Shared Flashcard Set

Details

Cell metabolism
gene regulation
29
Science
Undergraduate 2
09/22/2013

Additional Science Flashcards

 


 

Cards

Term
what are the benefits for eukaryotes from gene regulation?
Definition
  • respond to changes in nutrient availability
  • respond to enviromental stresses
Term
what is gene regulation necessary to ensure?
Definition
  • expression of genes in an accurate pattern during the arious developmental stages in the life cycle
  • differences among distinct cell types
Term
transcriptional factors
Definition

proteins that influence the ability of RNA polymerase to transcribe a given gene

have two main types

Term
General transcription factors
Definition
  • required for the binding of RNA pol to the core promoter and its progression to the elongation stage
  • necessary for basal transcription
Term
regulatory transcription factors
Definition
  • serve to regulate the rate of transcription of target genes
  • influence ability of RNA pol to begin transcription of particular genes
Term
activator
Definition
a regulatory protein that increases the rate of transcription
Term
enhancer
Definition
the sequence a activator (regulatory protein) binds to
Term
repressor
Definition
a regulatory protein that decreases the rate of transcription
Term
silancer
Definition
the sequence the repressor (regulatory protein) binds to
Term
combinatorial control
Definition

eukaryotic genes are regulated by many factors

  • 1+ activator proteins stimulating transcription
  • 1+repressors inhibiting transcription
  • activators/repressors being modified (binding small effector molecules, protein-protein interactions, covalent modification)
  • regulatory proteins alter nucleosome near promoter
  • DNA methylation may inhibit transcription
Term
transcription factor protein regions... or domains
Definition

have specific funcitons

  • one domain could be for DNA-binding
  • another provides a binding site for effector molecules
Term
motif
Definition
a domain, or portion of a domain, that has a very similar structure in many different proteins
Term
homodimer
Definition
formed by two identical transcription factors
Term
heterodimers
Definition
formed by two different transcription factors
Term
response elements are...
Definition
  • bidirectional (function forward or reverse)
  • usually located within a few hundred nucleotides upstream of promoter
Term
what are the tree common ways that function of regulatory transcription factors can be modulated?
Definition
  1. binding of small effector molecule, such as a hormone
  2. protein-protein interactions
  3. covalent modification such as phosporylation
Term
protein-protein interaction
Definition
example: two transcription factors to bind forming a homodimer on a response element on DNA
Term
steroid receptors
Definition

regultory transcription factors that respond to steroid hormones

(hormone binds to transcription factor)

Term
action of steroid hormones?
Definition

affect gene transcription

  • produced by endocrine gland
  • secreate into bloodstream
  • taken up by cells responding to the hormone
Term
what are the different ways in which cells respond to steroid hormones?
Definition
  • Glucocorticoids (influence nutrient metabolism)(promote glucose utilization, fat mobilization and protein breakdown)
  • Gonadocorticoids (estrogen and testosterone) (influence growth and funciton of gnads)
Term
how is chromatin remodeling carried out?
Definition
by diverse multiprotein machines that reposition and restructure nucleosomes
Term
what two conformations can the chromatin structure alternate between
Definition
  • closed (chromatin tightly packed)(transcription difficult/impossible)
  • open (chromatin acessible to transcription factors)
Term
what are three of the 50 enzymes that have been found in mammals to selectively modify the amino acid terminal tails of histones?
Definition
  1. acetylation
  2. methylation
  3. phosphorylation
Term
DNA methylation
Definition

a change in chromatine structure that silances gene expression (carried out by enzyme DNA methyltransferase)

common in some eukaryotes

Term
is DNA methylation heritable?
Definition

yes

may explain genomic imprinting

(specific genes in gametes are methylated)

Term
alternative splicing
Definition

pre-mRNA can be spliced in more than one way

produces more than one polypeptide with different amino acid sequences

large sections of teh coding region are the same, resulting in alternative versions of a protein that ahve similar functions resulting in enough difference in amino acid sequences to provide each polypeptide with its own unique characteristic

Term
stability of mRNA
Definition
  •  varies considerably (minutes or days)
  • can be regulated so that its half-life is shortened or lengthned (influencing mRNA concentration/consequently gene expression)
  • effected by factors such as
  1. length of polyA tail
  2. Destabilizing elements
Term

micro RNAs

(miRNAs)

 

Definition

and short-interfering RNAs (siRNAs) cause RNA interference where genes do not encode a protein and gives rise to small RNA molecules.

They are encoded by genes

Term
benefits of RNA interference
Definition
  • presents a newly identified form of gene regulation
  • may offer a defensive mechanism agains certain viruses (RNA double-stranded RNA viruses)
  • may play a role in silencing certain transposable elements (random insertion may place an element near a cellular promoter which will produce a silencing RNA)
Supporting users have an ad free experience!