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Year 1 Biology Ellie M > Animal Development > Flashcards

Animal Development Flashcards

(85 cards)

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1
Q

When haploid gametes dude, what is produced?

A

A diploid zygote

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2
Q

What are the 3 initial processes through which a gamete becomes a zygote which becomes a whole animal?

A

Fertilisation
Cleavage
Gastrulation

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3
Q

What is cleavage?

A

Cell division

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4
Q

What is gastrulation?

A

Cell / tissue movement and organisation

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5
Q

What does morphogenesis mean?

A

Making form

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6
Q

What is the name for multiple fertilisation of an egg?

A

Polyspermy

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7
Q

How is polyspermy prevented after fertilisation? (Describe the 2 ways)

A

Fast block to polyspermy - an electrical response of the plasma egg membrane, preventing a second sperm fusing with the membrane
Slow block to polyspermy - critical granules fuse with the egg’s plasma membrane, releasing their contents. Enzymes separate the plasma and vitelline membranes. Mucopolysaccharides cause water to enter the peri-vitelline space, physically separating the two membranes. The contents harden

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8
Q

When the vitelline membrane is separated from the plasma membrane with hardened contents between them, what is the membrane now called?

A

Fertilisation membrane

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9
Q

What two things are eggs surrounded by?

A

Jelly coat

Vitelline membrane/envelope

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10
Q

What is the acrosomal reaction?

A

When sperm makes first contact, the acrosome discharges it’s contents by exocytosis, Hydrolytic enzymes are released which allow the acrosomal process to penetrate the egg’s jelly coat. The plasma membranes of the sperm and egg fuse, so the sperm contents can enter the cytoplasm of the egg

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11
Q

At the beginning of cleavage, what does the egg divide into?

A

Nucleated blastomeres

No increase in embryo size

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12
Q

After a nucleated blastula, what is the 33 cell stage called?

A

Morula (solid ball of cells)

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13
Q

What does a morula then form?

A

Blastula

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14
Q

What is a blastula and what is the fluid-filled cavity inside it called?

A

Animal embryo when it is a hollow ball of cells

Blastocoel

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15
Q

How is cleavage accomplished?

A

By abolishing the growth period between cell divisions (G1 and G2 phases of the cell cycle)

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16
Q

What is different about cleavage in insects?

A

There is no cell division, only nuclear division

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17
Q

What 3 types of tissue become evident in gastrulation?

A

Endodermal
Ectodermal
Mesodermal

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18
Q

Which types of tissue move inside the embryo?

A

Endodermal and mesodermal

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19
Q

Which type of tissue remains external to the embryo?

A

Ectodermal

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20
Q

What is invagination?

A

Cells turn inside out or fold back on themselves to form a cavity

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21
Q

Which type of cells invaginate in the blastula?

A

Endodermal

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22
Q

Once the embryo is 2 layers of cells thick, what is it called?

A

Gastrula

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23
Q

What is the interior space of the gastrula called?

A

Archenteron

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24
Q

What is the point of invagination of endodermal tissue called?

