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Transmission Genetics (Mendelian or Classical)
- Principles of Genetics
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- => How traits are passes down from parent ->
- offspring
- **Focus is on the individual
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- *Explores the genetic composition of the GROUP
- ->how it changes & evolves over time
- *Populations are Dynamic structures = composition changes in response to environment
*climate*predation*selective mating*geography
*Population genetics examines what we know as the GENE POOL Ex: how prevalent is a particular gene in a population? = gene frequency
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- Concerned with the molecular structure & function of
- genes in the cell
- How genes are maintained & transmitted at the cellular level
From 1 cell to the next cell upon division- Focus on the cellular processes of replication, transcription & translation
->mechanistic approach to understanding gene transmission
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Pangenesis
Each different cell type in the body carried specific particles of information = (gemmules) that provided the instructions for how that cell functions At the time of conception,- the gemmules from all over the body would localize to the reproductive tissue then the info is transferred to the embryo upon fertilization (egg & sperm join)
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Preformationism
- little preformed beings Inside the egg or sperm there exists a miniature adult- Means that all traits would come from only 1 parent
- Ovist - if believed preformed individual arose from the egg
- Spermist - if you believed the preformed individual arose from the sperm
- Does not support the observation that we inherit traits from both parents
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Inheritance of acquired traits
- Traits that an individual develops throughout their life can now be inherited/passed down to offspring
- Cut off a mouses tail to make it shorter to make offspring's tail shorter - didn't work
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Blending Theory
- -offspring are a blend or mixture of both parental traits that creates a new trait in the offspring
- - results in dilution of trait & homogeneity of the population
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Cell Theory
- -Schleident & Schwann 1839
- -cells are the smallest unit of life
- -all living things are made up of cells
- -all cells come from pre-existing cells (applies to inheritance)
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Germplasm Theory
- -Germ cells (egg & sperm) like all cells in the body carry a complete set of the entire genetic material of that organism
- -gametes from the male & female join together at fertilization/reproduction
- -one inherits from both parents
- -very similar to pangenesis
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CHARACTERISTICS OF A CELL
- - have semi-permeable, lipid bilayer membrane that encloses the cellular contents & allows the transfer of nutrients into the cell & transport of waste out of the cell
- - cytoplasm that is the site of cellular metabolism & biochemistry
- - ribosomes that are the cellular machinery for making proteins
- - all cells store their genetic info in the form of DNA
- (exception - some acellular organisms (viruses) store their genetic info as RNA)
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3 MAJOR SUB DISCIPLINES OF GENETICS
- -Transmission Genetics (Mendelian/Classical)
- -Population Genetics
- -Molecular Genetics
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HEREDITY
-the transmission of traits/characteristics from 1 generation to the next
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THEORIES PROPOSED BASED ON HEREDITY OBSERVATIONS
- -Pangenesis
- -Preformationsim
- -Inheritance of acquired traits
- - Blending theory
- -Germoplasm Theory
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2 MAIN CLASSIFICATIONS OF CELLS
- -eukaryotes (true nucleus)
- -prokaryotes (no nucleus)
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EUKARYOTES
- -unicellular or multicellular
- -structurally complex
- ~10-100um in diameter
- ~cell is compartmentalized
- ~nucleus (genetic material is physically separated from the cytoplasm by a nuclear membrane)
- -6000-30000 genes
- -higher order/level of DNA packaging for DNA to fit in the cell that is done with histones
- -metabolically simple - only metabolizes Carbon
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PROKARYOTES
- -unicellular
- -structurally simple
- ~0.1-10um
- ~no true nucleus
- ~ genetic material is not bound by a membrane instead is completed as a nucleoid structure
- -1500-5000 genes
- -no histone proteins & minimal packaging of the DNA
- -metabolically complex - metabolizes C, N, S, Fe, P, & O
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