Lecture 1 Flashcards

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1
Q

development

A

process of progressive and continual change resulting in the formation of a complex multicellular organism from a single cell

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2
Q

development biology

A

study of processes that govern embryonic and other development processes throughout an organism’s life

studied at morphological and molecular level

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3
Q

genotype

A

an organism’s genetic makeup

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4
Q

phenotype

A

an organism’s observable characteristics/traits (physical/behavioural)

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5
Q

Objectives of development (2)

A

Cellular diversity and order within an organism

Continuity of life from generation to generation

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6
Q

Early ideas

A

Unexplainable force (beyond physical and chemical forces) created living entity

All embryos existed from the very beginning of time; first embryo of a species contained all future embryos

Preformation theory – tiny humans (homunculus) preformed in embryo that got bigger as the embryo developed

Epigenesis – new structures arose progressively

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7
Q

Development of cell theory of life

A

mid 1800s

Cell is the basic unit of life

Living organisms made of cells

New cells formed by division of pre-existing cells

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8
Q

Germ cells

A

Give rise to an embryo and pass characteristics to next generation

Fertilization results in formation of a single cell (zygote) that carries material from both parents

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9
Q

Studying development (5 kinds of studies)

A

DCEMT

Descriptive Studies

Comparative Studies

Experimental Embryology

Molecular Biology

Transgenic Organisms

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10
Q

Descriptive Studies

A
what do you see w the naked eye?
-	Naked eye observations
-	Single lens magnifiers
-	Compound microscopes
-	Microscopic observations
o	Fluorescent microscopy – allows to observe processes in real time
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11
Q

Comparative studies

A

comparing stages, diff species, diff organisms

  • As embryos grow the more their features/differences get more pronounced
  • Start similar then diverge proof of common ancestor
  • Comparing larval / embryonic stages can reveal ancestry (evolutionary embryology)
    o Think barnacle and shrimp example
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12
Q

Von Baer’s Laws

A
  1. General features of a larger group of animals appear earlier in development than specialized features of a smaller group
    a. i.e. early embryos appear very similar and the distinctive features appear only later in development
  2. Feature get less and less general until the most specialized features appear
  3. As the embryo of a given species develops, it diverges from the adult form of other species
  4. Early embryo of a higher animal is never like an adult of lower animal but only like an early embryo
    a. Human embryos never pass thru a stage that is equivalent to a fish or bird
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13
Q

Experimental Embryology (Developmental Studies)

A

• Modify normal developmental processes in order to study its underlying mechanisms
o What would happen if certain cells are killed?

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14
Q

Molecular Biology

A

how to manipulate DNA

  • study of the molecular basis for the events happening during development
  • when are the genes being expressed; which genes are being expressed
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15
Q

Transgenic Organisms

A
  • We can make and induce the changes that we want in an organism
  • Knock out gene and remove it and see what effect that has
  • Use recombinant DNA technologies to introduce foreign DNA/genes and study the effects
    o What happens when gene X is expressed in these cells?
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16
Q

Model organisms in development

A

Allow to study experimental effects under CONTROLLED environments

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17
Q

Main development processes (5)

A

CPMCG

Cell cleavage

Pattern Formation

Morphogenesis

Cell differentiation

Growth

18
Q

Main development processes (5)

  1. Cell cleavage
A
  1. Cell cleavage – fertilized egg divide into numerous smaller cells (no increase in cell size/volume)
19
Q

Main development processes (5)

  1. Pattern Formation
A
  1. Pattern formation – cellular activity spatially and temporally organized to allow for development of well-organized structure; fundamental bc it determines what to form and where
20
Q

Main development processes (5)

  1. Morphogensis
A
  1. Morphogenesis – after the foundation laid down, apoptosis (changing the morphology of the embryo; webbed fingers to no webbed digits) which is pre-programmed in your DNA
    a. Changes in 3d form that involves cellular migration and programmed cell death (apoptosis) among other processes)
21
Q

Main development processes (5)

  1. Cell differentiation
A
  1. Cell differentiation – overlaps with morphogenesis; the changes happen gradually
    a. Cells become structurally and functionally different from each other
    i. Different cell types (muscle, blood, skin)
22
Q

Main development processes (5)

  1. Growth
A
  1. Growth - increase in size associated with cell multiplication, increase in cell size, deposition of extracellular material (bones)
    a. Growth can also be morphogenetic can induce changes in overall shape
    b. Example: changes in size and shape in human fetus and ratio of head to body size over time
23
Q

True or false:

Main developmental processes are independent of each other and happen in a strict sequence

