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MCAT BIOLOGY FLASHCARDS > MCAT BIO CH. 6 PART 2 > Flashcards

MCAT BIO CH. 6 PART 2 Flashcards

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1
Q

How are materials taken into the cells for endocytosis? How do we assure its not mixed with the cell content?

A
  1. Invagination of cell membrane

2. Endosome; vesicle formed

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2
Q

What are three types of endocytosis?

A
  1. Phagocytosis
  2. Pinocytosis
  3. Receptor-mediated endocytosis
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3
Q

What does the literally translation of phagocytosis?

A

Cell-eating

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4
Q

What is the definition of phagocytosis?

A

Refers to the nonspecific uptake of large particulate matter into a phagocytic vesicle

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5
Q

What happens to the phagocytic vesicle after it is formed?

A

Fuses with the lysosome

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6
Q

What is an example of phagocytic human cells?

A

Macrophages - destroy viruses and bacteria

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7
Q

What does the literally translation of pinocytosis?

A

Cell-drinking

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8
Q

What is the definition of pinocytosis?

A

Nonspecific uptake of small molecules and extracellular fluid via invagination

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9
Q

How do primitive eukaryotic cells obtain nutrition?

A

{pinocytosis

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10
Q

What is receptor-mediated endocytosis?

A

Receptors bind to a specific molecule outside the cell

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11
Q

How does the cell know when it needs to conduct receptor-mediated endocytosis?

A

Site marked by pits coated with the molecule clathrin

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12
Q

What is an important example of receptor-mediated endocytosis?

A

Uptake of cholesterol from the blood

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13
Q

How are cholesterol transported through the blood, based on RME?

A

By large particles called lipoproteins

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14
Q

What is atherosclerosis?

A

A buildup of plaque on the walls of the arteries by cholesterol build up sticking to the walls

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15
Q

Does clathrin recognize and bind to lipoproteins?

A

No, fibrous protein inside the cell that associates with cytoplasmic portion of the cell receptors

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16
Q

Where is clathrin located?

A

Inside the cell

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17
Q

Which items from the cholesterol receptor-mediated endocytosis, are recycled?

A

Lipoprotein receptors

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18
Q

What are receptors?

A

Class of integral membrane proteins that transmit signals from the extracellular space into the cytoplasm

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19
Q

What is a ligand?

A

molecule that binds to the receptor

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20
Q

What are ligands usually based on cell-surface receptors?

A

Hormone or neurotransmitter

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21
Q

What is signal transduction?

A

Ligand binding to the receptor and causing intracellular response

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22
Q

Based on ligand binding to the receptor, how may it involve cancer?

A

Many cancers involves relaying their signal to the cytoplasm with or without a ligand

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23
Q

What are three types of signal-transducing cell-surface receptors?

A
  1. Ligand-gated ion channels
  2. Catalytic receptors
  3. G-protein linked receptor
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24
Q

What is ligand-gated ion channels?

A

Open an ion channel upon binding a particular neurotransmitter

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25
Q

What is example of a ligand-gated sodium channel?

A

Surface of muscle cel at the neuromuscular junction

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26
Q

What happens when the neurotramsiter ______ binds to the receptor, based on muscle cell?

A

acetylcholine; open Na+ channel; influx of sodium depolarizes muscle cell and causes contractions

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27
Q

Catalytic receptors have what?

A

Enzymatic active site on the cytoplasmic side of the membrane

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28
Q

Generally, the catalytic role of the catalytic receptors is that of a protein _____?

A

Kinase

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29
Q

What is a protein kinase?

A

An enzyme that covalently attaches P groups to proteins

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30
Q

What is an example of a kinase?

A

Insulin receptor is an example of a tyrosine kinase

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31
Q

What regulates the activity of kinases?

A

Modification of proteins with Ps

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32
Q

How does the G-protein linked receptor transmits information?

A

Transmits within the cell with the aid of a second messenger

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33
Q

What is the most important second messenger based on G-protein linked receptor transmitters?

A

cycle AMP (cAMP)

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34
Q

What is cycle AMP known as and why?

A

Universal hunger signal because it is the second messenger of the hormones epinephrine and glucagon

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35
Q

What is the purpose of glucagon?

A

Energy metabolism (glycogen and fat breakdown)

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36
Q

What is the first step to the G-Protein Mediated Stimulated Transduction Stimulated by Epinephrine?

A

Epinephrine arrives to cell surface and binds to a specific G-protein linked receptor

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37
Q

What happens when the G-protein linked receptor is activated after epinephrine binds?

