Animal Development Flashcards Preview

Year 1 Biology Ellie M > Animal Development > Flashcards

Flashcards in Animal Development Deck (85)
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1
Q

When haploid gametes dude, what is produced?

A

A diploid zygote

2
Q

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

A

Fertilisation
Cleavage
Gastrulation

3
Q

What is cleavage?

A

Cell division

4
Q

What is gastrulation?

A

Cell / tissue movement and organisation

5
Q

What does morphogenesis mean?

A

Making form

6
Q

What is the name for multiple fertilisation of an egg?

A

Polyspermy

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

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

9
Q

What two things are eggs surrounded by?

A

Jelly coat

Vitelline membrane/envelope

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

11
Q

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

A

Nucleated blastomeres

No increase in embryo size

12
Q

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

A

Morula (solid ball of cells)

13
Q

What does a morula then form?

A

Blastula

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

15
Q

How is cleavage accomplished?

A

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

16
Q

What is different about cleavage in insects?

A

There is no cell division, only nuclear division

17
Q

What 3 types of tissue become evident in gastrulation?

A

Endodermal
Ectodermal
Mesodermal

18
Q

Which types of tissue move inside the embryo?

A

Endodermal and mesodermal

19
Q

Which type of tissue remains external to the embryo?

A

Ectodermal

20
Q

What is invagination?

A

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

21
Q

Which type of cells invaginate in the blastula?

A

Endodermal

22
Q

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

A

Gastrula

23
Q

What is the interior space of the gastrula called?

A

Archenteron

24
Q

What is the point of invagination of endodermal tissue called?

A

Blastopore

25
Q

What does the internal endoderm eventually form?

A

Gut and associated organs

26
Q

What does the ectoderm eventually form?

A

Epidermis and central nervous system

27
Q

What does the mesoderm eventually form?

A

Muscle, circulatory system, reproductive organs, skeleton

28
Q

What is the mesoderm essential in the formation of?

A

The coelom (body cavity)

29
Q

What are animals with 3 tissues called?

A

Triploblastic

30
Q

What are animals with 2 tissues called?

A

Diploblastic

31
Q

If the blastopore forms the anus, what is the animal called?

A

Deuterostome

32
Q

If the blastopore forms the mouth, what is the animal called?

A

Protostome

33
Q

What type of cleavage do protostomes show?

A
Spiral cleavage (diagonal to vertical axis)
Determinate cleavage (fate set early)
34
Q

What type of cleavage do deuterostomes show?

A
Radical cleavage (parallel and perpendicular to vertical axis)
Indeterminate cleavage (fate set late)
35
Q

What does determinate cleavage cause?

A

A loss of development potential, as the cells maintain their differentiation fate regardless of their location

36
Q

What is neurulation?

A

The folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube

37
Q

What is the notochord?

A

A longitudinal flexible rod between the gut and nerve cord, providing skeletal support

38
Q

What tissue is the origin of the notochord?

A

Mesoderm

39
Q

What is the neural tube and how is it formed?

A

It becomes the brain and spinal cord

It is formed by induction

40
Q

What is induction?

A

Where a group of cells/tissues influence the development of another group through close-range interactions

41
Q

What is the neural crest?

A

It will form the brain and parts of sensory organs anteriorly and other structures posteriorly

42
Q

What is caused if the neural tube fails to close?

A

Spina bifida (leg paralysis)

43
Q

What forms from plate of dorsal ectoderm?

A

The neural crest, neural groove and neural plate

44
Q

What are the four extraembryonic membranes formed from the blastodisc?

A

Yolk sac
Amnion
Chorion
Allantois

45
Q

What is the amnion?

A

A membrane above the ectoderm

46
Q

What does the chorion develop from?

A

The trophoblast (the outer layer of cells of a blastocyst)

47
Q

What is the allantois?

A

An outpocket of embryo gut, which later becomes incorporated into the umbilical cord

48
Q

What causes changes in cell shape during tissue invagination?

