Unit 3 Flashcards
first discovered dna
frederick miescher
discovered that dna contained phospates
phoebus a. t. levine
discovered the helical structure by xray crystallography
rosalind franklin
described the 3-dimensional structure of the DNA molecule
james watson and francis crick
carries genetic information for the development and functioning of an organism
dna (deoxyribonucleic acid)
two types of dna that contain their genes
chromosomes and extra chromosomes
chromosomes and extra chromosomes example
plasmid
circular, double stranded dna attached to bacterial cell membrane
bacterial chromosomes
self-replicating extra chromosomal dna molecules
plasmids
types of plasmids
r factors, col factors, f (fertility) factors
code for antibiotic resistance
r factor
code for extracellular toxin production
col factors
plasmid that recombine itself with the bacterial chromosome
fertility factor
it is due to chemical alteration in dna
mutation
it could be spontaneous by chemical or physical means
mutation
one or more bases in there dna are altered
mutation
types of mutation
substitution, deletion, insertion
change of a single base
substitution
loss of a base
deletion
addition of a base
insertion
alter the dna gene content of bacteria
gene transfer
types of gene transfer
transformation, transduction, conjugation, transposition
occurs when plasmid dna is transferred from donor to recipient
conjugation
mechanism which enhances genetic flexibility among plasmids and bacterial chromosomes
transposition
segments of dna that can transpose or move extremely readily
transposons
other name for transposons
jumping genes
occurs when fragments of exogenous bacterial dna are taken up and absorbed
transformation
the recipient bacterium must be competent to absorb the exogenous fragments of bacterial dna
competence
transformation of genes from one bacterium to another results in:
a) change in pathogenicity of the bacterium b) change in the antibiotic sensitivity pattern of bacterium
occurs when fragments of chromosomal dna is transferred or transduced into a second bacterium by phage
transduction
