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MCAT BIOLOGY FLASHCARDS > MCAT BIO CH.6 PART 1 > Flashcards

MCAT BIO CH.6 PART 1 Flashcards

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1
Q

What is the function of nucleus?

A

Contain and protect DNA; transcription; partial assembly of ribosomes

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2
Q

Number of membranes surrounding nucleus?

A

2

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3
Q

What is the function of mitochondria?

A

Produce ATP via the krebs cycle and oxidative phosphorylation

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4
Q

Number of membranes surrounding mitochondria?

A

2

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5
Q

What is the function of ribosomes?

A

Synthesis of proteins

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6
Q

Number of membranes surrounding ribosomes?

A

0

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7
Q

What is the function of the RER?

A

Synthesis/modification of secretory, membrane-bound and organelle proteins

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8
Q

Number of membranes surrounding RER?

A

1

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9
Q

What is the function of the SER?

A

Detoxification and glycogen breakdown in liver; steroid synthesis in gonads

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10
Q

Number of membranes surrounding SER?

A

1

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11
Q

What is the function of the Golgi apparatus?

A

Modification and sorting of protein, some synthesis

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12
Q

Number of membranes surrounding Goldgi apparatus?

A

1

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13
Q

What is the function of the lysosomes?

A

Contain acid hydrolase that digest various substances

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14
Q

Number of membranes surrounding lysosomes?

A

1

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15
Q

What is the function of the peroxisomes?

A

Metabolize lipids and toxins using H2O

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16
Q

Number of membranes surrounding peroxisomes?

A

1

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17
Q

What is the nucleus surrounded by?

A

The nuclear envelope

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18
Q

What occurs in the nucleus in eukaryotes? Where does translation occur?

A

Replication, transcription and splicing; translation

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19
Q

Eukaryotic genome are organized into________, while the genome of prokaryotes is_______?

A

Linear molecules of double-stranded DNA; single circular DNA molecule

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20
Q

What is a chromosome?

A

Separate linear DNA molecule

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21
Q

What is a locus?

A

Specific location on the chromosome where the genes can be mapped

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22
Q

What happens to the gene in heterochromatin form?

A

Turned off and inaccessible

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23
Q

What happens to the gene in euchromatin form?

A

More loosely packed and allow genes to be activated

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24
Q

What is the purpose of nuclear matrix?

A

To support and provide overall structure and regulating gene expression

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25
Q

What are “domains” in the nucleus?

A

Chromosomal regions

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26
Q

What is the purpose of the nucleolus?

A

Ribosome factory

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27
Q

What does the nucleolus include?

A

RNA polymerases, rRNA, protein components the ribosome

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28
Q

What role would the loops of DNA in the nucleolus play?

A

DNA will serve as template for ribosomal RNA production

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29
Q

The nucleolus is responsible for the transcription of mRNA, tRNA and rRNA by_____?

A

Transcription of rRNA by RNA polymerase I

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30
Q

Transcription of tRNA and mRNA are done by RNA poly I?

A

False: other polys

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31
Q

How is the ribosome assembled in the nucleolus?

A

Partially

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32
Q

When does the ribosome become active, based on its production?

A

Remains inactive untila assembly is completed in the cytoplasm

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33
Q

What separates the nucleus from the cytoplasm?

A

Nuclear envelope

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34
Q

How many layers are composed of the nuclear envelope?

A

Two lipid bilayer membranes

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35
Q

What is the space between the nuclear membranes contiguous with?

A

With the lumen of the ER

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36
Q

Where are nuclear pores located?

A

Punctuated the nuclear envelope

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37
Q

What is the function nuclear pores?

A

Allows passage into and out of the nucleus

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38
Q

What size of molecules can enter the nucleus by diffusion?

A

Molecules smaller than 60 kilodaltons

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39
Q

What sequence do larger proteins require to enter the nucleus?

A

Nuclear localization sequence

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40
Q

What happens to proteins with the nuclear localization sequence?

A

Translated into the cytoplasm and then imported into the nucleus by specific transport mechanisms

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41
Q

Does RNA transport itself out through diffusion?

A

No, through a specific transport system rather than freely diffusing into the cytoplasm

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42
Q

The mitochondrion is the site of ______?