A

The cytoplasmic portion of the receptor activates G-protein

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38
Q

What happens when the G-protein inside the cell is activated from epinephrine?

A

GDP dissociates and GTP binds in its place

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39
Q

What is it considered when the GTP binds in its place to the protein?

A

The activated G-proteins

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40
Q

What does the activated G-proteins do when GTP has bounded?

A

Diffuse through the membrane and activate adenyl cyclase

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41
Q

What happens when adenyl cyclase is activated in the G-Protein Mediated Signal Transduction Stimulated by Epinephrine?

A

Adenyl cyclase makes cAMP from ATP

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42
Q

What does cAMP do once its created by the activation of adenyl cyclase?

A

cAMP activates cAMP-dependent protein kinases (cAMP-dPK) in the cytoplasm

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43
Q

What is the function of cAMP-dPK in the G-Protein Mediated Signal Transduction Stimulated by Epinephrine?

A

Phosphorylates certain enzymes

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44
Q

After phosphorylating certain enzymes, what cascade does that cause based on cAMP-dPK in the G-Protein Mediated Signal Transduction Stimulated by Epinephrine?

A

Then end result is mobilization of energy

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45
Q

What is an example of an enzyme that is activated based on cAMP-dPK in the G-Protein Signal thing?

A

Enzymes for glycogen breakdown will be activated and enzymes for glycogen synthesis will be inactivated

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46
Q

What are the two types of g-protein linked receptors?

A

Stimulatory (G subscript s)

Inhibitory (G subscript i)

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47
Q

For the G-protein linked receptors that have no involvement with cAMP, what do they do instead?

A

Their G-proteins activate an enzyme called phospholipase C

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48
Q

What does the activation of phospholipase cause, based on the G-protein linked receptors cascade?

A

Increase in cytoplasmic Ca2+

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49
Q

What is the common theme of all G-protein based signals?

A

Reliance on G-protein which is a signaling molecule that binds to GTP

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50
Q

What is cAMP considered in the G-Protein mediated Signal Transduction Stimulated by Epinephrine?

A

Second messenger

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51
Q

What is the internal cytoskeleton composed of in animal cells?

A
  1. Microtubules
  2. Intermediate filaments
  3. Microfilaments
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52
Q

Based on microtubules, intermediate filaments and microfilaments, what are they all three composed of?

A

A non-covalently polymerized proteins; massive example of a quaternary protein structure

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53
Q

What is the structural composition of microtubules?

A

Hollow rod composed of two globular proteins: alpha-tubulin and beta-tubulin

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54
Q

How are the alpha and beta tubulin attached to one another in microtubules?

A

Polymerized noncovalently

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55
Q

What do the alpha and beta tubulin form together?

A

Alpha-beta tubulin dimer and many dimers stick to one another noncovalently

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56
Q

Why can only one end of the microtubule elongate and not the other?

A

Because its anchored to the microtubule organizing center (MTOC)

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57
Q

Where is the MTOC located?

A

Near the nucleus

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58
Q

What is the first noticeable component within the MTOC?

A

A pair of centrioles

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59
Q

What is the structural component of centrioles?

A

A ring of nine microtubules triplets

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60
Q

What happens to the centrioles during cell division?

A

The centrioles duplicate themeselves, one pair moves to each end of the cell

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61
Q

What happens during mitosis, what is the role of microtubules in achieving mitosis?

A

Microtubules leave centrioles, attach to replicating chromosomes and pulls them apart

62
Q

What are asters?

A

Microtubules leaving the centrioles during mitosis

63
Q

What are polar fibers?

A

Microtubules connecting the chromosomes to the aster

64
Q

What is the name for the assembly of the asters, and polar fibers based on microtubules and centrioles and chromosomes?

A

Mitotic spindle

65
Q

What from the chromosome confirms the location of where the microtubules are supposed to connect?

A

Centromere of each chromosome contains a kinetochore

66
Q

What are kinetochore fibers?

A

Tiny microtubules attaching the centromere of each chromome to the spindle

67
Q

Based on mitosis, microtubules and centrioles, what is essential and what isn’t?

A

The MTOC is essential, the centrioles are not

68
Q

What are the two evidences that prove that centrioles are not essential?

A
  1. Plants

2. Experimenters

69
Q

What about plants prove that centrioles are not essential?

A

Plant cells lack centrioles but still undergo mitosis

70
Q

What about experimenters prove that centrioles are not essential?

A

Succeeded in removing the centrioles from animal cells and the cells were still able to undergo mitosis

71
Q

What do microtubules assist with in the cell, other than attaching to centromeres?

