L5 the cuticle Flashcards

(38 cards)

1
Q

What are 5 functions of the cuticle

A

Mechanical protection
Prevents desiccation
Protective barier against bacteria, viruses and tocins
Location of colours and patterns important for behaviour
Supports body and provides points for muscle attachment via connecting tonofilaments

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2
Q

What is likely to be seen in cuticle shape at a point where muscle is attached

A

Infolding

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3
Q

What is the living layer od the cuticle made of

A

Epithelial cells resting on connective tissue

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4
Q

Where does the non-livign layer of the cuticle come from

A

Secreted from the epithelial cells during moulting

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5
Q

What are the layers of the non-living cuticle and where are they

A

Epicuticle - thin and on outside
Procuticle - inside

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6
Q

What are the layers of the non-living cuticle and where are they

A

Epicuticle - thin and on outside
Procuticle - inside

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7
Q

What are the 2 definite layers of the epicuticle
What is their structure

A

Inner and outer epicuticle
Inner - thicker, lipoprotein layer
Outer - very thin

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8
Q

What are the 2 potential additional layers of the epicuticle
What is their structure and goal

A

Wax layer - water retention, bipolar molecules (hydro phobic / phillic)
Cement layer - protect wax layer from heat or abrasion

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9
Q

What direction do neighbouring chitin chains run in

A

Opposite

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10
Q

What holds chitin together

A

H bonds

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11
Q

What do chitins come together to form

A

Microfibrils

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12
Q

How is chitin arranged

A

Forms fibrils which wrap w/ proteins and assemble in to fibre
Fibre assembles to bundles

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13
Q

How do bundles arrange themselves

A

Parallel to eachother

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14
Q

What is the name for what bundles arrange themselves into

A

Pseudolayers

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15
Q

What structure do the pseudolayers take on

A

Stack into helices, rotated ariund central axis

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16
Q

How do microfibril alternate their production - what are the 2 forms

A

Helicoidally arranged and uni-directional

17
Q

What can limit growth of microfibril layers

18
Q

How are lamella arranged in helicoidal arrangement

A

Each layer (lamella) rotates anti-clockwise by fixed angle

19
Q

How are lamellae organised in unidirection microfibril

A

Lamellate alternated with uniformly orientated microfibrils in same direction

20
Q

Are soft cuticles more or less hydrophilic than hard cuticles

21
Q

Where are proteins secreted from

A

Golgi apparatus

22
Q

What molecules with a soft cuticle contain in higher proportions than a hard cuticle

A

Aspartic acid
Glutamic acid
Histidine
Lysine
Tyrosine

23
Q

What kind of insects are likely to have undifferentiated procuticle and why

A

Holometabolous larval insects
Allows larva to remain extensible and facilitates intrastadial growth
Permits changes in body form
Conserves energy

24
Q

What process results in a rigid cuticle

25
What part of an insect is likley to be heavily tanned
Mandibles
26
Is tanning reversible
Irreversible - cannot be eaten or reabsorbed
27
What is tanning and how many methods of it are there
Cross-linking between proteins to form hard matrix 3
28
What are the processes of tanning and what is the end product
Quinone tanning = protein becomes lijked to quinone, cuticle darkens B-sclerotinisation = protein linked to molecule, cuticle hard but colourless (e.g. Eyes) Melanin = fills gaps in protein matrix, cuticle darkens and protects against UV, influences thermoreg
29
Where might a membranous cuticle be found
Between sclerites
30
In a membronous cuticle, is the procuticle tanned or untanned
Untanned
31
What determines the degree of moement in a membranous cuticle
Extent of membrane (size) and method of articulation (monocondylic or dicondylic)
32
Is formation of a membranous cuticle irriversible
No
33
Where is ecoscuticle absent
Ecdysial lines
34
What occurs at the ecdysial lines
Cuticle splits duting ecdysis
35
What protein is found in elastic / extensible cuticle
Resilin
36
How does resilin maintain elasticity
Amino acids form cross-links between protein chains whcih prevents other cross-linking
37
What minerals may be added in calcification
Calcite Vaterite Hydroxyapatite
38
Which insects is calcified procuticle found in and why
Immature insects Calcification would make mature insects too heavy for flight