Chapter 8

Cell memory

The ability of differentiated cells and their descendants to maintain their identity.

Combinatorial control

The control of gene expression in which more than one regulatory protein is used and expression is allowed only in a specific combination of conditions.

Differentiation

process in which cells become specialized in structure and function

DNA methylation

The addition of methyl groups (�CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.

epigenetic inheritance

Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome.

gene expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

induced pluripotent stem cells (iPS)

Any cell, even a highly differentiated cell in the adult body, that has been genetically reprogrammed to mimic the pluripotent behavior of embryonic stem cells

long noncoding RNA (lncRNA)

A class of relatively long RNA molecules found in eukaryotes that do not code for proteins but provide a variety of other functions, including regulation of gene expression.

microRNA

A small, noncoding RNA molecule, typically about 21 bases long, that binds to mRNA to inhibit its translation.

positive feedback

A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state.

post-transcriptional control

Regulation of gene expression that occurs after transcription of the gene has begun; examples include RNA splicing and RNA interference.

Promotor

A region of DNA with a specific sequence that tells RNA polymerase where to begin transcription.

regulatory DNA sequences

DNA sequence to which a transcription regulator binds to determine when, where, and in what quantities a gene is to be transcribed into RNA

Regulatory DNA

A DNA sequence that can increase, decrease, turn on, or turn off the expression of a gene or a group of genes.

reporter gene

Gene encoding a protein whose activity is easy to monitor experimentally; used to study the expression pattern of a target gene or the localization of its protein product.

RNA interference (RNAi)

A technique to silence the expression of selected genes in nonmammalian organisms. The method uses synthetic double-stranded RNA molecules matching the sequence of a particular gene to trigger the breakdown of the gene's messenger RNA.

transcription regulators

proteins that determine whether and how frequently a gene will be transcribed into messenger RNA

transcription activators

speed up transcription by binding to region of DNA called enhancer

transcriptional repressor

A protein that binds to a specific regulatory region of DNA to prevent transcription of an adjacent gene.

differentiated cells contain what?

All the genetic instructions needed to direct the formation of a complete organism

List the 6 ways gene expression can be regulated for:DNA to RNA to Protein

1. Controlling when and how often a given gene is transcribed
2. Controlling how an RNA transcript is spliced or processed
3. Selecting which mRNA are exported from the nucleus to the cytosol
4. Regulating how quickly certain mRNA molecules are degraded
5

Many transcription regulators bind to DNA as ________

Dimers

Genes can be switched off by _________ proteins

Repressor

Genes can be switched on by _________ proteins

Activator

lac operon regulation

1. RNA polymerase must bind promoter and have access to the genes for 'on'
2. lac regulatory gene codes for repressor that binds to the operator when no lactose is present 'off'
3. binding of allolactose binds to repressor, preventing it from binding oper

Gene activation can occur at a distance in __________ cells

Eukaryotic

Chromosomes are arranged in DNA loops in
a) plant
b) animal
c) both

c) both plant and animal

True or false: a single transcription regulator can coordinate the expression of many different genes

True

True or false: combinations of few transcription regulators can generate many cell types during development

True

A combination of transcription regulators can induce a __________ cell into a _____________ into a pluripotent iPS cell

Differentiated
De-differentiated

A ________ feedback loop can generate cell memory
a) positive
b) negative

a) positive

5-methylcytosine occurs because of ........

Methylation of a cytosine base in the DNA double helix

Who inherits histone modification�son or daughter chromosomes?

Daughter chromosomes

What do miRNAs do?

regulate gene expression through targeting a complementary mRNA for destruction

RNAi can trigger what?

Transcriptional silencing

Long non coding RNA can serve as _________ bringing together proteins that function in the same cell process

Scaffolds

A differentiated cell can be reprogrammed into a _______ ________ by artificially expressing a different, specific set of regulators

Stem cells