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tim boswell material Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

discuss preformation and epigenesis explanations of animal development

A

preformation thwory is that the sperm contains a tiny human creature (homunculus) that simply gets bigger over time

epigenesis is the idea that new bodily structures arise over time

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2
Q

who theorised cell theory

A

schleiden and schwann

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3
Q

how do epithelial tubes form

A

epithelial cells tighten their ‘adhesion belt’ of actin filaments which causes invagination of the epithelial sheet

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4
Q

what is the pattern formation principle

A

the idea that cells become organised spatially and are given information about what to become

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5
Q

describe what bodily structures the three germ layers go on to become

A

endoderm; gut, liver and lungs

mesoderm; skeleton, muscles, blood vessels

ectoderm; skin, nervous system

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6
Q

discuss the two explanations of detemination (even though development probobly consists of parts of both)

A

mosaic development; chemicals and other determinants are distributed throughout cells unequally

regulative development; cell to cell communication and environmental signals determine fate

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7
Q

discuss evidence for mosaic and regulative development/determination

A

mosaic; if a 2-cell frog embryo has 1 cell destroyed, then only half an embryo develops

regulative; removing parts of an embryo often still leads to normal development

when a sea urchin embryo is rearranged, normal development still occours

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8
Q

what is the name of the two poles

name which one is on top/bottom

which pole develops quicker and therefore cosnsists of more cells but smaller ones

A 
animal pole (top)
vegetal pole (bottom)

the animal pole divides quicker

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9
Q

which embryo pole consists of much cytoplasm and little yolk, which is the orther way around

A

animal pole has much cytoplasm, little yolk

vegetal pole has much yolk, little cytoplasm

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10
Q

define holoblastic and meroblastic cleavage

A

complete cleavage
most protostomes and deuterostomes

incomplete cleavage; only superficial cleavage occours forming a cytoplasmic mass containg several nuclei (synctium)

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11
Q

discuss spiral and radial cleavage,

state if they perform holoblastic or mesoblastic cleavege

which method is used by protostomes and deutrrostomes

A

both are holoblastic (complete division)

radial; upper tier directly above lower tier
deuterostomes
equal yolk division between both poles

spiral; upper tier in between lower tiers
protostomes
yolk concentrated in one hemisphere (vegetal)

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12
Q

when do the animal and vegetal hemispheres develop

A

after cleavage (holoblastic/meroblastic methods)

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13
Q

when is embryo bilateral symmetry established rather aswell as radial symmetry

A

when the cells have cleaved and arrange into poles

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14
Q

which pole and hemisphere in an animal embryo contains dense yolk and which doesnt contain yolk

A

vegetal pole is yolky, animal pole has no yolk

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15
Q

which group of animals display a grey crescent and why do they display it

A

amphibians;
animal pole is pigmented and vegetal pole isint so when the cortical cytoplasm roates realtive to the inner cytoplasm a colour change occors

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16
Q

discuss the events that occour in tunicate eggs after fertilisation

A

cortical cytoplasm (yellow) moves to the vegatal pole and forms a crescent which then goes on to form muscle tissue due to this cytoplasm containing mRNA for macho1 transcription factor which switches on genes for muscle development

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17
Q

why does tunicate muscle development sopport mosaic development

A

the yellow cytoplasm at the vegetal pole forms muscle tissue due to the fact it contians mRNA for macho1 TF. sopports the idea of cytoplasmic determinants

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18
Q

which species (common name) is a model organisms for developmental work concerning organ development and apoptosis

why is this organism used

A

c. elegans (nematode worm)

embryogenesis only takes 15 hours

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19
Q

how many somatic cells does the nematode worm have. how mnay die during development

A
  1. 131
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20
Q

in the nematode worm, there is evidence for both mosaic and regulative development; discuss

A

mosaic; only the cells containg P granules (RNA and cytoplasm) becomes germ cells

regulative; moving the position of cells results in upside down development (normal development)

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21
Q

what is another name for a sea urchin

A

echinoderm

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22
Q

what is another name for an echinoderm

A

sea urchin

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23
Q

why are sea urchin eggs used to embryo development

A

many eggs produced by animal and released into water

eggs are easy to fertilise and observe because they’re transparent

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24
Q

what is a blastula and a blastocoel

A

a blastula is the hollow ball of cells that exists before gastrulation occours
a blastocoel is the fluid filled cavity in the blastula

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25
Q

name the animal whos gastrulation was studied and then describe that gastrulation

