Medical Biochemistry

Front 1

Which level of amino acid structure has the MOST influence on the unique, overall 3D appearance of a polypeptide (the peptide's native conformation)?

A) primary
B) secondary
C) tertiary
D) quaternary

Back 1

A) primary

Front 2

True/False: The individual amino acids on a polypeptide chain are numbered beginning from the carboxyl terminus to the amino terminus.

A) true
B) false

Back 2

false

Front 3

A polypeptide's secondary structure is established primarily due to the presence of:

A) peptide bonds.
B) hydrogen bonds.
C) phosphodiester bonds.
D) hydrophobic interactions.
E) hydrophilic interactions

Back 3

B) hydrogen bonds

Front 4

An intra-chain hydrogen bond can form between a carbonyl oxygen atom of one amino acid and the amide hydrogen of an amino acid located 4 residues further down the polypeptide chain. Repetitions of these bonds result most significantly in the formation of:

A) primary structure of a polypeptide.
B) alpha helices.
C) beta sheets.
D) tertiary structure of a polypeptide.
E) quaternary structure of a polypeptide.

Back 4

B) alpha helices.

Front 5

_______ residues are often found at the beginning of alpha helices whereas _____ are often found at the ends, respectively.

A) alanine, lysine
B) glutamine, proline
C) glycine, proline
D) proline, glycine
E) lysine, alanine

Back 5

D) proline, glycine

Front 6

True/False: Glycine and proline are often found at the areas where an alpha helix "bends."

A) true
B) false

Back 6

A) true

Front 7

Hydrogen bonding that occurs between carbonyl oxygens and amide hydrogens on two separate polypeptide strands typically take place in:

A) primary structure.
B) alpha helices.
C) beta sheets.
D) tertiary structure.
E) quaternary structure.

Back 7

C) beta sheets

Front 8

True/False: Beta-barrels are often formed between polypeptide chains of beta helices that are running parallel.

A) true
B) false

Back 8

B) false

Beta-barrels typically contain anti-parallel beta sheets.

Front 9

True/False: Anti-parallel beta sheets are typically more stable than parallel beta sheets.

A) true
B) false

Back 9

A) true

Front 10

Bends, turns, loops, coils, and coiled coils are structures that are characteristic of polypeptide _____.

A) primary structure
B) secondary structure
C) tertiary structure
D) quaternary structure
E) linear sequence

Back 10

B) secondary structure

Front 11

The embedding of hydrophobic residues within regions of a polypeptide refers most specifically to a peptide's ____ structure.

A) primary
B) secondary
C) tertiary
D) quaternary
E) linear

Back 11

C) tertiary

Front 12

The overall fold of a protein is attributed to:

A) the number of proline & glycine residues present within the polypeptide.
B) the number of hydrogen bonds present.
C) the presence of alpha helices and beta sheets.
D) its tertiary structure.
E) its quaternary structure.

Back 12

D) its tertiary structure.

Front 13

Noncovalent interactions such as hydrogen bonding, ionic interactions, and disulfide bonds can attribute to the stabliization of a protein's:

A) primary structure.
B) alpha helices.
C) beta sheets.
D) tertiary structure.
E) quaternary structure.

Back 13

D) tertiary structure.

Front 14

True/False: Hydrophilic side-chains on a protein often cause folding pack tightly into a core of protein to minimize exposure to water.

A) true
B) false

Back 14

B) false

Front 15

Chaperonins (also called heat shock proteins) can aid in the folding of proteins as the proteins are synthesized. To accomplish this, they require:

A) ATP.
B) coenzymes.
C) Bip's.
D) GroEL or GroES.
E) transferases.

Back 15

A) ATP

Front 16

Cis-trans isomerases and protein disulfide isomerases (PDI's) assist heat shock proteins such as Hsp60 & Hsp70 with:

A) the proper folding of proteins.
B) the transfer of ATP to chaperonins.
C) post-transcriptional protein modification.
D) alternative splicing.
E) cytosolic protein transport.

Back 16

A) the proper folding of proteins.

Front 17

True/False: Hsp60 and Hsp70 proteins are also referred to as Bip and GroEL/GroES, respectively.

A) true
B) false

Back 17

B) false

Hsp60 = GroEL/GroES
Hsp70 = Bip

Front 18

Risk factors for proteopathies, such as Alzheimer's disease, prion disease, and cataracts include:

I. an increase in the number of beta-sheets.
II. a decrease in protein production.
III. advancing age.

A) I
B) II
C) III
D) Two of the above.
E) All of the above.

Back 18

D) Two of the above - I and III

Front 19

True/False: Risk factors for proteopathies almost always involve a decrease in beta-sheet secondary structures.

A) true
B) false

Back 19

B) false

They almost always involve an INCREASE in beta-sheets.

Front 20

A hemoglobin molecule consists of:

A) 4 heavy chains and 4 light chains.
B) 4 alpha chains and 4 beta chains.
C) 2 alpha chains and 2 beta chains.
D) 2 heavy chains and 2 light chains.
E) 2 heme groups and 4 polypeptide subunits.

Back 20

C) 2 alpha chains and 2 beta chains.

