M1. major features of development

Question 1

major features of development

Answer 1

• cell differentiation
• cell communication
• cell division and / or growth
• pattern formation
• morphogenesis: changes in form

Question 2

development is progressive

Answer 2

• as embryo development proceeds the organizational complexity of the embryo vastly increases over time
• different cell types form spatial patterns emerge, major shape changes occur
• the embryo is first divided into a few broad regions (such as germ layers) and during subsequent development, these regions have their fates become more finely determined

Question 3

Cell differentiation

Answer 3

the process where cells become structurally and functionally different from one another
in humans 250 distinct cell types
many come from a single germ layer
as development occurs choices need to be made as to what cell it will become

Question 4

cell fate

Answer 4

describes what a cell will normally develop into if allowed to develop normally

Question 5

undifferentiated

Answer 5

describe cells with no structural features that indicate its future development
pre gene expression and response to signals

Question 6

competence or potency

Answer 6

the totality of all structures a cell can form if placed in an appropriate environment

can gain and loss competence as it develops

potency gradually becomes restricted during development

cells have memory and can remember ehat happened earlier in devlopment, starts with one of the 3 germ layers(broad) then they make a decison that sets its fate and is usually irreversible

cells gradually become determined or committed to a particular fate through the process of specification

Question 7

specification

Answer 7

the first stage of commitment, a state of development where cells take on characteristics of a particular fate but this fate can be reversible

Question 8

determination

Answer 8

the second stage of commitment, cell fate reaches a stable state and becomes irreversible

often assessed by detecting expression of genes that are characteristic of the cell fate in question

Question 9

development of the embryo is a succession of cycles over time or

Answer 9

1) being competent to form a particular cell type
2) being specified towards a particular cell type
3) then becoming committed to that cell type

Question 10

terminally differentiated

Answer 10

the stage of development reached when a cell expresses its mature fate or final cell type

Question 11

competence (experimental definition)

Answer 11

• competency is determined based on transplantation of cells to a different cellular environment
• can the cell when moved to a different environment can it make a different choice, is it competent to form into a different fate
• competence is the potential of the cell to develop into a different fate based on its new location

Question 12

specification (experimental definition)

Answer 12

• cell or a group of cells is specified if they develop according to their normal fate when cultured in isolation (explant)
• determines if a cell fate is stable when cells are isolated from their normal cellular environment

Question 13

determination (experimental definition)

Answer 13

• a cell or group of cells is determined if they develop according to their normal fate when transplanted to a different region of the embryo
• cells are not determined if they change fate according to their new location/cellular environment

Question 14

levels of competence

Answer 14

totipotent (greatest potency) -> pluripotent -> multipotent (least potency)

Question 15

stem cells:

Answer 15

undifferentiated cells that divide/replicate to replace themselves AND generate other cell types

Question 16

stem cells are self-renewing

Answer 16

one cell can differentiate into a variety of cells, while other remains a stem cell

Question 17

totipotent

Answer 17

potential to form all cell types in the complete embryo (fertilized egg)

Question 18

pluripotent

Answer 18

can form most cell types of the embryo but not all (embryonic stem cells)
not the placenta

Question 19

multipotent

Answer 19

can form more than one cell type but have limited potential ( tissue repair)

skin cells, blood cells

Question 20

zygote

Answer 20

a specialized single cell resulting from fertilization of an egg
the zygote posses genetic contributions from both parents

Question 21

somatic cells

Answer 21

make of the body ( the soma) of an organism, include all cells but germ cell, usually diploid 2N

Question 22

germ cells

Answer 22

cells that give rise to the gametes ( egg or sperm)

Question 23

pattern formation

Answer 23

cellular activity is organized in space and time so that well ordered structures develop in the embryo

Question 24

the animal body plan

Answer 24

four main positional axes of the embryo are 1) anterior/posterior, 2) dorsal/ventral, 3) right/left, 4) radial

Question 25

positional identity

Answer 25

cells can interpret their position within a coordinate system

Question 26

polarity

Answer 26

-cells have an intrinsic direction
~can be defined by direction within the embryo (i.e. anterior to posterior)
~cells can have their own polarity (i.e. asymmetric localization of cellular components

Question 27

in triploblasts cells are allocated to one of the three germ layers:

Answer 27

ectoderm
mesoderm
endoderm

Question 28

ectoderm

Answer 28

skin and neurons

Question 29

mesoderm

Answer 29

muscle, bones, heart and blood

Question 30

endoderm

Answer 30

respiratory/digestive tract -lungs, liver, intestine, pancreas

Question 31

major ways cells can form a pattern

Answer 31

~interpretation of positional values (french flag model)
~cell spacing and / or sorting (lateral inhibition and compartments)
(spacing and sorting patterns)

Question 32

spacing patterns

Answer 32

compartments

-cells in a compartment respect compartment boundaries and do no cross into the adjacent compartments

Question 33

sorting patterns

Answer 33

lateral inhibition

-cells inhibit neighbour cells from acquiring a similar fate

Question 34

morphogenesis:

Answer 34

changes in shape/ form of the developing embryo

gastrulation

Question 35

gastrulation

Answer 35

is and example -> prospective endoderm and mesoderm cells move from the outer surface to the inside of the embryo
~cellular changes involve cell migration, shape change, rearrangement and / or apoptosis (programmed cell death)