Gen Bio: Mendelian and Non-Mendelian Genetics

• The notes are for Gen Bio Reviewer

Gregor Mendel

• An Austrian Monk/Scholar who lived from 1822-1884
• Studied inheritance using pea plants
• Applied quantitative methods

Pea Plants (Pisum Sativum)

• Used by Mendel

Ideal Traits for Experiment on Inheritance

• Variability
• Controlled Mating
• Recombination of Sexual Reproduction
• Short Life Cycle
• Large Number of Offspring
• Convenience of Handling

Mendel's Experimental Results

• Concept of Unit Character- peas have factor(genes) and these occur in pairs
• Principle of Dominance and Recessiveness- dominant pair masks the impression of the other
• Law of Segregation- a pair of genes is separated during the formation of gametes

Definition of Terms

• Alleles- genes governing variation of the same characteristic
• Homozygous- have same version of alleles
• Heterozygous- have different alleles
• Genotype- genetic makeup of individual
• Phenotype- physical trait

Non-Mendelian Genetics

• Law of Incomplete Dominance- blending in traits, traits do not disappear, new traits come
• Codominance- both traits are visibles in offspring
• Nondisjunction- failure of the chromosome to separate, can occur in Anaphase I or II

Sex-linked Traits

• Usually attached to the X-chromosome
  • Examples include Hemophilia (blood-thinning), Color-blindness (inability to see colors properly), and Duchenne Muscular Dystrophy (gradual destruction of muscle cells)

Multiple Allelism

• Traits controlled by multiple genes: 3 genes; A, B, and O
  • A, B are dominant; O is recessive
  • Karl Landsteiner discovered blood types and made blood transfusions possible
  • Positive blood types are dominant and negative blood types are recessive

Blood Cells

• A-blood type- have A antigens, Anti-B antibody inside
• B-blood type- have B antigens, Anti-A antibody inside
• AB-blood type- have A and B antigens, no antibodies
• O-blood type- have no antigens, Anti-A and Anti-B antibodies

Protein Synthesis: Central Dogma

• Occurs in the ribosomes, Rough Endoplasmic Reticulum

Transcription

• DNA is used to create RNA
  • Initiation (premotor region)
  • Elongation (reading sequence)
  • Termination (termination region)

Translation

• RNA > protein

Genetic Engineering and Recombinant DNA

• Classical Breeding- choosing specific traits to breed organisms
• Genetic Engineering- changing molecules in DNA
• Cloning- make exact genetic copies of living things

Step-by-step for cloning

• Cleavage of DNA by restriction enzyme
• Select an appropriate vehicle for DNA
• Ligation(joining) of gene and plasmid- done by ligase
• Put the DNA in a plasmid

Recombinant DNA

• DNA gets spliced into a bacterial DNA
• The bacteria then splits, and the DNA gets cloned

Biolistic

• DNA and 24K gold are combined, and a gene gun shoots particles into cells. The DNA stays in the cell, and gold flies out the other side.

Heat Shock Treatment

• The cell gets heated to open the membrane
• Bacteria only

Electroporation

• Zap the cell membrane open
• Mammalian cells

Polymerase Chain Reaction

• Stimulates gene/DNA replication

Requires

• Target DNA
• Pair of DNA Primer
• Heat-resistant DNA Polymerase
• All four dNTP's (deoxyribonucleoside triphosphate) (A-T and G-C)

PCR Testing

• Denaturation- denature the DNA, heat to 95° celsius
• Annealing- DNA primer positioned, 45-60° celsius
• Extension- New DNA elongates from primer, 72° celsius

Genetically modified organism

• Organism with edited genes

History of Life formation

• Earth is 4.6B years old
• Life first formed 540M years ago

Eon

• Longest timeline of the Earth
• Divided into 4

Hadean Eon (4.6B yrs ago)

• Planetisimal formation and debris along the orbit of the Earth compress to form a planet

Archean Eon (4B yrs ago)

• Formation of life began with Primordial Soup
  • Lightning and elemental components: oxygen(isotope), hydrogen, nitrogen, phosphorus, calcium, iron, etc.
  • Presence of water (and lava)

Chemical (inorganic) Evolution of Life

1. Formation of simple organic compounds
2. Formation of simple organic molecules: nucleic acid
3. Formation of complex organic molecules: RNA and DNA

