unit 02: transcription and translation (final)

electron micrograph

photo taken using an electron microscope

genome

total DNA of an organism

chromosome

a molecule of DNA that contains genes

genotype

the hereditary (genetic) information within an organism’s genome

phenotype

the resulting expression of the genotype within an organism resulting in observable traits

deletion

one or more nucleotides are missing

insertion

one or more nucleotides are added

point mutation

change in a single base in the DNA, resulting in a different base pair

silent mutation

point mutation that changes a codon but not the resulting amino acid in the protein

nonsense mutation

point mutation that adds an early stop codon

wild-type

reference/non-mutant genotype in gene of interest

mutation

change in the genotype

mutant

an organism with a changed genotype, usually in a specific location in the DNA

missense mutation

point mutation that changes a codon and results in a different amino acid in the protein

frameshift mutation

change in the reading frame that often abolishes protein function

CRISPR/Cas9 genome editing

molecular tool used to perform highly specific edits on an organism’s genome (assuming genome already sequenced)

transcriptional control

turn transcription off/on and change how much mRNA is made

translational control

control amount of protein made by changing mRNA stability

post-translational control

control protein activity by modifications and degradation

operon

set of coding sequences for related proteins, all sharing the same promoter and terminator

operator

region of DNA where a regulatory protein binds

zero expression

no possibility of gene expression

basal expression

very low “background” level of gene expression from random low level of RNA polymerase binding to a promoter

low expression

more than bakground gene expression, but not abundant

high expression

transcription is occurring rapidly, many transcripts are being made, RNA polymerase recruitment to the promoter is strong

constitutive gene expression

gene expression is always on, but could be high or low

differential gene expression

gene expression is regulated up or down depending on the developmental or environmental conditions

negative transcriptional regulation

if the repressor protein binds to the operator region of DNA, it inhibits recruitment of RNA polymerase, and transcription does not occur

positive transcriptional regulation

RNA polymerase can bind to the promoter only if an activator protein binds the operator site on DNA near the promoter

strong promoters

have high affinity for binding RNA polymerase

weak promoters

have low affinity for binding RNA polymerase

anabolic operons

produce proteins that synthesize/build something

catabolic operons

produce proteins that break something down