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UVic BIOL 432 - Spring 2019 > Growth Hormone, Growth Factor, and Growth Diseases > Flashcards

Growth Hormone, Growth Factor, and Growth Diseases Flashcards

1
Q

How many cells in the adult human body? How many cell types?

A

Around 37 million cells of over 200 different types.

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2
Q

What is the placenta? Why is it necessary for growth?

A

An endocrine organ produced during pregnancy which supplies the developing fetus with nutrients as well as endocrine molecules.

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3
Q

What is the leading cause of low birth-weight infants? What else can affect fetal development?

A

Poor maternal nutrition. Drugs, illness, smoking, and fitness can also affect growth and mental development.

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4
Q

What long-term repercussions result from an infant having low birth-weight?

A

Greater odds for that child (if female) to give birth to another low birth-weight child. Low birth-weight is also associated with chronic diseases like obesity.

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5
Q

At what 5 stages of development do humans experience accelerated growth?

A
  1. Fetus
  2. Immediately after birth
  3. Two years olf
  4. Seven years old
  5. Puberty
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6
Q

What nutrient during childhood has the most impact on final adult height? What other nutrients can affect height?

A

Protein is the greatest determiner, but minerals (ex: calcium) and vitamins A and D also play a role.

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7
Q

Is vitamin D a true vitamin? Why? Why not?

A

No, it’s actually a hormone which binds to nuclear receptors and alters transcription of many cellular processes.

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8
Q

Why is breast milk considered the best source of nutrition for infants?

A

Any amount of breast milk can induce changes in DNA methylation which is thought to improve development.

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9
Q

What condition results from having too much growth hormone (AFTER PUBERTY)? Describe.

A

Acromegaly. High growth hormone causes high insulin-like growth factor 1 which stimulates the proliferation of bone, cartilage, and soft tissue.

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10
Q

How can acromegaly be treated?

A

Using growth hormone receptor antagonists can block its growth stimulating effects.

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11
Q

What characteristics develop as someone with acromegaly ages?

A

Size of nose, lips, and skin folds keep increasing throughout their life because of excess growth hormone production.

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12
Q

What is gigantism? At what stage of human development does it occur? How can this be caused?

A

A condition which occurs before puberty involving excessive growth due to high levels of growth hormone. Possibly due to somatotroph-releasing tumours.

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13
Q

What causes Laron’s dwarfism?

A

Caused by growth hormone receptor defect or insulin-like growth factor 1 defect.

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14
Q

How come some kids are just shorter than normal?

A

“Normal short kids” may just have low growth hormone binding protein.

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15
Q

How can ectopic tissue cause acromegaly or gigantism?

A

Tumour in a tissue (with GH receptors) other than the anterior pituitary causing upregulation of growth hormone.

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16
Q

What factors contribute to psychosocial dwarfism?

A

Environmental factors during development can cause reduced growth (can be social, nutritional, or even altitude).

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17
Q

How was growth hormone replacement therapy used to treat undersized children and aids? What issue arose? How was this problem solved?

A

Took GH from cadavers, but led to Creutzfeld-Jakob disease (prions in the brain, cause brain holes). Solved by creating human GH in mice and taking that instead.

18
Q

How do growth factors stimulate growth?

A

Have mitogenic properties and stimulate growth via proliferation and/or differentiation.

19
Q

What are proto-oncogenes? What can they become?

A

A category of genes with either replicative or apoptotic function that when mutated become cancer-causing oncogenes.

20
Q

What occurs in nerve cells which stop being stimulated?

A

The cells die.

21
Q

What 5 important growth factors make use of cytokine receptors?

A
  1. Growth hormone
  2. Erythropoietin (RBCs)
  3. Cytokines (immune fxn.)
  4. Colony stimulating factors (WBCs)
  5. Transforming growth factor beta
22
Q

How is tyrosine kinase associated with growth HORMONE cytokine receptors?

A

Cytokine receptors recruit accessory proteins which have tyrosine kinase domains.

23
Q

How is tyrosine kinase associated with growth FACTOR receptors?

A

The receptor has its own associated tyrosine kinase domain which phosphorylates other proteins.

24
Q

What 6 main growth factors which use growth factor receptors were discussed in class?

A
  1. Insulin-like growth factor 1
  2. Insulin-like growth factor 2
  3. Insulin
  4. Epidermal growth factor
  5. Nerve growth factor
  6. Platelet derived growth factor
25
Q

How does insulin-like growth factor 1 affect child development?

A

Responsible for protein synthesis a well as cell proliferation. Acts on growth hormone by negative feedback.

26
Q

How does insulin-like growth factor 2 affect the developing fetus?

A

Fetal growth hormone (esp. liver), mediates growth hormone effects.

27
Q

How does insulin act as a growth factor for a developing fetus?

A

Important for carbohydrate metabolism but also fetal growth.

28
Q

What effect does epidermal growth factor have on the developing fetus? How can it be affected by a mother who smokes during pregnancy?

A

Primes the fetal gut to absorb nutrients, also plays a role in fetal growth. Cause of low birth-weight and delayed growth for children of smoking mothers.

29
Q

What function does nerve growth factor serve in the body?

A

Promotes growth and maintenance of sympathetic NS and some sensory neurons.

30
Q

What is the biological purpose of platelet derived growth factor?

A

Stimulates wound healing. Allows damaged cells to respond to insulin-like growth factor 1.

31
Q

What 6 main steps outline the function of growth factor receptors?

A
  1. Dimerization upon ligand binding
  2. Autophosphorylation
  3. Recruit accessory proteins
  4. Recruited proteins phosphorylate
  5. Signalling complex forms
  6. Intended effect (cell division, etc.)
32
Q

When growth factor receptors autophosphorylate, what residues are recognized by SH2 domains on accessory proteins?

A

Phosphorylated tyrosine residues (in certain contexts).

33
Q

After growth factor receptors autophosphorylate, what is recognized by SH3 domains on accessory proteins?

A

Proline-rich areas, usually on other accessory proteins which have already been recruited.

34
Q

What is an Src?

A

A proto-oncogenic tyrosine kinase.

35
Q

What are 4 examples of phosphorylation cascades?

A
  1. MAPK
  2. PI3K
  3. PKB
  4. Ras/ERK
36
Q

What is RAS?

A

Rat sarcoma, a small G protein. Also a common oncogene.

37
Q

What is growth factor receptor bound protein 2 (GRB2)? What is it’s function?

A

It is a protein which contains both SH2 and SH3 domains (like growth factor receptor accessory proteins).

38
Q

What disease is associated with an excess of growth factor? How can this disease promote itself (positive feedback regulation)?

A

Cancer. Tumours can cause increased growth factor secretion.

39
Q

What disease is associated with a lack of growth factor?

A

Failure to grow/thrive. Apoptosis.

40
Q

What condition is caused by an overabundance of insulin-like growth factor 1? How does it relate to growth hormone?

A

Acromegaly. IGF-1 levels directly reflect GH levels. High growth hormone levels increase the levels of insulin-like growth factor 1.

41
Q

How does Rous sarcoma virus affect cell growth? What is it?

A

A retrovirus (acts as a viral mimic) which can cause cancer (an oncovirus). Reverse transcribes its RNA into cDNA then integrates into the host DNA.

42
Q

What is v-src? How does it affect the cell?

A

An active kinase inserted into a cell by a virus that mimics regular src (c-src, proto-oncogene) tyrosine kinase but can’t be regulated (oncogene).

UVic BIOL 432 - Spring 2019 (15 decks)

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