DNA and RNA Flashcards
what principles did mendel create in his publication?
principles of heredity, 1866
- characters are inherited as separate units
- there are two units per individual character
- one is dominant while one is recessive
what did sutton discover?
1902
-characters reside on chromosomes
describe the Avery-MacLeod-McCarty experiments
1943,
4 enzymes degrading sugar, DNA, RNA and proteins
- added to strain of pathogens
- only element able to transform non-violent bacteria is DNA degrading
- infecting mouse, dies for all except DNA degrading
- 3 controls: negative (no pathogen on mice), positive (pathogen on mice), 3rd (killed R bacteria with living S bacteria)
describe griffith’s experiment
1928
started from bacterial strain (pneumoco) which forms colonies on smooths and rough colonies
- s-strain is virulent -> infecting the mouse will die
- boiling the bacteria the mouse survives (destroying the pathogen)
- r-strain is non-virulent-> mouse recovers
- mixing dead S-strain and living R-strain -> mouse dies
- transposition from virulent to non-virulent causes disease -> changing non-virulent bacteria
describe Watson’s and crick’s findings on DNA
1953
- paper solved structure of DNA -> bases inside and phosphate outside
- used X-ray diffraction image of DNA by Rosalind Franklin
- DNA chains have 5’-3’ and polarity (two ends are different and at 1 end with have polar residue 3P) and follow an antiparallel structure
- A-T form 2 H bonds
- G-C forms 3H bonds (more stable than AT, form tighter interaction and more difficult to open)
- higher % of AT than GC as this allows for easier breaking of H bonds for replication
what is the purpose of the phosphate backbones?
wind around each other in a right handed double helix
- allows the bases to pack tightly and reach the energy required
- each turn of helix takes 10 nucleotides
how is hereditary information passed?
- DNA contains 4 units which then code into 20 amino acids (proteins)
- for going from DNA to proteins there is an intermediate molecule (RNA)
- each amino acid is coded by more than 1 triplet
- codons are 3 letter codes which make up amino acids
what are genes?
sequence of nucleotides that acts as a functional unit for the synthesis of one or more products (proteins or RNA molecules)
what was Jacob and Monod’s theory on genes and what disproved it?
1 gene is the DNA unit that contains the information for making a protein through a molecular messenger RNA .
Central dogma of molecular biology:
- duplicated genes make the same proteins (1 gene would not be enough to produce the needed amount of proteins)
- genes are interrupted by noncoding sequences (introns) that can be alternatively spliced to produce different proteins from the same DNA sequence
- from the same mRNA you can produce different proteins
- pseudogenes are replicated genes that do not encode for proteins
- genes encode regulatory or structural RNA molecules
what is RNA?
linear polymers made of nucleotides
- contain ribose sugar (OH) -> don’t need to be stable (easily broken down)
- thymine is substituted by uracil
- RNA is single stranded -> folds on itself according to complementarity of bases (intramolecular complementarity)
in what structure are genes contained?
chromosomes: single DNA molecule and the proteins that fold and pack the DNA into a compact structure
describe karyotyping
visualising the structure and appearance of chromosomes in an organism using dye
what is the role of nucleosomes?
core of 4 different proteins in double dosage (histones) for DNA to wrap around
- similar sequence of amino acid -> form very similar 2 dimensional structures
- Histones do not depend on the sequence of DNA (bind to any DNA -> + charges and bind to polar bond)
- histones are extremely mobile (histone ATP-dependent remodelling complex) -> ability to uncoil to allow for DNA replication
