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A&P Exam 1 > Chapter 3 - Cellular Organization > Flashcards

Chapter 3 - Cellular Organization Flashcards

1
Q

What is the approximate diameter of a typical cell?

A

0.1nm

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2
Q

Did Robert Hooke actually see cells?

A

No - just the outline of them

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3
Q

In what century were microscopes invented?

A

17th century (1665)

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4
Q

Name the 4 components of the cell theory

A
  1. Cells are the building blocks of all plants and animals
  2. All cells come from the division of preexisting cells
  3. Cells are the smallest units that perform all vital physiological functions
  4. Each cell maintains homeostasis at the cellular level. (Homeostasis at the tissue, organ, organ system, and organism reflects the combined action of many cells)
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5
Q

The human body contains _____ of cells

A

trillions

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6
Q

cytology is part of the broader discipline of …?

A

cell biology

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7
Q

cell biology integrates aspects of which 3 sciences?

A

chemistry
biology
physics

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8
Q

The human body contains how many general classes of cells and what are they

A

2 - somatic cells
sex cells (germ cells)

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9
Q

Name the 4 functions of the plasma membrane

A
  1. Physical isolation
  2. Regulation of exchange with the environment
  3. Sensitivity to the environment
  4. Structural support
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10
Q

What is the 1st part of the cell affected by changes in composition, pH, etc of the extracellular fluid?

A

cell membrane

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11
Q

The plasma membrane contains a variety of _______ that allow the cell to recognize and respond to specific molecules in its environment

A

receptors

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12
Q

Is the plasma membrane thin or thick? How many nm is it?

A

EXTREMELY THIN. ranges from 6-10nm in thickness

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13
Q

The cell membrane contains which 3 biomolecules?

A

carbohydrates, lipids, proteins

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14
Q

Which biomolecule makes up most of the SURFACE AREA of the plasma membrane?

A

lipids

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15
Q

What % weight is lipids in a cell membrane

A

42%

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16
Q

Why is isolation between the cytoplasm and extracellular fluid so important?

A

Because the compositions of the 2 are very different and the cell cannot survive if the differences are eliminated

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17
Q

Proteins account for about ____% of the weight of the plasma membrane

A

55%

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18
Q

Which are denser - proteins or lipids?

A

proteins

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19
Q

What are the 2 structural classes of membrane proteins?

A

Integral proteins and peripheral proteins

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20
Q

Can integral proteins be removed?

A

Not without damaging the cell membrane. It’s part of the membrane structure

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21
Q

Integral proteins are also known as …..? Why?

A

Transmembrane proteins because they span the width of the membrane one or more times

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22
Q

Can peripheral proteins be removed from the membrane?

A

Yes - they are bound to either the inner or outer surface of the membrane and are easily separated from it

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23
Q

Which are more abundant - peripheral or integral?

A

integral

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24
Q

Membrane proteins can have which 6 functions?

A
  1. Channel
  2. Carrier
  3. Anchoring
  4. Recognition
  5. Enzyme
  6. Receptor
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25
Q

What do anchoring proteins do? Where do they attach:
-Inside the cell
-Outside the cell

A

attach the plasma membrane to other structures and stabilize its position

inside the cell: cytoskeleton
outside the cell: another cell or extracellular protein fibers

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26
Q

Recognition proteins are also known as…?

A

Identifiers

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27
Q

Recognition proteins are crucial in the…?

A

immune system

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28
Q

Many important recognition proteins are…?

A

glycoproteins

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29
Q

Are enzymes in the plasma membrane peripheral or integral proteins?

A

could be either

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30
Q

Receptor proteins are sensitive to the presence of…?

A

ligands

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31
Q

What is a ligand?

A

extracellular molecule. Could be a small ion or a complex hormone

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32
Q

The binding of insulin to a receptor protein leads to….?

A

increase in the rate of glucose absorption by the cell

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33
Q

What do carrier proteins do?

A

bind solutes and transport them across the plasma membrane

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34
Q

Carrier proteins may require ___ as _______

A

ATP as an energy source

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35
Q

Do carrier proteins that transport glucose need ATP?

A

no

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36
Q

What does a channel do?

A

Permits the movement of water and small solutes across the plasma membrane

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37
Q

Why can ions not cross the plasma membrane??

