Karteikarten
Regulating Gene Expression
Karten in diesem Stapel (24)
- 1All the cells in an organism carry the same genes (DNA), but the structure and function of different cells varies. Why?Not all the genes in a cell are expressed (transcribed and used to make a functional protein) - they are selectively switched on or off
- 2Name the 3 levels in which gene expression is controlledTranscriptional level control
Post-transcriptional level control
Post-translational level control - 3Complete the sentences: Gene expression can be controlled at the transcriptional level by altering the ______ of transcription of ______. For example, increased transcription produces more ______, which can be used to make more protein.Gene expression can be controlled at the transcriptional level by altering the RATE of transcription of GENES. For example, increased transcription produces more MRNA, which can be used to make more protein.
- 4What are transcription factors?Proteins that bind to DNA and switch genes on or off by increasing or decreasing the rate of transcription
- 5What is the name for transcription factors that start transcription?Activators
- 6What is the name for transcription factors that stop transcription?Repressors
- 7TRUE OR FALSE: The shape of the transcription factor has no effect on its ability to bind to DNAFALSE
The shape of a transcription factor determines whether or not it can bind to DNA - 8Where do transcription factors bind to in eukaryotes?In eukaryotes, transcription factors bind to specific DNA sites near the start of their target genes - these are the genes they control the expression of
- 9Where do transcription factors bind to in prokaryotes?Control of gene expression often involves transcription factors binding to operons
- 10What is an operon?An operon is a section of DNA that contains a cluster of structural genes that are all transcribed together, as well as control elements and sometimes a regulatory gene
- 11What does the structural gene on an operon code for?The structural genes code for useful proteins, such as enzymes
- 12What are the control elements on an operon composed of?A promoter (a DNA sequence located before the structural genes that RNA polymerase binds to)
An operator (a DNA sequence that transcription factors bind to) - 13What does the regulatory gene on an operon code for?The regulatory gene codes for an activator or a repressor
- 14Complete the sentences: E. coli is a ___________ that respires glucose, but it can use _________ if glucose isn't available. The lac operon has three structural genes - ______, ______ and ______. The lac operon is around ________ base pairs long.E. coli is a BACTERIUM that respires glucose, but it can use LACTOSE if glucose isn't available. The lac operon has three structural genes - LAC Z, LAC Y and LAC A. The lac operon is around 6000 base pairs long.
- 15Describe the structure of the lac operon
- 16Outline what happens at the lac operon when lactose is NOT present
- 17Outline what happens at the lac operon when lactose IS present
- 18What is post-transcriptional level control?Control of gene expression that takes place after genes have been transcribed
- 19Complete the sentences: After transcription, mRNA in eukaryotic cells is ________ - that's because genes in eukaryotic DNA contains sections that don't code for _________ ______. These sections are called _________. The rest of the DNA that do code for amino acids are called ________.After transcription, mRNA in eukaryotic cells is EDITED - that's because genes in eukaryotic DNA contains sections that don't code for AMINO ACIDS. These sections are called INTRONS. The rest of the DNA that do code for amino acids are called EXONS.
- 20What happens to the introns and exons during transcription (before the mRNA strand exits the nucleus)?They are both copied into mRNA
Introns are removed from primary mRNA strands by a process called splicing - introns are removed and the exons are jointed together to form mature mRNA strands. This takes place in the nucleus. The mature mRNA then leaves the nucleus for translation. - 21What are mRNA strands containing introns and exons called?Primary mRNA transcripts
- 22What does post-translational level control involve?Protein activation
E.g. in protein synthesis, protein activation is controlled by molecules like hormones and sugars - 23Describe how some molecules control protein activation using cAMPSome molecules that control protein activation work by binding to cell membranes and triggering the production of cyclic AMP (cAMP) inside the cell.
cAMP then activates proteins inside the cell by altering their 3D structure. - 24PKA is an enzyme made of four subunits. What happens when cAMP binds? What happens when cAMP does NOT bind?When cAMP isn't bound, the four units are bound together and are inactive
When cAMP binds, it causes a change in the enzyme's 3D structure, releasing the active subunits
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- Der Nutzer hat seine Fachbereichs-Information gelöscht. Karteikarten am Regulating Gene Expression, erstellt von Gelöschter Nutzer am 05/03/2018.
- Erstellt von
- Gelöschter Nutzer · Mär 2018
- Aktualisiert
- 5 Mär 2018
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- 20
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- Erstellt von Yinka F · 18 Feb 2018
- Kopiert von Yinka F · 5 Mär 2018
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