L5 the cuticle

Question 1

What are 5 functions of the cuticle

Answer 1

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

Question 2

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

Answer 2

Infolding

Question 3

What is the living layer od the cuticle made of

Answer 3

Epithelial cells resting on connective tissue

Question 4

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

Answer 4

Secreted from the epithelial cells during moulting

Question 5

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

Answer 5

Epicuticle - thin and on outside
Procuticle - inside

Question 6

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

Answer 6

Epicuticle - thin and on outside
Procuticle - inside

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

What direction do neighbouring chitin chains run in

Answer 9

Opposite

Question 10

What holds chitin together

Answer 10

H bonds

Question 11

What do chitins come together to form

Answer 11

Microfibrils

Question 12

How is chitin arranged

Answer 12

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

Question 13

How do bundles arrange themselves

Answer 13

Parallel to eachother

Question 14

What is the name for what bundles arrange themselves into

Answer 14

Pseudolayers

Question 15

What structure do the pseudolayers take on

Answer 15

Stack into helices, rotated ariund central axis

Question 16

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

Answer 16

Helicoidally arranged and uni-directional

Question 17

What can limit growth of microfibril layers

Answer 17

Food supply

Question 18

How are lamella arranged in helicoidal arrangement

Answer 18

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

Question 19

How are lamellae organised in unidirection microfibril

Answer 19

Lamellate alternated with uniformly orientated microfibrils in same direction

Question 20

Are soft cuticles more or less hydrophilic than hard cuticles

Answer 20

More

Question 21

Where are proteins secreted from

Answer 21

Golgi apparatus

Question 22

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

Answer 22

Aspartic acid
Glutamic acid
Histidine
Lysine
Tyrosine

Question 23

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

Answer 23

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

Question 24

What process results in a rigid cuticle

Answer 24

Tanning

Question 25

What part of an insect is likley to be heavily tanned

Answer 25

Mandibles

Question 26

Is tanning reversible

Answer 26

Irreversible - cannot be eaten or reabsorbed

Question 27

What is tanning and how many methods of it are there

Answer 27

Cross-linking between proteins to form hard matrix 3

Question 28

What are the processes of tanning and what is the end product

Answer 28

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

Question 29

Where might a membranous cuticle be found

Answer 29

Between sclerites

Question 30

In a membronous cuticle, is the procuticle tanned or untanned

Answer 30

Untanned

Question 31

What determines the degree of moement in a membranous cuticle

Answer 31

Extent of membrane (size) and method of articulation (monocondylic or dicondylic)

Question 32

Is formation of a membranous cuticle irriversible

Answer 32

No

Question 33

Where is ecoscuticle absent

Answer 33

Ecdysial lines

Question 34

What occurs at the ecdysial lines

Answer 34

Cuticle splits duting ecdysis

Question 35

What protein is found in elastic / extensible cuticle

Answer 35

Resilin

Question 36

How does resilin maintain elasticity

Answer 36

Amino acids form cross-links between protein chains whcih prevents other cross-linking

Question 37

What minerals may be added in calcification

Answer 37

Calcite Vaterite Hydroxyapatite

Question 38

Which insects is calcified procuticle found in and why

Answer 38

Immature insects Calcification would make mature insects too heavy for flight