A

They do not dissolve in lipids

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38
Q

Many channels are highly _______

A

specific

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39
Q

Membranes are neither ___ nor ____

A

rigid nor uniform

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40
Q

Carbohydrates account for about ___% of the weight of the plasma membrane

A

3

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41
Q

Carbohydrates in the plasma membrane can be components in _____, ______, or _____

A

protoglycans, glycoproteins, glycolipids

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42
Q

What is the glycocalyx?

A

portions of proteoglycans, glycoproteins, or glycolipids that extend beyond the outer surface of the membrane

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43
Q

What are 4 functions of the glycocalyx?

A
  1. Protection and Lubrication
  2. Anchoring and Locomotion
  3. Specificity in binding (receptors)
  4. Recognition
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44
Q

Cytoplasm is a general term for the material located between the _____ and the ____ surrounding the ______

A

plasma membrane and the membrane surrounding the nucleus

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45
Q

Which contains more proteins - cytoplasm or extracellular fluid??

A

cytoplasm

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46
Q

Cytoplasm is a _____ with a ___like consistency

A

colloid with a gel like consistency

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47
Q

Cytoplasm =

A

cytosol + organelles

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48
Q

Another name for cytosol is _____ fluid

A

intracellular fluid

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49
Q

Cytosol contains …?

A

dissolved nutrients, ions, soluble/insoluble proteins, and waste products

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50
Q

What are organelles?

A

structures suspended within the cytosol that perform specific functions for the cell

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51
Q

What are 3 differences between the cytosol and extracellular fluid??

A
  1. Concentration of potassium ions is much higher in the cytosol than extracellular fluid. Sodium conc is much higher in extracellular fluid
  2. Cytosol has many more suspended proteins
  3. Cytosol has small reserves of amino acids and lipids while extracellular fluid is a transport medium ONLY - no reserves
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52
Q

What is fluid within tissues called?

A

interstitial fluid

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53
Q

What are inclusions?

A

masses of insoluble material within the cytosol

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54
Q

cellular organelles can be divided into 2 broad categories:

A
  1. nonmembranous organelles
  2. membranous organelles
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55
Q

What are the cell’s membranous organelles?

A

ER, golgi, lysosomes, peroxisomes, mitochondria, nucleus

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56
Q

What are the 3 components of the cytoskeleton?

A

microtubules, intermediate filaments, microfilaments

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57
Q

Which component of the cytoskeleton is the smallest?

A

microfilaments

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58
Q

Microfilaments are made up of _____

A

actin

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59
Q

microfilaments are generally less than ___nm in diameter

A

6

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60
Q

What are the 3 main functions of microfilaments?

A
  1. Anchor cytoskeleton to integral proteins
  2. Determine the consistency of the cytoplasm by interacting with other proteins
  3. Actin can interact with myosin to produce movement of the cell or change shape
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61
Q

Intermediate filaments range from __to__ nm in diameter

A

7 to 11nm

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62
Q

Intermediate filaments mainly serve as …?

A

structural support

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63
Q

List 3 functions of intermediate filaments.

A
  1. Strengthen the cell and help maintain its shape
  2. Stabilize the positions of organelles
  3. Stabilize the position of the cell with respect to surrounding cells through attachment to cell membrane
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64
Q

Intermediate filaments are.. (soluble/insoluble)

A

INSOLUBLE

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65
Q

Keratin fibers are which kind of filament?

A

intermediate filament

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66
Q

Most cells contain ______ built from the globular protein _____?

A

most cells contain MICROTUBULES built from the globular protein tubulin

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67
Q

microtubules have a diameter of about ___nm

A

25

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68
Q

Microtubules extend outward from a region near the nucleus known as…?

A

the centrosome

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69
Q

Name 4 functions of the microtubules.

A
  1. Forms the spindle apparatus during mitosis
  2. serve as a monorail system to move vesicles
  3. Form centrioles, cilia, flagella
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70
Q

What are thick filaments?

A

massive bundles composed of myosin

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71
Q

Thick filaments appear only in …?

A

muscle cells

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72
Q

myosin interacts with ____ to produce powerful contractions

A

actin

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73
Q

What are the small, finger-shape projections of the plasma membrane?

A

microvilli

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74
Q

centrioles are composed of….

A

short microtubules

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75
Q

centrioles are found in which cells?

A

all animal cells that can undergo mitosis

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76
Q

Which types of cells do NOT contain centrioles?

