6.1 Body Plans & apoptosis Flashcards Preview

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Flashcards in 6.1 Body Plans & apoptosis Deck (50):
1

What is morphogenesis?

Regulation of the pattern of anatomical development

2

What controls development of all organisms?

The same group of genes

3

The genes were discovered by scientists investigating what?

Fruit flies with strange mutations e.g. Legs in the place of antennae

4

Why are fruit flies easy to study?

Small
Short life cycle
Easy to keep

5

(Homeobox genes) what is a homeobox?

Section of DNA 180bp coding for part of a protein of 60 amino acids

6

(Homeobox genes) what is the part of the protein called and what is it similar in?

Homeodomain
Similar in plants animals and fungi

7

(Homeobox genes) why are homeobox genes regulatory genes?

Responsible for switching genes on and off

8

(Homeobox genes) how have the homeobox genes been linked to humans and mice?

Common ancestor
Mutations led to very different organisms
Many homeobox genes present in both have same nucleotide sequence

9

(Homeobox genes) what happens when the pax6 homeobox gene is mutated?

It causes a form of blindness in humans, mice and fruit flies

10

(Hox genes) what are hox genes?

Group of homeobox genes only present in animals

11

(Hox genes) what are hox genes responsible for?

Ensuring correct positioning of body parts

12

(Hox genes) mammals have how many clusters of hox genes?

4 on different chromosomes

13

(Hox genes) in what order are hox genes expressed?

In the order they appear on chromosomes

14

(Hox genes)how many hox genes do humans have?

39

15

(Body plans) how are body plans represented ?

Cross sections through the organisms showing arrangement of body tissue

16

(Body plans) what do diploblastic animals have?

2 primary tissue layers

17

(Body plans) what do triploblastic animals have?

3 primary tissue layers

18

(Body plans) what is a body plan?

Cross section through an animal showing arrangement of tissue layers

19

(Body plans) what is radial symmetry?

Animals having symmetry around a central axis (diploblastic)

20

(Body plans) what is bilateral symmetry?

Body can be divided into 2 mirror image halves

21

(Body plans) what is a coelom?

Fluid filled cavity within the mesoderm

22

(Body plans) the coelom enables independent movement of what?

The gut wall and body wall

23

(Body plans) the coelom provides space of what?

Enlargement and development of internal organs

24

(Body plans) what does the coelom act as?

Circulatory medium for transport
Storage area for excess or waste materials

25

(Body plans) give an example of how animals are segmented?

Rings of a worm
Vertebrates backbones

26

(Body plans) what do hox genes in the head control?

Development of mouth parts

27

(Body plans) segments are multiplied over time and specialise to do what?

Perform different functions

28

(Body plans) what do hox genes in the thorax control development of?

Wings
Limbs
Ribs

29

(Body plans) individual vertebrae have developed from segments in the embryo called what?

Somites

30

(symmetry) where is radial symmetry seen?

diploblastic animals like jellyfish which have no left or right side only a top and bottom

31

(symmetry) where is bilateral symmetry seen?

most animals
they have sides, a head and a tail

32

(symmetry) where is asymmetry seen?

sponges which have no lines of symmetry

33

what does mitosis do?

increases cell number for growth

34

what does apoptosis do?

programmed cell death - removes unwanted cells and tissues shaping body parts

35

what can cells undergoing apoptosis release?

chemical signals stimulating mitosis leading to remodelling of tissues

36

which genes regulate mitosis and apoptosis?

hox genes

37

(apoptosis) what are the stages of apoptosis?

cell shrinks
DNA & proteins degraded
mitochondria degraded
blebs containing broken down organelles form of cell surface
engulfed by phagocytes
phagocytes release signals to inhibit inflammation

38

(apoptosis) why do cells commit suicide?

defence against pathogens or damaged cells
or as part of normal development

39

(apoptosis) when cells are infected by viruses why do they undergo apoptosis?

cytotoxic t lymphocytes kill them by making them undergo apoptosis

40

(apoptosis) how do cells with DNA damage undergo apoptosis?

cells with damage to the DNA produce large amounts of the p53 protein which induces apoptosis

41

(apoptosis) what do some forms of radiotherapy and chemotherapy do?

set off apoptosis in cancer cells

42

(apoptosis) during synapse formation in the development of the NS what does apoptosis do?

removes extra synaptic connections so the right connections can be made to form a particular pathway

43

(apoptosis) how is apoptosis involved in trimming and shaping?

removes excess tissue between fingers and toes

44

(factors) what is stress and what is it due to?

condition when homeostatic balance in an organism is upset
die to external factors e.g. temperature or internal factors e.g. release of hormones

45

(factors) what can drugs do?

affect activity of regulatory genes

46

(factors) what did thalidomide do?

prevented normal expression of particular hox genes resulting in babies having shortened limbs

47

(factors) why is thalidomide sometimes used in cancer treatment?

stops development of tumours by preventing the networks of capillaries essential for tumours to grow and develop

48

what does it mean that oncology recapitulates ontology?

genes expressed in development of an embryo are expressed again by cancerous cells

49

(apoptosis) apoptosis depends on positive signals such as what?

growth factor for neurones
interleukin for mitosis of lymphocytes

50

(apoptosis) aptosis also depends on negative signals such as what?

high levels of oxidants e.g. peroxide ions
harmful radiation

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