Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Entomology > Hormones > Flashcards

Hormones Flashcards

1
Q

Which ecdysteroid is the immediate cause of moulting in insects?

A

20-hydroxyedysone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which ecdysteroid produces 20-hydroxyecdysone?

A

Ecdysone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which glands secrete the ecdysteroid Ecdysone?

A

The prothoracic glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does the conversion of ecdysone to 20-hydroxyecdysone occur?

A

Fat body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the structure and properties of Ecdysone and 20-hydroxyecdysone?

A

They are steroids with numerous -OH groups that are polar and therefore they are very soluble in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the purpose of binding proteins in relation to Ecdysone and 20-hydroxyecdysone?

A

They transport the steroids in the haemolymph (as they are soluble) and protect them from enzymatic attack or excretion - hence their availability is one method of regulating ecdysteroid levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does 20-hydroxyecdysone initiate moulting?

A

It acts directly on the hypodermis DNA and binds at specific receptor sites in the nuclei. It activates the genes responsible for the production of RNA. This leads to the production of enzymes responsible for cell division, growth and other changes that occur during moulting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is 20-hydroxyecdysone a general growth hormone? Why/why not?

A

No because some tissues are unaffected by it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Can insects synthesise steroids?

A

No, they must obtain them from their diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the fate of prothoracic glands in adults?

A

They degenerate and disappear except in Apterygota and the sub imago of Ephemeroptera

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is PTTH produced?

A

In the neurosecretory cells located in the pars intercerebium of the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is ecdysone produced?

A

The prothoracic glands are stimulated to produce ecdysone by PTTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of the corpora cardiaca?

A

To store and releases hormones produced by brain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does high concentrations of 20-hydroxyecdysone do?

A

Inhibits the release of PTTH and stimulates its synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of octopamine?

A

To potentiate the release of adipokinetic hormones (such as lipids when locusts start flying)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some hormones released by the corpora cardiaca?

A

Hypolipaemic hormone, hyperglycaemic hormone, eclosion hormone, antidueric hormone, cardioaccelerator hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the function of the hypolipaemic hormone?

A

To lower haemolymph fat levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the function of the hyperglycaemic hormone?

A

To increase haemolymph sugar levels (trehalose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the function of the antidiuretic hormone?

A

To reduce fluid secretion by the Malpighian tubules and rectum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of the cardioaccelerator hormones?

A

To fasten the heartbeat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is PTTH released?

A

It is produced by the neurosecretory cells in the pars intercerebium and the secretion from these cells passes along their axons within a pair of nerves to the corpora cardiac where it is stored in the swollen ends of the axons until they are released into the blood by action potentials passing down the axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the purpose of the juvenile hormone (JH)?

A

To control the way cells differentiate at each moult

23
Q

What happens at different concentrations of the juvenile hormone?

A

When it is present the larval form is retained but if it is present at very low levels then the adult form differentiates, for example low concentrations initiate the development of the internal reproductive organs in adults

24
Q

Where is the juvenile hormone produced?

A

In the corpora allata

25
Q

What is the corpora allata?

A

Small, spherical glands that arise from the ectoderm of the maxillary segment of the embryo - each receive a nerve from the corpora cardiaca adjacent to it

26
Q

How does JH regulate?

A

By using negative feedback to suppress the activity of the corpora allata

27
Q

What is the fate of the corpora allata in adults?

A

It recommences production of the juvenile hormone

28
Q

How many analogues of JH occur? Which insects do they predominate in?

A

4 - JH3 occurs in most insects but JH0, JH1 and JH2 occur in Lepidoptera

29
Q

Which four hormones orchestrate the events surrounding eclosion?

A

The ecdysis triggering hormone, the eclosion hormone, the cardioactive peptide and bursicone

30
Q

What is the hormonal process of moulting?

A

Preparation begins when declining ecdysteroid concentrations stimulate the degradation of the old endocuticle. The ecdysis triggering hormone is released into the hemolymph by the epitracheal glands and acts directly on the ventral ganglia cells to switch on pre-eclosion behaviour. This loosens the old cuticle from the new cuticle. The ecdysis triggering hormone stimulates brain cells to release the eclosion hormone. The eclosion hormone is released locally in the CNS and into the hemolymph. In the CNS it stimulates the release of bursicone. In the hemolymph it plasticises the cuticle and stimulates the release of CCAP in the ventral ganglia. CCAP switches off pre-eclosion behaviour and switches on eclosion behaviour. This results in the exuviae being shrugged off and lost. Contractions of the abdomen force hemolymph into the wings and wing spreading begins. Bursicon first further plasticises the cuticle and allows for the expansion of the wings and switches on sclerotization of the new cuticle.