A

mature red blood cells, skeletal muscle cells, cardiac muscle cells, and neurons - CELLS THAT CANNOT DIVIDE

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77
Q

What is the heart of the cytoskeletal system?

A

the centrosome

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78
Q

What is the centrosome?

A

the cytoplasm surrounding the centriole

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79
Q

the organization of centrioles is what kind of array? why?

A

9+0 array because there are no central microtubules as they form 3 “triplets”

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80
Q

Cilia are found on the cells lining which 2 tracts?

A

respiratory and reproductive

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81
Q

What is the array of cilia? why?

A

9 + 2 array. Nine PAIRS of microtubules surround a central pair

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82
Q

The microtubules in cilia are anchored to a ________ which has the same array as a centriole (9+0)

A

basal body

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83
Q

Cilium has 2 strokes:

A

power stroke and return stroke

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84
Q

During what stroke is the cilia relatively stiff?

A

power stroke

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85
Q

Which are the organelles responsible for protein synthesis?

A

ribosomes

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86
Q

Before protein synthesis can begin, what 3 things must join together?

A

small ribosomal subunit, large ribosomal subunit, mRNA

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87
Q

There are 2 types of ribosomes:

A

fixed ribosomes and free ribosomes

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88
Q

Where do free ribosomes produce proteins?

A

within the cytoplasm

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89
Q

What are proteasomes?

A

organelles that contain an assortment of protein-digesting enzymes (proteases)

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90
Q

What is the molecular “tag” attached to proteins for recycling?

A

ubitiquin

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91
Q

What kind of proteins are degraded by proteasomes?

A

-damaged/denatured proteins
-abnormal proteins (ex: those infected with viruses)

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92
Q

The ER is connected to the….

A

nuclear envelope

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93
Q

What are the 4 major functions of the ER?

A
  1. Synthesis
  2. Storage
  3. Transport
  4. Detoxification
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94
Q

The ER forms hollow tubes, flattened sheets, and chambers called..?

A

cisternae

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95
Q

The SMOOTH endoplasmic reticulum synthesizes….

A

lipids and carbohydrates

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96
Q

The smooth ER in ____ and ____ cells is responsible for the detoxification or inactivation of drugs

A

liver and kidney cells

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97
Q

What delivers proteins from the rough er to the golgi apparatus?

A

transport vesicles

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98
Q

is the proportion of rough ER to smooth ER the same in all cells?

A

NO - vary with the activities of the cell

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99
Q

Pancreatic cells that manufacture digestive enzymes contain more smooth or rough er?

A

RER

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100
Q

What are 3 major functions of the golgi apparatus?

A
  1. Modify and package secretions such as hormones and enzymes for release through exocytosis
  2. modify the plasma membrane
  3. package special enzymes within vesicles for use in the cytoplasm
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101
Q

Where are lysosomes produced??

A

The golgi apparatus

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102
Q

Lysosomes contain…?

A

digestive enzymes

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103
Q

What are primary lysosomes?

A

contain inactive enzymes. fuses with the membranes of damaged organelles

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104
Q

Lysosomes function in the deconstruction of…?

A

bacteria

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105
Q

Which are larger - lysosomes or peroxisomes?

A

peroxisomes

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106
Q

How are new peroxisomes produced?

A

From pre existing peroxisomes

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107
Q

What is the most abundant enzyme within the peroxisome?

A

Catalase

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108
Q

What do peroxisomes absorb and break down?

A

fatty acids and other organic molecules

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109
Q

In which cells are peroxisomes most abundant?

A

metabolically active cells such as liver cells

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110
Q

All membranous organelles aside from which one are in communication through the movement of vesicles?

A

mitochondria

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111
Q

What is the continuous movement and exchange in the cell called?

A

membrane flow

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112
Q

Which kind of cells lack mitochondria?

A

red blood cells

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113
Q

Which kind of cells have a LOT of mitochondria

A

heart muscle cells

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114
Q

Most of the chemical reactions that RELEASE energy occur in the ____ of the cell

A

mitochondria

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115
Q

Most of the chemical reactions that REQUIRE energy occur in the ____

A

cytoplasm

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116
Q

The first step of cellular respiration is called _____ and occurs in the _____

A

glycolysis, cytoplasm

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117
Q

During glycolysis, each ____ molecule is broken down into 2 molecules of ______

A

glucose is broken down into 2 molecules of pyruvate

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118
Q

Differentiate between the cytoplasm and the cytosol

A

Cytoplasm is the material between the plasma membrane and the nuclear membrane. Cytosol is the fluid portion of the cytoplasm

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119
Q

What is the function of the centriole??