A 
sea urchin(echinoderm).
posterior cell change shape and become the archenteron, some cells break off and become primary mesenchyme, some cells break off and attach themselves to both the roof of the embryo and the roof of the archenteron (secondary mesenchyme). the secondary mesenchyme have filament projections called filopodia which they contract to pull the archenteron through the embryo, forming a tube which eventually become the gut.

the blastopore is the end of the hole first created

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26
Q

do echinoderms perform radial or spiral cleavage

A

radial cleavege; they are deuterostomes

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27
Q

the first opening (blastopore) to the gut always becomes the XXXX in deuterostomes

A

anus

28
Q

what is important about the fourth wave of divisiion in echinoderms

A

the animal pole cells becomes smaller than the vegetal pole

tiny cells called micromeres form below the vegetal pole

29
Q

give an example of mosaic development in echinoderms

A

there is a level of predictability concerning which parts of the cytoplasm will become which germ layer, therefore there must be some internal programming

30
Q

in terms of echinoderm embryos;

wat would have if a 4 cell embryo is split into 4 cells, and why?

what would happen if the 8 cell embryo is split vertically and why?

what would happen if the animal hemisphere and 1 micromemre, and why?

what happens when the animal hemisphere and 4 micromeres are combined without vegetal pole, and why?

what would happen if the animal pole a set of micromeres at each pole were combined and why?

A

4 cell; 4 normal larvas develop (regulative)

8 cell; an animalised larva and a vegetalised larva would develop because the animal and vegetal pole have already developed (mosaic). the animal larva has ectodderm and the vegetalised larva has endoderm

animal hemisphere and 1 micromere; animalised larva

animal hemisphere and 4 micromeres; normal larva;

animal hemisphere and 8 micromeres; 2 archenteron, 2 blastopore etc

31
Q

discuss what micromeres are why they are important

A

they are 4 tiny cells underneath the vegetal pole which have been shown to be key to development. they are thought to contribute to the concentration gradients in the embryo that gives cells positional information key to pattern formation. may contain high concentrations of morphogens (gradient theory of development)

32
Q

what is the gradient theory and what evidence is there for it

A

the idea that concentration gradients of important chemicals are what lead to development. dyes were added to embryos and it was revealed that a lot of metabolic activity occours at the two poles of the embryo and that morphogens are at high concentrations at embryo poles

33
Q

what is the french flag model and who theorised it

A

Wolpert
every cell has the potentiol to become any other cell; it is the concentration of morphogens that determines cell fate. a threshold of chemical needs to be exceeded for a cell to be determined

34
Q

what is a GRN theory?

who worked on GRN’s?

which animal did he investigate them in??

A

gene regulatory network. the idea that development is controlled by regulation of genes (kernals) and that each cell expressed different regulatory DNA

Davidson

Echinoderms

35
Q

what are insulators

A

cis regulatory elements that block the action of enhancers

36
Q

what are the effects if one gene mutates in a kernal

A

the kernal may not funciton which may have massive developmental effects

37
Q

discuss the GRN for beta catenin

A

in the animal pole, no beta catenin is present so a repressor is transcribed which blocks genes neeeded for vegetal development (tbr, delta, ets, dri)

maternal beta catenin and otx mRNA are deposited in the micromeres and Veg2 layers;
expression of beta-catenin and otx as transcription factors ococur, which activates transcription of gene (pmar1) which inhibits the expression of a gene that would normally repress expression of genes needed for vegetal development (gastrulation and skeleton development)

38
Q

what is gametogenesis and how is done

A

formation of haploid cells (gametes) by meiosis
spermatogenesis
oogenesis

39
Q

what is the scientific name for a mature egg cell and what cell pathway leads to it

A

a mature egg cell is called an ovum.

a diploid precursor cell (oogonia) becomes a primary oocyte (diploid) which becomes a mature ovum (haploid) bia meiosis

40
Q

what is vitellogenesis, when does it occour and how long does it take

A

vitellogenesis is the increases in size and storage of nutrients that occours during oogenesis (egg formation). it takes place during an extended prophase which may take months/years

41
Q

describe the features of a mature egg (ovum)

A

1) presence of yolk (either lots/not much)
2) presence of a membrane which thickens upon fertilisation to stop further sperm entry
3) presence of mitochondria, ribosomes and mRNA

42
Q

what is the molecule contained in yolk

A

vitellin, a lipoprotein (phospholipid sphere containing lipids)

43
Q

what are the two ways oogenesis can be classified

A

relationship of oocyte to other cells

method of yolk synthesis

44
Q

descibe the 3 different relationships an oocyte can have with other cells during oogenesis and which animals have each pattern

