Genetics Flashcards
Father of modern genetics, inheritance patterns through garden peas looking for characteristics (colour, seed shape etc.). Discovered factors of inheritance (alleles), dominant and recessive traits.
Gregor mendel
found non-protein substance from nuclei of white blood cells from pus bandages, called nuclein (nucleic acid), evidence that proteins aren’t hereditary material
Friedrich miescher
isolated dna and rna based on diff types of sugars (deoxyribose and ribose), showed that they’re made up of individual units (nucleotides) which have a sugar, phosphate, and nitrogenous base. Also said that nucleotide units repeat which means dna is too simple to be genetic material
phoebus levene
trying to develop a vaccine for pneumonia. used mice and virulent and non-virulent pneumonococcus. Saw that when heat treated virulent and non-virulent mixed, mice still died. Discovered transformation - bacteria picking up DNA from environment.
frederick griffith
experimented using unicellular green algae (acetabularia). Removed either the foot or cap from different algae and they were able to regenerate if it contained a foot. He hypothesized that the hereditary information is stored in the nucleus.
joachim hammerling
worked with maclyn mccarty and colin macleod. described the transforming principle through further experimentation with griffiths work. Demonstrated DNA was transforming principle and further proved DNA as genetic material
oswald avery
used radioactivity labeled viruses to infect bacterial cells. to determine if protein or DNA was responsible for infecting bacterial cells and producing new viruses. Viral DNA had phosphorus, and protein had radioactive sulfur. Found infected cells contained radioactive phosphorus (DNA), proving DNA is hereditary material, being accepted by the scientific community.
alfred hershey & martha chase
experimented with viruses to determine if protein/RNA is responsible for viral replication. Isolated tobacco mosaic virus and the holmes ribgrass virus which contain protein and 1 strand of RNA. Made hybrid with RNA from HRV and protein from TMV. Infected tobacco plant and showed characteristics of HRV. Found evidence that RNA is the hereditary material that RNA is hereditary and in nucleic core.
Heine Fraenkel-Conrat
worked on organisms and analyzed DNA compositions. found that DNA compositions are species specific, differ in relative amts from one species to another. A = T, C = G. A+G = T+C
erwin chargaff
kings college london, worked on x-ray crystallography, looked at DNA. produced a x-ray diffraction pattern of DNA that suggested a helical shape, position groups of atoms, long and thin, uniform diameter of 2nm, dna coils every 3.4 nm
rosalind franklin + maurice wilkins
deduced the structure of DNA using chargaffs, wilkins and FRANKLINS work. Built a model of a double helix, based on uniform diameter, base pairing, hydrogen bonds, were given nobel prize
james watson and francis crick
double stranded packed into super coiled structure due to positive charged proteins and negative charged DNA
prokaryote dna
supercoiled DNA stored in
nucleoid region
1.2 mm long, can fit into a bacterium that is 0.001 mm long
e. coli chromosome
DNA twists into a double helix due to hydrogen bonding between the two strands, 2nm wide
step 1
dna (-) wraps tightly around histone proteins (+) in order to create nucleosomes
step 2
200 base pairs of DNA wrapped twice around a cluster of 8 histone proteins, then passed through a h1 protein to hold the shape, 11nm wide
nucleosomes
DNA between nucleosomes bind to the H1 histone proteins creating tightly packed chromatin also called a solenoidal fibre, 30nm wide
step 3
protein structure condenses into a chromosome, 1400 nm wide
step 4
pentose sugar, phosphate, organic base containing nitrogen
nucleotides
bond between sugar & phosphate
phosphodiester bond
bond between sugar and base
n-glycosidic bond
width of DNA
2nm
distance between each base pair
3.4nm
phosphate bridges, hydrogen bonding, hydrophobic interactions
3 forces of dna stability
depends on hydration level, sequence type, amount of supercoiling
dna conformation
a - dehydrated, b- naturally found in living organisms
conformations in organisms
replication = 2 new daughter strands that for a new double helix and the two original templates reform into original parent DNA molecule (WILL ALWAYS HAVE ORIGINAL PARENT)
conservative theory
watson & crick, daughter DNA is made up of one parent and one daughter strand, identical helices are formed
semi conservative theory
parent strands are broken up into fragments, new daughter strands are made up of an assortment of parental and new DNA
dispersive theory
e. coli cells grown in a heavy 15N medium, then transferred into a normal 14N medium and allowed to divide, 14N was incorporated into the new strands of DNA (first replication) Cells then allowed to divide again in 14N for more replications. Centrifuged DNA and cesium chloride added to create density gradient. More 14N as time goes on, less hybrid N. Proved semi conservative theory.
meselson and stahl experiment