A
  1. movement of chromosomes during cell division
  2. Organization of microtubules in cytoskeleton
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120
Q

What is the function of the cilia?

A
  1. Movement of materials over cell surface
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121
Q

What is the function of microvilli?

A

Increased surface area to facilitate absorption of extracellular materials

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122
Q

What % of ATP required by the cell is produced by the mitochondria?

A

95%

123
Q

What is the function of peroxisomes?

A

neutralization of toxic compounds

124
Q

A large amount of mitochondria in the cell indicates….

A

A high demand for energy

125
Q

Explain why certain cells in the ovaries and testes contain large amounts of smooth endoplasmic reticulum

A

SER synthesizes lipids, such as steroids. Ovaries and testes produce large amounts of steroid hormones and thus need large amounts of SER

126
Q

What organelle is usually the largest and most conspicuous structure in a cell?

A

The nucleus

127
Q

The nucleus serves as the _____ for cellular ______

A

control center for cellular operations

128
Q

Can a cell without a nucleus repair itself?

A

NO - it will disintegrate in 3-4 months

129
Q

Which kind of cells do not contain nuclei?

A

mature red blood cells

130
Q

Which kind of cells have MANY nuclei?

A

skeletal muscle cells

131
Q

What surrounds the nucleus, separating it from the cytosol?

A

a nuclear envelope

132
Q

What is the nuclear envelope?

A

a double layer separated by a narrow perinuclear space

133
Q

Where does chemical communication between the nucleus and cytoplasm occur?

A

nuclear pores

134
Q

Nuclear pores cover around what % of the surface of the nucleus?

A

10%

135
Q

The fluid contents of the nucleus are called the …..

A

nucleoplasm

136
Q

Most nuclei contain several dark staining areas called ___?

A

mucleoli

137
Q

What is the function of nucleoli?

A

synthesize ribosomal RNA, assemble ribosomal subunits

138
Q

The chemical “language” the cell uses is known as…

A

genetic code

139
Q

What is the functional unit of heredity?

A

a gene

140
Q

The nucleus contains what 4 things?

A

DNA, RNA, enzymes, proteins

141
Q

Each gene codes for a ____________

A

specific protein

142
Q

Each gene is located….

A

at a particular site on a specific chromosome

143
Q

What is the first step in the process of transcription?

A

RNA polymerase binds to the promoter

144
Q

the term “transcription” literally means….

A

“to copy” or “rewrite”

145
Q

Can DNA leave the nucleus?

A

NO

146
Q

Where in the cell does protein synthesis occur?

A

the cytoplasm

147
Q

What are the 2 strands called in DNA?

A

coding strand, template strand

148
Q

Before transcription can begin, what must happen to the DNA strand?

A

the 2 strands must be separated

149
Q

Does RNA polymerase attach uracil or thymine?

A

URACIL

150
Q

a 3 base mRNA sequence is called a…..

A

codon

151
Q

Which are spliced together in RNA PROCESSING - introns or exons?

A

exons. introns are snipped out.

152
Q

The amino acids are provided by ____ during the process of translation

A

tRNA

153
Q

tRNA carries a…

A

anticodon

154
Q

What is the first step in translation?

A

mRNA strand binds to a small ribosomal subunit

155
Q

Where does transcription occur?

A

the nucleus

156
Q

What is protein synthesis?

A

The assembling of functional polypeptides in the cytoplasm

157
Q

A series of ribosomes attached to the same mRNA strand is called a ….

A

polyribosome or polysome

158
Q

The nucleus has both ____ and _____ control over the cell

A

direct and indirect

159
Q

What is gene activation?

A

gene activation is the process of uncoiling the segment of DNA containing the gene and temporarily removing histones so that the gene can be expressed and affect cell function

160
Q

Transcription is the ____ of genetic _____ on a strand of ______

A

encoding of genetic instructions on a strand of mRNA

161
Q

What process would be affected by lack of the enzyme RNA polymerase?

A

This cell would not be able to transcribe RNA from DNA (transcription)

162
Q

What is permeability?

