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Zoology Semester 2 > APS136 2 > Flashcards

APS136 2 Flashcards

1
Q

What is development?

A

A series of progressive changes in form and function that occurs during an organism’s life
- embryonic stages precede birth, and development continues until death

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2
Q

Fertilisation is..

A

the fusion of eggs and sperm to produce a zygote

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3
Q

Cleavage is…

A

the division of cells to form a blastula

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4
Q

Gastrulation is…

A

the formation of tissue layers and a body axis

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5
Q

Organogenesis is…

A

the formation of organs

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6
Q

Morphogenesis is…

A

the mechanism of body shape formation

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7
Q

Fertilisation initiates…

A

the rapid divisions that produce the multicellular embryo

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8
Q

The cytoplasm and mitochondria of the zygote come from…

A

the egg

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9
Q

The nucleus of the egg is in the…

A

animal hemisphere

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10
Q

Nutrients accumulate in the…

A

vegetal hemisphere

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11
Q

In amphibians sperm enters at the … …; the cortex then rotates exposing the … … opposite

A

animal hemisphere, gray crescent

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12
Q

Proteins in the gray crescent control…

A

what form the cells will take

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13
Q

Vegetal cortical cytoplasm is …, whereas animal cortical cytoplasm is …

A

clear, opaque

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14
Q

Cells typically … in number at each cleavage

A

double

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15
Q

The line along which cells cleave is called the…

A

cleavage furrow

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16
Q

The cells in and before the blastula are called…

A

blastomeres

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17
Q

A blastula is…

A

a hollow ball of cells (with the hollow centre being called the blastocoel)

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18
Q

In animals, unlike plants, there is very little … during cleavage, so cells get … at each division, and the overall … stays more or less the same

A

growth, smaller, mass

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19
Q

What are the 3 different types of cleavage patterns? (vary between taxa)

A
  • Complete
  • Incomplete-discoidal
  • Incomplete-superficial

+ the pattern depends on the amount of yolk and the orientation of spindles

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20
Q

With no yolk, cells are all..

A

equal in size at cleavage

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21
Q

Yolk … the cleavage furrow, so cells divide …

A

impedes, asymmmetrically

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22
Q

When there is lots of yolk, the cleavage furrows don’t penetrate the yolk, so cleavage is …. A … forms on top of the yolk in birds.

A

incomplete, blastodisc (discoidal cleavage)

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23
Q

In insects, … … cleavage occurs. The … migrate to the edge and the … grows inward, partitioning the … into individual …

A

superficial incomplete, nuclei, membrane. nuclei, cells

  • no cytokinesis
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24
Q

What are the 3 ways in which mitotic spindles affect cleavage pattern?

A
  • Radial cleavage - mitotic spindles form at right-angles or parallel to animal-vegetal axis
  • Spiral cleavage - mitotic spindles are at oblique angles to animal-vegetal axis
  • Rotational cleavage - first division is parallel to a-v axis, second is at right angles
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25
Q

Early in development, cells are…

A

totipotent

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26
Q

At … the cells’ fate becomes fixed

A

determination

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27
Q

At … the cells become structurally and functionally specialised

A

differentiation

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28
Q

What are the three tissue layers?

A
  • Endoderm (inner layer) - digestive tract, circulatory tract and respiratory tract
  • Ectoderm (outer layer) - epidermis and nervous system
  • Mesoderm (middle layer) - bone, muscle, liver, heart and blood vessels
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29
Q

In sea urchins, the blastula … at the vegetal hemisphere to from a …. Primary and secondary … forms between the endoderm and ectoderm, and an … forms (primitive gut)

A

invaginates, blastopore, mesenchyme, archenteron

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30
Q

In birds, the blastodisc … will form into the embryo, and the … will form the extraembryonic membranes. Gastrulation in birds starts when … … moves along the blastodisc from the anterior to the posterior, leaving the … … in its wake.

