Chapter 9 Flashcards
Molecular Genetics
the study of DNA structure and function at the molecular level.
Molecular genetic technology used in
Biochemistry, cell biology, and microbiology
Genetic material criteria (4):
- Information: The genetic material must contain the information necessary to construct an entire organism.
- Transmission: During reproduction, the genetic material must be passed from parents to offspring.
- Replication: Because the genetic material is passed from parents to offspring, and from mother cell to daughter cells during cell division, it must be copied.
- Variation: Within any species, a significant amount of phenotypic variability occurs.
1880s: August Weismann and Carl Nägeli
Championed the idea that a chemical substance within living cells is responsible for the transmission of traits from parents to offspring. The chromosome theory of inheritance was developed, and experimentation demonstrated that the chromosomes are the carriers of the genetic material.
Steptococcus Experiment
Type S and R
Type S: kills mouse + isolated bacteria
Type R: mouse survives + no isolated bacteria
Heat killed S type: mouse survives + no isolated bacteria
Living R and killed S: mouse dies + isolated bacteria
This is called TRANSFORMATION
Digesting Enzymes
DNase: Digest DNA
RNase: Digest RNA
Protease: Digest proteins
- When the mouse extract was treated with DNase it lost it’s ability to convert R to S type
- DNA is the transforming principle
Nucleotides
Form the repeating structural unit of nucleic acids
Link to form a strand of DNA or RNA
3 components: One phosphate group, a pentose sugar, and a nitrogenous base
Vary depending on sugar and nitrogenous base
Sugars: deoxyribose and ribose
Bases: purines and pyrimidines
Purine bases
Adenine
Guanine
Contain double ring structures
Pyrimidines
Thymine
Cytosine
Uracil
Single ring structured
Standard numbering system
Bases and sugars
Number (1-9)
The nitrogen and carbon atoms found in ring structure of bases (1-9) for purines and (1-6) for pyrimidines
How to describe nucleic acids
Based on 3 structural features:
The type of sugar, base, and phosphate groups
Nucleoside
When a sugar is attached to only a base
Ribose Nucleotides end in -sine
Deoxyribose nucleotides begin with deoxy-
Phosphodiester linkage
The linkage of DNA and RNA
*A phosphate group connects 2 sugar molecules via Ester bond
Chargaffs rule
The amount of A in DNA equals the amount of T, and the amount of G equals C
Base pairs
The double stranded structure (DNA) is stabilized by a pair of bases in opposite strands that are hydrogen bonded to each other
AT/GC rule: purines (AG) always bond with pyrimidines (TC)
10 nucleotides per 360° in helix
B DNA
Predominant form of DNA, right handed helix, 10 base pairs per 360°, bases centrally located and hydrogen bonds located perpendicular
Z DNA
Left handed, zig zag, 12 base pairs, bases are tilted
*At high ionic strength formation of Z DNA confirmation is favored by purines or pyrimidines
Plays a role in: transcription, and chromosome structure
RNA strands
Few hundred to several thousands strands longer, shorter than DNA
Made during transcription using one of the DNA strands as a template, creating 1 complementary RNA strand
Base pairing between A and U also G and C can occur in one or 2 separate RNA molecules
Factors of RNA structure
Hydrogen bonding between base pairs, stacking between bases, and hydrogen bonding between bases and backbone regions ALSO reactions with ions, molecules, and large proteins
RNA folding is key to the molecules structure and function