Front 21

In sickle-cell anemia there is a single change in the amino acid sequence of a ____ chain of hemoglobin where a normal ____ residue is wrongly substituted for a _____ residue.

A) alpha, lysine, valine
B) alpha, valine, glutamic acid
C) alpha, glutamic acid, valine
D) beta, glutamic acid, valine
E) beta, valine, glutamic acid

Back 21

E) beta, valine, glutamic acid

Front 22

Hair keratin consists of many:

A) glycine & valine residues.
B) alpha helices.
C) alpha chains & beta chains.
D) heavy chains & light chains.
E) beta sheets.

Back 22

B) alpha helices.

Front 23

Which of the following correctly lists the structures that make up a hair, from smallest to largest?

A) alpha helix, protofibril, microfibril, macrofibril
B) alpha helix, microfibril, macrofibril, protofibril
C) alpha helix, macrofibril, microfibril, protofibril
D) microfibril, alpha helix, protofibril, macrofibril
E) microfibril, alpha helix, macrofibril, protofibril

Back 23

A) alpha helix, protofibril, microfibril, macrofibril

Front 24

Hair contains a lot of sulfur, due to the fact that hair contains many ____ residues.

A) glycine
B) glutamic acid
C) arginine
D) aspartic acid
E) cysteine

Back 24

E) cysteine

Front 25

Which of the following is a cause of protein denaturation?

I. glycosylation
II. low concentrations of urea
III. solvents that disrupt hydrophobic bonds

A) I
B) II
C) III
D) Two of the above
E) All of the above

Back 25

D) Two of the above

Front 26

A molecule that has been implicated in nephropathy and retinopathy in diabetes mellitus is:

A) Hsp60
B) Hsp70
C) hemoglobin A1c
D) alpha-synuclein
E) prions

Back 26

C) hemoglobin A1c

Front 27

True/False: When hemoglobin becomes glycosylated, it loses its function, which is why it is often implicated in various proteopathies.

A) true
B) false

Back 27

B) false

Front 28

True/False: Hemoglobin A1c level is proportional to the average blood glucose concentration in a patient over the three to four weeks.

A) true
B) false

Back 28

B) false

It is usually indicative over a period of one to three months.

Front 29

What is the approximate percentage of cysteine residues in human hair?

A) 0.1%
B) 4%
C) 8%
D) 14%
E) 24%

Back 29

D) 14%

Front 30

There are ___ possible codons that code for ____ possible amino acids.

A) 20, 16
B) 64, 64
C) 32, 16
D) 64, 20
E) 64, 16

Back 30

D) 64, 20

Front 31

The 2 amino acids that each have only 1 codon are:

A) cysteine & methionine
B) methionine & histidine
C) tryptophan & methionine
D) cysteine & glycine
E) glycine & valine

Back 31

C) tryptophan & methionine

Front 32

AUG is the sequence that codes for the only START codon that initiates translation. What amino acid does "AUG" also code for?

A) cysteine
B) tryptophan
C) glycine
D) serine
E) methionine

Back 32

E) methionine

Front 33

The "wobble" phenomenon related to amino acids refers to a codon's:

A) 1st position.
B) 2nd position.
C) 3rd position
D) none of the above
E) all of the above

Back 33

C) 3rd position

Front 34

True/False: The genetic code is almost universal among all living organisms, with an exception being the genetic code used to translate mitochondrial RNA and proteins.

A) true
B) false

Back 34

A) true

Front 35

During translation, the genetic code of mRNA is read from:

A) 3' to 5'
B) 5' to 3'

Back 35

B) 5' to 3'

Front 36

Prokaryotic ribosomes are composed of _____ subunits, whereas eukaryotic ribosomes are composed of ____ subunits.

A) 30S, 50S
B) 40S, 60S
C) 50S, 70S
D) 30S, 40S
E) 70S, 80S

Back 36

E) 70S, 80S

Front 37

The G-protein dependent transporter that transports ribosomal subunits from the nucleolus to the cytoplasm is called:

A) Nmd30.
B) Hsp70
C) GTP
D) GroEL
E) cis/trans isomerase

Back 37

A) Nmd30.

Front 38

Which of the following is a true statement about tRNA molecules?

I. The 5’ end of the tRNA nucleotide strand usually ends with a G (guanosine)
II. The 3’ end usually consists of the nucleotide sequence CCA
III. Amino acids are attached to tRNA at the 3’ end

A) I
B) II
C) III
D) Two of these is true
E) All of these are true

Back 38

E) All of these are true

Front 39

True/False: The 5' end of tRNA usually ends with a C.

Back 39

false

5' end of tRNA usually ends with a G (guanosine)

Front 40

True/False: The 3’ end of a tRNA molecule usually consists of the nucleotide sequence CCA.

Back 40

true

Front 41

True/False: Amino acids are attached to a tRNA molecule at the 3’ end.

Back 41

true

Front 42

In the 3D structure of tRNA, you will find a D loop near the 5’ end, a T loop near the 3’ end, and an anticodon loop in the middle. (These loops provide the “clover leaf” shape.)

Back 42

true

Front 43

In the 3D structure of tRNA, the 3' end is associated with the ___, and the 5' end is associated with the ____.

