Chapter 19: Gene Expression Flashcards
Gene expression in eukaryotes is _______
Differential
Differential gene expression is responsible for:
- Forming specialized cell types (i.e. liver, muscle)
RNA splicing has this impact on gene expression:
Splicing means that the same DNA sequence can translate into several different types of proteins
Identical twins having different hair type is caused by
Different expressed alleles and different gene regulation
Mosaicism is a condition where:
The same gene can result in differently expressed phenotypes
I.E. people with differently colored eyes
Both eukaryotes and prokaryotes control gene expression at these levels:
Transcription, post-transcription, translation, post-translation
These levels of gene expression control are unique to eukaryotes
- Chromatin remodeling
- RNA processing
- Regulation of mRNA life span or stability
Chromatin is:
A single strand of DNA compacted into a size that can fit into a cell nucleus
Chromatin condensation means that:
It is too dense to be read by RNA Polymerase and thus can’t be transcribed
Chromatin condensation plays a key role in regulating gene expression
Chromatin remodeling is:
A process where chromatin around target genes is decondensed so that it is readable by RNA Polymerase
Cells detect molecular signals to do these two things
- Produce specific proteins
2. Trigger transcription
Chromatin contains _____ wrapped around _____
DNA, Nucleosomes
Nucleosomes consist of:
Negatively charged DNA wrapped twice around 8 positively charged histone proteins
Chromosomes reside in _____ _____ of the nucleus
Distinct territories
Chromatin is remodelled in these 3 ways:
- DNA Methylation
- Histone modification
- Chromatin-remodelling complexes
DNA Methylation adds _____ to cytosines in DNA
methyl (-CH3) groups
Methylated CpG sequences:
- Are recognized by proteins
2. Trigger chromatin condensation
Actively transcribed genes usually have ____ methylated CpG sequences near promoter
few
More Methylation = ______ Transcription
Less
The Codon for a Methyl Group is:
CG
Histone protein modification can be caused by:
- Acetyl Groups (-COCH3)
- Methyl Groups (-CH3)
- Phosphate groups and short peptide chains
Histone protein modification can promote either _______ or ________
Chromatid condensation or decondensation
Adding Acetyl means ________
Chromatin decondenses (less compact)
Removing Acetyl means _________
Chromatin condenses (more compact)
A histone code is __________
A set of particular modifications that sets the state of condensation for particular genes
True or False: Acetylation of histones is usually associated with activation of genes
True
What is the function of Histone acetyltransferases (HATs)
Adds acetyl groups to histones, decondensing chromatin (decompacting)
What is the function of Histone deacetylases
Removes acetyl groups from histones, leading to chromatin condensation (compacting)
“Go” (correlated with increase in transcription) processes for gene expression
Acetylation of histones, DNA demethylation
“Slow” (correlated with decrease of transcription) processes for gene expression
Deacetylation of histones, DNA methylation
Cancers involve _________
Uncontrolled cell division
Mutations lead to cancer when they affect:
- Genes that stop or slow cell cycle
2. Genes that trigger cell growth and division by initiating specific phases of cell cycle
True or False: Many of the genes that are mutated in cancer influence gene regulation
True
Tumor suppressors are:
Proteins that stop or slow cell cycle when conditions are unfavorable (ex. DNA damage)
Proto-oncogenes are:
Genes that stimulate cell division (stimulate cell cycle to continue)
Proto-oncogenes are normally active:
Only when conditions for cell division are favorable
In cancer cells, proto-oncogenes:
Stimulate growth at all times because a mutation has converted them to oncogenes
True or False: For cancers to develop, only one mutation must occur within a single cell
False
Transcription factor p53:
Is a tumor suppressor, promotes DNA repair and cell cycle arrest
Will a DNA strand with more acetyl groups will be more or less condensed? Will this increase or decrease RNA transcription.
Less condensed, will increase RNA transcription
Chromatin remodeling complexes are:
Proteins that either knock histones out of chromatin or can slide nucleosomes around to remodel the chromatin
Gene expression regulation leads to _________ which leads to __________
Differential gene expression, cellular differentiation (or cellular specialization)
Define cellular differentiation (AKA cellular specialization)
Differently functioning cells as a result of differential gene expression
Define an Oncogene
A malfunctioning proto-oncogene that promotes cell division at all times instead of only in favorable conditions
Histones are __ charged and DNA is __ charged
Positively, Negatively
Gene expression regulation is the regulation of:
What specific genes are expressed
This causes differential gene expression and therefore cellular differentiation/specialization
Histones are acetylated by ____ and deacetylated by ____
HATs (Histone acetyltransferases)
HDATs (Histone deacetylases)
Methyl groups are attached when you see a __ and a __ next to each other in a DNA sequence
C, G
Methyl groups are added to DNA sequences by _____
DNA methyl transferase
More DNA Methylation means:
More compact DNA, less gene expression
Unique features of info flow in eukaryotes
- RNA Processing
- Histone acetylation
Regulation at translation
Ribosomes don’t bind to each other
Post-translational regulation
Activation and deactivation of proteins via phosphorylation or dephosphorylation