unit 2 chap 8 Flashcards
how are genotype and phenotype connected?
through rna
how is the genotype preserved?
replication
genotype vs phenotype
genotype - the genetic makeup of an individual
phenotype - observable characteristics of an individual
prokaryote genome
- single circular chromosome
- inheritance through vertical and horizontal transmission
what is the process of gene expression
dna –> rna –> protein
transcription
dna –> rna
uses mrna to go from DNA to rna using rna polymerase
translation
rna –> protiens
uses trna to read mrna and bring amino acids to be linked
what is the function of rrna
direct the steps of protein synthesis
what is the function of the ribosome
where protein synthesis takes place by making peptide bonds with rrna
sense vs antisense
sense - dna storage 5’ to 3’
antisense - what mrna transcripts
auxotroph
mutant organism that requires a particular nutrient that the normal one doesn’t
what are the different effects of mutation?
silent
- it doesn’t affect the
lethal
- kills the host
beneficial
- mutation helps w survival
what is mutations caused by chemical or radiation called?
mutagens
spontaneous mutation
random mistakes during replication
types of base substitution
missense mutation
- non lethal
- amino acid subsitituion
nonsense mutation
- lethal
- premature stop codon forms
frameshift
- lethal
- insertion or deletion of a single base
vertical vs horizontal gene transfer
vertical - identical daughter cells
horizontal - new combination of genes(donor DNA may recombine w recipient chromosomal DNA and form new gene)
what are the different types of horizontal gene transfer
transformation,
conjugation,
transduction,
transformation
- upatake of “naked DNA” form the environment
- requires competence, come naturally competent and others can be artificially competent( by chemical or electrical shock)
- if cell not competent DNA is degraded
conjugation
- transfer of dna via cell to cell contact (donor - recipient)
- uses sex pillus
- uses f+ and f- cells
- f+ and f- results in f+
- f- and hfr results in recombinant f- cell(bc f+ factor is at end of chromosome and cant stay connected long enough for it to transfer)
transduction
- dna transfer via viral intermediate(phages)(a part of viral replication)
- viral DNA mix w host and when lysis each virus born can have part of host and part of of viral and go insert to other cells
- generalized transduction: any host gene can transfer
- specialized transduction: only specific genes(ex shiga toxin, diphtheria toxin, cholera toxin)
transposition
- transfer of transposons(have a transposase gene that rec inverted repeat sequences and snips it and jumps around)
2 types- simplest: insertion sequences: have only transposase
- complex: have transposase + other genes
- transposons can move from cell to cell via plasmids or viral DNA(transposon can jump to plasmid from chromosome and that’s transferred)
recombination
RecA protein - mediates recombination btwn donor and recipient
- occurs at crossbridges
- allows gain of new functions, repair defective/damaged DNA and genes, promotes diversity
Frederick Griffith principle
discovered that dead virus dna can still infect live virus
plasmids
small extra chormosomal circular segments of dna
- replicate autonomously and contain own origin or replication
- conjugative plasmids are trasferable have f+ factor and have origin for conjugative transfer
- metabolism, virulence and resistance genes on plasmid
- can have artificial plasmid
what is the difference btwn hfr and f+ cells
f+ have f+ strain in plasmid
hfr have f+ in chromosomes(comes from recombination btwn chromosomes and plasmid)
transposons
mobile genetic elements naturally jump around chromosome
happens every 10^-5 to 10^-7/generation
