detect and respond chk points Flashcards
What is an animal hormone?
Chemical messages produced in small amounts by endocrine glands. They are transported through the bloodstream to all parts of the body but will only have an effect on specific target organ/ cell. They modify the activity of a cell as a result of interaction with specific receptors.
Why do hormones only affect target cells?
Hormones only affect target cells as target cells alone hace the protein receptors that match the specific hormone.
Are hormones excreted or secreted? Which type of gland produces hormones?
They are secreted in the bloodstream.
Why are the receptors for steroid hormones within a cell whereas protein-based hormones’ receptors are on cell surfaces?
Steroid hormones are lipid soluble so therefore are able to pass easily through cell membranes.
How do pheromones differ from hormones?
- pheremones are released into the atmosphere whereas hormones are released into the blood
- pheremones are more volatile
- pheremones provide communication between individuals whereas hormones provode communication between cells within one individual
What is the major role of pheromones?
Are chemicals released by animals to atract members of the opposite sex of the same species.
What is the role of plant growth regulators?
Control the growth responses in plants so that growth occurs in the correct way so that the timing of the plant activity is optimal.
Outline the effects that auxins can have on plant growth.
They are made in young leaves and buds of plants. They control the enlargment and elongation in cells.
What is the major effect of cytokinins?
They promote cell division and hence cell growth.
What are the major effects of gibberellins?
They promote cell elongation and reproductiom.
Decribe 2 major effects that abcidisic has on plants.
- inhibits growth
- affects stomatal aperture
What is meant by signal transduction?
Series of pathways occurring within a cell after a hormone is detected by the cell and results in the cellular response.
Why is the initiation of signal transduction specific?
The receptors that detect the particular signalling molecules are designed to identify and respond to that molecule only.
What is apoptosis?
Programmed cell death. The death of the cell is ordered to maintain the overall health of the organism
What signal initiates apoptosis?
- signals inside the cell:
When a cell is seriously damaged, mitochondrial proteins are activated leading to the destruction of mitochondria and DNA - signals from outside the cell:
These are identified by death signal receptors in the cell membrane. When these receptors are activated the cell shrinks, DNA and mitochondria break down. The components of the dead cell are then engulfed by phagocytes and recycled.
