Development of Multicellular Organisms I: General Principles of Development Flashcards

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1
Q

What controls development?

A

gene expression

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2
Q

The genome of all cells in an organism are identical, but what makes us different?

A

Expression of genes are different.

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3
Q

Cells have “memory”. What is this referring to?

A

Retain record of signals their ancestors received during embryonic development.

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4
Q

What does the expression of genes by a cell depend on?

A

Environment, both present and past.

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5
Q

True or False:

Homologous proteins are functionally interchangeable.

A

True

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6
Q

What is the cells that cohere to form a sheet of epithelial cells facing the external medium known as?

A

This sheet constitutes the ectoderm.

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7
Q

What is ectoderm a precursor of?

A

Ectoderm - precursor of nervous system and epidermis.

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8
Q

What structures is endoderm a precursor of?

A

Endoderm - precursor of gut, lung, and liver.

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9
Q

What is formed when a group of cells move into the space between ectoderm and endoderm?

A

mesoderm

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10
Q

What structures is mesoderm a precursor of?

A

Mesoderm - precursor of muscles and connective tissue.

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11
Q

What is gastrulation?

A

Transformation of a hollow sphere of cells into a structure with a gut.

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12
Q

What is gene duplication?

A

Higher organisms have several homologs of the same gene.

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13
Q

What term describes higher organisms having several homologs of the same gene?

A

gene duplication

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14
Q

What are the two classes of proteins that are the most important for development?

A
  • cell adhesion and cell signaling proteins

- gene regulatory proteins (e.g., transcription factors and DNA binding proteins)

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15
Q

Where are the instructions for producing a multicellular animal contained?

A

Non-coding regulatory DNA associated with each gene.

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16
Q

In development, what contains regulatory elements that serve as binding sites for gene regulatory proteins?

A

DNA

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17
Q

What does regulatory DNA define for development?

A

Regulatory DNA defines the sequential program for development.

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18
Q

The coding sequences in DNA are similar in most organisms, but what makes one organism different from another?

A

Non-coding sequences make one organism different from another and provide uniqueness.

the coding sequences in DNA are similar in most organisms

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19
Q

True or False:

Cells make developmental decisions long before they show any outward signs of differentiation.

A

True

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20
Q

What does a “determined” cell mean?

A

Cells that are fated to develop into a specialized cell type despite changes in environment.

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21
Q

Cells that are fated to develop into a specialized cell type despite changes in environment are called?

A

determined

22
Q

What does a “completely undetermined” cell mean?

A

Cells that can change rapidly due to alterations in environment.

23
Q

Cells that can change rapidly due to alterations in the environment are called?

A

completely undetermined

24
Q

What does a “committed” cell mean?

A

Cells that have some attributes of a particular cell type but can change with environment.

25
Q

Cells that have some attributes of a particular cell type but can change with environment are called?

A

committed

26
Q

True or False:

Before acquiring a particular fate, cells express genes that are markers of their location (e.g., regionally determined).

A

True

27
Q

What is the position specific character of a cell called?

A

positional value

cells retain “memory” of positional value

28
Q

What does positional value of a cell refer to?

A

position specific character of a cell

cells retain “memory” of positional value

29
Q

In cellular differentiation, what allows cells to become different?

A

asymmetric division (e.g., development of germ cells)

significant sets of molecules distributed unequally between daughter cells

30
Q

How are significant sets of molecules distributed between daughter cells?

A

Significant sets of molecules distributed unequally between daughter cells.

31
Q

How are cells born the same but can become different due to what?

A

Due to change in environment after birth (different molecules induced).

these molecules then directly or indirectly alter pattern of gene expression between the 2 cells

32
Q

Cells born the same can become different due to change in environment after birth (different molecules induced). How do these molecules alter pattern of gene expression?

A

These molecules then directly or indirectly alter pattern of gene expression between the 2 cells.

33
Q

What is asymmetric division?

A

Sister cells are born different.

34
Q

What is symmetric division?

A

Sister cells become different as result of influences acting on them after their birth.

35
Q

In inductive signaling, what is the most important environmental cues?

A

Signals from neighboring cells.

36
Q

What is inductive signaling?

A

Induction of a different developmental program in select cells in a homogeneous group leading to altered character.

37
Q

Induction of a different developmental program in select cells in a homogeneous group leading to altered character is known as what?

A

inductive signaling

38
Q

What are the types of signals in inductive signaling?

A
  • Short Range: cell-cell contacts

- Long Range: substances that can diffuse through the extracellular medium

39
Q

Positive Feedback

A
  • System starts off homogeneous and symmetrical.
  • Environment imposes weak asymmetry.
  • Positive feedback amplifies effect.
  • Broken asymmetry is “all or none” phenomenon.
  • Irreversible - once achieved external signal becomes irrelevant.
  • Positive feedback provides cells with memory.
40
Q

What does positive feedback provide cells with?

A

memory

41
Q

Look over slide 27.

A

Asymmetry generated by positive feedback mechanism.

42
Q

What is a morphogen?

A

A long range inductive signal that imposes a pattern on a field of cells.

exert graded effects by forming gradients of different concentrations

each concentration can direct the target cells into a different developmental pathway

43
Q

What is the gradient of morphogens formed by?

A

(a) localized production of an inducer that diffuses away from its source
(b) localized production of an inhibitor that diffuses away from its source and block the action of a uniformly distributed inducer

44
Q

What do morphogens need?

A

‘on’ and ‘off’ system

antagonists or extracellular inhibitors bind to the signal or its receptor and block interaction

45
Q

What are signaling pathways the ultimate result of?

A

Ultimate result of inductive events is change in DNA transcription.

46
Q

In signaling pathways, what does the response depend on?

A

Spatial and temporal expression of different sets of genes.

47
Q

What are the proteins in the ligand family that bind to receptor tyrosine kinase (RTK)?

A
  • EGF
  • FGF (branchless)
  • Ephrins
48
Q

What are the proteins in the ligand family that signal TGF-beta superfamily?

A
  • TGF-beta
  • BMP (Dpp)
  • Nodal
49
Q

What ligand signals the Wnt signaling pathway?

A

Wnt (wingless)

50
Q

What ligand signals the Hedgehog signaling pathway?

A

Hedgehog

51
Q

What ligand signals the Notch signaling pathway?

A

Delta