Ch 8 Flashcards
Describe how DNA serves as genetic information.
Flows from DNA to RNA to proteins.
replication-transcription-translation
polymerase
copies DNA
semiconservative
double helix of parent DNA splits to make daughter strand
*one old to make one new
protein synthesis
translation from RNA
transcription
DNA is transcribed to make RNA
*R in transcRibed for RNA
What is the direction of DNA synthesis
5’ to 3’
prokaryotes protein synthesis
simutaneous transcription and translation- single circular DNA
eukaryotes protein synthesis
uses exons and introns- introns cut out and exons glued together w snRNPs
operons
a set location of DNA that code for a gene
operon examples
lac operon- induction
trp operon- repression
3 parts of an operon
- control region- where promoter located
- operator- on/off switch
- structural genes
constitutive genes
expressed at a fixed rate
repressible genes
on until off- blocks polymerase
inducible genes
off until turned on- blocks polymerase
catabolic genes
needs food source
epigenetic control
methylating nucleotides- methylated (off) genes are passed to offspring
- not permanent
- biofilm behavior
microRNA
RNA is degraded
spontaneous mutations
occur in the absence of a mutagen
base substitution mutation
point mutation w outcome of missense or nonsense mutation
frameshift mutation
insertion or deletion of one or more nucleotide pairs
chromosome
structure containing DNA that physically carries hereditary information; the chromosomes contain the genes
gene
a segment of DNA that encodes a functional product, usually a protein
DNA nucleotides
adenine, thymine, cytosine, and guanine
DNA synthesis (6) Replication
- DNA copied by DNA polymerase in the 5’-3’ direction
- Initiated by an RNA primer
- leading strand is synthesized continuously
- lagging strand is synthesized discontinuously
- Okazaki fragments
- RNA primers are removed and Okazaki fragments joined by a DNA polymerase and DNA ligase
replication fork
point where strands of DNA split
outcome from base mutation
missense (change in amino acid) or nonsenses mutation (results in a stop codon)
how are mutations repaired?
photolyase- seperates thymine dimers
excision repair
horizontal gene transfer
transfer of genes between cells of the same generation
4 methods of horizontal gene transfer
- genetic transformation
- genetic recombination
- conjugation
- transduction by bacteriophage
vertical gene transfer
occurs during reproduction between generation of cells- parent to daughter cell
plasmids
contain genes for resistance (antibiotic), conjugation (sex pili), and production of toxins
transposons
segments of DNA that can move from one region to another
promoter
starts transcription process- where RNA polymerase binds to the DNA strand
terminator
stop codon that ends transcription
codon
3 nucleotide sequence where mRNA is translated
AUG- start codon
anticodon
codons found on the tRNA
mRNA
created at the end of transcription- what codes the DNA
ribosome
where protein synthesis occurs
rRNA
makes up a ribosome
tRNA
transfer RNA that bring the amino acid that combines with the mRNA to make proteins