A)

Back 43

3' = T loop

5' = D loop

Front 44

What is the name of the enzyme that charges tRNA?

Back 44

amino-acyl tRNA synthetase

Front 45

What does amino-acyl tRNA synthetase require in order to charge a tRNA molecule?

Back 45

ATP !

Front 46

At what end of a tRNA molecule does amino-acyl tRNA synthetase attach an amino acid?

Back 46

3' end

Front 47

What are the 3 main steps of translation?

Back 47

Initiation, Elongation, & Termination

(the same as transcription !)

Front 48

What 3 things constitute the "Pre-Initiation Sequence" in translation?

Back 48

1. methionyl-tRNA molecule (tRNA bound to a START codon)
2. initiation factor 2 (elF2)
3. strand of mRNA

Front 49

a) A tRNA molecule that is bound to a START codon is known as ____.

b) What is the START codon?

Back 49

a) methionyl-tRNA

b) AUG (methionine)

Front 50

What is the functions of elf4E, elF3, elF4A, & elF4G ?

Back 50

They are initiation factors that bind to the 5' end of an mRNA strand.

Front 51

What is the function of a poly-A binding protein (PABP) in translation?

Back 51

It binds a the 3'-poly-A tail on an mRNA strand to a tRNA molecule.

Front 52

What do methionyl-tRNA & elF2 bind to in order to complete a translational "Pre-initiation complex?"

Back 52

a small (40S) ribosomal subunit

Front 53

What occurs after charged-tRNA binds to the AUG start codon?

Back 53

elF2 hydrolyzes a GTP molecule & removes initiation factors bound the the small ribosomal subunit

Front 54

What are the specific ways that translation can be regulated with respect to elF2 and elF4?

Back 54

1. elF2 can be PHOSPHORYLATED thus inactivating it

2. elF4 can be inactivated by DE-PHOSPHORYLATION

Front 55

What pathologic condition can occur due to an inherited mutation on elF2B protein subunits?

Back 55

Leukoencephalopathy wtih Vanishing White Matter (VWM)

This can occur secondary to head trauma.

Front 56

What is the difference between the methionyl-tRNA in prokaryotes & eukaryotes?

Back 56

prokaryotes have a FORMYLATED form of Met-tRNA

Front 57

What are the initiation factors required by prokaryotes for translation (comparable to elF's) and how many are there?

Back 57

There are 3 prokaryotic initiation factors:

IF-1, IF-2, and IF-3

Front 58

a) Does the Shine-Dalgarno sequence refer to an aspect of prokaryotic or eukaryotic translation?

b) Does it refer to the SMALL or LARGE ribosomal subunit?

Back 58

a) prokaryotic

b) small ribosomal subunit

Front 59

What does streptomycin inhibit in bacterial translation? tetracyclines?

Back 59

Streptomycin inhibits initiation via binding the 30S subunit

Tetracycline inhibits the binding of aminoacyl-tRNA to the A site

Front 60

What is the difference between amino-acyl tRNA and methionyl-tRNA ?

Back 60

amino-acyl tRNA = charged tRNA (tRNA bound to an mRNA strand at the 3' end)

methionyl-tRNA = initiator tRNA that has elF2 bound to it

Front 61

During what stage of translation does aminoacyl-tRNA bind to EF1-alpha and a GTP molecule?

Back 61

elongation

Front 62

What enzyme forms the peptide bonds on a polypeptide in the P site of a ribosome?

Back 62

peptidyltransferase

Front 63

What molecule moves an uncharged tRNA from the P-site to the E-site on a ribosome, which requires GTP?

Back 63

elongation factor-2 (EF2)

Front 64

What enzyme ends the process of translation at the ribosome after the A-site reads a STOP codon?

Back 64

peptidyltransferase

Front 65

What molecule serves as the primary source of carbon in a fatty acid chain?

Back 65

glucose

Front 66

What enzyme converts pyruvate into acetyl-CoA?

Back 66

pyruvate dehydrogenase

Front 67

Once a molecule of citrate leaves a mitochondrion, what enzyme converts citrate into acetyl-CoA?

Back 67

citrate lyase

Front 68

What is the pathway in which citrate can be "recycled" into pyruvate?

Back 68

citrate -> oxaloacetate -> malate -> pyruvate

Front 69

What molecule serves as a "reducing agent" for fatty acid synthesis?

Back 69

NADPH

Front 70

Is insulin an ACTIVATOR or INHIBITOR of fatty acid synthesis?

Back 70

ACTIVATOR

Insulin uses a PHOSPHATASE to stimulate fatty acid synthesis via de-phosphorylation of acetyl-CoA carboxylase.

Front 71

Is glucagon an ACTIVATOR or INHIBITOR of fatty acid synthesis?

Back 71

INHIBITOR

Glucagon uses a KINASE to inhibit fatty acid synthesis via phosphorylation of acetyl-CoA carboxylase.

Front 72

What molecule is an end-product inhibitor of fatty acid synthesis via downregulation of citrate formation?

Back 72

palmitoyl CoA

Front 73

What is the 16-carbon end product of fatty acid synthesis?

Back 73

palmitate

Front 74

Where does elongation occur in a cell with respect to fatty acid synthesis?