A

ATP synthesis and oxidative phosphorylation

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43
Q

What does the matrix include, what type of enzymes?

A

Pyruvate dehydrogenase and the enzymes of the Krebs cycle

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44
Q

What occurs in the inner membrane of the mitochondria?

A

Electron transport chain and ATP synthase

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45
Q

What are cristae, based on the mitochondria?

A

Inner membrane projections into the matrix

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46
Q

What from the inner membrane in mitochondria allows for the proton gradient for ATP synthesis?

A

Its impermeable to the free diffusion of polar substances

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47
Q

What are structural components of the outer membrane of mitochondria?

A

Smooth, contains large pores that allow free passage of small molecules

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48
Q

What is the space between the mitochondria membranes?

A

Intermembrane space

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49
Q

Why is the inner membrane folded into cristae in mitochondria?

A

Increase surface area

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50
Q

How is the genome of mitochondria?

A

A single circular DNA molecule

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51
Q

What does the mitochondria genome code for?

A

rRNA, tRNA, proteins, and ETC components, parts to he ATP synthase complex

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52
Q

What is the evolutionary theory of mitochondria?

A

Endosymbiotic Henry of mitochondria; independent unicellular organism living within larger cells

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53
Q

What does mitochondrial exhibit that is important with reproduction?

A

Maternal inheritance

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54
Q

Why is the mitochondrial only inherited from the mother?

A

The cytoplasm of the egg becomes the cytoplasm of the zygote

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55
Q

What does the sperm contribute in reproduction?

A

Only genomic nuclear DNA

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56
Q

Why is the rough ER called rough?

A

Large number of ribosomes bound to its surface

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57
Q

What is the purpose of the ribosomes for the rough ER?

A

Site of protein synthesis for proteins targeted to enter the secretory pathway

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58
Q

What type of enzymes may be present in the smooth ER although its usually not actively involved in protein processing?

A

Steroid hormone biosynthesis enzymes for gonads or degradation of environmental toxins in the liver

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59
Q

What does the ER do that’s important with protein localization?

A

Key role in directing protein traffic to different parts of the cell

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60
Q

Where do proteins that are translated on free cytoplasmic ribosomes go?

A

Peroxisomes, mitochondria, nucleus or in cytoplasm

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61
Q

Where do proteins that are translated on the rough ER ribosomes go?

A
  1. Secreted into extracellular environment
  2. Integral plasma membrane proteins
  3. In the membrane or interior of the ER, Golgi apparatus or lysosomes
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62
Q

Based on the rough ER, which membranes is it in contiguous with?

A

Interior of the ER, Golgi Apparatus, lysosomes, and the extracellular environment

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63
Q

Proteins synthesized on the rough ER are transported in vesicles to which location first?

A

From the ER to the Golgi apparatus

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64
Q

After the proteins go to the Golgi apparatus, where does it go? (Based on ER)

A

To the plasma membrane or lysosome

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65
Q

What decides if a protein is translated on the rough ER or not?

A

Determined by the sequence of the protein itself

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66
Q

All proteins, even the ones from the rough ER, begins translation where?

A

Start translation in the cytoplasm

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67
Q

Which proteins have the signal sequence to continue translation on rough ER?

A

Secreted proteins and lysosome proteins

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68
Q

Where is the signal sequence from ER ribosomal proteins?

A

Amino acid sequence at their N-terminus

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69
Q

How is the signal sequence from ER ribosomal proteins recognized? What does it then do?

A

By the signal recognition particle (SRP); binds to the ribosome

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70
Q

One the ribosome-SRP complex is made, what occurs to it, based on ER?

A

Rough ER has STP receptors that dock the ribosome-SRP complex on the cytoplasmic surface along with the polypeptide and the mRNA

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71
Q

What happens to the polypeptide since the complex gets bound to the STP receptors, based on ER?

A

Translation pushes the polypeptide into the ER lumen, signal peptide first

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72
Q

What happens after rough ER ribosomal translation is complete?

A

Signal peptidase removes the signal peptide from the polypeptide

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73
Q

Where is the signal peptidase located?

A

In the ER

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74
Q

What happens to secreted proteins after the signal peptide is removed, based on ER?

