C2.1 Chemical Signalling (HL) Flashcards
What is chemical signalling?
A process by which cells, tissues, and organisms communicate using signalling molecules.
What are the two types of cell-to-cell interactions in chemical signalling?
- Direct interactions
- Indirect interactions
What are ligands?
Signalling molecules that include hormones, neurotransmitters, cytokines, and growth factors.
What role do receptors play in chemical signalling?
Receptors exhibit specificity to ligands due to the structure of their binding sites.
What are the main functions of chemical signalling in humans?
- Maintaining homeostasis
- Development
- Immune response
- Neural function
- Metabolic regulation
What initiates the cascade of biochemical reactions in signal transduction?
Conformational change in the receptor caused by ligand binding.
What are some specific cellular responses that can result from activated signalling pathways?
- Changes in gene expression
- Activation or inhibition of enzymes
- Alteration of ion channel activity
- Modulation of cellular metabolism
What is quorum sensing in bacteria?
A process where bacteria communicate to coordinate group behaviour in response to cell density.
What are autoinducers?
Small signalling molecules released by bacteria that diffuse and accumulate in their environment.
What types of autoinducers do Gram-positive and Gram-negative bacteria use?
- Gram-positive: processed oligopeptides
- Gram-negative: acylated homoserine lactones (acyl-HSLs)
How does Vibrio fischeri utilize quorum sensing?
Releases N-acyl homoserine lactone to bind to regulators and induce the lux operon.
What is the function of the lux operon in Vibrio fischeri?
Regulates luminescence by encoding regulatory and luminescent proteins.
What chemical reaction produces light in bioluminescence?
The oxidation of luciferin by luciferase.
What hormone is produced by the pancreas in response to high blood glucose levels?
Insulin
What hormone is produced by the pancreas in response to low blood glucose levels?
Glucagon
What are hormones?
Chemicals secreted by endocrine glands into the extracellular fluid that act on target organs/tissues
What are neurotransmitters?
Chemical substances that carry signals from one neuron to another or from a neuron to a target cell
What are cytokines?
Small proteins important in cell signalling related to immune response
Which cells primarily secrete cytokines?
White blood cells such as macrophages and lymphocytes
What are the three main types of hormones?
Amines, peptide hormones, and steroids
What are amine hormones derived from?
Amino acids, specifically tyrosine and tryptophan
Give an example of an amine hormone.
Epinephrine (adrenaline)
What are peptide hormones?
Hormones in the form of polypeptide chains or small proteins
ex: insulin
What are steroid hormones derived from?
Cholesterol