Final Review Flashcards
What determines if you are male or female?
Presence of SRY gene
If male doesn’t have sry gene then they develop as
Female
What is the difference between post transcriptional modifications and post translational modifications
Post Transcriptional - g cap, poly A tail, splicing
Post Translational - phosphorylation, methylation, acetylation, proteolysis, glycosylation
How do we initiate transcription
Attach to Promoter
What is special about the promoter, what is found within it
Transcription factors bind to TATA box, CpG islands
Difference between DNA methylation and histone
DNA methylation - decrease transcription
Histone Methylation - increases transcription
polymorphism
DNA variation that is really common
Penetrance vs Variable Expressivity
Penetrance - Proportion of individuals with a certain genotype that shows the expected phenotype
Variable Expressivity - Variable degree to which the genotype can be expressed in an individual
X-
XXY-
XXX-
XYY-
X- turner syndrome
XXY- kinefelter syndrome
XXX- normal
XYY- normal
Role of SRY gene in sex determination
Embryo develops testies, no SRY develops ovaries
What are the 3 main types of inheritance of mitochondria and chloroplast DNA
Maternal organelles in offspring derived from the mother
Paternal from father
Biparental from either the mother or the father
What is the difference between DZ and MZ twins
DZ - fraternal
MZ - identical
How to do concordance rate?
36 MZ twins both with, 40 MZ twins half with, 336 MZ twins neither
36(36+40)=47%
Hybrid Vigor
cross between two different true breeding homozygotes result in stronger phenotype
Epigenetics
changes in expression in a gene of set of genes without a change in DNA sequence, changes are HERITABLE and stable, but are REVERSIBLE
What are epigenetics’ two main processes
DNA methylation, chromosomal protein alteration
Cytosine residues in DNA can be modified by the _____ addition of a _______ group
covalent, methylation
Clusters of CpG sites in the genome are called?
CpG islands, they are often found in promoters that are unmethylated
Effects of DNA methylation
attracts proteins that are involved in the repression of transcription
important for development
cause cancer mutations
What is chromatin remodeling
changes in chromatin structure
Acetyltion of histones modifies nucleosomes to make DNA more accessible results in ___________. Histones are demethylated nucleosomes that remain intact holding DNA compact results in ____________.
Increased transcription
Blocked transcription
Euchromatin vs Heterochromatin
Euchromatin - diffuse and light; contains DNA that is transcribed into mRNA
Heterochromatin - condensed and dark; DNA not transcribed, heavy methyls
Barr Bodies can be seen…
in interphase in human females (cheek cells)
Xist
non-coding RNA on the X chromosome
major effector of the X-inactivation process.
3 Things in X-Inactivation
early in development, random inactivation, result in clones
(Ex: Calico Cat)
DNA sequences regulate rate of transcription what are two examples of them
Promoters: directly in front of the gene
Enhancers: farther away
Both are DNA sequences
What are the two examples of transcription factors. They must assemble on the chromosome before RNA polymerase can bind to promoter
General and regulatory
_______ binds to the TATA box; then other transcription factors bind, forming a transcription complex
TFIID
TF interacts with RNA polymerase
Transcription factors regulate the rate of transcription
true
Positive and negative regulator examples
positive - enhancers, gene is not normally transcribed activator binds to stimulate transcrption
negative - silencers, gene is normally transcribed but binding of repressor prevents transcription
Can multiple genes be regulated at the same time
yes
Enzyme changes nucleotide sequences. RNA editing –> ________. They are NOT _________. Goes to specific locations and changes _____.
change mRNA, splicing, one
miRNA this is post transcriptional
small regulatory of noncoding RNA important for gene expression
RISC complex
uses the siRNA or miRNA as a template for recognizing complementary mRNA
What are the three ways to regulate mRNA translation:
miRNA, 5’ end if G cap is not present at mRNA translation, repressor proteins block translation directly
Protein Modifications:
Proteolysis, glycosylation, phosphorylation
Proteolysis - cleaving by proteases
Glycosylation - addition of sugars to form glycoproteins
Phosphorylation - addition of phosphate groups by kinases
How do CDKs get actively degraded
they are tagged with ubiquitin which binds to proteasome complex and are digested
Promoter gene expression depends on…
promoter, enhancers and multiple transcription factors
What is the most efficient way to regulate gene expression
mRNA transcription
a clustor of gene with a single promoter is an ______
operon
An operon consists of
a promotor, two or more protein coding genes, an operator (operator binds to a repressor protein which blocks transcription
Lac Operon is always off or on?
OFF it is inducable (need receptor to turn on)
How does lac work?
Lactose trigger on, binds to repressor, chhanges shape, falls off, translation ocurs
Mutation in LacI would always be ___ because repressor won’t be able to be made
off
Operator is mutated in LacI would cause it to be ___
ON, because it is only when the promoter is mutated that the LacI is off
The repressor protein has two binding sites:
one for operator
one for inducer
Inducer:
compound that inhibits gene expression by inhibiting a repressor
Activator:
Binds DNA directly to influence RNA polymerase
If the inducer is absent operon is ___
off, when bound it is on and the inducer binds changing the shape of the repressor
_______ binding next to the lac operon promoter activates the operon
CRP-cAMP