A

The protein is transported in the interior of vesicles, through the Golgi, to the plasma membrane, released by exocytosis

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75
Q

What are transmembrane domains and where are they located?

A

Hydrophobic amino acid residues located on integral membrane proteins

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76
Q

Where do the transmembrane domains pass through, based IMN (integral membrane proteins)?

A

Through lipid bilayer membranes

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77
Q

What are transmembrane domains basically, based on IMN?

A

Signal sequences found int he interior of the protein but NOT AT THE N-TERMINUS

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78
Q

During translation, the transmembrane domains are threaded through what?

A

The ER membrane

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79
Q

What type of initial post-translation modification of proteins may occur in the rough ER?

A

Disulfide bond formation, glycosylation

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80
Q

What is the default target for proteins that go through the secretory path based on protein traffic for ER?

A

Plasma membrane

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81
Q

What are needed for the protein to end up elsewhere than the plasma membrane (ex. Golgi, ER, lysosome)?

A

Targeting signals

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82
Q

Proteins that are made in the cytoplasm but need to be sent to an organelle are apart of the secretory pathway. T/F

A

False

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83
Q

What sequence do proteins made in cytoplasm but need to be transported to a different organelle, need?

A

Localization signals

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84
Q

What is the structure of the Golgi Apparatus?

A

Group of membranous sac stacked together

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85
Q

What are the functions of the Golgi?

A
  1. Modification of proteins made in RER
  2. Sending proteins to destinations
  3. Synthesis of macromolecules
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86
Q

Based on the modification of proteins made in RER, what is the Golgi especially important for?

A

Modification of oligosaccharidse

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87
Q

The vesicle traffic too and from the Golgi are…?

A

Unidirectional

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88
Q

What is retrograde traffic based on the Golgi traffic?

A

Proteins hat reside in the ER may accidentally escape and must be brought back to the ER from the Golgi

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89
Q

Based on Golgi, the portion closest to the ER are called….and the portion further from the ER are called…?

A

cis stack, trans stack

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90
Q

What is the medial stack based on Golgi?

A

The middle stack

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91
Q

What happens to the proteins in the vesicle once they reach the Golgi?

A

Fuse with the cis stack

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92
Q

What occurs after the protein vesicle fused with the cis stack of the Golgi?

A

Modified and transferred to the medial stack, further modified and pass to the trans stack

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93
Q

How does the proteins leave the Golgi?

A

At the trans face in transport vesicles

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94
Q

What happens if the vesicle contains proteins anchored to its membrane?

A

These proteins will remain attached to the cel as cell-surface proteins

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95
Q

What is the constitutive secretory pathway based on Golgi?

A

Vesicles from the Golgi immediately to the cell surface

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96
Q

What is the regulated secretory pathway?

A

Specialized secretary cells store secretory proteins in secretory vesicles and release them at certain times

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97
Q

What is the lysosome responsible for?

A

Degradation biological macromolecules by hydrolysis

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98
Q

Does lysosome have a membrane?

A

Yes

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99
Q

Where are the lysosome proteins made?

A

In the RER

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100
Q

What is autophagy and which organelle processes it?

A

Self-eating and lysosome

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101
Q

What is phagocytosis and which organelle processes it?

A

Cell eating and lysosome

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102
Q

What is the purpose of macrophage?

A

Apart of the immune system, engulfing bacteria and viruses

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103
Q

Where do bacteria and viruses end up to be degraded?

A

End up in a phagocytic vesicle that will fuse with a lysosome

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104
Q

What is crinophagy and which organelle processes it?

A

Digestion of excess secretory proteins and lysosome

105
Q

What happens after hydrolysis that occurs in the lysosome?

A

Release molecular building blocks into the cytoplasm for reuse

106
Q

What enzyme is responsible for degradation in the lysosomes?

A

Acid hydrolase

107
Q

What do the acid hydrolases need in order to be activated, based on lysosome?

A

Only hydrolyze substrate when they are in an acidic environment

108
Q

What happens to the cell if the lysosome ruptures?

A

The enzymes will not damage the cell because the acidic fluid will be diluted

109
Q

What is the peroxisome?

