Molecular Genetics Flashcards
James Watson and Francis Crick
Found the structure of DNA
Rosalind Franklin and Maurice Wilkins work were critical for this (X-Ray crystallography)
Alfred Hershey and Mary Chase
Used bacteriophages to prove that DNA must be the genetic material
Backbone of DNA is made of
Sugar-phosphate components
DNA rungs are made up of
Nitrogenous bases
Nucleotide is made up of what
A sugar (deoxyribose) attached to a phosphate and a nitrogen base
Nitrogen bases of DNA are
Adenine with Thymine
Guanine with Cytosine
Nucleic acid strands are always what to each other
Anti-parallel
Semi conservative
Replication of DNA-daughter cell has one old strand and one new strand
DNA replication
1-begins at origin of replication
2-enzyme helicase unravels DNA(replication bubble formed)
3-DNA polymerases catalyze elongation of new DNA
4-DNA polymerase III matches nucleotides 5’ to 3’
5-continuous on 5’ to 3’(leading strand), segments in 3’ to 5’(lagging)
6-lagging strand pieces=Okazaki fragments, sealed by DNA ligase
Factors contributing to the accuracy of DNA replication
1-specificity of base pairing
2-mismatch repair=special repair enzymes fix incorrectly paired nucleotides
3-nucleotide excision repair=incorrectly placed nucleotides are removed by enzymes(nucleases) and filled with correct nucleotides
Telomeres
- To avoid losing the terminal genes, the linear ends of eukaryotic chromosomes are capped with these.
- short repetitive nucleotide sequences that do not contain genes
A bacterial chromosome
One double-stranded, circular DNA molecule associated with a small amount of protein
Eukaryotic chromosomes
Linear DNA molecules associated with large amounts of protein
Chromatin: DNA and proteins are packed together as this
Gene expression
The process by which DNA direct the synthesis of proteins or in some cases RNAs
The one gene one polypeptide hypothesis
Each gene codes for a polypeptide, which can be or can constitute a part of a protein
Transcription
The synthesis of RNA using DNA as a template. It takes place in the nucleus of eukaryotic cells
mRNA
Produced during transcription and it carries the genetic message of DNA to protein making machinery of the cell in the cytoplasm which is the ribosome
How to produce mRNA
Transcription results in pre-mRNA, which undergoes RNA processing to yield the final mRNA
mRNA in prokaryotes
Transcription results directly in mRNA, which is not processed. Transcription and translation can occur simultaneously
Translation
The production of a polypeptide chain using the mRNA transcript and occurs at the ribosomes
Triplet code
The instructions for building a polypeptide chain are written as a series of three nucleotide groups called the triplet code
Template strand
During transcription, only one strand of DNA is transcribed and it is called the template strand. The mRNA that is produced to said to be complementary to the original DNA strand. The mRNA base triplets are called codons. They are written in the 5 to 3 direction