A

The property of the plasma membrane that determines precisely which substances can enter or leave the cytoplasm

163
Q

A membrane through which NOTHING can pass is said to be….

A

impermeable

164
Q

A membrane through which ANY substance can pass without difficulty is said to be….

A

freely permeable

165
Q

The plasma membrane of a cell is said to be….

A

selectively permeable

166
Q

Passage across the cell membrane is either _____ or ______

A

passive or active

167
Q

What are the 3 major categories of transport across the cell membrane?

A

diffusion, carrier-mediated transport, vesicular transport

168
Q

Is diffusion a passive or active process?

A

passive

169
Q

The difference between high and low concentration is called a..

A

concentration gradient

170
Q

What are 5 factors that influence diffusion rates?

A
  1. Size
  2. Distance
  3. Temperature
  4. Concentration gradient
  5. Electrical forces
171
Q

The larger the molecules size, the _____ the diffusion

A

slower

172
Q

The higher the temperature, the _____ the diffusion rate

A

faster

173
Q

The smaller the concentration gradient, the ______ the diffusion rate

A

slower

174
Q

Which substances can pass through the plasma membrane by SIMPLE DIFFUSION

A

nonpolar, uncharged molecules such as alcohol, fatty acids, and steroids

175
Q

What are membrane channels?

A

Very small passageways created by transmembrane proteins

176
Q

Can water molecules and other small ions enter/exit freely through membrane channels?

A

YES

177
Q

leak channels are also called..?

A

passive channels

178
Q

Can glucose fit through the membrane channels?

A

No - it’s too big

179
Q

What is the function of a leak/passive channel?

A

They remain open and allow the passage of ions across the plasma membrane

180
Q

The higher the solute concentration, the ____ the water concentration

A

lower

181
Q

Water molecules tend to flow across a membrane towards the solution with higher or lower solute concentration?

A

HIGHER- because the more solute there is, the less water. Water is simply moving down its concentration gradient

182
Q

What is osmosis?

A

The diffusion of water across a semi permeable membrane

183
Q

What is osmotic pressure?

A

Indication of the force with which water moves into a solution as a result of solute concentration

184
Q

How can osmosis be prevented?

A

Resisting the change in volume by applying HYDROSTATIC PRESSURE

185
Q

Why is there a higher water permeability than solute permeability across a membrane?

A

water molecules can cross a membrane through AQUAPORINS

186
Q

Water molecules can cross a membrane through which two things?

A

Solute channels and aquaporins

187
Q

Are there more solute channels or aquaporins?

A

Aquaporins

188
Q

What is another name for osmolarity?

A

osmotic concentration

189
Q

What is osmolarity?

A

The total solute concentration in an aqueous solution

190
Q

What does the term isotonic mean?

A

A solution that does not cause an osmotic flow of water into or out of a cell

191
Q

What is tonicity?

A

Description of how the solution affects a cell

192
Q

What will happen if a red blood cell is in a HYPOTONIC solution?

A

Water will flow into the cell, causing it to swell and burst

193
Q

What is the term for when a red blood cell swells and bursts?

A

hemolysis

194
Q

What will happen when a cell is placed in a HYPERTONIC solution?

A

The cell will lose water by osmosis, shrivel, and dehydrate

195
Q

What is the term for the shrinking of red blood cells?

A

crenation

196
Q

Why is saline (NaCl) used when giving patients large volumes of fluid to combat blood loss or dehydration?

A

sodium and chloride are the most abundant ions in extracellular fluid to little net movement across the membrane occurs. saline is ISOTONIC to body cells

197
Q

Does the crossing of water through the membrane require energy??

A

NO

198
Q

When is a solution said to be hypertonic?

A

When a cell is placed in solution with a HIGH solute concentration.

199
Q

When is a solution said to be HYPOTONIC?

A

When a cell is placed in a solution with a LOW solute concentration

200
Q

What would happen if we drank ocean water??

A

Sea water is very hypertonic. Water would rush out of our own body cells and our cells would lyse

201
Q

Diffusion proceeds until….

A

equilibrium is reached

202
Q

How would a decrease in the concentration of oxygen in the lungs affect the diffusion of oxygen into the blood?

A

Oxygen would diffuse much more slowly into the blood because the concentration gradient is lower

203
Q

Why is using a 10% salt solution as a nasal spray useful in relieving congestion?