A

epiblast, hypoblast, Hensen’s node, primitive streak

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31
Q

In mammals, the … forms into the placenta. The inner cell mass contains the …, which becomes the embryo, and the … which becomes the extraembryonic membranes

A

trophoblast, epiblast, hypoblast

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32
Q

… occurs early in organogenesis and begins the formation of the nervous system in vertebrates

A

neurulation

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33
Q

The anterior end of the … … develops into the brain

A

neural tube (forms above the notochord)

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34
Q

Blocks of mesoderm called … produce the vertebrae, ribs, and muscles of the trunk and limbs

A

somites

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35
Q

… … cells produce peripheral nerves

A

neural crest

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36
Q

The yolk sac is for…

A

nutrient transfer

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37
Q

The amniotic sac is for…

A

protection

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38
Q

The chorion is for…

A

gas/water exchange

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39
Q

The allantois is for…

A

waste storage

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40
Q

Development is controlled by…

A
  • the cytoplasm
  • genes
  • the external environment
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41
Q

Nuclear DNA does 2 things:

A
  • replicates itself

- makes protein (by transcription of RNA) - doesn’t occur in early embryos - transcription isn’t switched on

42
Q

All enzymes and proteins involved in cell division are provided by…

A

the cytoplasm

43
Q

All metabolic cycles and instructions for driving cell division are controlled by…

A

the cytoplasm

44
Q

Zygotic cytoplasm comes from the …, so early development is under … control

A

mother, maternal

45
Q

… … is the transition from maternal control to embryo control

A

genomic activation

46
Q

The timing of genomic activation varies

  • In pigs and rats it occurs at the … cell embryo
  • In humans and cattle it occurs at the … cell embryo
  • In frogs it occurs at the … cell embryo
A
  • 4-8
  • 8
  • 3,000-4,000
47
Q

Differentiation results from differential … …

A

gene expression

48
Q

Differential gene expression is influenced by…

A

the cytoplasm and the extracellular environment

49
Q

What does genomic equivalence mean?

A

No information is lost in the early stages of embryonic development

50
Q

In amphibians, cytoplasmic factors in the … … are necessary for development

A

gray crescent

51
Q

What are the two mechanisms that give rise to chemical signals involved in development?

A
  • Cytoplasmic segregation - a factor is unequally distributed in the cytoplasm and ends up in some daughter cells but not others (and in different concentrations among cells), causing different differentiation
  • Induction - a factor is secreted by some cells to induce others to differentiate
52
Q

Cells “know” where they are in an animal by interpreting … …. This is given by the concentration gradient of a …

A

Positional information, morphogen

53
Q

A signal is considered to be a morphogen if…

A
  • it directly affects target cells

- different concentrations cause different effects

54
Q

The cells that become the bones and muscles of a limb receive positional information, then organise appropriately. Cells at the base of the bud make a morphogen (…) whose gradient determines the ….-…. … if the limb.

A

BMP2

Anterior-posterior axis

55
Q

Highest dose of BMP2 –>

Smallest dose of BMP2 –>

A

Thumb

Little finger

56
Q

In mammals, some development genes are active only if they come from a …, others only if they come from an …. This is called … …

A

Sperm, egg, genetic imprinting

  • male-male zygotes don’t produce an embryo
  • female-female zygotes don’t form a placenta
57
Q

Prader-Willi syndrome results from…

A

a deletion on paternal chromosome 15

58
Q

Angelman syndrome results from…

A

a deletion on maternal chromosome 15

59
Q

… … influence the number, boundaries and polarity of the body segments

A

Segmentation genes

60
Q

… … organise large areas along the anterior-posterior axis

A

Gap genes

61
Q

… … … divide the embryo into units of two segments each

A

Pair rule genes

62
Q

… … … determine segment boundaries

A

Segment polarity genes

63
Q

… … are expressed along the length of the body and determine what the segments will become

A

Homeotic genes

64
Q

In mice, 4 families of homeotic genes, called … genes, control differentiation along the body axis

A

Hox

65
Q

Temporal and spatial expression of hox genes follows the same pattern as their linear order on the…

A

chromosomes

66
Q

Antennapedia causes…

A

legs to grow instead of antennae in drosophila

67
Q

Bithorax results in…

A

an extra thorax in drosophila

68
Q

… is programmed cell death, caused by the activation of “…” genes

A

apoptosis, death

69
Q

Human embryos have webbed hands and feet, the enzyme … stimulates apoptosis

A

caspase

70
Q

C. elegans has 1,090 somatic cells, … are programmed to die

A

131

71
Q

Sometimes an environmental factor is necessary for successful development, for example, house mice raised in microbe-free environments lack … …, and these induce gene expression in the …, which is essential for normal … development

A

gut bacteria, intestine, capillary

72
Q

Neurulation is primarily under genetic control, but environmentally derived material in the form of … and … are also needed

A

vitamins, minerals

73
Q

Neural tube defects can be reduced if pregnant women receive adequate…

A

folic acid

74
Q

In tibet, a lack of … in the diet causes … in adults and … in babies

A

iodine, hyperthyroidism, cretinism

75
Q

Environmental factors can also disrupt development. For example, …, found in the corn lily plant, causes birth defects in lambs. It inhibits the action of the … … protein, which is involved in the formation of the neural system

A

cyclopamine, sonic hedgehog

76
Q

A clone is…

A

an individual that is genetically identical to another individual (not necessarily phenotypically identical)

77
Q

What are the mechanisms of cloning?