Back 74

smooth ER

Front 75

What are the 4 major steps of elongation in fatty acid synthesis?

Back 75

1. condensation
2. reduction
3. dehydration
4. reduction (again)

Front 76

What are the 3 major classes of omega fatty acids?

Back 76

1) omega-3
2) omega-6
3) omega-9

Front 77

What are the 2 ESSENTIAL fatty acids?

Back 77

linoleic acid (omega-6)
&
alpha-linolenic acid (omega-3)

Front 78

To increase the intake of linoleic acid (an eicosanoid precursor to arachidonic acid), one could start eating more _____.

A) plant oils
B) cold-water fish
C) walnuts
D) eggs

Back 78

A) plant oils

Plant oils, such as canola, corn, sunflower, & olive are good sources of linoleic acid, an ESSENTIAL omega-6 fatty acids.

Front 79

Which of the following are precursors to ANTI-inflammatory molecules?

A) triglycerides
B) sphingolipids
C) omega-3 fatty acids
D) omega-6 fatty acids

Back 79

C) omega-3 fatty acids

Front 80

Which of the following are precursors to PRO-inflammatory molecules (vs. anti-inflammatory)?

A) triglycerides
B) sphingolipids
C) omega-3 fatty acids
D) omega-6 fatty acids

Back 80

D) omega-6 fatty acids

Front 81

What fatty acid molecule is produced by adipocytes via use of the enzyme DHAP (dihydroxyacetone phosphate)?

Back 81

glycerol-3-phosphate

Front 82

What 2 molecules are required for the synthesis of triglycerides, prior to the formatio of DAG (diacylglycerol)?

Back 82

glycerol-3-phosphate
&
fatty-acyl CoA

Front 83

What molecule adds carbon atoms, two at a time, to elongate fatty acid chains?

Back 83

fatty acid synthase complex

(which is composed of phosphopantetheine & ACP - acyl carrier protein)

Front 84

In the process of fatty acid synthesis, what molecule must be converted to citrate because it can NOT exit mitochondria?

Back 84

acetyl CoA

Front 85

What are the 3 major components of a triglyceride (triacylglycerol)?

Back 85

1. glycerol
2. fatty acid chain
3. fatty acid chain

Front 86

What are the 4 major components of a glycerophospholipid, such as phosphatidylserine?

Back 86

1. glycerol
2. fatty acid chain
3. phosphate functional group
4. polar head group

Front 87

What are the 4 major components of sphingomyelin?

Back 87

1. sphingosine "backbone"
2. fatty acid chain
3. phosphate functional group
4. polar head group

Front 88

What are the 3 major components of a glycolipid?

Back 88

1. sphingosine "backbone"
2. fatty acid chain
3. carbohydrate

Front 89

What are the 5 major components of an ether glycerolipid?

Back 89

1. glycerol
2. ether functional group
3. fatty acid chain
4. phosphate functional group
5. polar head group

Front 90

Which of the following is NOT an amphipathic molecule?

A) triacylglycerol
B) phosphatidylethanolamine
C) platelet activating factor
D) sphingomyelin
E) phosphatidylserine

Back 90

A) triacylglycerol

Amphipathic molecules typically have a non-polar fatty acid chain bound to a polar head group.

Front 91

Which of the following is a component of myelin sheaths that surround neurons?

A) triacylglycerol
B) phosphatidylethanolamine
C) platelet activating factor
D) sphingomyelin
E) phosphatidylserine

Back 91

D) sphingomyelin

Front 92

Which of the following can function as an antioxidant?

A) triacylglycerol
B) phosphatidylethanolamine
C) platelet activating factor
D) sphingomyelin
E) phosphatidylserine

Back 92

C) platelet activating factor (PAF)

PAF is a type of Plasmalogen (ether glycerolipid) which plays a role in inflammatory reactions.

Front 93

Which of the following contains an ether functional group?

A) triacylglycerol
B) phosphatidylethanolamine
C) platelet activating factor
D) sphingomyelin
E) phosphatidylserine

Back 93

C) platelet activating factor (PAF)

Front 94

Eicosanoids are fatty acids that form inflammatory precursor molecules. What 2 major enzymes are required for synthesis of eicosanoids?

Back 94

cyclooxygenase (COX) & lipoxygenase

Front 95

What are the 5 major classes of lipids?

Back 95

1. triglycerides (triacylglycerols)
2. phospholipids
3. sphingolipids
4. eicosanoids
5. cholesterols

Front 96

Which of the following would be considered the most "healthy" fatty acid?

A) saturated fat
B) hydrogenated fat
C) trans unsaturated fat
D) cis unsaturated fat
E) LDL

Back 96

D) cis unsaturated fat

Front 97

Which of the following is composed of a four-ring aliphatic structure?

A) triacylglycerol
B) plasmalogen
C) ether glycerolipid
D) eicosanoid
E) cholesterol

Back 97

E) cholesterol

Front 98

Which of the following refers to a site where the cell membrane invaginates & also plays an important role in endocytosis?

A) caveolae
B) phosphatidylcholine
C) mannose-6-phosphate
D) eicosanoid
E) phosphatidylinositol

Back 98

A) caveolae

Front 99

Which of the following is typically NOT found on the inner leaflet of the cell membrane?