A

Small organelles that perform a variety of metabolic tasks

110
Q

What do the enzymes produce as a byproduct in the peroxisome?

A

Produce hydrogen peroxide

111
Q

Why is the byproduct from peroxisome important in the body? (H2O2)

A

Essential for lipid breakdown in many cell types

112
Q

How to peroxisome assist in the liver?

A

Detoxification of drugs and chemicals

113
Q

Why can hydrogen peroxide be contained in the peroxisome?

A

Contained an enzyme called catalase which converts it into H2O and O2

114
Q

What do animal cells rely on instead of cell wall?

A

Internal cytoskeleton

115
Q

What type of cells have a cell membrane and a cell wall?

A

Bacteria, plants and fungi

116
Q

What do fungi have in the cell wall?

A

Chitin

117
Q

All of the membranes of the cella re composed of what?

A

Lipid bilayer membranes

118
Q

What are the three most common lipids in eukaryotic membranes?

A

Phospholipids, glycolipids, and cholesterol

119
Q

Which lipid is most abundant in eukaryotic membrane?

A

Phospholipids

120
Q

What is an example of a phospholipid in eukaryotic membrane?

A

Phosphatidyl choline

121
Q

What is the structure phosphatidyl choline?

A

Two long hydrophobic fatty acids esterified to glycerol and a charged phosphoric choline group

122
Q

Are phospholipids hydrophobic or hydrophilic?

A

Both

123
Q

What is the structure glycolipids?

A

Fatty acids groups and carbohydrate side chains

124
Q

Are glycolipids hydrophobic or hydrophilic?

A

Both

125
Q

Why can the bilayer membrane reseal and repair itself easily?

A

Lowest energy state for these molecules

126
Q

What do fatty acids form in the presence of water?

A

Micelles

127
Q

What is the structure of a phospholipid?

A

Phosphate and glycerol head with two hydrophobic fatty acid tails, one unsaturated with a bent

128
Q

What happens if a phospholipid is in the presence of water?

A

Forms a lipid bilayer

129
Q

What type of molecule are cell-surface receptors?

A

Proteins

130
Q

What are cell-surface receptors?

A

Bind extracellular signaling molecules and relay these signals into the cell

131
Q

What are channel proteins?

A

Selectively allow ions or molecules to cross the membrane

132
Q

What are the two types of membrane proteins?

A

Integral or peripheral

133
Q

Where are integral membrane proteins located?

A

Embedded in the membrane and held by hydrophobic interactions

134
Q

What are transmembrane domains?

A

Membrane-crossing regions

135
Q

At which point in the secretory pathway would the insertion of transmembrane domains int the membrane occur?

A

As the protein is translated and threaded across the ER membrane

136
Q

Where are integral membrane proteins located?

A

Stuck to integral membrane proteins

137
Q

Integral proteins may have what base on the membrane?

A

Complex pattern of transmembrane domains and portions not within the membrane

138
Q

What is the current understanding of membrane dynamics?

A

Fluid mosaic model

139
Q

What is the fluid mosaic model?

A

The membrane is seen as a mosaic of lipids and proteins that are free to move back and forth fluidly

140
Q

What does it mean when it states membrane has polarity?

A

Inside face and outside face remain different

141
Q

All glycosylations are found…?

A

On the extracellular face

142
Q

What is the exception to the fluidity of the membrane?

A

Some proteins are anchored to the cytoskeleton and cannot move in any direction

143
Q

How does composition of lipids in the membrane affect fluidity of the membrane?

A
  1. Unsaturated fatty acids - Kink - Increase Fluidity

2. Saturated - Tightly packed - Less Fluidity

144
Q

Other than the composition of the lipid membrane themselves, what interactions also are major determinant in the membrane fluidity?

A

Hydrophobic van der Waals interacts between the fatty acid side chains

145
Q

Which type of fatty acids would have strong van der Waals?

A

Saturated

146
Q

Which molecule plays an important role in maintaining optimal membrane fluidity?

A

Cholestrol

147
Q

How does cholesterol play an important role in maintaining optimal membrane fluidity?

A

Fitting into the membrane interior

148
Q

What is molarity?

