Unit 4 DNA Flashcards
operon (3)
- found in bacteria and phages
- consisting of a promoter
- an operator
Operator
A sequence of nucleotides to which an active repressor can attach
What does the binding of a repressor prevent
Prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon
Promoter
binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place
Repressor
A protein that inhibits gene transcription happens in both prokaryotes and eukaryotes
RNA Polymerase
an enzyme responsible for copying a DNA sequence into an RNA sequence, duyring the process of transcription.
Lagging strand
- a discontinuously synthesize DNA strand
- elongates by means of okazaki fragments
- synthesized in a 5’to 3’ direction away from the replication fork
Leading strand
- The new complementary DNA strand synthesize continuously
- along the template strand toward the replication fork
- in the mandatory five prime to three prime direction
Transformation
- a change in genotype and phenotype due to the assimilation is external DNA
- horizontal gene transfer
helicase
An enzyme that untwists the double helix of DNA at replication forks separating the two strands and making them available as template strands
miRNA
Single-stranded RNA molecule that can degrade or prevent translation of an mRNA with a complementary sequence
splicesomes
splice mRNA by interacting with the ends of an RNA intron
why does tRNA have the shape it has?
hydrogen bonds hold it together
feedback inhibition
a matabolic pathway acts as an inhibitor of an enzyme within that pathway
transduction
- a process in which phages (viruses) carry bacterial DNA from one bacterial cell to another.
reverse transcriptase
an enzyme coded by certain viruses (retroviruses) that use RNA as a template for DNA synthesis
framshift mutation
it occurs when nucleotides are inserted/ deleted from a gene AND THEN the number inserted/deleted is not a MULTIPLE OF 3. results in improper coding
exons
- the real gene
- expressed/ coding DNA
what region can exons refer to?
the region of DNA from which the sequence was transcribed
intron
- the junk
- in between sequence
coordinately regulated cluster of genes who’s products function in a common pathway
operon
RNA primer
- builds by primase
- serves as a starter sequence for DNA polymerase III
plasmid (4)
- small ring or DNA that carries few genes
- replicates separately from bacterial chromosomes
- can carry antibiotic resistance
- used in cloning
point mutation
- single base change
- base pair substitution
transcription
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase
translation
plate where the code in the mRNA is converted into an amino acid sequence in a protein
acetylation of histone proteins
DNA binding proteins to interact with exposed sites to activate gene transcription and downstream cellular functions
methylation of DNA
- when methyl groups are added to the DNA molecule
corepressor
substance that inhibits the expression of genes
trp operon
codes for the components for production of tryptophan
DNA polymerase 1
essential for removing of the RNA primers from the fragments and replacing it with the required nucleotides
DNA polymerase 3
essential for the replication of the leading and the lagging strands
mRNA
molecule carries a portion of the DNA code to other parts of the cell for processing
tRNA
molecules that carry amino acids to the ribosome for polymerization into a polypeptide
rRNA
- makes polypeptides
- (assemblies of amino acids) that go to make up proteins.
