Hormones/Signal Transduction Flashcards Preview

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Flashcards in Hormones/Signal Transduction Deck (64)
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31

What is the first messenger

The extracellular molecule that binds to the receptor is he first messenger.

32

What is the second messenger?

Molecules that relay signals received at the receptors on the cell surface.

33

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

34

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

35

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

36

Explain the steps o the negative feedback model if there is an increase in temperature

Stimulus-Increase in temperature
Receptor-Thermoreceptor
Control Center- CNS
Effector- Sweat glands and blood vessels
Response- Sweating and blood vessels dilate
Feedback- Decrease in body temperature

37

Explain extracellular fluid

Fluid on the outside of the cell
e.g tissue fluid and plasma

38

Explain intracellular fluid

Located on the inside of cells
e.g cytosol

39

Define Homeostasis

Processes which are responsible for maintaining a constant internal environment.

40

What are some aspects of internal environment that need to be kept stable?

-Temp
-pH
-ion concentration and nutrient levels

41

What is the external environment for unicellular organisms?

Water or air

42

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

43

What are the two main systems involved in coordiniation and regulation of internal environments of multi cellular organisms

Nervous System
Hormonal

44

Steps in stimulus response model

1. Stimulus
2. Receptor
3. Control Centre
4. Effector
5. Response

45

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

46

What organisms are chemical messengers found in?

Plants and Animals

47

What are the main groups of hormones?

Steroids
Protein/peptide
Amino acid derivatives

48

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. `

49

Where are protein based hormones receptors located?

Outside of the cell

50

Where are lipid based hormones receptors located?

Within the cytoplasmic

51

Briefly explain cell junctions

Allow molecules to readily pass through adjacent cells wwithout crossing cell membranes.
-Occurs in both plant and animal cells

52

What are the two broad groups that hormones are placed in?

-Water soluble
-Lipid Soluble

53

What are the three steps in cell signalling?

1. Signal reception
2.Signal Transduction
3. Cell's Response

54

What does each step in signal transduction lead to the molecule becoming?

Amplified

55

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

56

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)

57

Explain the role of auxins in plant cells

Cause growth and elongation of plant cells

58

What do auxins cause

Positive phototropism (plant grows in the direction of the light)

59

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.

60

Explain cytokinins

Cause growth and divison of plant cells