A

Mediate transport of substances within the cell

72
Q

What is an example of microtubules assisting with transport of substances within the cell?

A

Nerve cells, materials are transported from the cell body to the axon terminus on a microtubule railroad

73
Q

What is the purpose of cilia?

A

Move fluid past the cell surface

74
Q

What is an example of cilia being present in the human body?

A

Cilia on lining cells of the human respiratory tract sweep mucus towards the mouth

75
Q

Wha tis mucociliary escalator?

A

Cilia on lining cells of the human respiratory tract sweep mucus towards the mouth

76
Q

What is flagellum?

A

Large “tail” which moves the cell by wiggling

77
Q

The only human cell that has flagellum is…?

A

Sperm

78
Q

What is the structure of cilia and flagella?

A

Cilia are small and flagella are long but they have the same structure with 9 + 2 arrangement of microtubules

79
Q

How are microtubules bound to one another, the ones forming the 9 ring?

A

Contractile protein calle dyne

80
Q

What does dynein cause for the filaments?

A

Cause movement of the filament past one another

81
Q

What is the purpose of the basal body?

A

Anchor Cilium or flagella

82
Q

What is the structure of the basal body?

A

A ring of nine triplets of microtubules

83
Q

What is the structure component of the basal body?

A

A ring of nine triplets of microtubules

84
Q

What are microfilaments?

A

Rods formed in the cytoplasm

85
Q

How are microfilaments formed?

A

Polymerization of the globular protein actin

86
Q

How are microfilaments formed from actin?

A

Actin monomers form a chain, two chains wrap around each other to form an actin filament

87
Q

What are microfilaments responsible for?

A

Gross movements of the entire cell

88
Q

What type of movements are microfilaments responsible for?

A

Pinching the diving parent cell into two daughters cell

89
Q

What is amoeboid movement; what is the protein responsible for it?

A

Change of cytoplasmic structure; causes cytoplasm plus cell to flow in one direction; microfilament

90
Q

What is different between microtubules and microfilaments, compared to intermediate filaments?

A
  1. Intermediate filaments are heterogeneous, composed of a wide range of polypeptides
  2. More permanent while micros disassemble and reassemble as needed
91
Q

What does intermediate filaments seem to be involved in, based on structure?

A

Involved in providing strong cell structure such as resisting mechanical stress

92
Q

What is the basement membrane?

A

A strong molecular sheet made of collagen under the epithelium

93
Q

What is tight junction?

A

Epithelial cells prevent movement freely between two areas

94
Q

What are desmosomes?

A

Epithelial cells held together but do not form a complete cell

95
Q

What are gap junctions?

A

Holes allowing ions to flow back and forth between them

96
Q

What is another term for tight junctions and why?

A

Occluding suctions because they form a seal between the membranes of adjacent cells, blocking flow molecules across the entire cell layer

97
Q

How do tight junctions relate to the plasma membrane?

A

Block the flow of molecules within the plane of the plasma membrane

98
Q

What is the apical surface?

A

The surface of the plasma membrane facing the intestinal lumen

99
Q

What is the bas-lateral surface?

A

The cell facing the tissues beneath the plasma membrane

100
Q

How do the apical surface and bas lateral surface relate to the tight junctions?

A

Aplical surface has different membrane proteins than the plasma membrane on the other side of the baslateral surface

101
Q

Why are desmosomes called point desmosomes?

A

They are concise points, not bands all the way around the cell

102
Q

How is the desmosomes anchored to the plasma membrane?

A

By plaque formed by the protein keratin

103
Q

Where do the intermediate filaments attach based on the desmosomes?

A

To the inside of the desmosomes

104
Q

The fluid mosaic model describes the plasma membrane as fluid, how does that relate to desmosomes? Can they move freely?

A

No because they are anchored by the intermediate filaments

105
Q

What do gap junctions allow that desmosomes don’t?

A

Allows cytoplasms to mix by pore-like connections between adjacent cells

106
Q

Gap junctions disallow the mixing of….?

A

Polypeptides and organelles

107
Q

In what part of the body are gap junctions pertinent?

A

In smooth muscle and cardiac muscle, they allow the membrane depolarization of an action potential to pass directly from one cell to another

108
Q

What are all the phases of the cell cycle?

A
  1. G1, S, G2, mitosis and cytokinesis
109
Q

What does the S phase of the cell cycle entail?

A

The cell actively replicates it genome

110
Q

What does the M phase of the cell cycle entail?

A

Mitosis and cytokinesis

111
Q

What is mitosis?

A

Partitioning of the cellular components (genes and organelles) in two halves

112
Q

What is the interphase based on cell cycle?

