lec 2- how a single cell gives rise to an organism

Question 1

what are the two ways a single cell, give rise to a complex, multicellular organism?

Answer 1

1. multiple rounds of cellular division
2. cells take on different identities and develop into specific organs, limbs, and other parts of the organism, must occur in correct time and space

Question 2

what processes overlap in time and space during embryogenesis?

Answer 2

cleavage, pattern formation, morphogenesis, cell differentiation, and growth

Question 3

what is cleavage?

Answer 3

after the cell is fertilized, multiple rounds of cell division occur which divide the zygote into smaller cells

Question 4

what is pattern formation?

Answer 4

the organization of cells so a correctly organized embryo can form, overall body plan is laid down

Question 5

what are the main body axes of an embryo with a head and a tail?

Answer 5

anterior = head
posterior = tail
Dorsal = back
ventral = front
right
left

Question 6

what are the germ layers of pattern formation of vertebrates and what do they give rise too?

Answer 6

endoderm = guts, liver, lungs
mesoderm = skeleton, muscle, kidney, heart, blood
ectoderm = epidermis of skin, nervous system

Question 7

what are the germ layers of insects and what do they do?

Answer 7

endoderm = gut
mesoderm = muscle, heart, blood
ectoderm = cuticle, nervous system

Question 8

what are the axis in pattern formation of plants?

Answer 8

apical-basal axis = shoot to root
radial axis = centre of stem outwards

Question 9

when do both of the axes in a plant form?

Answer 9

during embryogenesis

Question 10

what is morphogenesis?

Answer 10

development of shape or morphology

Question 11

what happens during morphogenesis in animals?

Answer 11

gastrulation occurs, endoderm and mesoderm move inside, creating the gut mouth and anus

Question 12

what happens during morphogenesis in plants?

Answer 12

morphogenesis occurs throughout a plants life and forms leaves, stems, flowers, and roots

Question 13

what is the difference between animal and plant morphogenesis?

Answer 13

animal morphogenesis only occurs during embryogenesis and cell move, while in plants it occurs throughout their lifee and no cell movement occurs, rather they expand their cells

Question 14

does morphogenesis allow a plant to change its form in response to the environment?

Answer 14

yes

Question 15

what is cell differentiation?

Answer 15

the process by which cells become different from one another

Question 16

are pattern formation, morphogenesis and cell differentiation closely related processes?

Answer 16

yes

Question 17

how long does it take for an embryo to grow in humans?

Answer 17

form established in 8 weeks, and growth occurs later

Question 18

what are the 3 steps for a cell to become different?

Answer 18

1. specification: cell aquire the ability to develop into a certain cell type, can change if different signals received, specified if develop without signals
2. determination: stable change in the identity of the cell, it can’t turn into any other cell type
3. differentiation: cell takes on its final identity

Question 19

what happens inside cells as they develop from an undifferentiated state into specific cell types?

Answer 19

changes in gene expression occur

Question 20

how do scientists figure out the specific fates of embryonic cells?

Answer 20

fate mapping experiments

Question 21

what is the cell labelling experiment?

Answer 21

when the cell is labelled early and scientists look at later stages to see what happened to the marked cells

Question 22

how do scientists know if a cell is specified?

Answer 22

by the isolation experiment

Question 23

what is the isolation experiment?

Answer 23

scientists remove the cell and culture them in an area devoid of signals, if the cell still takes on its original fate, it is specified

Question 24

how do scientists tell if a cell is determined?

Answer 24

by the transplantation experiment

Question 25

what is the transplantation experiment?

Answer 25

scientists take a cell from one side of the embryo and put it on the other side, if it keeps its original fate, it was determined