Cell Biology: Chapter 8

What is differentiation?

when cells become different from one another

Why are cells differentiated?

they express (transcribe, translates) genes differentkly

What are examples of house keeping genes?

tRNA and mRNA

What are house keeping genes?

expressed in virtually every cell and type

Are house keeping genes directly responsible for differentiation?

no

How are house keeping genes in cells normally?

on and translated constantly

What do different cells express?

different numbers of genes

What is something that different cells within the same organism have?

same DNA

What is something that is different for different cells within the same organism?

different protein types

What is responsible for differentiation and how things are expressed?

spatial and temporal regulation

What are the two cell types (generalization)?

Stem and differentiated

What are stem cells?

cells that still can differentiate

What are differentiated cells?

can no longer change cell type

What is an example of gene expression being altered in response to external signals?

Hormones

What do hormones do?

change transcription at cellular level

What are hormones?

cell-to-cell communication molecule for regular gene expression

What can affect gene expression?

environmental factors (temperature, starvation)

How is expression regulated in the information flow pathway?

many diff levels

How can different cell types respond to the same regulatory signal/factor differently?

different combos of control for same gene

Where is regulation the most effective?

DNA level

What are regulatory DNA sequences recognized by?

transcription factors (TF)

What are transcription factors (TF)?

regulators that pos and/or neg regulate transcription

Where do transcription factors (TF) act?

major/minor groove or wrap around DNA

What kind of TF is required for all genes?

universal/general

What does TF binding to regulatory sequences control for most genes?

expression and expression levels

Where can regulatory genes be?

anywhere, any gene, on either side, and not necessarily close

What do all proteins interacting with DNA interact with?

specific sequences

What is the role of activators?

promotes binding

What is the role of repressors?

prevents binding

What is the role of trp operon in E. coli?

help produce tryptophan if needed

What the role of trp operon?

interacts with operator as inactive repressor so proper shape if achieved

When referring to trp operon, why is it important that tryptophan persence determines the proper shape?

Because tryptophan prevents RNA polymerase from interacting with the operator as the repressor shape is changed

What is trp operon in E. coli an example of?

environmental regulation

What is the role of lac operon in E. coli?

allows lactose use in glycolysis when glucose isn’t avaliable and only lactose is present

What does the lac operon have?

promoter and repressor

Why can eukaryotic TC regulation happen from a distance?

flexiblility

What is the TC complex formation formed by at the promoter?

via mediator activity

In eukaryotes, what does stacking layers of control through many transcription regulators allow for?

more control

What does each transcriptional mediator need?

multiple binding sites

What occurs when transcriptional mediators are interacting?

affectors mediate shape and then transcription

What can eukaryotic TC also be regulated by?

changes in chromatin packing

What can TC activators recruit to facilitate or decrease TC?

chromain-remodeling complexes (enzymes)

How is chromatin packing only allowed?

if transcription and regulation factors are present

What does chromatin packing use?

chromosome loop-forming clamp proteins

What are chromosome loop-forming clamp proteins?

allow sequences bind together so enhancer is closer to promoter

What happens if there is no DNA access or regulation?

TC turned off

What do enhances activate?

binding sequence

What is CRISPR in bacteria?

naturally occuring molecules from bacteria to combat viruses

Why does CRISPR glue things to itself?

so DNA isn’t cleaved and still can be used in genome

Because CRISPR depends on bacterial enzyme Cas9, what is Cas9 used for naturally?

break mutant copeies to replace with better ones

What is Cas9 referred to as?

repair mechanism

Why does Cas9 hydrolyze dsDNA?

to form ds breaks

Because CRISPR is not sequence specific, what does it rely on instead?

guide RNA

What is the role of guide RNA?

targets specific DNA sequences

What is guide RNA an example of?

small RNA

What parts of CRISPR allow for multiple applications for editing genes?

sequence specific guide RNA and non-sequence specific DNA hydrolysis

Why does CRISPR target one genome spot, not multiple?

huge sequence

What forms when Guide RNA invades ds DNA?

complimentary base pairs

Despite CRISPR being able to destroy genetic materials, why is it used in humans?

can be used anywhere with high specificity

What qualities of CRISPR allow it to be used in humans?

cheap and easy to utilzie

What is synthesized target RNA used for in humans?

treats sickle cell anemia in hemoglobin gnee

How does target RNA work?

finds mutated gene, binds to it, and breaks it. Broken is replaced with functional copy

What can eukaryotic TC regulation be the result of?

collective activity of many diff TF

What can different combos of TF result in?

diff cell types

What determines how different responses to TFs happen?

target cell and protein type

How many eukaryotic genes can be regulated simultaneously by a single TF?

many

What is glucocorticoid?

key that acitivates GCR

What does activated GCR do?

complete any # of combination locks depending on the cell/gene in question

What happens when differnet regulatory protein types are stacked?

diff cell types that interact with each other

What do genes in a structure do to other genes and structure?

regulate

How do different genes regulate other genes?

negative regulation