A

G1, S and G2

113
Q

Where does the cell mostly spends its time?

A

Interphase

114
Q

How do cells that are less capable of reproducing themselves, reproduce?

A

By reproduction of less specialized pre-cursor cells called stem cells

115
Q

What happens during the interphase?

A

Genome is spread out and DNA is accessible for the enzymes to replicate

116
Q

What happens at the end of the S phase?

A

The nucleus contains two contains two complete copies of the genome

117
Q

What are the four stages of mitosis?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
118
Q

What is the first sign of prophase?

A

Genome becomes condensed and tightly packed chromosomes instead of diffuse chromatin

119
Q

What are homologous pairs?

A

Identical-appearing sister chromatin pairs (23 pairs of pairs)

120
Q

What are important factors that occur during prophase?

A
  1. Nucleolus disappear
  2. Spindle and kinetochore fibers appear
  3. Centriole pairs move to opposites
121
Q

What is pro metaphase?

A

Nuclear envelope converts itself into many tiny vesicles

122
Q

What are important factors that occur during metaphase?

A
  1. Chromosomes line up
123
Q

What is the term used when describing the chromosomes lining in the middle of the cell?

A

Metaphase plate

124
Q

Why can the chromosomes line up at the center of the cell?

A

Because the kinetochore of each sister chromatid is attached to spindle fibers that attach to MTOC at opposite ends

125
Q

What are important factors that occur during anaphase?

A
  1. Spindle fibers shorten
  2. Centromeres pulled apart
  3. Cell elongates
  4. Cleavage furrow
126
Q

What is the cleavage furrow during anaphase accomplished by?

A

Ring of microfilaments encircling the cell and contracting

127
Q

What are important factors that occur during telophase?

A
  1. Nuclear membrane forms
  2. Chromsomes decondense
  3. Nucleolus becomes visible
128
Q

What is the ploid number for the daughter nucleus after mitosis ?

A

2n chromsomes

129
Q

What is a karyotype?

A

Display of an organism’s genome

130
Q

When is the picture taken for karyotypes?

A

Metaphase

131
Q

What is oncogenes?

A

Mutated genes that induce cancer

132
Q

When was the first oncogene found?

A

Isolated from a retrovirus found in chickens

133
Q

What are teratomas?

A

Oncogenes cause tissues to dedifferentiate and tumors with formed tissues from multiple germ layers

134
Q

What are protooncogenes?

A

Normal versions of genes that allow for regular growth patterns but can be converted into oncogenes under the right circumstances

135
Q

How can the conversion of protooncogenes create oncogenes?

A

Conversion may be due to mutation or because of exposure to a mutagen

136
Q

What do tumor suppressor genes do?

A

Produce proteins that are the inherent defense system to prevent the conversion of cells into cancel cells

137
Q

What are the two primary means of cancer prevention?

A
  1. Detect damage to the genome and halt cell growth and division
  2. Trigger programmed cell death if the damage is too severe
138
Q

What is an example of a product of a tumor suppressor gene?

A

p53

139
Q

How does the process of apoptosis start?

A

Cell shrinks and cytoskeleton disassembles, nuclear envelope breaks down and genome broken into pieces

140
Q

What enzymes are responsible for apoptosis?

A

Family of proteases called caspases

141
Q

Why are caspases called that way?

A

Have a cysteine in their active site and they cleave their target proteins at aspartic acid sites

142
Q

How are the caspases initially produced?

A

In their inactive form, procaspases

143
Q

How many caspases are there in humans and how are they grouped?

A

12 and they’re grouped by two categories, initiators or effectors

144
Q

What are initiator caspases?

A

Response to extra or intra cellular cell death signals by clustering together and activate each other

145
Q

What does the clustering of initiator caspases lead to?

A

Cascade to activate effector capsases

146
Q

What are effector caspases?

A

Effector caspases cleave a variety of cellular proteins to trigger apoptosis

147
Q

What is oxidative stress?

A

Level of production of reactive oxygen species outstrips the cell’s ability to detoxify them

148
Q

Why can oxidative stress cause cancer?

A

The damage it can cause sets up conditions in the cel to allow oncogenes to become active and cell growth to be impacted

149
Q

Why is creating oxidative stress sometimes beneficial for the body?

A

Used in immune system; activated phagocytes produce it to kill pathogens

150
Q

What does the ability to restore damaged tissues depend on?

A

Depends on how stem cells are maintained in the body of an organism

151
Q

What is senescence?

A

The process of biological aging which occurs at both the cellular and organismal level

MCAT BIOLOGY FLASHCARDS (23 decks)

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