6.1 Body Plans & apoptosis

Question 1

What is morphogenesis?

Answer 1

Regulation of the pattern of anatomical development

Question 2

What controls development of all organisms?

Answer 2

The same group of genes

Question 3

The genes were discovered by scientists investigating what?

Answer 3

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

Question 4

Why are fruit flies easy to study?

Answer 4

Small
Short life cycle
Easy to keep

Question 5

(Homeobox genes) what is a homeobox?

Answer 5

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

Question 6

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

Answer 6

Homeodomain

Similar in plants animals and fungi

Question 7

(Homeobox genes) why are homeobox genes regulatory genes?

Answer 7

Responsible for switching genes on and off

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

(Hox genes) what are hox genes?

Answer 10

Group of homeobox genes only present in animals

Question 11

(Hox genes) what are hox genes responsible for?

Answer 11

Ensuring correct positioning of body parts

Question 12

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

Answer 12

4 on different chromosomes

Question 13

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

Answer 13

In the order they appear on chromosomes

Question 14

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

Answer 14

39

Question 15

(Body plans) how are body plans represented ?

Answer 15

Cross sections through the organisms showing arrangement of body tissue

Question 16

(Body plans) what do diploblastic animals have?

Answer 16

2 primary tissue layers

Question 17

(Body plans) what do triploblastic animals have?

Answer 17

3 primary tissue layers

Question 18

(Body plans) what is a body plan?

Answer 18

Cross section through an animal showing arrangement of tissue layers

Question 19

(Body plans) what is radial symmetry?

Answer 19

Animals having symmetry around a central axis (diploblastic)

Question 20

(Body plans) what is bilateral symmetry?

Answer 20

Body can be divided into 2 mirror image halves

Question 21

(Body plans) what is a coelom?

Answer 21

Fluid filled cavity within the mesoderm

Question 22

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

Answer 22

The gut wall and body wall

Question 23

(Body plans) the coelom provides space of what?

Answer 23

Enlargement and development of internal organs

Question 24

(Body plans) what does the coelom act as?

Answer 24

Circulatory medium for transport

Storage area for excess or waste materials

Question 25

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

Answer 25

Rings of a worm | Vertebrates backbones

Question 26

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

Answer 26

Development of mouth parts

Question 27

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

Answer 27

Perform different functions

Question 28

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

Answer 28

Wings Limbs Ribs

Question 29

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

Answer 29

Somites

Question 30

(symmetry) where is radial symmetry seen?

Answer 30

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

Question 31

(symmetry) where is bilateral symmetry seen?

Answer 31

most animals | they have sides, a head and a tail

Question 32

(symmetry) where is asymmetry seen?

Answer 32

sponges which have no lines of symmetry

Question 33

what does mitosis do?

Answer 33

increases cell number for growth

Question 34

what does apoptosis do?

Answer 34

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

Question 35

what can cells undergoing apoptosis release?

Answer 35

chemical signals stimulating mitosis leading to remodelling of tissues

Question 36

which genes regulate mitosis and apoptosis?

Answer 36

hox genes

Question 37

(apoptosis) what are the stages of apoptosis?

Answer 37

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

Question 38

(apoptosis) why do cells commit suicide?

Answer 38

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

Question 39

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

Answer 39

cytotoxic t lymphocytes kill them by making them undergo apoptosis

Question 40

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

Answer 40

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

Question 41

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

Answer 41

set off apoptosis in cancer cells

Question 42

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

Answer 42

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

Question 43

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

Answer 43

removes excess tissue between fingers and toes

Question 44

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

Answer 44

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

Question 45

(factors) what can drugs do?

Answer 45

affect activity of regulatory genes

Question 46

(factors) what did thalidomide do?

Answer 46

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

Question 47

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

Answer 47

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

Question 48

what does it mean that oncology recapitulates ontology?

Answer 48

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

Question 49

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

Answer 49

growth factor for neurones | interleukin for mitosis of lymphocytes

Question 50

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

Answer 50

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