Independent assortment
Sex
Crossing over
Alternative splicing
Mutations
Sending it to different environments
Acetylation of histone tails – lose and the gene is expressed
Methylation of the gene – controls its transcription
Random fertilization
Regulation of Gene Expression:
 Operons:
o A gene with a promoter and an operator
o Operator – works with something else to control the genes
 First 2 Operons:
o Tryptophan (amino acid) operon – default setting is turned on, but
when there’s tryptophan, the bacteria turn it off sometimes.
o Lac operon
 Upstream of a DNA strand means the RNA polymerase is going the other
way
 Operator also controls the RNA polymerase whether it’ll run through the
upstream or not
Tryptophan Operon:
 TrypR is a regulatory gene
 Tryptophan makes tryptophan. The repressor protein is inactive. When
tryptophan binds to the repressor protein, the repressor protein is active.
Then, it binds with the operator. Then it blocks RNA polymerase.
 Regulatory gene – the
 Corepressor
Lac Operon in E.coli:
 The default is turned off (the regulatory protein is active)
 The inducer binds with the repressor, which makes it inactive
 No milk, no lactase
 Have milk, have lactose
 Allolactose is the inducer, induces the lactase by binding to the repressor
18.5 diagram cAMP:
 Cyclic AMP (gay) – running out of sugar/last phosphate
 CAP protein is inactive, cAMP will bind and it’ll be activated
 Active CAP activates the RNA polymerase/activates the gene
 Get rid of the repressor and activator must bound to the promoter in
order for the gene to be expressed
 We have lactase, no lactose, no glucose
Prokaryotes regulates expression at the transcription level
Eukaryotes regulates expression at transcription, RNA processing and
translation.
Small interfering RNAs or micro RNAs – interferes or stops proteins by
complementarying the piece of protein, so that the protein won’t go to the
ribosome
Histone modifcations –
 The more acetylation, the more expression you get
Acetylation and methylation can control the gene expression
18.6:
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Demethylation and acetylation increases the gene expression
Transcription – primary transcript will control the expression
RNA processing –
Transport to cytoplasm –
Translation –
Secondary, tertiary, and quaternary structure –
Destination of the cell –
Attacking/Degrading the protein happens after expressing the gene
Epigenetic Inheritance:
 Something outside of your gene that can be inherited
 Inheritance of traits transmitted by mechanisms not directly involving the
nucleotide sequence
 If the thing that controls the gene isn’t coming from the cell’s genome
18.8 Diagram: Eukaryotic gene and its transcript
 Termination region is in a eukaryotic gene – area where termination
stops
 Enhancer (increase some property) – they act like promoters (attract
RNA polymerase)
 If those enhancers move or bend, then it’ll be next to promoters, which
will attract even more RNA polymerase (more transcription)
 Activators are chemicals that binds to the enhancer region and causes it
to bend to the promoter
18.9 Diagram:
 Distal control element – far away from the operon
 DNA bending protein – bends the DNA
 Activators are now over the promoter
 RNA polymerases are attracted
 One gene can make more than 1 different genes
18.10 Diagram:
 Albumin gene is in livers
o Activators are coming from the liver

o Binds to the enhancer making the albumin gene expressed,
crystalline gene isn’t expressed
Crystalline gene is in lens or eyes
o Activators bind to the enhancer making the crystallin gene
expressed, but albumin gene isn’t expressed
mRNA degradation Initiation of Translation –
Protein Processing and Degrading –
18.12 Diagram:
 Ubiquitin is the kiss of death
 Once the ubiquitin binds to the protein, the protein will enter the
proteasome
 The protein will be destroyed/destroyed
microRNAs
 Small single-stranded RNA molecules
RNA interference or small interfering RNAs
 Ds
Cell Differentiation – the process by which cells become specialized in structure
and function is based on the activators and the transcription factors
Morphogenesis – creation of form
Cytoplasmic determinants – maternal substances in the egg that influence the
course of early development
Cytoplasmic determinants give morphogenesis
Induction makes the something same, gives determination
18.16 Diagram:
 Embryonic stem cell is not determined and not differentiated
 Adult stem cell is determines, but not differentiated (Myoblast)
Pattern formation – Cytoplasmic determinants and inductive signals both
contribute to the development of a spatial organization in which the tissues and
organs of an organism are all in their characteristic places
Positional information – the molecular cues that control pattern formation
Homeotic genes – control whole set of patterns of genes
Embryonic lethals – mutations with phenotypes causing death at the embryonic
or larval stage
Maternal effect gene – genes from the mom that will affect the youngster
Egg-polarity genes – knowing the top and the end
Bicoid – two-tailed
Morphogens – any substances that changes the shape (which is the head which is
the tail)
Cancer – disruption of the cell cycle
Oncogenes – genes that cause cancer (problems with certain genes lead to
cancer)
Proto-oncogenes – code for proteins that stimulate normal cell growth and
division
Tumor-suppressor genes – inhibit cell division, makes proteins that suppress the
cell cycle
MPF and CDK (mitosis ch. 14)
18.20 Diagram:
 Translocation or transposition (epistasis) can cause oncogene
 Lose control of its expression due to the moving of its locus
18.21 Diagram:
 Cell cycle-stimulating pathway
 Cell cycle-inhibiting pathway – UV light comes in and damages the
genome
 Point mutation
Ras gene – a gene that’s related to cancer found in rats (uncogene)
P53 gene – gene found in humans (uncogenes)
One cancer can lead to many other cancers