Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
52 Cards in this Set
- Front
- Back
An ___ is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway. |
operon |
|
The ___ is/are arranged sequentially after the promoter. |
Genes of an operon |
|
A ___ is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place. |
promoter |
|
A ___ codes for a protein, such as repressor, that controls the transcription of another gene or group of genes |
regulatory gene |
|
5. Regulatory proteins bind to the ___ to control expression of the operon. |
operator |
|
A ___ is a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter. |
repressor |
|
An ___ is a specific small molecule that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, thus switching an operon on. |
inducer |
|
What molecule binds to promoters in bacteria and transcribes the coding regions of the genes? |
RNA polymerase |
|
What is allosteric regulation? |
In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity. |
|
Under which conditions are the lac structural genes expressed most efficiently? |
No glucose, high lactose |
|
What happens to the expression of the lacI gene if lactose is not available in the cell? |
There is no change—the lacI gene is constitutively expressed. |
|
Which of the following enzymes converts ATP to cAMP? |
Adenylyl cyclase |
|
Regulatory proteins bind to _____. |
the operator |
|
operon is not transcribed |
lac operon: lactose absent; trp operon: tryptophan present |
|
operon is transcribed, but not sped up by the positive control |
trp operon: tryptophan absent; lac operon: lactose present, glucose present |
|
operon is transcribed quickly through postive control |
lac operon: lactose present, glucose absent |
|
Negative control:When lactose is absent |
the repressor protein is active, and transcription is turned off. |
|
Negative control:When lactose is present |
the repressor protein is inactivated, and transcription is turned on. |
|
Positive control:When glucose is absent |
another regulatory protein (CAP) binds to the promoter of the lac operon, increasing the rate of transcription if lactose is present |
|
Modification of chromatin structure:Methylation of histone tails in chromatin can promote condensation of the chromatin. T or F |
TRUE |
|
Modification of chromatin structure:DNA is not transcribed when chromatin is packaged tightly in a condensed form. |
TRUE |
|
Modification of chromatin structure:Some forms of chromatin modification can be passed on to future generations of cells. |
TRUE |
|
Modification of chromatin structure:Acetylation of histone tails is a reversible process |
TRUE |
|
An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter. |
This arrangement of genes is common in bacteria. For example, genes involved in lactose metabolism are clustered in the lac operon of E. coli, and genes involved in tryptophan metabolism are in the trp operon. |
|
What molecule binds to promoters in bacteria and transcribes the coding regions of the genes? |
RNA polymerase is the enzyme that binds to promoters and transcribes the coding regions of genes into RNA. |
|
What is allosteric regulation? |
In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity. |
|
Which of the following enzymes converts ATP to cAMP? |
Adenylyl cyclase converts ATP to cAMP, which helps CAP bind and facilitates binding of RNA polymerase to the lac promoter. |
|
What is the function of a spliceosome? |
RNA processing |
|
histone acetylation |
acetyl groups are attached to positively charged lysines in histone tailsloosens chromatin structure, promotes initiation of transcription |
|
DNA Methylation: |
addition of methyl groups (methylation) can condense chromatin; Reduces transcription |
|
phosphorylation |
the addition of phosphate groups; next to a methylated amino acid can loosenchromatin |
|
DNA Methylation |
*DNA methylation inactivates genes *Methylation patterns are inherited *Removal of methyl groups can turn on genes *Methylation permanently regulates expression of certain maternal or paternal alleles at start ofdevelopment |
|
Regulation of Transcription Initiation |
Chromatin-modifying enzymes control gene expression by making a region of DNA either more orless able to bind the transcription machinery |
|
Activators |
(specific transcription factors) bind to enhancer DNA sequences and then to mediatorproteins. |
|
Bending of DNA by a protein enables _________ to influence a distant promoter. |
enhancers |
|
Alternative RNA splicing |
*Enables multiple mRNA’s from same transcript *The primary transcript can be spliced in more than one way. *The two mRNA's are translated into different but related muscle proteins |
|
mRNA Degradation |
Lifespan of mRNA determined by untranslated (UTR) regions at 3’ end of molecule |
|
Protein Processing |
May be needed to make a protein functionMay involve chemical modification of the protein before it will function |
|
Protein Degradation |
Regulates length of time that protein functions |
|
Regulation by Noncoding RNAs |
Play multiple roles in controlling gene expression |
|
microRNAs (miRNAs) |
About 22 nucleotides long Bind to complementary mRNA Associate with one or more proteins in a complex Complex degrades target RNA or blocks its translation |
|
Small interfering RNAs (siRNAs) |
Similar size & function to miRNAs Blocking gene expression by siRNAs is called RNA interference (RNAi) |
|
Chromatin Remodeling by ncRNAs |
Can change chromatin structureResponsible for X chromosome inactivationfemale mammals, prevents expression of genes on one of X chromosomesCan cause re-formation of highly condensed heterochromatin at the centromere ofeac chromatidafter DNA replication |
|
Proto-oncogenes |
code for proteins that stimulate normal cell growth & division |
|
Genetic changes convert these to _______ (cancer causing genes) |
Oncogenes |
|
_________ (rat sarcoma gene) mutation leads to excessive cell divisio |
ras gene *Tumor suppressor genes inhibit abnormal cell division *Mutation in Ras makes Ras abnormally active |
|
Mutant cell cycle stimulating pathway |
- Mutation makes Ras abnormally active, with or without growth factor bound to receptor - leads to excessive cell division and cancer |
|
Excessive cell division (cancer) |
Tumor suppressor p53 gene stops cell cycle after DNA damage-p53 is known as “guardian angel of the genome” |
|
Multistep Cancer Development |
Involves somatic mutationsMutations accumulate over time (age)As you age, mutations accumulate, so older people tend to have more cancers |
|
DNA changes that can lead to cancer |
- One active oncogene (dominant) - Mutation/loss of several tumor-suppressor genes (recessive) |
|
Inherited Predisposition |
- Breast cancer: mutation in BRCA1 or BRCA2 gene increases susceptibility - DNA sequencing can detect these mutations |
|
Viruses associated with some 15% of human cancer cases |
- Epstein-Barr virus linked to Burkitt’s lymphoma- Papillomaviruses linked to cervical cancer - HTLV-1 virus causes type of adult leukemia |