A
  • Natural
  • Embryo splitting
  • Reprogramming somatic cells
  • Nuclear transfer
78
Q

What is the primary mechanism of natural cloning?

A

Asexual reproduction

79
Q

Blastomeres in a 2 cell embryo sometimes separate naturally at an early stage, resulting in..

A

monozygotic twins

80
Q

Reprogramming somatic cells: sometimes differentiation is …. A carrot root cell can be “tricked” into forming a new plant that is a clone of the original

A

reversible

81
Q

Why is somatic cell nuclear transfer (SCNT) controversial?

A
  • The technique is invasive
  • There are technical problems
  • It gives rise to an ethical dilemma (potential for human to be cloned)
82
Q

What two features allow cloning by nuclear transfer?

A
  • The nucleus of every somatic cell contains a complete copy of the individual’s genome
  • A fertilised egg is totipotent
83
Q

How is SCNT done?

A

The DNA (nucleus) from one cell is combined with a fertilised egg that has been enucleated

84
Q

What were the first sheep cloned by nuclear transfer called?

A

Megan and Morag (cloned from embryonic cells)

- Dolly was first cloned from adult somatic cells

85
Q

What was the name of the first transgenic sheep clone?

A

Polly
- Wilmut and Campbell’s goal was to produce a flock of transgenic sheep that could produce therapeutically useful proteins

86
Q

What are some potential uses of cloning?

A
  • Developmental research, using clones as controls
  • Conservation (e.g. rare or extinct species)
  • Cloning of elite livestock
  • Disease resistant farming
  • Assisted reproductive techniques
  • Therapeutic cloning

+ Pharming
+ Xenotransplantation

87
Q

Clones have … of their own

A

mutations

88
Q

Stem cells are … cells that are capable of extensive …

A

undifferentiated, proliferation

89
Q

Stem cells produce…

A
  • more stem cells

- differentiated progeny cells

90
Q

Stem cells in the lab can be induced to differentiate using … …

A

signal molecules

- e.g. stem cells given vitamin A derivatives form nerve cells

91
Q

Darwin recognised that relationships among organisms could be deduced from similarities among their …

A

embryos

92
Q

Evolutionary Developmental biology (evo devo) looks at..

A
  1. How changes in the genes that regulate development affect the adult forms of organisms
  2. How those genes have changed during the course of evolution
  3. How these changes have influenced evolution
93
Q

Many developmental genes are highly …

A

conserved
- e.g. the same genes drive the development of the fly’s compound eye and the house mouse’s camera-like eye
+ the same set of hox genes provide anterior-posterior information in both mammal and insect embryos

94
Q

A huge variety of animals are produced by…

A

a common set of instructions

95
Q

Morphological changes can result from…

A
  • Mutations in genes that regulate development
  • Changes in the spatial expression of developmental genes
  • Changes in the temporal expression of developmental genes
96
Q

… makes all of these pathways of evolution easier

A

modularity

97
Q

Development is sensitive to…

A

environmental and social conditions

98
Q

In mosquitos, a blood meal stimulates production of vitellogenin, a necessary component of …

A

eggs

99
Q

In leafhoppers, gut bacteria are necessary for…

A

normal abdomen development

100
Q

The squinting bush brown butterfly has a dry-season and a wet-season with different … …. Temperature during pupation determines … …. This is an example of polyphenism

A

Wing colouration, adult form

<20 degrees C –> dry season form develops
>24 degrees C –> wet season form develops
(temperature affects expression of distal-less gene - increased expression during wet season)

101
Q

If spadefoot toad ponds begin to dry up, the tadpoles…

A
  • Develop a wider mouth, powerful jaw muscles and a modified intestine
  • Speed up development by eating other tadpoles

Zoology Semester 2 (15 decks)

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