Cell Signalling Flashcards
What is homeostasis?
Involves processes responsible for maintaining a relatively constant environment. It provides cells with a relatively stable environment so that cells can function properly
In animals what are the two ways in which a chemical message can occur?
- nervous system- synapse
- endocrine system- hormones
What is action potential?
Nerve impulse
What are the three types of neurons?
- sensory
- inter/ relay
- motor/ effector
What are the types of cell signalling molecules?
- steroid hormone
- simple gases
- neurotransmitters
- peptide hormones + growth factors
- fatty acid derivatives
What’s an example of a steroid hormone?
Progesterone
What is an example of a simple gas?
Nitric oxide
What is an example of a neurotransmitter?
Adrenaline
What is an example of a peptide hormone or growth factor?
Insulin
What is an example of a fatty acid derivative?
Prostaglandins
What is the endocrine system?
Regulates the body’s processes by releasing chemical messages called hormones into the bloodstream
How can the endocrine system be stimulated?
Hormonal, humoral or neural stimulus
What are the two major types of hormones?
- amino acid/ polypeptide-membrane receptors
- steroids- soluble in lipids
What is it called when multiple reactions occur as a result of others?
Cascade effect
Are steroids hydrophobic or hydrophilic?
Hydrophobic
Are large peptide hormones hydrophobic or hydrophilic?
Hydrophilic
Are steroids able to pass through the membrane?
Yes
Are large peptide hormones able to move through the membrane?
No
What are the different types of pheromones?
Trail,alarm, territorial, sex
Which are the major cells that secrete cytokines?
White blood cells (immune cells)
What are the effects cytokines can have?
Stimulatory, inhibitory, regulatory
What are pheromones?
Are chemical signalling molecules for communication between members of one animal species
How do neurotransmitters move across across the synaptic cleft?
- neutron is stimulated, it’s nerve impulse in the form of an electrical signal along the axon
- vesicles form containing neurotransmitters
- impulse is transmitted across the synaptic cleft by neurotransmitter molecules released from vesicles in the pre-synaptic neutron
- The neurotransmitter molecules diffuse across the synaptic cleft and bind with receptors on the post-synaptic neuron
Neurotransmitters are the chemical signalling molecules of which type of cells?
Nerve cells
What are the two types of signalling of nerve cells?
- communication within a nerve cell, known as action potential
- communication between nerve cells uses chemical signals known as neurotransmitters
How do hormones travel to their target cell?
Via the bloodstream
How do hydrophilic hormones reach target cells?
Through the blood from site of production to specific target
How do hydrophobic hormones reach target cells?
They are transported through the blood but are attached to a protein carrier
Are amino acid derivatives hydrophobic or hydrophilic?
Hydrophilic
Are lipid-derived hormones hydrophobic or hydrophilic?
Hydrophobic
Are peptide and protein hormones hydrophobic or hydrophilic?
Hydrophilic
Do hydrophobic hormones directly or indirectly activate genes?
Directly
Do hydrophilic hormones directly or indirectly activate genes?
Indirectly
Can polar signalling molecules cross the lipid bilayer of the plasma membrane?
No
Can non polar signalling molecules cross the lipid bilayer of the plasma membrane?
Yes
Can hydrophilic signalling molecules cross the lipid bilayer of the plasma membrane?
No
Can hydrophobic signalling molecules cross the lipid bilayer of the plasma membrane?
Yes
What are the name of receptors located on the cell membrane called?
Cell-surface receptors
What are the names of the receptors located either in the cytosol or nucleus of the target cell called?
Intracellular receptors
What are the three stages of cellular communication?
Signal reception, signal transduction, cellular response
How is the signal travelled in the endocrine system?
Long-distance travel
How is the signal travelled in the paracrine system?
Travel to nearby cells
How are signals travelled in the autocrine system?
One cell receives the same signal
What is the reception stage?
A signal from the cells external environment
What is the transduction stage?
Transduction of the signal into a form that can bring about a cellular response
What is the cellular response stage?
Cellular response to the signal that comprises physical, biochemical or physiological changes brought about by the effector proteins in the cell
What are the two types of receptors called?
Cell surface and intracellular receptors
Where are cell surface receptors located?
Located on the membrane
Where are intracellular receptors located?
Either the cytosol or nucleus
What is signal transduction?
A process that converts a signal from outside the cell into a response within the cell
When doe signal transduction begin?
After a signalling molecule bonds to its specific receptor, changing its shape and activating it
What are some major differences between plant and animal hormones?
Animal are produced by glands
plant are mainly produced by cells in growing areas
Animal hormones typically travel via the bloodstream whilst plants usually travel by the phloem tissue
What are auxins responsible for?
Cell division and growth in cell size
What cytokinins responsible for?
Increase in cell division
What are gibberellins responsible for?
Cell division and growth in cell size
What is abscisic acid responsible for?
Dormancy
What is ethylene responsible for?
Ageing
What stimulates the ripening of mature fruits?
Ethylene
What promotes lengthening of the stem?
Auxin and gibberellic acid
Where are cytokinins made?
Young fruits
Where are auxin and gibberellic acid made?
Young leaves and buds
What does a release of abscisic acid do?
Causes the closure of stomata
In what direction do auxins travel?
From shoot to root
What is a tropism?
The growth of a plant in response to a stimulus
What are two examples of a stimulus that results in the growth of a plant?
Water and light
Does auxin travel to the light or shaded side of a plant?
Shaded
What occurs when there is an increase in auxin cells in shaded area?
Causes cells to elongate to a greater degree than those in light area
What is apoptosis?
A process that is genetically controlled and highly regulated cell destruction
What is the role of apoptosis?
Ensure balance between cell production and cell lose
What are the plant hormones?
Auxin, cytokinins, gibberellins, ethylene, abscisic acid
What is necrosis?
Unplanned cell death such as that occuring when cells suffer trauma and die prematurely
What is the difference between apoptosis and necrosis?
Apoptosis is planned while necrosis is unplanned
What is the negative feedback system?
A system where the response to a particular stimulus reversed the direction of that stimulus
What is a pheromone?
A signalling molecule produced by a cell that attaches to a specific receptor and triggers a specific response
What is signal transduction?
The series of events that occur after the receipt of a specific signal and which result in a response
What is apoptosis?
Programmed cell death
