Flashcards in Hormones/Signal Transduction Deck (64)
What is the first messenger
The extracellular molecule that binds to the receptor is he first messenger.
What is the second messenger?
Molecules that relay signals received at the receptors on the cell surface.
What are some potential responses to the signal transduction pathways?
May lead to activation of genetic material (DNA)
-This can lead to the production of proteins
Explain the signal transduction of steroids
-Lipid soluble hormone passes through the cell membrane and binds to a receptor in the cytosol
-Then forms a hormone-receptor complex
-Then the complex enters the nucleus
-Then the complex will act on genes
Discuss hormone longevity
Hormones do not last forever
Once they have delivered their message they are degraded by enzymes
Excreted the body via kidneys or faeces
Explain the steps o the negative feedback model if there is an increase in temperature
Stimulus-Increase in temperature
Control Center- CNS
Effector- Sweat glands and blood vessels
Response- Sweating and blood vessels dilate
Feedback- Decrease in body temperature
Explain extracellular fluid
Fluid on the outside of the cell
e.g tissue fluid and plasma
Explain intracellular fluid
Located on the inside of cells
Processes which are responsible for maintaining a constant internal environment.
What are some aspects of internal environment that need to be kept stable?
-ion concentration and nutrient levels
What is the external environment for unicellular organisms?
Water or air
What are some ways that unicellular organisms maintain their own internal environment
-Regulate the composition of the cytosol by the cell membrane
-Use flagella to move away from undesired stimuli
What are the two main systems involved in coordiniation and regulation of internal environments of multi cellular organisms
Steps in stimulus response model
3. Control Centre
Explain the two steps in negative feedback
-Stimulus is dectected and a response is produced
-The response will either oppose the stimulus or bring back the original stimulus to normal levels
What organisms are chemical messengers found in?
Plants and Animals
What are the main groups of hormones?
Amino acid derivatives
Explain why hormones act on specific cells?
They only act on cells that have a specific cell receptor site that is only found within the target cell. IF the cell does not have that specific receptor site then it will not bind to it. `
Where are protein based hormones receptors located?
Outside of the cell
Where are lipid based hormones receptors located?
Within the cytoplasmic
Briefly explain cell junctions
Allow molecules to readily pass through adjacent cells wwithout crossing cell membranes.
-Occurs in both plant and animal cells
What are the two broad groups that hormones are placed in?
What are the three steps in cell signalling?
1. Signal reception
3. Cell's Response
What does each step in signal transduction lead to the molecule becoming?
Explain the process of signal transduction when a g protein-linked receptor is involved
-A protein or peptide hormone will activate a membrane receptor
-May activate G protein
-G protein causes a cascade and therefore signal transduction
- Leading to cells response
Explain signal transduction in regards to steroid hormone receptors
1. Lipid soluble hormone passes through the cell membrane
2. Binds to a receptor protein found inside of the cells
3. Hormone-receptor complex enters the nucleus
4. Binds to s specific regulator site for the targeted gene
5. Simtulating the gene to produce mRNA
6. Then read by ribosomes to produce a specific protein
(essentally activates gene expression)
Explain the role of auxins in plant cells
Cause growth and elongation of plant cells
What do auxins cause
Positive phototropism (plant grows in the direction of the light)
Where are auxins most commonly found in the plant?
In the dark side as they move away from the light
hence the elongate more due to the unevenness in the shoot.