BIO 340 ANSWERS AND QUESTIONS SET A+
✔✔CAP - ✔✔catabolite activator protein
✔✔lacl - ✔✔repressor protein
-contains two binding sites, one for the operator and one for allolactose (the inducer)
-I⁻unable to bind to operator
✔✔lacZ - ✔✔B-galactosidase
-cleaves lactose into monosaccharides (glucose and galactose)
✔✔lacY - ✔✔permease
-faciilitates lactose transport across the cell membrane
✔✔lacA - ✔✔transacetylase
- protects against harmful by-products of lactose metabolism
✔✔lacO - ✔✔operator
-binds repressor proteins to black transcription of operon genes
✔✔lacP - ✔✔promoter
-binds RNA polymerase
✔✔Which molecule serves as the inducer for lac operon? - ✔✔allolactose
-allolactose inactivates the lac repressor, which allows transcription of the lac operon to
occur
✔✔Which of the following conditions will result in the GREATEST levels of transcription
of the lac operon? - ✔✔lactose and cAMP present, glucose absent
-soem pactos is converted to allolactose, which inactivates the lac repressor, and cAMP
activates CAP. The combination of inactive repressor and active CAP results in the
highest level of transcription of the lac operon
***LACTOSE & CAMP NEEDED***
, ✔✔Which of the following mutations will result in LOWEST level of transcription of the
lac operon when lactose is present? - ✔✔a mutation int eh lac repressor that prevents it
from binding allolactos
-a mutation that prevents the lac repressor from binding to the inducer, allolactos, will be
uninducible. These mutations are known as super-repressors because they cannot be
removed from the operator even in the presence of allolactos
✔✔Chromatin Structure - ✔✔-human DNA is about 2m long
fits in the nucleus, which is 10⁻⁵ m in diameter
-condenses and organized
✔✔nucleosome - ✔✔basic unit of chromatin organization
✔✔IMPORANT step in gene regulation - ✔✔allowing regulatory proteins to access DNA
(chromatid remodeling and modification:unwrapping DNA)
-occurs either before or simultaneously with transcription imitation and elongation
✔✔chromatin remodeling - ✔✔-sliding nucleosomes along DNA
-removing nucleosomes
✔✔chromatin modification (covalent) - ✔✔-adding or removing acetyl or methyl groups
-alters DNA binding affinity to nucleosomes
✔✔histone acetlytransnferase (HAT) - ✔✔activates transcription (loosens)
✔✔histone deacetylase (HD or HDAC) - ✔✔deactivates transcription (tighten)
✔✔what effect will histone lysine acetylation have on chromatin structure? - ✔✔loosen it
up
✔✔transcriptional control - ✔✔no mRNA synthesis
✔✔translational control - ✔✔no protein synthesis
✔✔post-translational control - ✔✔no product due to regulation of enzymes activity
✔✔**no inhibition or obstruction of a gene --> transcription --> translation is constitutive
expression** - ✔✔
✔✔**modifications of the gene expression pathway is regulated, different levels of
control** - ✔✔
✔✔negative control - ✔✔the absence of an INDUCER allows the repressor protein and
or it co-repressors to INHIBIT transcription.
✔✔CAP - ✔✔catabolite activator protein
✔✔lacl - ✔✔repressor protein
-contains two binding sites, one for the operator and one for allolactose (the inducer)
-I⁻unable to bind to operator
✔✔lacZ - ✔✔B-galactosidase
-cleaves lactose into monosaccharides (glucose and galactose)
✔✔lacY - ✔✔permease
-faciilitates lactose transport across the cell membrane
✔✔lacA - ✔✔transacetylase
- protects against harmful by-products of lactose metabolism
✔✔lacO - ✔✔operator
-binds repressor proteins to black transcription of operon genes
✔✔lacP - ✔✔promoter
-binds RNA polymerase
✔✔Which molecule serves as the inducer for lac operon? - ✔✔allolactose
-allolactose inactivates the lac repressor, which allows transcription of the lac operon to
occur
✔✔Which of the following conditions will result in the GREATEST levels of transcription
of the lac operon? - ✔✔lactose and cAMP present, glucose absent
-soem pactos is converted to allolactose, which inactivates the lac repressor, and cAMP
activates CAP. The combination of inactive repressor and active CAP results in the
highest level of transcription of the lac operon
***LACTOSE & CAMP NEEDED***
, ✔✔Which of the following mutations will result in LOWEST level of transcription of the
lac operon when lactose is present? - ✔✔a mutation int eh lac repressor that prevents it
from binding allolactos
-a mutation that prevents the lac repressor from binding to the inducer, allolactos, will be
uninducible. These mutations are known as super-repressors because they cannot be
removed from the operator even in the presence of allolactos
✔✔Chromatin Structure - ✔✔-human DNA is about 2m long
fits in the nucleus, which is 10⁻⁵ m in diameter
-condenses and organized
✔✔nucleosome - ✔✔basic unit of chromatin organization
✔✔IMPORANT step in gene regulation - ✔✔allowing regulatory proteins to access DNA
(chromatid remodeling and modification:unwrapping DNA)
-occurs either before or simultaneously with transcription imitation and elongation
✔✔chromatin remodeling - ✔✔-sliding nucleosomes along DNA
-removing nucleosomes
✔✔chromatin modification (covalent) - ✔✔-adding or removing acetyl or methyl groups
-alters DNA binding affinity to nucleosomes
✔✔histone acetlytransnferase (HAT) - ✔✔activates transcription (loosens)
✔✔histone deacetylase (HD or HDAC) - ✔✔deactivates transcription (tighten)
✔✔what effect will histone lysine acetylation have on chromatin structure? - ✔✔loosen it
up
✔✔transcriptional control - ✔✔no mRNA synthesis
✔✔translational control - ✔✔no protein synthesis
✔✔post-translational control - ✔✔no product due to regulation of enzymes activity
✔✔**no inhibition or obstruction of a gene --> transcription --> translation is constitutive
expression** - ✔✔
✔✔**modifications of the gene expression pathway is regulated, different levels of
control** - ✔✔
✔✔negative control - ✔✔the absence of an INDUCER allows the repressor protein and
or it co-repressors to INHIBIT transcription.
