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- substrate in a reaction, stimulates the expression of a specific gene or genes
- Binding site for a repressor protein, located near start of an operon
- transcript inhibitor
- DRAW AN OPERON
Negative control –
- regulatory protein binds to DNA and shuts down transcription
- Positive control –
- occurs when a regulatory protein binds to DNA and triggers transcription. Glucose levels low, cyclic AMP (camp) croduce, cAMP interacts with CAP to increase transcription of lac operon. When glucose is abundant, cAMP is rare and positive control does not occur
Negative control , repressor present, lactose absent.
- Repressor binds to DNA
- Transcription is blocked
Negative control, repressor present, lactose present
Lactose (inducer) binds to repressor, repressor releases from DNA, transcription occurs
Negative control, no repressor present, lactose present or absent
Positive control, cAMP present
- cAMP-CAP complec forms and binds to DNA at CAP site.
- RNA polymerase binds the promoter efficiently
- Transcription occurs frequently
Positive control, cAMP absent
CAP does not bind to DNA, RNA polymerase binds to promoter inefficiently, transcription occurs rarely
Describe the basic structure of chromatin and relate its structure to gene regulation.
Chromatin consists of DNA complexed with histones and other proteins , compose chromosomes
one of several positively charged proteins associated with DBA in the chromatin of eukaryotic cells
repeating bead-like unit of eukaryotic chromatin, consisting ofabout 200 nucleotides of DNA wrapped twce around eight histone proteins
Chromatin structure –
has DNA wrapped around histones to form nucleosomes, nucleosomes packed into 30-nm fibers, 30-nm fibers attached to scaffold proteins, entire assemble folded into highly condensed structure observed during cell division
An individual develops as cells divide, move, or expand in a ___ way
- Directional way.
- Begin to express certain genes rather than others, signal to each other about where they are, what they are doing, and what thyep of cell they are becoming. Selected cells die in a regulated manner during development.
Programmed cell death, highly regulated aspect of development
Cell movement or growth
- Cells move past one another within a block of animal cells, causing drastic shape changes in the embryo
- Certain cells can break away from a block of animal cells and migrate to new locations
- Plant cells can divide along certain planes and expand in specific directions, causing changes in shape
Undifferentiated cells specialize at specicific times nad places. Cells that do not undergo differentiation called stem cells
- Embryonic cells divide, die, grow, move, or differentiate in response to signals from other cells
- Signals tell cells where they are in time and space, activating transcription factors that turn specific genes on or off, resulting in differentiation
Molecules thatprovide spatial information. Fundamental impact on early development. Present in a concentration gradient, provie cells with information about their position along the anterior posterior or apical-basal body axis