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Identify two examples of a cell responding to its environment.
one example is the immune response the other is the plant stomatal response. when a pathogen enters the body, immune cells detect it. they respond by releasing signaling molecules called cytokines that help gather other immune cells to the infection site. in plants, guard cells surrounding stomata respond to environmental cues as they open during the day to allow gas exchange for photosynthesis and close during the night or drought to limit water loss.
What is apoptosis?
apoptosis is programmed cell death and is controlled.
Why would a cell undergo apoptosis?
cells undergo apoptosis for many reasons. during development, certain cells need to die in order to shape organs and tissues, such as the webbed fingers in embryos. also, if a cell is damaged or infected, it can trigger apoptosis to prevent harm to surrounding cells and the body.
What is a transcription factor?
a transcription factor is a type of protein that is crucial in regulating gene expression. think of it as a molecule “switch” that helps control when genes are turned off & on and when and to what extent genes are expressed.
How does a transcription factor change gene expression?
a transcription factor binds to specific sequences of DNA near the genes they regulate which can either promote transcription (activators) or repress transcription (repressors). in promoting transcription, transcription factors encourage the gene to be expressed by helping RNA polymerase (the enzyme responsible for transcribing DNA into RNA) to do its job. in repressing transcription, transcription factors inhibit gene expression by blocking RNA polymerase or other necessary machinery.
How can a signal change the phenotype of an organism?
a signal can change the phenotype of an organism by influencing the way its genes are expressed. for example, in some animals, changes in temperature can trigger the expression of genes that lead to a fur color change for camouflage. also, during development, signals can guide cells to differentiate into specific types like muscle or nerve cells, affecting the entire phenotype.