A) phosphatidylserine
B) phosphatidylcholine
C) phosphatidylinositol
D) phosphatidylethanolamine
E) glycolipid

Back 99

B) phosphatidylcholine

Front 100

Which molecule is found in greatest concentration in the membrane of endoplasmic reticulum?

A) phosphatidylserine
B) phosphatidylcholine
C) phosphatidylinositol
D) phosphatidylethanolamine
E) glycolipid

Back 100

B) phosphatidylcholine

Front 101

What 2 molecules make up the greatest proportion of the cell plasma membrane?

A) phosphatidylserine
B) phosphatidylcholine
C) phosphatidylinositol
D) sphingomyelin
E) glycolipid

Back 101

B) phosphatidylcholine and D) sphingomyelin

Front 102

Which of the following is typically NOT found in a cell plasma membrane?

A) glycolipid
B) sphingomyelin
C) phosphatidylinnositol
D) alpha-helices
E) beta-barrels

Back 102

E) beta-barrels

Beta-barrels are only found in outer membranes of Gram-negative bacteria and outer membranes of mitochondria and chloroplasts.

Front 103

When a group of alpha-helices together form a transmembrane channel, what groups line the lumen of the channel?

A) polar amino acid R-groups
B) nonpolar amino acid R-groups

Back 103

A) polar amino acid R-groups

Front 104

Which of the following is also known as "lecithin"?

A) phosphatidylserine
B) phosphatidylcholine
C) phosphatidylinositol
D) phosphatidylethanolamine
E) sphingomyelin

Back 104

B) phosphatidylcholine

Front 105

What is produced during the reaction where malate is converted to pyruvate? (hint: it is also produced during glycolysis)

Back 105

NADPH

Front 106

In the mitochondrion, what enzyme catalyzes the conversion reaction of pyruvate to acetyl CoA?

Back 106

pyruvate dehydrogenase

Front 107

What is the 16-carbon molecule that serves as the backbone for adding additional 2-carbon molecules?

Back 107

palmitate

Front 108

What enzyme catalyzes the reaction that converts malonyl CoA to palmitate?

Back 108

fatty acid synthase

Front 109

True/False: After consumption of carbohydrates, the ratio of insulin/glucagon decreases.

Back 109

false

The ratio INCREASES after a meal.

Front 110

What are the 2 essential fatty acids?

Back 110

linoleic acid &
alpha-linolenic acid

Front 111

When forming a triglyceride, what 2 components form phosphatidic acid, the precursor of diacylglycerol?

Back 111

glycerol-3-phosphate & fatty acyl CoA

Front 112

What is the carrier molecule that transports triglycerides to cells, especially those of muscle & adipose?

Back 112

VLDL

Front 113

Which of these is typically NOT found on the outside of the cell membrane?

a) sphingomyelin
b) phosphatidylcholine
c) phosphatidylinositol
d) glycolipids
e) the hydroxide group of a cholesterol molecule

Back 113

c) phosphatidylinositol

Front 114

Which of the following is the source of PUFAs, the precursors to eicosanoids?

a) phospholipids
b) sphingolipids
c) cholesterols
d) glycolipids
e) omega-6 fatty acids

Back 114

a) phospholipids

Front 115

The molecule formed by the addition of palmitoyl CoA to the amino acid serine?

a) diacylglycerol
b) sphingosine
c) phosphatidylcholine
d) acetyl CoA
e) sphingomyelin

Back 115

b) sphingosine

Front 116

The baby that is born with respiratory distress syndrome (RSD) would likely have shown a ratio of ______ to sphingomyelin less than 2:1, which indicates insufficient lung surfactant.

a) cholesterol
b) phosphatidylserine
c) phosphatidylethanolamine
d) phosphatidylcholine
e) PAF

Back 116

d) phosphatidylcholine

Front 117

Which of the following plays a significant role in ABO blood typing?

a) cholesterols
b) phosphatidylserines
c) phosphatidylcholines
d) sphingolipids
e) PAFs

Back 117

d) sphingolipids

Front 118

Lovastatin and pravastatin are drugs that lower cholesterol by inhibiting:

a) pyruvate dehydrogenase
b) HMG-CoA synthase
c) fatty acid complex synthase
d) glucose-3-phosphatase
e) NADPH

Back 118

b) HMG-CoA synthase

Front 119

Which of the following reactions is the rate-limiting step of cholesterol synthesis?

a) acetyl CoA to mevalonate
b) mevalonate to isoprenes
c) isoprenes to squalene
d) squalene to 4-ring structure

Back 119

a) acetyl CoA to mevalonate

This step is catalyzed by the enzyme HMG-CoA synthase.

Front 120

Where are lipids primarily synthesized within a cell?

a) Golgi
b) smooth ER
c) rough ER
d) mitochondria
e) polyribosomes

Back 120

b) smooth ER

Most lipid is produced in smooth ER while a minor amount is also produced in the mitochondria.

Front 121

True/False: The smooth ER tends to be more tubular than rough ER.

Back 121

true

smooth ER = more tubular
rough ER = more "plate-like"

Front 122

True/False: Chronic use of some drugs, such as barbituates, will induce a decrease in the amount of smooth ER, resulting in drug tolerance.

