosis behaved in the same way as Mendel's hereditary determinants do - Problem: Need more genes then there were chromosomes |
|
|
William Bateson (again) |
(1906) - Discovered co-segregation of genes in breeding experiments with plants - Found violations of Mendel's law of independent assorment |
|
|
Thomas Hunt Morgan (again) |
- Most productive genetics lab in the 20th century - Breed Drosophila fruit flies - Used radiation to induce mutations = to discover new gene Achievements 1. Sex linkage: X chromosome had certain phenotypes 2. genetic maps: Genes are assigned to certain parts on the chromosome |
