BIO 240 Topics 8,9,10 || WELL-ENLIGHTENED WITH CORRECT ANSWERS.
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Course
BIO 240
Institution
BIO 240
Replication correct answers DNA must be retained intact, yet copied to make new cells
Transcription correct answers DNA must be turned into multiple "working copies" to provide instructions for enzymes/structural proteins production
Translation correct answers RNA must be read and decoded to ...
BIO 240 Topics 8,9,10 || WELL-ENLIGHTENED WITH
CORRECT ANSWERS.
Replication correct answers DNA must be retained intact, yet copied to make new cells
Transcription correct answers DNA must be turned into multiple "working copies" to provide
instructions for enzymes/structural proteins production
Translation correct answers RNA must be read and decoded to form the enzymes/structural
proteins of the cell
DNA repair correct answers systems must have the ability to deal with damage
Transcription in Bacteria correct answers - involves RNA polymerase = core enzyme + sigma
factors
- sigma factor picks certain genes and not other genes for transcription
- sigma factors directo RNA pol to a promoter
Rho-dependent correct answers rho protein follows RNA pol and removes it from the DNA
when it reaches a termination sequence
- half of genes terminate this way
Rho-independent correct answers RNA hairpin loop forms, causing RNA pol to dissociate
from the DNA
- stops on a weak codon and falls off DNA ("terminator loop" stops it)
Translation in Bacteria correct answers - the small ribosome subunit and the Shine-Dalgarno
sequence help align all the machinery to the correct starting location
- multiple Shine-Dalgarno sequences allow bacterial mRNA to be polycistronic
Polycistronic correct answers more than one gene in the mRNA strand
Regulation correct answers - must conserve resources so you do not die
- cells do not require all gene products at all times
- Different environmental conditions
- Permits condition-specific responses
Constitutive genes correct answers - means that there is no regulation and they stay on all the
time
- key cellular enzymes are constitutive
ex. (TCA cycle, ATP synthases)
Inducible genes correct answers only required at particular times
Regulating protein activity correct answers 1. Covalent modifications
- covalent modifications may also alter enzyme conformations
- 3 covalent modifications
ex. phosphorylation, acetylation, methylation, glycosylation (attach these molecules and it
changes the conformation of the active site)
, - some covalent modifications increase enzyme activity and some decrease
2. Allosteric Regulation
- other site
- involves allosteric proteins/ enzymes
- many enzymes use allosteric regulation mechanisms
- activity inhibition or activation from binding of an allosteric effector molecule
- in some cases makes the substrate bind better
- in other cases it causes the substrate to not bind efficiently
- this alters the conformation and the substrate and no longer bind (for inhibition)
The Operon correct answers transcriptional unit with a series of structural genes and their
transcriptional regulatory elements
ex. the lac operon
Regulating Transcription correct answers - Energy is conserved by controlling the synthesis
of enzymes
- Many control mechanisms work to prevent transcription of genes when they are not
required
- Positive and negative control (E. coli has genes under one/both/neither)
- Some operons can have more than one promoter, each with own control system
Positive control of transcription correct answers - allosteric protein acts to activate mRNA
synthesis
- regulatory protein helping transcription to proceed more efficiently
- common for catabolic genes
- RNA polymerase and sigma factor don't bind very well to the promoter (an activator helps)
Effectors correct answers Effectors are small molecules that binds to activator or repressor
proteins, modifying their gene regulation activity
Co-inducer or co-activator: a substance that turns on enzyme production
- increases transcription by enabling an activator or disabling a repressor
Co-repressor: a substance that binds and activates a repressor
- decrease transcription by enabling a repressor
Negative control of transcription correct answers - allosteric protein acts to prevent mRNA
synthesis
- stops transcription
- involves operator site and a regulatory protein
- may involve specific repression or induction in response to conditions
Repression correct answers - inhibit transcription in response to a signal
- minority of enzymes are controlled by repression
- typically affects anabolic enzymes
Induction correct answers - derepression of enzyme production in response to a signal
- typically affects catabolic enzymes
- ex. lac operon
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