A
  • These developmental processes are neither independent nor strictly sequential
24
Q

Generalized Animal Life Cycle

A
Fertilization
Cell Cleavage
Gastrulation
Organogenesis
Birth
Metamorphosis
Gametogenesis

*not all organisms adhere to this life cycle

25
Q

Generalized Animal Life Cycle

  1. Fertilization
A

Fertilization: fusion of gametes gives embryo its genome

26
Q

Generalized Animal Life Cycle

  1. Cell Cleavage
A

Cell cleavage: series of rapid mitotic divierions cytoplasm divided into numerous smaller cells (blastomeres) which from a sphere (blastula)

27
Q

Generalized Animal Life Cycle

  1. Gastrulation
A

Gastrulation: blastomeres undergo extensive movement and arrangement that changes their relative position to each other; giving rise to three germ layers

a. Endoderm: inner layer (respiratory and GI tract)
b. Ectoderm: outer layer (skin, CNS)
c. Mesoderm: middle layer (muscle, blood, heart)

28
Q

Generalized Animal Life Cycle

  1. Organogenesis
A

cell interaction results in rearrangements to produce tissue and organs

29
Q

Generalized Animal Life Cycle

  1. Birth
A

Birth

30
Q

Generalized Animal Life Cycle

  1. Metamorphosis
A

change from sexually immature form (larva) to sexually mater adult form

a. The young form looks significantly diff from adult form (tadpole frog) but does not happen in all species

31
Q

Generalized Animal Life Cycle

  1. Gametogensis
A

Development of gametes from precursor cells (germ cells are set aside for reproductive purposes)

32
Q

Life of a frog

Fertilization

A

Fertilization is external = female releases eggs, male frog fertilizes them

Amplexus – male grasps the female around the belly and eggs fertilized upon release

Following fertilization is cell cleavage (volume of egg stays the same)

Morula – solid mass of cells formed after rapid mitosis

33
Q

Life of a frog

Gastrulation

A

Start of gastrulation when an invagination (blastopore) forms 180 degrees from point of sperm entry
• This becomes the dorsal side of the embryo
• Eventually forms a ring
• Point of migration of cells
Mesoderm and endoderm towards interior
Ectoderm towards exterior; expands to enclose the entire embryo

34
Q

Life of a frog

Organogenesis

A

Starts w formation of notochord (condensed rod of cells of dorsal mesoderm that runs from head to tail)
• Notochord produces chemical signals that direct the formation of NS cells form ectoderm
• Changes in cell shape; rising up from round body
• Neural precursor cells elongate, stretch, and fold form neural tube (forms brain + spinal cord) which then gets covered by ectoderm (cells that eventually form the back(

Mesodermal cells next to neural tube / notochord become segmented form somites (segmented blocks of mesoderm that become muscles, spinal column and skin (dermis)

Mouth and tailbud area develop to give the tadpole structure

Neuronal connections develop
gills form to mature tadpole

35
Q

Life of a frog

Metamorphosis

A

Initiated by different hormones, dependent on the environment

  • Limbs develop
  • Tail recedes
  • Cartilage in the skull is replaced by bone
  • Tadpole teeth disappear and the mouth / jaw develop
  • Intestines become shorter
  • Gills regress and lungs enlarge
36
Q

Life of a frog

Gametogenesis

A

Development of germ cells begins after metamorphosis become mature after undergoing meiosis

37
Q

Fate maps

Two Types of Cells (2) in an embryo

A
  1. Epithetial cells – tightly connected to each other in sheets or tubes
    (cell polarity, cell adhesion to each other and ECM, stationary)
  2. Mesenchymal cells – unconnected/loosely connected to each other and can operate as independent units

(no cell polarity, loss of cell adhesion, ability to migrate and invade)

38
Q

Morphogenesis is the result of…

A

Morphogenesis is a result of (6):

  • Direction and number of cell divisions
  • Changes in cell shape
  • Cell movement / migration
  • Cell growth / proliferation
  • Cell death (apoptosis)
  • Changes in cell membranes and secreted products
39
Q

Fate map (definition)

A

diagram of early embryo that shows which tissues will give rise to each region in growing embryo

  • done by tracing ‘cell lineage’ and ‘mapping’ it to adult structures
40
Q

Fate maps created using:

A

Created using:
• Direct observation (embryos with few cells, different coloured pigments in blastomere cytoplasm)
• Dye marking (coloured, fluorescent)
• Radioactive labelling
• Genetic markers
• Genetic labelling (transgenic, chimeric)
• Selective cell surgery

41
Q

Embryogenesis

A

includes everything from fertilization to birth