Gene Regulation Flashcards
protein structures**
primary protein structure: sequence of amino acids that make up protein (peptide bonds)
secondary protein structure: amino acids linked by weak hydrogen bonds –> forms either alpha helix or beta sheet
tertiary protein structure: unique 3-D structure of protein –> links of alpha helixes and beta sheets; single protein
quaternary protein structure: multiple proteins coming together to form complex (multiple tertiary proteins)
post-translational modification + 3 examples
chemical changes that occur after a protein has been produced; modification to one or more amino acid on protein that has been translated
examples: methylation, lipidation, acetylation, hydroxylation
what is a mutation?**
changes in nucleotide sequence of DNA; can be errors or environmental changes
types of mutations**
point mutations = one DNA base change
- silent mutation: no effect on amino acid
- missense mutation: changes amino acid from one to another
- nonsense mutation: change creates stop codon
- insertions and deletions (frameshift mutations, changes entire frameshift) : inserts or deletes nucleotide –> NOTE: 3 nucleotides added or removed = silent
sickle cell anemia**
- missense mutation
- caused by change in glutamic acid to Valene
- impacts hemoglobin protein in blood cells
- leads to structural change which leads to sickle cell shape
- sickle celled cells do not carry oxygen as efficiently as normal red blood cells –> leads to oxygen deprivation
operons
cluster of related genes controlled by single promoter during transcription
which is in which cell:
operons, introns, DNA polymerase, RNA polymerase
operon: only in prokaryotes
introns: only in eukaryotes
DNA polymerase: in both types –> for DNA replication
RNA polymerase: in both –> for transcription; to transcribe DNA into RNA
operon examples
Lactose operon (in E. coli): operon codes for 3 proteins, LacZ (B-galactosidase), LacY, and LacA that are involved in breakdown of milk sugar, lactose
- negative regulation: when lactose absent, repressor protein, Lac1, binds to operator region, and prevents transcription of operon
- if lactose is present –> binds to repressor protein, Lac1 –> Lac1 changes shape + releases hold on operator region which allows transcription of operon and production of proteins LacZ, LacY, LacA
Tryptophan operon (of E.coli): synthesis of amino acid, tryptophan –> when lots of tryptophan, tryptophan binds to repressor protein, TrpR, and promotes TrpR binding to operator region which blocks trp operon production
Comparison of Lac1 and TrpR:
- lactose binds to repressor protein, Lac1, and prevents it from binding to operator
- trp binds to repressor, TrpR, and that binds to operator
what is an operator?
region within promoter where transcriptional repressor binds
epigenome
chemical modification in histones (protein complexes which wrap around DNA) or on DNA –> same as post-translational modifications just done on histones (methylation, acetylation, phosphorylation)
- changes how DNA is wound
- changes in gene expression without mutation*
genetic diseases
sickle cell anemia: autosomal recessive disease
Tay Sachs: autosomal recessive disease –> cannot produce enzyme that metabolizes lipids used in brain tissue
Down’s syndrome: nondisjunction; 3 copies of chromosome 21
Klinefelter’s syndrome: nondisjunction; mother’s XX pair doesn’t separate –> son has XXY