Back 122

false

Chronic drug use would cause an INCREASE in smooth ER.

Front 123

What are the 3 types of cytoskeletal filaments? (Also, name them in order from smallest to largest)

Back 123

1. microfilaments (actin, myosin)
2. intermediate filaments
3. microtubules

Front 124

True/False: Charged Phospholipid-Transporting Proteins carry phospholipids from the smooth ER membrane to the plasma membrane.

Back 124

true

Charged PTP's carry phospholids from SER to cell membrane; they then return to the SER uncharged.

Front 125

In erythrocytes, a defect in ____ can lead to a condition known as heriditary spherocytosis.

a) collagen
b) desmin
c) keratin
d) spectrin
e) dynein

Back 125

d) spectrin

Front 126

Which of the following is NOT a characteristic of microvilli?

a) can increase the surface area of a polarized cell
b) are stabilized by actin filaments
c) are composed of tubulin
d) are anchored at the terminal web
e) is sometimes interwoven with a glycocalyx

Back 126

c) are composed of tubulin

Tubulin is a protein component of MICROTUBULES.

Front 127

Microtubules are stablized by proteins known as:

a) actins
b) MAPs
c) vimentins
d) keratins
e) lamins

Back 127

b) MAPs

(Microtubule-Associated Proteins)

Front 128

Movement of organelles within a cell is associated with what type of cytoskeletal elements?

a) microfilaments
b) intermediate filaments
c) microtubules
d) keratins
e) desmins

Back 128

c) microtubules

Organelle movement is due to Microtubule-Organizing Centers, which are composed of microtubules.

Front 129

Vinblastin, taxol, and vincristine are examples of anti-cancer chemotherapeutics that effectively destabilize:

a) microfilaments.
b) intermediate filaments.
c) microtubules.
d) keratins.
e) desmins.

Back 129

c) microtubules.

Front 130

Which of the following is true?

a) microvilli attach to a cell's surface at basal bodies
b) centrioles are made up of microtubules & play a role during mitosis
c) cilia function to increase the surface area of a cell
d) flagella are composed of microfilaments
e) centrioles are composed of 9 sets of microtubule doublets, arranged in a "pinwheel" fashion

Back 130

b) centrioles are made up of microtubules & function during mitosis

Front 131

What cytoskeletal elements allow pathologists to identify cancer cells that are otherwise too de-differentiated to classify by light microscopy?

a) microfilaments
b) intermediate filaments
c) microtubules
d) dyneins
e) desmosomes

Back 131

b) intermediate filaments

Front 132

Cancer cells that are of epithelial origin can be specifically identified by special microscopic techniques that detect:

a) keratin proteins.
b) vimentin proteins.
c) desmin proteins.
d) lamin proteins.
e) actin proteins.

Back 132

a) keratin proteins.

Front 133

The cytoskeletal elements that are prominent in the nuclear lamina & the nuclear envelope surrounding the rough ER are:

a) microfilaments
b) intermediate filaments
c) microtubules
d) dyneins
e) desmosomes

Back 133

b) intermediate filaments

Front 134

What are the 3 types of motor proteins and in what direction does each typically direct movement?

Back 134

1. myosins: plus-end directed
2. kinesins: plus-end directed
3: dyneins: minus-end directed

Front 135

a) What 2 motor proteins direct intracellular MICROTUBULE-based motility?

b) In which directions?

Back 135

a,b) kinesins: plus-end

dyneins: minus-end

Front 136

The movement of intracellular organelles towards the periphery of the cell (towards the + end) is known as:

a) kinesin walking
b) antegrade transport
c) retrograde transport
d) diapedesis
e) sliding

Back 136

b) antegrade transport

The motor protein typically responsible for antegrade transport is KINESIN.

Front 137

The movement of intracellular organelles towards the center of the cell (towards the - end) is known as:

a) kinesin walking
b) antegrade transport
c) retrograde transport
d) diapedesis
e) sliding

Back 137

c) retrograde transport

The motor protein typically responsible for antegrade transport is DYNEIN.

Front 138

Which of the following is true regarding axonemes?

a) possess dynein arms that allow for movement
b) are composed of microtubules arranged in 9 sets of triplets that are arranged in a "pinwheel" pattern
c) possess dynein arms that convert bending motion into sliding motion

Back 138

a) possess dynein arms that allow for movement

Note: Axonemes are composed of microtubules arranged in 9 sets of doublets that surround 2 central microtubules

Front 139

The cross-linking protein responsible for converting the sliding-to-bending movement of microtubule dynein arms is:

a) keratin
b) kinesin
c) laminin
d) nexin
e) vimentin

Back 139

d) nexin

Front 140

Which of the following protein filaments does NOT have polarity (+ and - ends)?

a) microfilaments
b) intermediate filaments
c) microtubules

Back 140

b) intermediate filaments

Front 141

Proteins that are destined to become integral membrane proteins, lysosomal proteins, or secretory proteins are produced where within the cell?