A

Blastopore

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25
What does the internal endoderm eventually form?
Gut and associated organs
26
What does the ectoderm eventually form?
Epidermis and central nervous system
27
What does the mesoderm eventually form?
Muscle, circulatory system, reproductive organs, skeleton
28
What is the mesoderm essential in the formation of?
The coelom (body cavity)
29
What are animals with 3 tissues called?
Triploblastic
30
What are animals with 2 tissues called?
Diploblastic
31
If the blastopore forms the anus, what is the animal called?
Deuterostome
32
If the blastopore forms the mouth, what is the animal called?
Protostome
33
What type of cleavage do protostomes show?
``` Spiral cleavage (diagonal to vertical axis) Determinate cleavage (fate set early) ```
34
What type of cleavage do deuterostomes show?
``` Radical cleavage (parallel and perpendicular to vertical axis) Indeterminate cleavage (fate set late) ```
35
What does determinate cleavage cause?
A loss of development potential, as the cells maintain their differentiation fate regardless of their location
36
What is neurulation?
The folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube
37
What is the notochord?
A longitudinal flexible rod between the gut and nerve cord, providing skeletal support
38
What tissue is the origin of the notochord?
Mesoderm
39
What is the neural tube and how is it formed?
It becomes the brain and spinal cord | It is formed by induction
40
What is induction?
Where a group of cells/tissues influence the development of another group through close-range interactions
41
What is the neural crest?
It will form the brain and parts of sensory organs anteriorly and other structures posteriorly
42
What is caused if the neural tube fails to close?
Spina bifida (leg paralysis)
43
What forms from plate of dorsal ectoderm?
The neural crest, neural groove and neural plate
44
What are the four extraembryonic membranes formed from the blastodisc?
Yolk sac Amnion Chorion Allantois
45
What is the amnion?
A membrane above the ectoderm
46
What does the chorion develop from?
The trophoblast (the outer layer of cells of a blastocyst)
47
What is the allantois?
An outpocket of embryo gut, which later becomes incorporated into the umbilical cord
48
What causes changes in cell shape during tissue invagination?
The action of microtubules (made of tubulin) and actin filaments
49
How do cells move during gastrulation/neurulation?
They cytoskeleton extends the cell causing it to move
50
What is convergent extension?
The tissue of an embryo is restructured to converge (narrow) along one axis and extend (elongate) along a perpendicular axis by cellular movement
51
How is cell adhesion achieved?
It is controlled by the extracellular matrix (ECM)
52
What is the extracellular matrix (ECM)?
A mixture of secreted glycoproteins which act to guide cells. ECM fibres can act as tracks to direct movement
53
How is migration via the extracellular matrix blocked?
Antibodies added to fibronectin (a component of ECM)
54
What is an example of an adhesion molecule that holds cells together?
Cadherin | Adheres junctions to bind cells within tissues together
55
How can cell movements through an embryo be traced?
Antibodies bound to cellular markers are used
56
As an embryo develops...
The development potential reduces
57
The fate of every cell is determined by...
Gene expression
58
How was animal cloning achieved?
By reversing the determination of a differentiated cell
59
Asymmetrical division during cleavage leads to...
Asymmetrical distribution of cytoplasmic determinants
60
How is cell-cell induction possible?
The signals used may be molecules attached to the cell membrane or locally-diffusing molecules
61
What are the three sections of the common fruit fly?
Head Thorax Abdomen
62
How does cleavage occur in fruit flies?
Only nuclei divide, then they migrate to the periphery of the embryo and become secondarily separated by membranes
63
What are maternal effect genes?
Genes in the mother of an organism, which determine the characteristics of the offspring
64
What is an example of a maternal effect protein in fruit flies?
Bicoid protein | Transcribed from DNA of mother, not offspring themselves
65
How does bicoid protein affect offspring?
Bicoid mRNA accumulates at anterior end of egg and is transcribed. Diffuses through embryo, providing gradient for morphogenesis
66
If no bicoid protein is produced, how does the offspring develop?
With two posterior ends and no anterior end
67
When bicoid is injected into a bicoid mutant, what happens?
The anterior pole is re-established
68
What is bicoid an example of?
Transcription factor - it controls the transcription of other genes
69
What are gap genes?
They are vital in the formation of organisms with segmented bodies. Each gene is responsible for one segment
70
What are examples of gap genes?
Kruppel and Hunchback
71
What can inhibit gap gene translation?
Maternal effect gene products
72
What are pair-rule genes?
A specific region of every other segment is missing if one of these genes mutates
73
What controls the expression of pair-rule genes?
Differing concentrations of gap gene proteins, as they encode transcription factors controlling pair-rule gene expression
74
What is an example of a pair-rule gene?
Hairy
75
What are segment polarity genes?
These control the anterior and posterior polarity of each segment in organisms. They are expressed after gap and pair-rule genes have been expressed
76
What is an example of a segment polarity gene?
Engrailed
77
What are homeotic genes?
These determine the identity of each segment of the fruit fly
78
What is a subset of homeotic genes?
Hox genes
79
What are hox genes vital in?
Determining embryonic development along the axis of the embryo
80
What is the protein product of a hox gene?
Homeodomain
81
What is a homeodomain?
A DNA binding region which binds to the specific regulatory proteins of target genes and begins transcription of these genes, which are necessary for the correct development of the segment
82
How long is the homeodomain and how many helices does it consist of?
180 base pairs | 4 helices
83
What order are homeotic genes found on the chromosome?
In the same order that they must be on the insect itself
84
What is the difference in placement of homeotic genes in vertebrates compared to insects?
In vertebrates the genes are found in different chromosomes
85
In animals, homeotic genes are...
Highly conserved (remain the same for long periods of time)

Year 1 Biology Ellie M (28 decks)

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