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Bio 432 > Topic 2 - Hormone Biosynthesis and Receptors > Flashcards

Topic 2 - Hormone Biosynthesis and Receptors Flashcards

1
Q

Transcription

A

Is the 1st step of gene expression, where a particular segment of DNA is copied into RNA
- by the enzyme RNA polymerase

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2
Q

Splicing

A

Is the editing of the precursor mRNA. Introns are removed and exons are joined together

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3
Q

Translation

A

mRNA is decoded by a ribosome, outside the nucleus, to produce a specific amino acid chain or ploypeptide

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4
Q

Promoter

A

Is a region of DNA that initiates transcription of a particular gene

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5
Q

Enhancer

A

Is a short region of DNA that can be bound by proteins to increase the likelihood that transcription of a particular gene to occur
- Usually referred to as TF (transcription factor)

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6
Q

What do insulin and prolactin synergistically stimulate?

A

Beta-casein mRNA translation by cytoplasmic polyadenylation

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7
Q

What kind of protein is beta- casein?

A

Milk protein

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8
Q

What enzyme transcribes genes to mRNA?

A

RNA polymerase 2

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9
Q

What does transcription initiation require?

A

Many general and specific transcription factor protein binding promoters

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10
Q

Where does transcription start site usually occur?

A

Just after a TATA box

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11
Q

What do activators do?

A

Then bind enhancer DNA sequences and increase transcription – hormone influence

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12
Q

What do repressors do?

A

They bind silencer DNA sequences and decrease transcription – hormone influence

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13
Q

How do chromatin remodelling complexes weaken histone DNA interactions and DNA folding?

A

They use ATP-driven conformational change

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14
Q

HATs

A

Histone acetylases

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15
Q

What do HATs do and whats the result?

A

They add acetyl groups to histones resulting in more open conformation

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16
Q

HDACs

A

Histone deacetylases

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17
Q

HRE

A

Hormone response element

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18
Q

Hormone response element

A

Is a short sequence of DNA within the promoter of a gene that is able to bind a specific hormone receptor complex and therefore regulate transcription

19
Q

Does HRE influence RNA polymerase directly for indirectly?

A

Indirectly

20
Q

What do HRE influence?

A

Histone acetyl transferases

21
Q

What do hormones open up, and why?

A

The open up proteins to enhance transcription

22
Q

RNA processing steps (6)

A
  1. Splicing introns, leaving exons
  2. Cap 5’ end of RNA
  3. Poly-A tail on 3’ end
  4. Mature mRNA exported
  5. Translation starts
  6. Translation continues until stop codon is reached
23
Q

Protein synthesis steps (7)

A
  1. Ribosomes translate mRNA; NAC binds
  2. Signal sequence targets protein to signal recognition particle
  3. SRP docks with receptor on ER and translocation channel forms
  4. Translation & cotranslational modifications
  5. Cleavage signal sequence peptide
  6. Chaperones fold and control quality
  7. Ribosomal subunits recycled; channels close; folded protein chain in ER
24
Q

What kind of energy drive protein synthesis? (2)

A

ATP and GTP hydrolysis

- But also need a functional mitochondria and respiration

25
Q

NAC

A

Nascent chain associated complex

26
Q

SRP

A

Signal recognition particle

27
Q

What makes up pre-hormone (non-functional; in ER)? (3) Example?

A
  • single peptide + hormone + cryptic peptide

- Eg) Hepcidin pre-prohormone 85AA

28
Q

What makes up prohormone (non-functional; in ER)? (2) Example?

A
  • hormone + cryptic peptide

- Eg) Hepcidin prohormone 60AA

29
Q

What is a mature hormone (functional; in Golgi)? Example?

A
  • Processed hormone

- Eg) mature hepcidin 25AA

30
Q

How are hormones secreted outside of the cell?

A

Vesicular transport

31
Q

What does brefeldin A do?

A

It inhibits protein transport from the ER to the golgi body indirectly by preventing association of coat COP-II protein to the golgi membrane

32
Q

What are 3 types of coat proteins?

A
  1. COP-I
  2. COP-II
  3. Clathrin
33
Q

What are coat proteins used?

A

In vesicular traffic in the secretory and endocytic pathways

34
Q

How can you monitor when using coat proteins?

A

By using fluorescents

35
Q

Coat associated protein - I

A

Mediates retrograde transport from the trans- to the medial- to the cis-Golgi/cis-Golgi network to the rough ER
–> Bring back mature proteins that arent being released

36
Q

Coat associated protein - II

A

Mediates transfer of vesicles from the rER to the cis-Golgi /cis-Golgi network.
–> Bring forwards motion in the golgi where they can be released, fused with lysosomes and broken down or recycled

37
Q

Clathrin

A

Mediates transfer of vesicles that bud from the trans-golgi netork and the plasma membrane and that then fuse with late endosomes

38
Q

COP

A

Coat associated protein

39
Q

Vesicular secretion steps (6)

A
  1. Sorting hormones for secretion
  2. COP and vesicle formation
  3. Budding and trafficking (v/t-SNARE)
  4. Uncoating
  5. Docking
  6. Fusion to target membrane
40
Q

What energy source drives vesicular secretion? (1)

A

GTP hydrolysis

41
Q

What 2 things influence the half-life of mRNA?

A
  1. 5’cap

2. Length of 3’poly A tail

42
Q

What factors affect protein stability? (4)

A
  1. Glycosylation
  2. Phosphorylation state
  3. Metabolic degradation
  4. Internalization (presence of proteolytic enzymes)
43
Q

How are vascular and non-vascular hormone secretion transported across the plasma membrane?

A

Directly

44
Q

What does the rER produce, and what is it used in?

A
  • Produces oxidases

- Used in sER and are controlled by HRE that change the amount of P450

Bio 432 (19 decks)

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