A

Concentration of a solution (moles of solute) per volume (in liters) of solution

149
Q

What is the equation for molarity?

A

(M) = # moles of solute / # liters of solution

150
Q

What is molality?

A

Concentration in terms of moles of solute per MASS (kg) of solvent

151
Q

What is the equation for molality?

A

Molality (m) = # moles of solute / # kg of solvent

152
Q

Why is molality useful when measuring something involving temperature?

A

It does not change with temperature

153
Q

Why is the molar and molal concentrations of dilute aqueous solution usually the same?

A

A liter of water has a mass of one kg

154
Q

What is mole fraction?

A

The fraction of moles of a substance relative to the total moles in a solution

155
Q

What is the equation of mole fraction?

A

mole fraction of S = Xsubscript s = # moles of substance S / total # moles in solution

156
Q

When is mole fraction useful?

A

When more than one solute is present

157
Q

What happens when ionic substances dissolve?

A

They dissociate into ions

158
Q

What are electrolytes? Why?

A

Free ions in a solution; they can conduct electricity

159
Q

What is partial dissociation of an ionic substance?

A

A certain percentage of the ions will remain paired

160
Q

What are strong electrolytes?

A

Solutes that dissolve completely

161
Q

What are weak electrolytes?

A

Remain ion-paired to some extent

162
Q

What are nonelectrolytes?

A

Covalent compounds that don’t dissociate into ions

163
Q

Which electrolytes are better conductors?

A

Solutions of strong electrolytes are better conductors of electricity than those of weak electrolytes

164
Q

What is the van’t Hoff factor (i)?

A

Tells us how many ions one unit of substance will produce in a solution?

165
Q

What is another term for van’t Hoff?

A

Ionizability (i)

166
Q

If a molecule is non-ionic, what would be its ionizability factor?

A

1

167
Q

What would be the ionizability of NaCl?

A

2 since it dissociates into Na and Cl

168
Q

What would be the ionizability of CaCl2?

A

3 since it dissociates into 1Ca and 2Cl

169
Q

What does the colligative properties depend on?

A

On the number of solute particles in the solution rather than the type of particle

170
Q

What is an important key factor when calculating colligative properties?

A

The identity of the particle is not important

171
Q

When stating for colligative properties, that 1M of solution of any solute, the change in colligative property will…?

A

Be the same no matter what the size, type or charge of the solute particles

172
Q

If you have one mol of sucrose, how many number of particles in solution of 0.5 mol of NaCl?

A

The same because sucrose i is 1 and NaCl i is 2, so it would be the same

173
Q

What are the four types of colligative properties?

A
  1. Vapor-Pressure Depression
  2. Boiling-point elevation
  3. Freeing-point depression
  4. Osmotic pressure
174
Q

What is vapor pressure?

A

The pressure from the gaseous phase of a liquid that evaporated from the exposed surface of the liquid

175
Q

How does the intermolecular forces and vapor pressure correlate?

A

The weaker a substance’s intermolecular forces, the higher its vapor pressure (more easily it evaporates)

176
Q

What are liquids said to be volatile?

A

Liquids with high vapor pressure

177
Q

What happens when a solute is dissolved into a solvent?

A

More energy is required to enter the gas phase

178
Q

Why is more energy required to enter the gas phase when a solute is dissolved into a solvent?

A

The solvent molecules need to break away from their interactions with the solute before they can enter gas phase

179
Q

What happens if you add more solute to the same solution, based on vapor pressure?

A

Will decrease its vapor pressure

180
Q

What is the boiling-point elevation referring to?

A

The increase in boiling point directly related to the number of particles in a solution and the type of solvent

181
Q

Do we have to take in consideration the ionizability in the boiling-pint elevation?

A

Yes

182
Q

What is the equation for boiling-point elevation?

A

delta Tsubscript b = ksubscriptb(i)(m)

183
Q

Describe each component of the boiling-point elevation formula?

A

kb - solvent’s boiling point
i - solute’s van’t Hoff factor
m - molal concentration of the solution

184
Q

What is the kb of water based on boiling point elevation?

A

kb = 0.5 degree celsius / m

185
Q

What happens to the liquid when attempting to freeze hen a solute is present?

