Diff11 - 41

Question 1

What are the three kinds of growth?

Answer 1

Hyperplasia, hypertrophy, accretion

Question 2

Outline cell proliferation

Answer 2

Gap 1 - cell enlarges; Synthesis - DNA replication; G2 - end of interphase; Mitotic - cell actually divides

Question 3

What controls the mechanics of cell proliferation?

Answer 3

Cyclins > cyclin dependent kinases > trigger proteins

Question 4

Describe the status of fully differentiated cells

Answer 4

G0

Question 5

Outline cell division in early drosophila

Answer 5

Syncytium - single cell, multiple nuclei; rapid synchronous cell cycles with only S and M phases; at 14th cycle, G2 is introduced, and cellularisation occurs; each cell acquires its own cell division rate - mitotic domains

Question 6

What controls cell division in mitotic domains?

Answer 6

String - protein

Question 7

Outline string expression

Answer 7

Maternal during 1st 13 divisions, zygotic after 13th

Question 8

What delays certain mitotic domain mitosis?

Answer 8

Tribble - inhibitor of string

Question 9

Characterise limb size

Answer 9

Intrinsic sizing - absolute dimensions, not number of cells

Question 10

What determines the size of a structure?

Answer 10

No just rate of growth, but also duration

Question 11

What determines the size of drosophila?

Answer 11

Size of larva - determined by insulin signaling which affects duration and rate of larval growth

Question 12

What important mammalian factors determine growth patterns?

Answer 12

IGF1/2

Question 13

What does IGF stand for?

Answer 13

Insulin-like growth factors

Question 14

What controls post-embryonic mammalian growth?

Answer 14

Growth hormone

Question 15

What mediates GH effects?

Answer 15

IGFs

Question 16

Where is GH made?

Answer 16

Pituitary gland

Question 17

What induce GH release?

Answer 17

GH releasing hormone

Question 18

What inhibits GH release?

Answer 18

Somatostatin from the hypothalamus

Question 19

How does GH feedback work?

Answer 19

GH promotes somatostatin and inhibits GHRH; GH promotes IGF1/2; GH promotes GHRH

Question 20

What is an oncogene?

Answer 20

Activated proto oncogene - genes that if mutated lead to a loss of growth control

Question 21

What is a suppressor gene?

Answer 21

Genes that normally inhibit growth - a loss of which leads to a loss of growth control

Question 22

What are teratomas?

Answer 22

Similar to embryonic cells and can give rise to tissues from all three germ layers

Question 23

What is another term for molting?

Answer 23

Ecdysis

Question 24

What are intermolt stages called?

Answer 24

Instars

Question 25

How many instars do drosophila undergo before pupation?

Answer 25

3

Question 26

What is molting activated by?

Answer 26

Activation of stretch receptors, followed by release of protothoracicotropic hormone from the corpus alatum, which leads to the release of ecdyson from the protothoracic gland

Question 27

Outline the influence of ecdyson

Answer 27

Cuticle separates from epidermis, freed epidermal cells proliferate, fluid barrier is secreted, new cuticle is secreted

Question 28

What can influence metamorphosis?

Answer 28

Nutrition, temperature and light

Question 29

What do external cues for metamorphosis affect internally?

Answer 29

Affect the relative levels of juvenile hormone and ecdysone

Question 30

What is the role of juvenile hormone?

Answer 30

Prevention of metamorphosis

Question 31

What is the role of ecdysone?

Answer 31

Promotion of metamorphosis

Question 32

What two chemicals balance metamorphosis in frogs?

Answer 32

Prolactin (-) and thyroxine (+)

Question 33

What is interesting about thyroxine?

Answer 33

Positively feeds back; has different effects on different limbs (generation of limbs, degeneration of tail)

Question 34

What is senescence?

Answer 34

Age dependent decline in vital physiological functions

Question 35

Give an example of wear and tear senescence

Answer 35

Feeding muscles in c.elegans

Question 36

Give an example of genetically programmed senescence

Answer 36

Drosophila

Question 37

What is the disposable soma theory?

Answer 37

Natural selection tunies life history of the organism so that sufficient resources are invested in maintaining the repair mechanisms that prevent aging at least until that organism has reproduced and cared for its young

Question 38

What factors are thought to contribute to control of aging?

Answer 38

DNA damage and oxygen radicals, genetic mutations, binge eating

Question 39

How does the c.elegans extend its life?

Answer 39

IGF signalling inhibits FOXO, which regulates increased resistance to stressors such as antimicrobial genes

Question 40

How does binge eating affect life span?

Answer 40

Reduction in caloric intake can extend life span - possibly due to reduced reactive oxygen generation, possibly downregulation of IGF

Question 41

What are sirtuins?

Answer 41

Protein deacetylases and are thought to be the target of resveratrol - compound from red wine!