31
Q

What is pre-eclosion behaviour?

A

A series of abdominal rotations and wriggling movements which loosen the old cuticle from the new cuticle

32
Q

What is CCAP?

A

Crustacean cardioactive peptide

33
Q

What is the role of Bursicon in moulting?

A

Plasticises the cuticle and allows for expansion of the wings and switches on sclerotisation of the new cuticle

34
Q

What is the role of CCAP in moulting?

A

To switch off pre-eclosion behaviour and switch on eclosion behaviour to shrug off the old cuticle

35
Q

What is the role of the eclosion hormone in moulting?

A

To stimulate the release of bursicone in the CNS and to stimulate the release of CCAP in the ventral ganglia as well as plasticise the cuticle

36
Q

What is the role of the ecdysis triggering hormone in moulting?

A

To switch on pre-eclosion behaviour and to stimulate the release of the eclosion hormone

37
Q

What initiates moulting?

A

Declining ecdysteroid concentrations stimulate the degradation of the old endocuticle and stimulates the release of the ecdysis triggering hormone from the epitracheal glands

38
Q

What does the presence of prostaglandins in insects suggest?

A

Prostaglandins are shared by invertebrates and vertebrates which suggests they have a highly conservative structure over extremely long periods of evolution

39
Q

Which system controls short-term coordination?

A

Nervous System

40
Q

Which system controls long term physiological, developmental and behavioural coordination?

A

Endocrine System

41
Q

What are hormones?

A

Chemicals produced within an organism’s body that are transported to another site where they have an effect

42
Q

What are the arthropod moulting hormones?

A

PTTH and Ecdysteroids

43
Q

What is the function of PTTH, structure and where is it produced?

A

Produced by neurosecretory cells and released by corpora cardiaca and it controls activity of prothoracic glands (controls synthesis of ecdysteroids). It is a peptide.

44
Q

Function of ecdysteroids, structure and where are they produced?

A

Produced in prothoracic gland (ecdysone) and fat bodies (20-hE). They control apolysis and the development of the new cuticle. They are steroids.

45
Q

How is PTTH regulated and transported?

A

Poorly known, release is inhibited by 20-hE and transport is water soluble

46
Q

How are ecdysteroids regulated and transported?

A

Ecdysteroids are produced by the prothoracic gland which is regulated by PTTH, it is also controlled by CNS and inhibitory hormones. Transport is bound by protein.

47
Q

What are the other moulting hormones and what are their function?

A

Ecdysis triggering hormone (ETH): triggers release of eclosion hormone.

Eclosion Hormone (EH): triggers release of CCAP and bursicone

Crustacean cardioactive peptide: Causes blood inflow in thorax and expansion of wings

Bursicone: plastication and then sclerotisation of new cuticle

48
Q

Describe the structure, function and source of the juvenile hormone

A

They are sesquiterpenes that are formed in the corpora allata (juveniles) or gonads (adult). They are regulated by neurosecretory cells, directly by CNS and low titre synthesis. They are transported bound by proteins. They control metamorphosis and gonadotropic hormones (adults).

49
Q

What does the JH do?

A

It maintains larval characteristics during moulting. High titre of JH means ecdysone promotes larva-to-larva moults. Lower titre of JH means ecdysone promotes pupation. Absence of JH means the formation of the adult. It works by affecting gene expression in the cell nuclei. In adults, it controls the production of eggs and vitellogenesis (deposition of yolk) into developing eggs.

50
Q

What key genes are associated with metamorphosis?

A

Kr-h1, Broad and Ecdysone-inducible protein 93F (E93)

51
Q

What is the Kr-h1 gene?

A

It is associated with the maintenance of the larval condition. It is induced by the JH through the JH receptor ‘Met’. It suppresses expression of Broad and E93. The removal of either JH, ‘met’ or Kr-h1 produces the same developmental response (the larval initiate the premature metamorphosis).

52
Q

What is the broad gene?

A

It activates genes specific to the pupal stage and suppresses adult/larval stages. It is induced by 20hE acting in the absence of JH. It disappears when the pupa begins the transformation to the adult. The treatment of pupa with JH allows broad to be reinduced by 20hE and a second pupal moult ensues.

53
Q

What is the E93 gene?

A

It is the stage specifying gene for the adult. It first appears during the prepupal stage and is high in pupa during the formation of the adult. It reduces the expression of Broad and Kr-h1 allowing profession to the adult. The knockdown of E93 results in a repeat of the pupal moult.

Entomology (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions