QUIZ 2 Flashcards
Which of the following statements about signaling substances is wrong?
A. Signaling molecules secreted by neurons to signal to other neurons are called neurotransmitters
B. In a broader sense all signaling molecules arriving from extracellular space can be considered hormone
C. Signaling molecules secreted by neurons into the circulation to regulate the behavior of other non-neuronal cells is called a neurocrine hormone
D. Substances that are secreted by one type of cells into circulation and act upon other cell types are called hormones
E. Some nutrients/metabolites can function as hormones
C. Signaling molecules secreted by neurons into the circulation to regulate the behavior of other non-neuronal cells is called a neurocrine hormone
Which of the following features of endocrine system allows for organisms to maintain homeostasis?
A. Complex communication network through multiple hormones
B. General high concentrations of hormones in circulation
C. Complex communication networks with redundant functions
D. Complex communication networks with precise positive and negative interactions
E. High specificity between hormones and their receptors
C. Complex communication networks with redundant functions
Which of the following statements about endocrine glands is false?
A. They secrete one or more hormones into circulation and thus regulate function of other organs
B. Unlike exocrine glands, they do not have ducts for secretion of hormones
C. Peptide hormones are stored, while lipid hormones are not.
D. Ovarian corpus luteum is not a gland as it is not a permanent structure in the ovary
E. All the statements above are correct
D. Ovarian corpus luteum is not a gland as it is not a permanent structure in the ovary
Which of the following statements about hormone receptors is false?
A. Protein hormones being water soluble have receptors in the cell membrane
B. Hormone receptors are single or multiple proteins in complex
C. Eicosanoids being fat soluble have intra-cellular receptors
D. Intracellular receptors typically elicit slower response as they mainly regulate transcription
E. All the statements above are correct
C. Eicosanoids being fat soluble have intra-cellular receptors
Which of the following hormones is (are) transported in the circulation as bound to “hormone binding proteins”?
A. Estradiol
B. Thyroid hormone
C. Insulin-like growth factor 1 (IGF-1)
D. Only A and B, as they are hydrophobic hormones
E. All three hormones are transported with binding proteins
E. All three hormones are transported with binding proteins
Which of the following hormones is (are) stored in secretory granules in the cells where they are synthesized?
A. Progesterone
B. Follicle stimulating hormone (FSH)
C. Insulin
D. Testosterone
E. Only B and C are stored in secretory granules
E. Only B and C are stored in secretory granules
Which of the following statements concerning signal transduction by the insulin receptor is not correct?
A. Activation of the receptor protein kinase activity results in the activation of additional protein kinases.
B. The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.
C. Binding of insulin to the receptor activates a protein kinase.
D. Binding of insulin to the receptor results in a change in its quaternary structure.
E. The receptor protein kinase activity is specific for tyrosine residues on the substrate proteins.
B. The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.
Which of the following kinases plays an important role in epinephrin signaling?
A. PKA
B. PKB
C. PKC
D. Both A and C
E. All kinases listed above
D. Both A and C
Which of the following kinases plays an important role in growth hormone signaling?
A. PKA
B. PKB
C. PKC
D. Both A and C
E. All kinases listed above
B. PKB
Which of the following statements about G-protein coupled receptor (GPCR) signaling is correct?
A. Second messenger AMP is important for this signaling pathway
B. G-alpha protein disassociates from the receptor to activate its substrates
C. Nucleic phosphodiesterase is important to activate GPCR signaling
D. PI3-kinase plays a role in GPCR signaling through IP3 and Calcium
E. All the statements above are correct
B. G-alpha protein disassociates from the receptor to activate its substrates
Which of the following hormones is synthesized from proteins coded from two different genes?
A. Insulin
B. Luteinizing hormone (a gonadotropin)
C. Calcitonin
D. Adrenaline
E. Thyroid hormone
B. Luteinizing hormone (a gonadotropin)
Gluconeogenesis is_____
a) modification of glucose into protein
b) helpful to reduce blood glucose after sugar consumption
c) synthesis of glucose from a non-carbohydrate precursor
d) synthesis of glycogen from glucose
e) breakdown of glycogen into glucose
c) synthesis of glucose from a non-carbohydrate precursor
Which one of the following statements about eukaryotic gene regulation is not correct?
a) Access to promoters is restricted by the structure of chromatin.
b) Most regulation is negative involving repressors.
c) Larger and more multimeric proteins are involved in regulation of transcription.
d) Transcription and translation are separated in both space and time.
e) Alternative splicing of mRNA takes place as gene is being transcribed.
b) Most regulation is negative involving repressors.
Glycosis is _______
a) a pathway of glucose metabolism
b) a pathway of fatty acid metabolism
c) a pathway of protein metabolism
d) a pathway of nucleic acid metabolism
e) a pathway of steroid metabolism
A a) a pathway of glucose metabolism
Which of the following statements is false about human cells?
a) Human cells are eukaryotic
b) Cells do not have cell wall
c) Cells are organized to form tissues
d) Regulation of gene expression is complex due to involvement of promoters and enhancers
e) All human cells have nucleus
e) All human cells have nucleus
What is not true concerning ketone bodies?
a) They are metabolized to pyruvate for energy in tissues
b) They are produced by the liver, to be transported to other tissues as energy molecules
c) They are water soluble and thus easily transported through blood
d) Acetyl-CoA is the precursor for ketone body synthesis in the liver
e) The levels of ketone bodies in circulation increases during starvation
a) They are metabolized to pyruvate for energy in tissues
Which of the following tissues respond to insulin by up-taking glucose?
a) Muscle
b) Adipose tissue
c) Liver
d) Only the liver and muscle
e) Only muscle and adipose
e) Only muscle and adipose
Which of the following is not a hormone-producing organ?
a) Hypothalamus
b) Pituitary
c) Adrenal gland
d) Thyroid
e) Liver
e) Liver
Which of the following is not an intermediate of the citric acid cycle?
a) Acetyl-CoA
b) Citrate
c) Oxaloacetate
d) Succinyl-CoA
e) ⍺-Ketoglutarate
a) Acetyl-CoA
The ion channel that opens in response to acetylcholine is an example of a ____________ signal transduction system.
a) G-protein
b) ligand-gated
c) receptor-enzyme
d) nuclear receptor
e) voltage-gated
b) ligand-gated
Protein translation takes place in the_____
a) Nucleus
b) Cytoplasm
c) Cell membrane
d) Mitochondria
e) Extracellular space
b) Cytoplasm
In comparison with the resting state, actively contracting human muscle tissue has a _________
a) higher concentration of ATP
b) higher rate of lactate formation
c) lower consumption of glucose
d) lower rate of oxygen consumption
e) lower ratio of NADH to NAD+
b) higher rate of lactate formation
Triacylglycerols are composed of:
a) A glycerol backbone
b) Three fatty acids
c) Amide linkages between the fatty acids and glycerol
d) A and B above
e) A, B, and C above
e) A, B, and C above
Ketone bodies are produced from the metabolism of:
a) Fatty acids
b) Carbohydrates
c) Amino acids
d) Nucleic acids
e) Ketone bodies are not produced by mammals
a) Fatty acids
When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because:
a) Glycolysis does not occur to significant extent under aerobic conditions
b) Muscle is metabolically less active under aerobic than anaerobic conditions
c) The lactic acid generated is rapidly incorporated into lipids under aerobic conditions
d) Under aerobic conditions, the metabolic pathway is the pentose phosphate pathway that does not produce lactate
e) Under aerobic conditions, most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate
e) Under aerobic conditions, most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate
Which of the post-translational modifications is known to result in a reduction in protein concentration?
a) Addition of Phosphate group (phosphorylation)
b) Addition of Acetylation group (acetylation)
c) Addition of Methylation group (methylation)
d) Addition of Ubiquitin groups (ubiquitination)
e) Localization of protein to the mitochondria
d) Addition of Ubiquitin groups (ubiquitination)
Which one of the following is true about the genetic code?
a) All codons recognized by a given tRNA encode different amino acids
b) The codons are absolutely identical in coding for amino acids in all living organisms
c) Multiple codons may encode the same amino acid
d) The base in the middle position of the tRNA anticodon sometimes permits “wobble” base pairing with two or three different codons
e) The first position of the tRNA anticodon is always adenosine
c) Multiple codons may encode the same amino acid
Gene silencing by RNA interference acts by ________________ of the target gene.
a) inhibiting translation
b) degradation of the mRNA
c) inhibiting transcription
d) inhibiting alternative splicing
e) inhibiting poly-A tail formation
b) degradation of the mRNA
Alternative splicing of mRNA may result in:
a) a shift in the ratio of mRNA produced from two adjacent genes.
b) attachment of the poly(A) tail to the 5’ end of an mRNA.
c) inversion of certain exons in the final mRNA.
d) the production of the same protein from two different genes.
e) the production of two distinct proteins from a single gene.
e) the production of two distinct proteins from a single gene.
β-oxidation is _______
a) a pathway of glucose metabolism
b) a pathway of fatty acid metabolism
c) a pathway of protein metabolism
d) a pathway of nucleic acid metabolism
e) a pathway of steroid metabolism
b) a pathway of fatty acid metabolism
Glycogen is converted to monosaccharide units by:
a) Glucokinase
b) Glucose-6-phosphatase
c) Glycogen phosphorylase
d) Glycogen synthase
e) Glycogen’s
C c) Glycogen phosphorylase
The first reaction in glycolysis that results in the formation of an energy-rich compound is catalyzed by
a) glyceraldehyde 3-phosphate dehydrogenase
b) hexokinase
c) phosphoglycerate kinase
d) phosphofructokinase-1
e) None of these enzymes participate in glycolysis
a) glyceraldehyde 3-phosphate dehydrogenase
Energy required by the ATP synthase enzyme for its function comes from:
a) Chemical potential created by transfer of H+ ions out of mitochondria into cytoplasm
b) Electrochemical potential created across the inner mitochondrial membrane
c) Electrochemical potential created by transfer of H+ ions into mitochondrion
d) Electrical potential created by transfer of H+ ions from extracellular matrix into cytoplasm
e) ATP synthase does not require energy for its function
b) Electrochemical potential created across the inner mitochondrial membrane
Which of the following contains the highest percentage of triacylglycerols?
a) Chylomicrons
b) VLDL (very low-density lipoprotein)
c) LDL (low-density lipoprotein)
d) HDL (high-density lipoprotein)
e) None of the above contain triacylglycerols
A a) Chylomicrons
Which of the following is not a feature of signal transduction?
a) Integration of multiple pathways toward the same downstream response
b) Signal amplification
c) Covalent binding between the ligand and the receptor
d) Desensitization or adaptation of the receptor
e) Actually all the above are features of signal transduction
c) Covalent binding between the ligand and the receptor
Cell synthesizes ATP in ________
a) The mitochondria
b) The cytoplasm
c) The nucleus
d) Both mitochondria and cytoplasm
e) Both mitochondria and nucleus
d) Both mitochondria and cytoplasm
What are the 3 pillars for cellular communication ?
Proliferation (what type of cell to become)
differentiation
Homeostasis
What is the difference between nervous and hormonal (endocrine) communication ?
Hormonal is more direct, goes directly to any cell. however not be faster than nervous system communication
What is the first hormone discovered ?
secretin
Who discovered the first hormones ?
Ernest Starling (father and William Bayliss
What does hormone mean? (Etymology)
In greek: I excite, i arose, i set in motion
What does endocrine mean? (Etymology)
In greek and latin: internal secretion
What is the classical definition of hormone?
Chemical messenger from one cell, carried into bloodstream and act on target cell
What is a ligand ?
Everything that come from outside and signal through a receptor
Name 3 chemical signals/messenger (goes out of the cell).
- hormones
- growth factors
- cytokines/chemokines
- neurotransmetters
- mitogens/morphogens
- membrane bound/ECM ligands
What are the 3 layers of signaling networks?
- within cells (intracelluar)
- between cells (intercellular)
- Between tissues/organs (intertissues)
Name the 4 classes of signals based on generation and delivery.
- autocrine signaling (regulate the cell its from)
- Juxtacrine (need to be beside each other)
- Paracrine (not beside but in same tissue)
- Endocrine (through circulation)
(TF) a same hormone can regulate 2 types of cells to have the same outcomes?
False the respond may be completely different based on the target cells (e.g. epinephrin in muscle and liver)
What is signal integration within cells?
Response of a cell is an integrated response to all signals exposed
What is the composition of an endocrine gland?
- parenchyma
- blood vessels
- no ducts (otherwise exocrine)
(TF) a lipid hormone producing cell need to contain mitochondrion, lipid droplet and smooth endoplasmic reticulum (SER).
True
(TF) a protein hormone producing cell need to contain mitochondrion, lipid droplet and smooth endoplasmic reticulum (SER).
False
Name 2 transient endocrine glands.
- Ovarian follicle
- corpus luteum
- placenta
Explain the difference in the composition of endocrine cells producing protein-hormone vs lipid-hormone.
Protein producing
Need RER: protein synthesis
Secretory granules to store protein hormones
Golgi complex cleaves off vesicles into storage granules
Lipid producing
Need lipids droplet to store the precursor necessary
SER -> steroidogenesis takes place
Mitochondria spherical rather than elongated bc that’s also where steroidogenesis takes place
Not a lot of RER bc produce protein for their survival and not for hormone producing
Which level to measure hormone concentration?
ng/ml or pg/ml
Name 2 type of lipids hormones.
- steroids
- eicosanoids
What are the 3 chemical nature possible of hormones?
- lipids
- proteins
- amino acid derivates
(TF) Epinephrine is a protein hormone.
false
a amino acid derivates
What is the name of enzymes involve in steroidogenesis?
Steroidogenic enzymes
Name the 2 mitochondrial electron transporters involve in steroidogenesis?
ADR = adrenodoxin reductase
Adx = adrenodoxin
Name the 2 microsomal electron transporters involve in steroidogenesis?
POR = P450 oxidoreductase
B5 = cytochrome b5
Which enzyme is necessary to convert androgen into estrogen ?
aromatase
Explain the sequential chain rx to make cortisone
steroidogenesis:
cholesterol
Pregnenolone
Progesterone
17OH-progesterone
11-deoxycortisol
Cortisol
Cortisone
Cholesterol De Novo is synthesized from…
acetyl-CoA
Name 2 steroid hormones produces from adrenal glands
Mineralocorticoids (mineral homeostasis)
Glucocorticoids (glucose metabolism)
Name 3 steroid hormones produced by gonads (ovaries/testis).
- estrogens
- progestogens
- androgens
(TF) all enzymes are in the mitochondria ?
false
mitrochondria
endoplasmic reticulum/microsomes
some in both
(TF) prostaglandins is part of eicosanoid hormones?
true
What is the difference between protein and lipid hormones
protein:
water soluble
larger
linear chain linked by disulfide bridges
3D structure (for receptor)
Stored in secretory vesicles (granules) in the cytoplasm
indirect mechanism of action
receptor in plasma membrane
lipid:
use binding protein in circulation
longer half-life
receptor in cytoplasm and nucleus
direct mechanism of action
What are the steps of protein hormone synthesis?
transcription
translation
post-translational modification (cleavage, addition, delocatization)
What is the start codon for mRNA
AUG Methionine
What are the steps of translation of peptide hormones?
- Activation tRNA is aminoacylated (methionine)
- initiation RNA binds to small ribosome
- elongation peptide bond formation until stop codon
- termination
- protein folding
Calcitonin gene is produced in which endocrine gland?
thyroid
(TF) CGRP is produced when the 4ft exons included?
false, that’s calcitonin
4ft is excluted and 5, 6th included
typically in neurones
What is a signal sequence ?
peptide sequence is cleaved off when protein hormone synthesized
name 2 post-translational peptide modification
- Lipophilic leader sequence (signal peptide) is
cleaved by peptidase. - Formation of disulfide bridges between cysteines
and glycosylation. - Transport by vesicles into the Golgi. Further
glycosylation and proteolytic cleavage. - Packaging into vesicles. Sometimes together with
an activating peptidase.
Name Thyroid hormones
- Thyroxine (T4)
- Triiodothyronine (T3)
name 2 hormones secreted by Adrenal medulla
- Epinephrine
- Norepinephrine
- Dopamine
(TF) dopamine is a Tyrosine derivatives.
True
where hydrophilic hormones are stored ?
Stored in secretory vesicles (granules) in the cytoplasm
Exocytosis definition and exemple when used in hormones.
Exocytosis is the process by which cells move materials from within the cell into the extracellular fluid.
when prohormone of hydrophilic hormone are released to activate the hormone
name 4 things that can control the synthesis and secretion of hormones.
Neural inputs
– Brain
– Hypothalamus
Hormonal stimulation/inhibition
– Releasing factors/hormones
– Inhibitory factors
– Feedback system
Metabolic status
– Stress
– Blood concentrations of substances
* Ca
* Glucose
* Water
What is apoptosis?
Programmed cell death
what are the 4 possible response from a cell to a signal ?
survive
divide
differentiate
die
associate the cellular response to the target protein
- metabolic enzyme
- gene regulatory protein
- cytoskeletal protein
a. altered gene expression
b. altered cell shape or movement
c. altered metabolism
- metabolic enzyme c. altered metabolism
- gene regulatory protein a. altered gene expression
- cytoskeletal protein b. altered cell shape or movement
(TF) Hydrophobic (lipid-hormone) need a receptor to enter the cell membrane.
False
Protein-hormone (hydrophilic) need a receptor to enter the cell membrane
Hydrophobic (lipid-hormone) can go directly into cell
do they have cell surface receptors or intracellular receptors?
a. bile acids
b. Hydrophilic hormones
c. hydrophobic hormones
d. prostaglandins
e. leukotrienes
a. bile acids BOTH
b. Hydrophilic hormones cell surface receptors
c. hydrophobic hormones intracellular receptors
d. prostaglandins cell surface receptors
e. leukotrienes cell surface receptors
What AA is most present in cell surface receptor?
cysteine
what are the 3 domaines of a cell surface receptor ? and their difference.
Same receptor have 3 domaines (part of protein): ectodomain, transmembrane, cytoplasmic
Can give specific function
They are modulor and can be change: can put ectodomain from one receptor to another recptor (to change the response to a signal)
Ectodomain amino end
Cytoplasmic is carboxyl end
ectodomain, cytoplasmic hydrophilic
Transmembrane hydrophobic so can stay in lipid bilayer
(TF) the cleaved out ectodomain of growth hormone receptor acts as its binding protein.
True
What are the 3 AA in signaling protein that are modulated by phosphorylation and why ?
Serine, threonine and tyrosine
Why, bc all have polar hydroxyl group easily exchange for phosphate group
Phosphate come from ATP
Which enzymes can reversed phosphorylation ?
phosphatases
What is the ratio of phosphorylated serine and threonine vs phosphorylated
tyrosine ?
(100:1)
Explain how tyrosine phosphorylation act.
beginning of enzymatic cascade
create docking site for protein (Like SH2 and SH3 (docking site when tyrosine w/in that domain is phosphorylated)
3 types of cell surface receptors?
- G-protein coupled receptors (GPCR)
- Tyrosine Kinase Receptors (RTK)
Intrinsic TK activity
Recruited TK activity - Serine-Threonine kinase receptors (RSTK)
Explain process GPCR
see note
How discovered the plant mimosa pudica (touch-me-not)
Jean-Jacques Mairan
Explain each of these rhythms:
circadian rhythm
infradian rhythm
ultradian rhythm
circadian rhythm: 24-hour (eg body temp, sleep-wake)
infradian rhythm: longer cycle (reproductive, hibernation)
ultradian rhythm: shorter cycle (sleep stages, heartbeat)
When is the peak of theses hormones ?
a. cortisol
b. GH
c. melatonin
a. cortisol 6-8am
b. GH 1hafter sleeping
c. melatonin midnight
What is the change in the rhythms of Gonadotrophin during and after puberty?
Puberty: at night
Adult: pulsatile fashion
Associate the enzyme with the pathway.
- Glycogen synthase
- Phosphorylase b kinase
- Pyruvate kinase
- Pyruvate dehydrogenase
complex
- Hormone-sensitive lipase
a. Glycogen breakdown
b. Triacylglycerol mobilization and fatty
acid oxidation
c. Glycolysis
d. Glycogen synthesis
e. Pyruvate to acetyl-CoA
Glycogen synthase -> Glycogen synthesis
Phosphorylase b kinase -> Glycogen breakdown
Pyruvate kinase -> Glycolysis
Pyruvate dehydrogenase
complex -> Pyruvate to acetyl-CoA
Hormone-sensitive lipase -> Triacylglycerol mobilization and fatty acid oxidation
Explain desensitization-resensitization cycle
see note
Name the 5 ways a target cells can become desensitized to a signal molecule
- receptor sequestration
- receptor down-regulation
- receptor inactivation
- inactivation of signaling protein
- production of inhibitory protein
Name each G protein alpha subunits
- Gs⍺ alpha: Activates adenylate cyclase
- Gi⍺ alpha: Inhibits adenylate cyclase
- Gq⍺ alpha: Activates phospholipase C
- IP3 and DAG and Ca signaling
- Go⍺ alpha: Activates ion channels
- G12/13⍺: regulate Actin cytoskeleton
Explain GPCR signaling through IP3 and Ca
see note
(TF) IP3 act as second messenger and activate PKC.
False
IP3 act as second messenger and activate receptor calcium channel
(TF) hormones may use more than one G-protein
True