A

The action of microtubules (made of tubulin) and actin filaments

49
Q

How do cells move during gastrulation/neurulation?

A

They cytoskeleton extends the cell causing it to move

50
Q

What is convergent extension?

A

The tissue of an embryo is restructured to converge (narrow) along one axis and extend (elongate) along a perpendicular axis by cellular movement

51
Q

How is cell adhesion achieved?

A

It is controlled by the extracellular matrix (ECM)

52
Q

What is the extracellular matrix (ECM)?

A

A mixture of secreted glycoproteins which act to guide cells. ECM fibres can act as tracks to direct movement

53
Q

How is migration via the extracellular matrix blocked?

A

Antibodies added to fibronectin (a component of ECM)

54
Q

What is an example of an adhesion molecule that holds cells together?

A

Cadherin

Adheres junctions to bind cells within tissues together

55
Q

How can cell movements through an embryo be traced?

A

Antibodies bound to cellular markers are used

56
Q

As an embryo develops…

A

The development potential reduces

57
Q

The fate of every cell is determined by…

A

Gene expression

58
Q

How was animal cloning achieved?

A

By reversing the determination of a differentiated cell

59
Q

Asymmetrical division during cleavage leads to…

A

Asymmetrical distribution of cytoplasmic determinants

60
Q

How is cell-cell induction possible?

A

The signals used may be molecules attached to the cell membrane or locally-diffusing molecules

61
Q

What are the three sections of the common fruit fly?

A

Head
Thorax
Abdomen

62
Q

How does cleavage occur in fruit flies?

A

Only nuclei divide, then they migrate to the periphery of the embryo and become secondarily separated by membranes

63
Q

What are maternal effect genes?

A

Genes in the mother of an organism, which determine the characteristics of the offspring

64
Q

What is an example of a maternal effect protein in fruit flies?

A

Bicoid protein

Transcribed from DNA of mother, not offspring themselves

65
Q

How does bicoid protein affect offspring?

A

Bicoid mRNA accumulates at anterior end of egg and is transcribed. Diffuses through embryo, providing gradient for morphogenesis

66
Q

If no bicoid protein is produced, how does the offspring develop?

A

With two posterior ends and no anterior end

67
Q

When bicoid is injected into a bicoid mutant, what happens?

A

The anterior pole is re-established

68
Q

What is bicoid an example of?

A

Transcription factor - it controls the transcription of other genes

69
Q

What are gap genes?

A

They are vital in the formation of organisms with segmented bodies. Each gene is responsible for one segment

70
Q

What are examples of gap genes?

A

Kruppel and Hunchback

71
Q

What can inhibit gap gene translation?

A

Maternal effect gene products

72
Q

What are pair-rule genes?

A

A specific region of every other segment is missing if one of these genes mutates

73
Q

What controls the expression of pair-rule genes?

A

Differing concentrations of gap gene proteins, as they encode transcription factors controlling pair-rule gene expression

74
Q

What is an example of a pair-rule gene?

A

Hairy

75
Q

What are segment polarity genes?

A

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
Q

What is an example of a segment polarity gene?

A

Engrailed

77
Q

What are homeotic genes?

A

These determine the identity of each segment of the fruit fly

78
Q

What is a subset of homeotic genes?

A

Hox genes

79
Q

What are hox genes vital in?

A

Determining embryonic development along the axis of the embryo

80
Q

What is the protein product of a hox gene?

A

Homeodomain

81
Q

What is a homeodomain?

A

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
Q

How long is the homeodomain and how many helices does it consist of?

A

180 base pairs

4 helices

83
Q

What order are homeotic genes found on the chromosome?

A

In the same order that they must be on the insect itself

84
Q

What is the difference in placement of homeotic genes in vertebrates compared to insects?

A

In vertebrates the genes are found in different chromosomes

85
Q

In animals, homeotic genes are…

A

Highly conserved (remain the same for long periods of time)