Back 141

ribosomes bound to rough ER

Note: different from polyribosomes that produce cytoplasmic proteins

Front 142

Flattened sacs of smooth and rough ER are refered to as:

a) caveolae
b) cisternae
c) cristae
d) lamina

Back 142

b) cisternae

Front 143

A cell from an exocrine gland that functions solely to produce and secrete protein hormones would likely have all of the following except:

a) prominent smooth ER
b) prominent rough ER
c) prominent nucleolus
d) many ribosomes
e) many mitochondria

Back 143

a) prominent smooth ER

This is an important feature of a cell that produces, stores, and secretes lipid (steroid) products.

Front 144

True/False: Polyribosomes produce proteins that are usually either secreted or integrated into the plasma membrane.

Back 144

false

Polyribosomes typically produce proteins that eventually remain within the cytosol or mitochondrial proteins.

Front 145

The Golgi apparatus is composed of several membranous structures known as:

a) cisternae
b) cristae
c) caveolae
d) lamina
e) nexins

Back 145

a) cisternae

Front 146

True/False: Vesicles that leave the ER carrying proteins for modification and packaging enter the Golgi apparatus at its trans (maturing) face.

Back 146

false

Vesicles enter the Golgi at the cis (forming) face.

Front 147

True/False: The face of the Golgi that faces the ER & cell nucleus is the trans (maturing) face.

Back 147

false

The cis (maturing) face is the portion of the Golgi that directly faces the ER and nucleus.

Front 148

Which of the following post-translational modifications does NOT usually occur in the Golgi apparatus?

a) glycosylation of proteins
b) addition of Signal Recognition Sequences (SRPs)
c) phosphorylation of lysosomal enzymes
d) sulfation
e) removal of mannose sugars

Back 148

b) addition of Signal Recognition Sequences (SRPs)

SRP's are added to proteins for modification, prior to entering the rough ER

Front 149

a) What are the 3 possible outcomes of a modified protein after it leaves the Golgi?

b) 3 outcomes of a protein leaving a polyribosome?

Back 149

a) 1. secretion 2. to lysosomes 3. integrated in cell membrane

b) 1. stored in cytosol 2. to mitochondria 3. to nucleus

Front 150

Which of the following is a linker protein located within microvilli?

a) dynein
b) kinesin
c) myosin
d) keratin
e) fimbrin

Back 150

e) fimbrin

Front 151

Which of the following is a protein that can coat vesicles leaving the rough ER?

a) mannose-6-phosphate
b) COPI
c) COPII
d) SRP
e) clathrin

Back 151

c) COPII

Front 152

Which of the following structures could be labeled by a cytochemical marker that can specifically bind to acid phosphatases?

a) smooth ER
b) rough ER
c) cis-face of Golgi
d) trans-face of Golgi
e) nuclear lamina

Back 152

d) trans-face of Golgi

Front 153

Which of the following is a protein that can coat vesicles that are transported from the Golgi to the rough ER?

a) mannose-6-phosphate
b) COPI
c) COPII
d) SRP
e) clathrin

Back 153

b) COPI

Front 154

What are 2 methods of secretion that can occur as a vesicle leaves the Golgi?

Back 154

1. constitutive: vesicles & their contents travel to the plasma membrane for exocytosis

2. regulated: vesicles are coated with clathrin and leave the Golgi where they condense with other vesicles & then secreted

Front 155

Which of the following conditions occurs as a result of defects in mannose phosphotransferases in the Golgi?

a) I-cell disease
b) hereditary spherocytosis
c) Marfan's syndrome
d) amyloidosis
e) Gauchier's disease

Back 155

a) I-cell disease

Front 156

Active transport involves movement across a gradient from an area of (high, low) concentration to an area of (high, low) concentration.

Back 156

low to high concentration (against a gradient)

Front 157

Which of the following ions is typically found in highest concentration relative to the inside a cell?

a) Na
b) K
c) Cl
d) Ca
e) H

Back 157

b) K

Front 158

What disease occurs as a result of defective chloride membrane channels?

Back 158

Cystic Fibrosis

Front 159

Which of the following can NOT diffuse across a plasma membrane?

a) ethanol
b) molecular oxygen
c) molecular carbon dioxide
d) steroid molecules
e) glucose

Back 159

e) glucose

Front 160

Which of the following is NOT an example of a channel that operates via facilitated diffusion?

a) ion-gated channel
b) ligand-gated channel
c) voltage-gated channel
d) Na/K pump
e) mechanically-gated channel

Back 160

d) Na/K pump

Front 161

The channel that permits the entry of acetylcholine into a cell is a/an:

a) ion-gated channel.
b) ligand-gated channel.
c) voltage-gated channel.
d) Na/K pump.
e) mechanically-gated channel.

Back 161

b) ligand-gated channel

Front 162

The specialized channel that is opened via stimulation of stereocilia on hair cells in the ear is an example of a/an:

a) ion-gated channel.
b) ligand-gated channel.
c) voltage-gated channel.
d) Na/K pump.
e) mechanically-gated channel.

Back 162

e) mechanically-gated channel.

Front 163

The specialized channel that allows the entry of sodium into a neuronal axon during the propagation of an action potential is an example of a/an:

a) ion-gated channel.
b) ligand-gated channel.
c) voltage-gated channel.
d) Na/K pump.
e) mechanically-gated channel.

Back 163

a) ion-gated channel.