A

Less able to achieve solid state as solute particles interfere with arrangements of the solvent molecules

186
Q

What is the formula for freezing-point depression?

A

delta T f = -k subscript f (im)

187
Q

In the freezing-point depression, what does kf stand for?

A

The solvent’s freezing-point depression constant

188
Q

In the freezing-point depression, what does i stand for?

A

The solute’s van’t Hoff factor

189
Q

In the freezing-point depression, what does m stand for?

A

Molal concentration

190
Q

What is the kf for water in freezing-pain depression?

A

1.9 degree celsius / molal concentration

191
Q

According to which law explains diffusion?

A

Second law of thermodynamics

192
Q

Why does diffusion lead particles to spread out and occupy all available space?

A

Maximizing entropy

193
Q

A solute will always diffuse__________ (in which direction)? What does that mean?

A

Down its concentration gradient; from high to low concentration

194
Q

What is the different between osmosis and diffusion?

A

Osmosis is diffusion in which solvent diffuses rather than solute

195
Q

If a cell is placed in a hypotonic solution, what will happen to the cell?

A

Cell will burst

196
Q

In osmosis, the direction is not permeable to what…?

A

To solutes

197
Q

What does the work tonicity mean?

A

Describe osmotic gradient

198
Q

What does isotonic solution mean?

A

The solvent concentration is the same inside and outside

199
Q

What does hypertonic solution mean?

A

Solution has more total dissolved solutes than the cell

200
Q

What does hypertonic solution mean?

A

Solution has less total dissolved solutions than the cel

201
Q

What other isotonic terms may be used to describe osmosis?

A

isoosmotic, hyperosmotic, and hypoosmotic

202
Q

Based on water moving down its concentration gradient, how would that be described in terms of cell?

A

Into a cell

203
Q

What is the tendency of water based on particles presence and osmosis?

A

Moved towards where there are more particles

204
Q

Osmosis describes the new movement of water across a ________from a region of _______?

A

semipermeable membrane from a low solute concentration to a region of higher solute concentration

205
Q

What is the symbol for osmotic pressure?

A

Π

206
Q

What is osmotic pressure?

A

The pressure it would take to stop osmosis from occurring

207
Q

What is the osmotic pressure of a solution equation?

A

Π = MiRT

208
Q

What is Π and what’s the units?

A

osmotic pressure, atm

209
Q

Based on the osmotic pressure formula, what does the M symbolize?

A

Molarity of the solution

210
Q

Based on the osmotic pressure formula, what does the i symbolize?

A

van’t Hoff factor

211
Q

Based on the osmotic pressure formula, what does the R symbolize?

A

is the universal gas constant

212
Q

What is the the universal gas constant?

A

0.0821 L-atm /K-mol

213
Q

Based on the osmotic pressure formula, what does the T symbolize?

A

Temperature in kelvins

214
Q

What is passive transport?

A

Any thermodynamically favorable movement of solute across a membrane

215
Q

What are two types of passive transport?

A
  1. Simple diffusion

2. Facilitated diffusion

216
Q

What is simple diffusion?

A

Diffusion of a solute through a membrane without help from a protein

217
Q

What is facilitated diffusion?

A

Specific integral membrane proteins allow material to cross the plasma membrane down a gradient

218
Q

What is an example in the human body of facilitated diffusion?

A

Glucose shuttled across RBC lipid bilayer by a protein

219
Q

What are two types of protein that aid in facilitated diffusion?

A
  1. Channel proteins

2. Carrier proteins

220
Q

What is selective permeability membrane?

A

Permeability to some things despite impermeability to most things

221
Q

What are channel proteins?

A

Allow material that cannot pass through the membrane by simple diffusion to flow through

222
Q

Ion channels are said to be ___? What does that mean?

A

Gated; the channel is open in response to specific environmental stimuli

223
Q

What is a voltage gated ion channel?

A

Response to a change in the electric potential across the membrane

224
Q

What is a ligand-gated ion channel?

A

Opens in response to binding of a specific molecule

225
Q

The regulation of membrane potential by gated ion channel plays a key role in what part of the body?

A

Nervous system

226
Q

Can ion channels move a ion against an electrochemical gradient?

A

No

227
Q

What are carrier proteins?