A

the salt solution is hypertonic with respect to the cells lining the nasal cavity. water from the cells of the nasal cavity would rush out, causing the cell to shrink, relieving the congestion

204
Q

Is vesicular transport a passive or active process?

A

ALWAYS ACTIVE

205
Q

Is carrier mediated transport a passive or active process?

A

passive or active, depending on the substance transported and the nature of the transport mechanism

206
Q

Another word for cotransport

A

symport

207
Q

Another word for countertransport

A

antiport

208
Q

What are 2 examples of carrier-mediated transport?

A

-Facilitated diffusion
-Active transport

209
Q

Does facilitated diffusion require ATP?

A

no

210
Q

In facilitated diffusion, the molecule to be transported must first bind to….

A

the receptor site on the carrier protein

211
Q

All cells move glucose across there membrane through….

A

facilitated diffusion

212
Q

Does active transport require ATP?

A

YES

213
Q

Is active transport dependent on concentration gradient?

A

NO

214
Q

All cells contain carrier proteins called..?

A

ion pumps

215
Q

What is an EXCHANGE PUMP?

A

When more than one kind of ion is transported by a carrier protein in OPPOSITE DIRECTIONS

216
Q

What are the 2 principle cations in body fluids?

A

Sodium and potassium

217
Q

Sodium ion concentrations are high in ____ but low in ____

A

high in the extracellular fluids, but low in the cytoplasm

218
Q

Homeostasis within the cell depends on the ejection of sodium ions and the recapture of potassium ions. This exchange occurs by a…?

A

sodium-potassium exchange pump

219
Q

What phrase do you use to remember # sodium/potassium ions?

A

2 k in, 3 na out

220
Q

What is secondary active transport?

A

energy doesn’t come from ATP, but from a sodium ion gradient (or any substrate)that was produced by ATP

221
Q

Is the sodium potassium exchange pump an example of primary or secondary active transport? why?

A

primary active transport because the pump directly uses ATP to function

222
Q

Vesicular transport is known as ____transport. Why?

A

bulk. Tiny droplets of fluid and solutes are transported rather than single molecules

223
Q

What are the 2 major categories of vesicular transport?

A

endocytosis and exocytosis

224
Q

What are the 3 major types of endocytosis?

A
  1. Receptor-mediated endocytosis
  2. Pinocytosis
  3. Phagocytosis
225
Q

Endocytic vesicles are generally known as….

A

endosomes

226
Q

In receptor mediated endocytosis, what are the molecules called that bind to the receptors?

A

Ligands

227
Q

What are coated vesicles?

A

endosomes that are formed when receptors are covered with ligands and pinch off the plasma membrane

228
Q

coated vesicles fuse with _____ to form ____

A

primary lysosomes to form secondary lysosomes

229
Q

Which 2 important molecules enter the cell through receptor mediated endocytosis?

A

iron and cholesterol

230
Q

What is pinocytosis?

A

Formation of endosomes filled with extracellular fluid

231
Q

Are receptors and ligands involved in the process of pinocytosis?

A

NO

232
Q

In phagocytosis, material is brought into the cell enclosed in a _____

A

phagosome

233
Q

Phagocytosis is performed by what kind of cells?

A

macrophages

234
Q

Describe the process of carrier -mediated transport

A

Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane. They are specific, have saturation limits, and are regulated (by hormones)

235
Q

During digestion in the stomach, hydrogen ions rise to higher levels than in the cells lining the stomach. Which transport process must be operating?

A

Active transport process because energy must be used to transport something against its concentration gradient

236
Q

Describe endocytosis

A

The movement of relatively large volumes of extracellular material into the cytoplasm via the formation of a membranous vesicle

237
Q

Phagocytosis mainly moves which 2 things?

A

bacteria and debris

238
Q

Describe exocytosis

A

The ejection of cytoplasmic materials by the fusion of a membranous vesicle with the plasma membrane

239
Q

What is the process by which certain types of white blood cells engulf bacteria?

A

phagocytosis

240
Q

Does the inside of the plasma membrane have a slight positive or negative charge with respect to the outside?

A

slight negative charge

241
Q

What is transmembrane potential?

A

the potential difference across a plasma membrane

242
Q

What is potential difference?

