Barnes (Genetic material) Flashcards
1
Q
What did DeVries, Correns and Tschermak do?
A
- repetition of Mendel’s work (pea plants)
- distinguished between genotype and phenotype
- must be genetic material –> must be replicated, stored and expressed, variation by mutation
2
Q
What did Miescher do?
A
- WBCs
- studied chem composition of nuclei
- found nuclein (DNA)
- showed not protein, as not digested by pepsin protease and contains no S
- didn’t contain H, C, O, P
3
Q
What did Flemming do?
A
- salamanders
- dev novel microscopic techniques to observe fixed, stained cells
- discovered chromatin = fibrous structure in nucleus, easily stained
- postulated transforms into thread like chromosomes at mitotic division
4
Q
What did Sutton and Boveri do?
A
- grasshopper and worms
- used cytology and microscopy to find where genetic material carried
- grouping in pairs and separation consistent w/ Mendel’s laws of heredity
- diff combos of chromosomes would cause variation
- theory of inheritance = chromosomes req for embryonic dev, carry Mendel’s factors, linear structures w/ genes along
5
Q
What did Morgan do?
A
- investigated whether heritable mutations in Drosophila
- linked mutant white eye phenotype to unusual chromosome composition
- so genes must be on chromosome
6
Q
What did Garrod do?
A
- cause of alkaptonuria in humans
- what urine composition shows about metabolism
- noticed ran in families
- linked human disorders to metabolic defects
- build up of intermediates from breakdown of proteins cause disease
- proposed diseases inborn errors of metabolism and differences in metabolism between healthy people
7
Q
What did Beadle and Tatum do?
A
- established 1 gene-1 enzyme hypothesis
- niacin prod studied as model pathway
- niacin synthesised in series of biochem steps, by series of enzymes
- gen mutations in DNA of individual cells using X-rays
- X-rays cause DNA breaks in double helix, repaired imperfectly, causing stable mutations
8
Q
What is minimal growth media?
A
- contains only nutrients organism cannot synthesise itself, WT organism should be able to grow
9
Q
What is complete media?
A
- contains extra nutrients
- should make up for some defects in metabolic pathways and allow mutant cells to grow
- WT cells also able to grow
10
Q
What was the method for Beadle and Tatum’s experiment?
A
- used X-rays to gen many mutant cells
- grew each mutant in complete media 1st to get lots of identical cells
- grew identical cells (same mutation) in minimal media supplemented w/ intermediates
- observed growth
11
Q
What did Griffith go?
A
- S. pneumoniae
- S strain (smooth) w/ polysaccharide coat is pathogenic
- R strain (rough) w/o polysaccharide coat is not pathogenic
- polysaccharide coat forms capsule, protection from IS
- killed S by heating to high temp = mouse lives
- inject dead S into mice w/ live R = mouse dies
- as R cells transformed, changing genotype
12
Q
What did Avery, Macleod and McCarthy do?
A
- cont Griffith’s research to find molecule responsible for transformation
- systematically destroyed each component of S strain extract using enzymes that specifically digest each type of molecule
- combined w/ live R to test for transformation
- mouse only lived when DNA destroyed
- in order for bacteria to be virulent, req DNA encoding polysaccharide coat
13
Q
What did Hershey and Chase do?
A
- investigated which part bacteriophage T2 injected into bacteria
- labelled bacteriophage DNA w/ radioactive isotope
- infect unlabelled bacteria w/ radioactive phage
- separate phage ghosts from infected bacteria
- test bacteria and phage ghosts for radioactivity
- knew DNA contained phosphate and proteins contained S
- if DNA genetic material then P DNA would be bacteria labelled and S protein phage ghost labelled
14
Q
What did Kossul do?
A
- identified diff nucleobases in nucleic acids
- discovered thymine
15
Q
What did Levene do?
A
- nucleotides assembled into strings and components joined by covalent bonds
- thought 4 nucleotides in same seq in each DNA molecule, so too simple to make up genetic material of cell