Biological Evolution of Life

1. Coacervate formation (Cytoplasm)
2. Primary living organism-the first living cell; prokaryote
3. Origin of autotrophs- bacteria evolved into photosynthetic autotrophs

Proterozoic Eon (2.5B yrs ago)

• Cognogeny- cell diversification/evolution
• Hydrothermal Vents- small volcanoes found deep underwater, where cells first formed

Phanerozoic Eon (540M yrs ago - present)

• Eon of living

Paleozoic Era

• Old life

Cambrian Period (544-505m yrs ago)

• Trilobites, Cambrian explosion

Ordovician Period (505-440m yrs ago)

• First fishes

Silurian Period (440-410m yrs ago)

Devonian Period (410-360m yrs ago)

• Age of fishes, and different species of fish
  • Evolved with the ability to breathe on surface and with seeds

Carboniferous Period (360-290m yrs ago)

• Many plants grew and died, leading to large deposits of carbon from dead plants (current fossil fuels)
• First amphibians lived on water and land, first organisms to live on land
• Mississipian Period- age of crinoids (sea lilies/ feather stars)
• Pennsylvanian Period- age of plants

Permian Period (290-245m yrs ago)

• Age of amphibians, pangea formed
• 1st mass extinction; Permian extinction - 85% of the world population died

Mesozoic Era(245 - 65M yrs ago)

• Age of Dinosaurs
• Continental Drift- proposed by Alfred Wegener

Triassic Period

• 245-200m yrs ago, age of reptiles
  • Pangea started to separate and ended with mass extinction

Jurassic Period

• 200-145m yrs ago
• Reptiles became dinosaurs, and was known as the Golden age of dinosaurs
  • Birds also evolved and flowering plants emerged at this time

Cretaceous Period (145-65m yrs ago)

• Age of dinosaurs (T-rex, raptors)
• Cretaceous Extinction

1. Chicxulub Asteroid- Chicxulub asteroid hit the Earth
2. Supervolcano eruption- Volcanic eruptions caused thick black smoke shutting out the sun killing plants then killing the dinosaurs
3. Photosynthesis shut down

Cenozoic Era (66M yrs ago - present)

• Age of mammals

Paleogene Period (66-23m yrs ago)

• First primates evolved - not direct ancestors

Neogene Period

• Modern rainforest and grassland, first human ancestors

Quaternary Period (2.55m yrs ago-present)

• Age of man - appearance of the first man "Lucy" - oldest fossil

Fossils

• Preserved remains of dead organisms

Dating Fossils

• Relative Dating
• Law of Superposition
• Law of Original Horizontality
• Law of Cross-cutting relationship

Hardy-Weinberg Equilibrium

• States that in a stable population, the genetic variation will remain constant from one generation to the next

Evolution and Taxonomy

• Evolution- organisms change or adapt to survive, gradual change of organism, mutation is the main cause of evolution Vestigial Structures- organs whose functions cease to exist, functions lost due to evolution
• Malthusian Theory- 'diseases, famine, and other natural calamities maintain balance by eliminating the weakest organisms.
• Catastrophism- Georges Cuvier and natural history shows catastrophic events that altered the way life developed.
• Gradualism- James Hutton, proposed species appeared by the gradual transformation
• Jean-Baptiste de Lamarck and Theory of needs- 'organisms change because they need to'.

Theory of use and disuse

• Traits that are used stay and traits that are unused are discarded

Theory of acquired traits

• Traits are acquired from parents

Charles Darwin

• 'survival of the fittest'
  • Evolution is a product of: Species overproduction as creatures tend to overreproduce and this increases the population.

Competition

• Organisms compete for resources

Variation

• No two individuals are the same with differentiation of traits

Adaptation

• Process of becoming better suited for your environment

Natural selection

• Better adapted individuals survive, the rest die

Speciation

• Adaptations gradually accumulate
  • Slowly, former related species no longer interbreed and form new species

Taxonomy

• Cladistics and Phylogeny
  • Classification of organisms by Carolus Linnaeus, the one that grouped organisms, Kingdom, Phylum, Class, Order, Family, Genus, Species.
  • Carl Woese added the Domains: Eukarya, Prokarya, Archaea.

Notes cover Mendelian genetics, including Gregor Mendel's experiments with pea plants and his laws of inheritance: dominance, segregation, and independent assortment. Key terms like alleles, homozygous, heterozygous, genotype, and phenotype are defined. The notes also touch on Non-Mendelian genetics.