Front 164

Clathrin, adaptin (AP2), and dynamin are elements that play a significant role in:

a) active transport.
b) cell "crawling."
c) cell "walking."
d) receptor-mediated endocytosis.
e) transport of vesicles from rough ER to the Golgi.

Back 164

d) receptor-mediated endocytosis.

Front 165

The formation of endosomes that eventually fuse with lysosomes within a cell requires:

a) clathrin.
b) caveolae.
c) dynein.
d) keratin.
e) mannose-6-phosphate.

Back 165

a) clathrin.

This is the process of clathrin-dependent receptor-mediated endocytosis.

Front 166

Familial hypercholesterolemia is a condition resulting in increased serum cholesterol that can be due to a defect in:

a) lysosomal storage.
b) lipid rafts.
c) LDL receptors.
d) ion-gated channels.
e) mechanically-gated channels.

Back 166

c) LDL receptors.

Front 167

A molecule that is typically required for the transcytosis of particles across intercellular space is:

a) COPI
b) COPII
c) clathrin
d) caveolae
e) dynein

Back 167

d) caveolae

Front 168

Porins are specialized transport proteins that are found on the outer membrane of:

a) rough ER
b) smooth ER
c) Golgi
d) mitochondria
e) lysosomes

Back 168

d) mitochondria

Front 169

The phospholipid that plays a significant role in the inner membranes of mitochondria by aiding in formation of an electrochemical gradient is:

a) cardiolipin.
b) phosphatidylcholine.
c) phosphatidylinositol.
d) sphingomyelin.
e) plasmalogen.

Back 169

a) cardiolipin.

Front 170

The molecule that interacts with proteins at the surface of the outer mitochondrial membrane is:

a) COPI
b) COPII
c) TIM
d) TOM
e) SRP

Back 170

d) TOM

Front 171

The protein that forms a transmembrane channel across mitochondrial membranes, allowing for the entry of small particles is:

a) COPI
b) COPII
c) TIM
d) TOM
e) SRP

Back 171

c) TIM

Front 172

Which of the following is NOT located in the mitochondrial matrix?

a) calcium stores
b) TCA cycle enzymes
c) mitochondrial DNA
d) mitochondrial RNA
e) ATP synthetase

Back 172

e) ATP synthetase

Front 173

Mitochondria contain their own source of DNA, which are capable of coding for ____ mitochondrial proteins.

a) 4
b) 13
c) 25
d) approximately 300
e) approximately 800

Back 173

b) 13

Front 174

Which of the following products is MOST likely to originate from a cell that contains mitochondria possessing tubular cristae, rather than cristae that are plate-like?

a) antibodies
b) cortisone
c) acetylcholine
d) chymotrypsin
e) hemoglobin

Back 174

b) cortisone

Tubular cristae are located most prominently in mitochondria of cells that function in producing steroid-hormones & lipids.

Front 175

What does the "H" refer to in the Gibbs free energy equation?

a) free energy
b) entropy
c) enthalpy
d) temperature
e) activation energy

Back 175

c) enthalpy

Front 176

Regarding the Gibbs free energy equation, what values for "H" and "S" will ALWAYS result in a spontaneous reaction?

Back 176

a negative "H" (enthalpy) and a positive "S" (entropy) value

Front 177

What does the "S" refer to in the Gibbs free energy equation?

a) free energy
b) entropy
c) enthalpy
d) temperature
e) activation energy

Back 177

b) entropy

Front 178

Regarding the Gibbs free energy equation, what values for "H" and "S" will ALWAYS result in a non-spontaneous reaction?

Back 178

a positive "H" (enthalpy) and a negative "S" (entropy) value

Front 179

What are 2 equations that can be used to compute the enthalpy in a system?

Back 179

1. H = (Temp)x Change in Entropy)

2. H = G / [Temp x Change in Entropy]

Front 180

What are the 2 equations for calculating Gibbs free energy with respect to the Thermodynamic Triquetri?

Back 180

1. G = Go + RT (ln Keq)

2. G = Go + RT (ln MAR)

MAR = Mass Action Ratio

Front 181

A Reduction Potential refers to the ability to (accept/donate) electrons.

Back 181

accept

DONATE = oxidation

Front 182

MFM/OPP: A Mediterranean Diet may include high or moderate portions of all of the following except:

a) olive oil
b) poultry
c) beans
d) red meat
e) nuts

Back 182

d) fish

Mediterranean diets tend to be low to moderate in dairy, fish, & poultry and also consists of very little red meat.

Front 183

MFM/OPP: True/False - A high ratio of omega-6 to omega-3 fatty acids in the diet makes an inflammatory reaction more likely to occur in the body (i.e. hypersensitivity)

Back 183

true

Front 184

MFM/OPP: True/False - A high ratio of HDL to LDL correlates to an increased risk of heart disease.

Back 184

false

high LDL = increase risk
low LDL = lower risk

Front 185

MFM/OPP: Metabolic Syndrome may consist of all of the following except:

a) abdominal obesity
b) low LDL:HDL ratio
c) hypertension
d) elevated C-reactive proteins
e) high amount of serum PAF or PAF-1

Back 185

b) low LDL:HDL ratio