P1 L1 Flashcards
What does forward/classical genetics seek to find?
The genetic basis of a phenotype or trait
How is phenotype defined in classical genetics?
It is the appearance of an individual or the manifestation of a particular genotype
What is the definition of genotype?
It is the specific composition of the genetic information
What is the main goal of classical genetics?
To isolate and analyze mutants to understand changes in DNA
What does reverse/molecular genetics seek to find?
What phenotypes arise from particular genetic sequences
Gene mutated -> Returned to Organism -> Observe Phenotype
What are the advantages of working with bacteria?
- easy to grow and manipulate
- haploid
- asexual reproduction
- clones can be isolated on agar plates
Define haploid and explain the advantage
one copy or allele of each gene - easier to identify mutations
only have one chromosome, also called a nucleoid.
Screening vs selection
Screening: shows different phenotypes
Selection: allows only one specific phenotype to grow.
Screening identifies resistant bacteria, while selection isolates rare mutants
What are bacteriophages?
Viruses that infect bacteria
This makes it possible to move DNA between bacteria
Gregor Mendel has:
a) showed that hereditary traits do not occur in random proportions in the offspring
b) carried out crossing experiments on pea plants
Johannes Friedrich Miescher
The chemistry of the nucleus.
He isolated phosphate-rich structures (nuclein) that are known today as nucleic acids.
Phoebus Levene
-> The chemical composition of nucleic acid.
“DNA is too simple to code genes”
He assumed that the proteins carry the genetic information
What are the 3 components of DNA?
Base + sugar + phosphate
(genetic information + structure and backbone)
DNA vs RNA
clockwise double helix
Sugar:
Desoxyribose vs Ribose
Bases:
[Adenine, Guanine, (purine)] [Thymin, Cystosin (pyramine)] vs
[Adenine, Guanine,] [Uracil, Cytosin]
Nucleoside:
dAdenosine, dGuanosine, dThymidine, dCytodine vs
aenosine, guanosine, uridine, cytadine
Nucleotide: (sugar + base)
dAMP, dGMP, dTMP, dCMP vs
AMP, GMP, UMP, TMP
DNA/RNA Pairing
A-T/U
C-G
What is the difference between DNA and RNA?
DNA contains thymine, while RNA contains uracil; DNA has deoxyribose, RNA has ribose
What is the significance of the 5’ and 3’ ends of a nucleotide chain?
They indicate the polarity of the strand, with 5’ being the phosphate end and 3’ being the hydroxyl end
Frederick Griffith’s research?
He studied/demonstrated bacterial transformation and the epidemiology of bacterial pneumonia with mice
What characteristic does the S-strain and R-strain of Streptococcus pneumoniae have?
S-strain: It has a polysaccharide capsule and is virulent
R-strain: strain has no capsule and is non-virulent
What did Griffith conclude about the transformation factor?
It was passed from the heat-inactivated S-strain to the living R-strain - mouse died
r - lives
s - dies
s inactivated - lives
s inactivated + r - dies ^^
Oswald Avery Findings
If the DNA is destroyed, the S-strain cannot be reactivated and the mouse remains alive. He discovered this through selection and tested this with other destroyed parts of the cell (e.g. proteins, RNA, lipids, etc.).
DNA = genetic information
Erwin Chargaff contributions to the understanding of DNA?
He discovered the base pairing rules in DNA
What is the structure of DNA as proposed by Watson and Crick?
A double helix with antiparallel complimentary strands
What are the dimensions of a DNA in nm and per 10 base pairs?
Diameter: 2 nm
One turn: 3.4 nm (10 base pairs)
minor groove: 1.2 nm
major groove: 2.2 nm
1A = 0.1nm