A

Can transport molecules through membranes by facilitated diffusion

228
Q

What do channel proteins form to allow the ion to flow through the semipermeable membrane?

A

Tunnel through the membranes

229
Q

How is carrier proteins different than channel proteins?

A

Carrier proteins bind to the molecule and go through conformational change to let the molecule through

230
Q

What are uniports based on carrier proteins?

A

Transport only one molecule across

231
Q

What are symports?

A

Carry two substances across a membrane in he same direction

232
Q

What are anti ports?

A

Carry two substances in opposite directions

233
Q

What is a pore based on osmosis?

A

Tube through the membrane so large that its not selective

234
Q

What type of molecules may not be able to cross a pore even though its not selective?

A

Molecule may not cross if it has the wrong charge and just barely small enough to cross

235
Q

What is the composition of pores?

A

Polypeptides called porins

236
Q

Where are pores present, based on other topics we’ve studied in different chapters?

A

Double nuclear membrane, outer mitochondrial membrane, gram-negative bacterial outer membrane

237
Q

Why doesn’t eukaryotic membrane have pores?

A

Because pores destroy the barrier function of the membrane

238
Q

What type of kinetics is exhibited in facilitated diffusion and why?

A

Saturation kinetics; finite number of integral membrane proteins

239
Q

What is the flux?

A

The rate of diffusion

240
Q

What is active transport?

A

Movement of molecules through the plasma membrane against a gradient

241
Q

How is the input of energy processed for the active transport?

A

The transport process is coupled to a process which is thermodynamically favorable (delta G < 0)

242
Q

For active transport, what can the gradient being pumped against involve?

A

Electric potentials that form a combined electrochemical gradient that must be pumped against

243
Q

What is primary active transport?

A

The transport of a molecule is coupled to ATP hydrolysis

244
Q

What is secondary active transport?

A

The transport process is not coupled directly to ATP hydrolysis

245
Q

How is the secondary active transport processed, based on ATP?

A

ATP used first to create a gradient, and then the potential energy in hat gradient drives the transport of some other molecule

246
Q

What is ATP called in the secondary active transport?

A

Indirect as its not ATP used to drive the transport

247
Q

What is an example of secondary active transport?

A

Glucose driven against glucose concentration gradient by the co-transport of sodium ions down the sodium electrochemical gradient established by an ATPase pump

248
Q

What is an example of an active transport that is the prime example of it?

A

Na + / K + ATPase

249
Q

What is Na + / K + ATPase?

A

A transmembrane protein in the plasma membrane of all cells in the body

250
Q

What is the activity provided by that Na + / K + ATPase?

A

Pump 3 Na + out of the cell, 2 K + into the cell, hydrolyze 1 ATP to drive these ions against their gradients

251
Q

What happens to the sodium pumped outside of the cell on the Na + / K + ATPase?

A

Stays outside of the cell since plasma membrane is impermeable

252
Q

What happens to the potassium pumped inside of the cell on the Na + / K + ATPase?

A

Movees down its concentration gradient by leaking outside through potassium leak channels

253
Q

Why is the potassium leak channels important for the cell?

A

Maintain osmotic balance with its surroundings

254
Q

What happens to the charge of the cell when potassium leaves?

A

The exist of potassiums positive creates an electric potential with a net negative charge on the interior of the cell

255
Q

The concentration gradient provided by Na + / K + ATPase is the driving force behind______of many different molecules?

A

Secondary active transport

256
Q

What are the three reasons the Na + / K + ATPase is important?

A
  1. Maintain osmotic balance
  2. Establish resting membrane potential
  3. Creates Na [M] gradient to drive 2nd active transport
257
Q

Why is chloride so concentrated outside the cell?

A

The cell contains millions of negative charges on macromolecules inside the cell; Cl outside is to maintain negative charged substance outside concentrated

258
Q

Based on the Na, K, Cl and Ca based on intracellular and extracellular concentration, tell me of their trends?

A

Ca2+: least amount intra and extra
Na+: little intra, lots extra, more than Cl for both
K+: lots intra, little extra,
Cl-: little intra, lots extra, less than Na+

MCAT BIOLOGY FLASHCARDS (23 decks)

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