UNIT 4 DAY 2 - YOUR INNER SHARK, FLY AND SPONGE

Question 1

what are the cranial nerves that twist through our skull?

Answer 1

• trigeminal
• facial

Question 2

bones that form the skull

Answer 2

• plates: cover our brains, large plates fit together like jigsaw puzzle pieces and form majority of the cranium
• blocks: lie underneath brain, form platforms, are complicated bones and have many arteries and nerves running through them
• rods: bones that make our jaw, ears and throat, bones start to develop like rods –> ultimately break up and change shape to help us chew, swallow and hear

Question 3

4 embryonic arches

Answer 3

1. first arch tissues to form the upper and lower jaws, 2 tiny ear bones and all the vessels and muscles that supply them
2. 2nd arch forms the 3rd small ear bone, a tiny throat bone and most of the muscles that control facial expression
3. 3rd arch forms bones, muscles and nerves deeper in the throat, we use these to swallow
4. 4th arch forms the deepest part of our throats, including parts of our larynx and the muscles and vessels that surround it and help it function

Question 4

adult human structures derived from 4 embryonic arches

Answer 4

1. upper and lower jaws, ear bones, vessels and muscles needed for those features
2. ear bone, throat bones, muscles that control facial expression
3. muscles and nerves that are deep in the throat
4. deepest part of the throat, larynx, muscles and vessels needed for this feature

Question 5

cranial nerves that drain the 4 embryonic arches

Answer 5

1. trigeminal nerve
2. facial nerve
3. glossopharyneal
4. vagua

Question 5

shark structures

Answer 5

1. jaws
2. supporting jaw bones
3. throat muscles move to gills
4. larynx

Question 6

similarity of cranial nerves in sharks and humans?

Answer 6

-structures in sharks arise from the same nerves, in generated by same nerves and exhibit relative functions to human structures

Question 7

role of HOX in development of 4 embryonic arches

Answer 7

• genes that direct development of the anterior-posterior axis
• eg. mammals and insects

Question 8

why are the invertebrate marine creatures called Amphioxus and the fossil Haikouella are considered the closest relatives to animals with heads and vertebrae

Answer 8

• Amphioxus is a worm, an invertebrate that shares many features with backbones animals
  –> lacks a backbone, but has a nerve cord that runs along its back
  –> rods also run parallel to the nerve cord
  –> rod (notochord), filled with jelly-like substance and provides support to the body
• Amphioxus and Haikouella have notochords, nerve cord, gill slits like the cartilages that form our jaws, ear bones and part of the voice box, rods support these gill slits

Question 9

similarities between organisms in embryos rather than adults

Answer 9

• embryos, can see the common structure
• species end up looking different but all look similar at the start

Question 10

embryonic germ layers and the organs they form in the adult

Answer 10

• ectoderm
• endoderm
• mesoderm

Question 11

ectoderm

Answer 11

forms outer part of the body (skin) and the nervous system

Question 12

endoderm

Answer 12

• inside layer, forms many inner structures of the body

Question 13

mesoderm

Answer 13

middle later, forms tissues in between the git and skin (including skeleton and muscles)

Question 14

Spemann experiment conclusion

Answer 14

• from one egg, can come more than 1 individual (identical twins)
• demonstrated in early embryo, some cells have capacity to form who new individuals on their own

Question 15

Mangold experiment conclusion

Answer 15

• discovered that a small patch of tissue that was able to direct other cells to form an entire body plan

Question 16

Vogt experiment conclusion

Answer 16

• able to produce a map of embryo that shows where every organ originates from in the egg

Question 17

how do geneticists use mutants to locate the genes called Hox genes that control development

Answer 17

• breed mutants to make whole population where every individual has a genetic error
• using variety of molecular markers, compare genes of individuals with mutations to those without
• allows them to pinpoint the region and likely stretch of chromosome response for mutant effect

Question 18

how many of these genes are found in flies and humans, their position on the chromosomes and their order activity in the front to back organisation to fly and human bodies

Answer 18

• flies have 8 genes that make such mutants
• these genes lie next to one another on one of the long DNA strands
• these genes that affect the head segment lie next to those that affect the segments in the middle of the fly, the part of the body that contains the wings
• these bits of DNA in turn lie next to the ones that control the development of the rear part of the fly
• humans have 4 sets of these genes
• the activity of the gene matches its position on the DNA: genes active in the head lie at one end, those in the tail at another, with genes affecting the middle of the body lying at the end

Question 19

in what sense do we have an inner fly?

Answer 19

• despite differences in numbers, humans are active from front to back in a very precise order just as fly genes are

Question 20

relationship between the organiser and the newly-discovered noggin?

Answer 20

• organiser control development of structure back-belly side
• noggin turn on cells that are needed to create a back-belly

Question 21

how does mapping hox and noggin genes reveal our inner sea anaemone?

Answer 21

• we may not look much like sea anemones but the recipe that builds is is more intricate version of the one that builds them
• we both have a front and a back a body plan set up by the versions of the same gene

Question 22

how many hox genes are in an anemone

Answer 22

• 2 hox genes

Question 23

bastula

Answer 23

• hollow ball of cells

Question 24

bastopore

Answer 24

• the indentation that during gastrulation leads to the formation of the archenteron

Question 25

dorsal lip of the blastopore

Answer 25

• induces surrounding cells to differentiate

Question 26

archenteron

Answer 26

• endoderm-lined cavity, formed during gastrulation, that develops into the digestive tract of an animal

Question 27

blastocoel

Answer 27

• the fluid-filled cavity of a blastula

Question 28

gastrulation

Answer 28

• the process in which a gastrula develops from a blastula by the inward migration of cells

Question 29

neurulation

Answer 29

• formation of the neural tube

Question 30

neural folds

Answer 30

• raised ridges in the neural plate that surrounds the deepening neural groove

Question 31

neural plate

Answer 31

• thickened region of the ectodermal layer that gives rise to the neural tube

Question 32

neural crest cells

Answer 32

• found at the tip of each neural fold
• migrate outwards to form the nervous system

Question 33

notochord

Answer 33

• a rod of tough, flexible material that runs the length of a creatures body, providing majority of its support

Question 34

neural tube

Answer 34

• an embryonic structure that gives rise to the central nervous system

Question 35

hedgehog

Answer 35

• distinguish front from back,
• fruit flies

Question 36

sonic hedgehog

Answer 36

• universal digits

Question 37

archenteron

Answer 37

internal cavity of the early gut that forms during gastrulation in the developing embryos

Question 38

organiser

Answer 38

• function of genes active in organisers is the control development of structures along the dorsal-ventral (back-belly) axis

Question 39

ectoderm which forms which of the following organs in adult vertebrae

Answer 39

skin and brain

Question 40

8 hox genes found in flies

Answer 40

39 hox genes found in humans, mice