A

solitary; egg floats in body fluid
polychaeta

association with follicle cells (somatic) which provide physical sopport.
locusts for example have an entire organ (panoistic ovary) full of follicle cells. the oocytes develop in tubes called ovarioles, and is then passes to a tnother tube called the oviduct which is pushed into soil and used to lay eggs

nutrimentary association; oocyte is associated with sister cells called nurse cells in a chamber which is surrounded by follicle cells
drosophila

45
Q

what are nurse cells derived from and what is their function

A

nurse cells are derived from oogonia germ cells and their function is provide the oocyte with nutrients and RNA

46
Q

describe the 2 different ways a oocyte can be catagorised in terms of how it synthesis yolk

A

autosynthesis; oocyte takes up amino acids and carbohydrates and performs yolk synthesis itself

heterosynthesis; other cells perform yolk synthesis, and proteins like vitellogenin are taken up by the oocyte

47
Q

what are two pieces of evidence are there sopport the idea that oocytes can perfom heterosynthesis of yolk proteins

A

identical proteins to those in yolk have been found in body fluid

microscopy shows that vesicular transport occour at oocyte plasma membrane

48
Q

how are some oocytes able to autosynthesise yolk proteins

A

because of maternal deposits of amino acids

49
Q

which animals perform autosynthesis and which perform hetrosynthesis

A

autosynthesis is done by those who perform solitary oogenesis; polycheate

heterosynthesis is done by those who perform follicular and nutrimentary oogenesis

50
Q

whcih animal is a model organism of body plan development and how long does full development from a fertilised egg take

A

drosphila

9 days

51
Q

which type of cleavage does drosphila perform

A

merblastic (incomplete cleavage)

52
Q

discuss the nobel prize winning work of Nusslein-Volhard and Wieschaus

A

treated drosophila embryos with chemical mutagens and investigated how each gene mutation effected the body plan of the larva

53
Q

what evidence is there that drosophila cytoplasm have developmental signals in them

A

if the anterior cytoplasm from a wild type drosophila is placed anteriorlly in a mutated drosophila with no anterior structures (bicoid mutant), then anterior structures will develop

if the cytoplasm is placed in the middle of the mutated drosophila embryo, then anterior head like structures will develop in the middle of the mebryo

54
Q

what is the name given to a larva with mutaitons meaning no head segments develop

A

bicoid mutation

55
Q

summarise how maggots (fly larva) are formed

A

the mRNA of maternal effect genes is deposited in the oocyte unequally so that when expression occours there in a protein gradient; a cascade of gene activation occurs, (one set of genes activating another causing refinement of pattern formation) with different genes being expressed in different parts of the embryo leading to different structures

56
Q

name the 5 sets of genes that are involved in drosophila body plan development

A 
maternal effect genes
gap genes
pair rule genes
segment polarity genes
segmentation genes
selector genes
57
Q

name the maternal effect genes

name where they are highly concentrated

name what they cause development of and how

A

bicoid; anterior; morphogen which causes development of anterior structure.
promotes tranlation of hunchback and inhibits translation of caudal (gap genes)

nanos; posterior; promotes translation of caudal and inhibits translation of hunchback

oskar; posterior; linked to nanos

gurken; posterior

58
Q

where is oskar (maternal mRNA) highly concentration

A

posterior pole of the drosophila embryo

59
Q

how to maternal mRNA’s come to be highly concentrated in particular areas of the embryo

A

the gurken maternal mRNA is translated posteriorly, and attched to the torpedo receptor on the posterior follicle cells, which then signal for cytoskeleton rearrangement, causing maternal mRNA’s to move along the cytoskeleton to where they are known to be highly concentrated

60
Q

when is a dorsal ventral axis established in drosophila embryo

A

after the gurken protein has bound to torpedo receptors it moves dorsally and establishes this axis

61
Q

what causes the nucleus to move dorsally

A

after the gurken mRNA has been translated and the protein has binded to the torpedo receptor, gurken mRNA moves dorsally and then so does the nucleus

62
Q

where does drosophila maternal mRNA come from

A

nurse cells

63
Q

name one gap gene and 3 genes it represses

A

hunchback gene expressed anteriorly and represses knirps, kruppel and gianto

64
Q

what happens when gap genes are mutated

A

segments are deleted

65
Q

name the two pair rule genes and what each’s expression leads to

A

even skipped gene (eve_ leads to development of odd numbered parasegments

fushi tarazu (ftz) leads to development of even numbered parasegments

66
Q

what does expression of pair rule genes lead to

A

development of 14 parasegments (precursor segments)

molecular biology (3 decks)

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