AP Biology - 6.5, 6.6 Regulation of Gene Expression, Gene Expression, + Cell Specialization

what accounts for phenotypic differences b/w organisms?

differences in gene expression

define gene expression

process by which instructions in DNA are transcribed and translated into a functional protein

what are regulatory sequences?

• DNA stretches that interact w/ proteins

• can promote or inhibit protein synthesis

• assisted by regulatory proteins

the interactions of what two things controls transcription?

regulatory proteins + regulatory sequences

what do epigenetic changes relate to?

• involve modifications of DNA or histones

• slight chemical modifications → tight or loose packing of DNA

• packing + unpacking regulates gene expression

fill in the blank: observable cell-differentiation results from gene expression for -(1)- proteins

(1) tissue specific

true or false: cells within a multicellular organism have the same DNA sequences

• true

what are tissues

• groups of cells w/ the same function

• specific function derived from the presence of specific proteins

• phenotype based on gene combination expressed

define cell differentiation

cells within the same organism having different phenotypes

define transcription factors

• proteins that promote or inhibit transcription of gene

• presence helps determine how a cell differentiates

what is the result of sequential gene expression?

• the process of development from a undifferentiated cell to a differentiated cell

define operons:

• closely-linked genes producing a single mRNA molecule during transcription

• controlled by same regulatory sequence

operons are only found in…

prokaryotes

the lac operon is an example of an…

inducible system

what are the two types of regulatory systems?

inducible system + repressible system

key difference b/w inducible and repressible system:

• default state off vs. default state on

• inducer molecule vs. corepressor

what are inducers?

• molecules that can bind to regulatory protein + cause conformational change

• reg protein released from operator → RNA polymerase freed to transcribe operon’s genes

• ex. allolactose

what are other factors that help regulate the lac operon?

• amount of glucose

• low glucose → other TFs bind to reg sequence to further promote transcription

• high glucose → those TFs are absent

what are corepressor molecules?

• proteins that inhibit gene expression by binding to transcription factors rather than directly binding to DNA themselves

regions of an operon

• promoter

• operator

• genes to be transcribed

• terminator

define promoter

DNA region where RNA polymerase binds to initiate transcription

define operator

binding site for regulatory proteins which can influence the transcription of the operon genes

define terminator

nucleic acid sequence marking the end of an operon during transcription

transcription is initiated by the…

interaction b/w regulatory proteins, regulatory genes, and TFs

what do negative regulatory molecules do?

• they inhibit gene expression by blocking transcription

what do small RNA fragments do?

• encoded by DNA

• can break down mRNA in cytoplasm, can block transcription

gene regulation influences what?

• leads to differential gene expression and thus influences cell products + function