A

When positive and negative charges are held apart

243
Q

What is the unit of measurement for potential difference?

A

millivolts

244
Q

If the plasma membrane were freely permeable to sodium ions, how would the transmembrane potential be affected?

A

the transmembrane potential would move closer to zero

245
Q

What is the genetically controlled death of cells?

A

apoptosis

246
Q

What is DNA replication?

A

the duplication of the cell’s genetic material

247
Q

When does DNA replication begin?

A

When enzymes (helicases) unwind the strands

248
Q

In what stage of the cell cycle does DNA replication occur?

A

interphase

249
Q

What is the function of the enzyme ligase in DNA replication?

A

splices segments of the lagging strand together

250
Q

DNA polymerase can oly build in which direction?

A

5’ - 3’

251
Q

How many stages of interphase are there and what are they?

A

3 - G1, S, G2

252
Q

In which phase of interphase does DNA replication occur?

A

S phase

253
Q

The completion of which process marks the end of cell division?

A

cytokinesis

254
Q

When does the cytokinesis process usually begin?

A

late anaphase

255
Q

What is the correct sequence of events during mitosis?

A

prophase, anaphase, metaphase, telophase

256
Q

How can the frequency of cell division be estimated?

A

by the number of cells in mitosis at any time

257
Q

What term is used to discuss the rates of cell division?

A

mitotic rate

258
Q

The longer the life expectancy, the _____ the mitotic rate

A

slower

259
Q

What is the only function of stem cells?

A

the production of daughter cells

260
Q

Do dividing cells use energy?

A

YES - unusually large amounts

261
Q

Describe interphase and identify its stages

A

interphase is the portion of a cell’s life cycle in which the chromosomes are uncoiled and all normal cell functions except MITOSIS are underway. G1,S,G2,G0
G0=not preparing for cell division

262
Q

A cell is actively manufacturing enough organelles to serve 2 functional cycles. This cell is probably in what phase of its life cycle?

A

G1

263
Q

What would happen if spindle fibers failed to form in a cell during mitosis?

A

the cell would not be able to separate the chromosomes into 2 sets. if cytokinesis occurred, the result would be 1 cell with 2 sets of chromosomes and 1 cell with none

264
Q

In which phase of mitosis is the nucleus disassembled?

A

metaphase

265
Q

In which phase of mitosis do nuclei start to form on either side of the cell?

A

telophase

266
Q

Where do the 3 checkpoints occur during the cell cycle?

A

G1, G2, M (during metaphase to ensure the chromosomes are lined up in the middle correctly)

267
Q

If a cell fails at any checkpoint and cannot repair itself, what happens to it?

A

apoptosis

268
Q

M-phase promoting factor is assembled from which 2 parts?

A

CDC2, cyclin

269
Q

What does MPF do?

A

promotes the process of cell division (mitosis)

270
Q

When will MPF appear in the cytoplasm and promote mitosis?

A

When cyclin levels are high

271
Q

When do cyclin lvels increase?

A

As the cell life cycle proceeds

272
Q

What can stimulate the division of specific types of cells?

A

various extracellular compounds, generally peptides

273
Q

What is the term for a group of proteins stimulating the the division of specific types of cells?

A

growth factors

274
Q

What are repressor genes?

A

Genes that inhibit cell division

275
Q

What is an important tumor suppressor protein?

A

p53

276
Q

What are the DNA-protein complexes that form caps at the end of chromosomes?

A

telomeres

277
Q

Define growth factor, and identify several growth factors that affect cell division

A

A growth factor is an extracellular compound such as a peptide or hormone that can stimulate the division of specific cell types.
ex: chalones, EGF, FGF, NGF

278
Q

What is another name for a tumor?

A

a neoplasm

279
Q

If a tumor is benign, the cells usually remain within…..

A

the epithelium or connective tissue capsule

280
Q

the tumor of origin is called the _______ and the spreading process is called _____

A

primary tumor, invasion

281
Q

What is metastasis?

A

The dispersion of malignant cells to other tissues and organs, establishing a secondary tumor

282
Q

When do normal cells become malignant?

A

When a mutation occurs in a gene involved in cell growth, differentiation, or division

283
Q

The modified, malignant genes are called…?

A

oncogens

284
Q

Do cancer cells use energy efficiently?

A

no - they grow and multiply at the expense of healthy tissues

285
Q

Define differentiation

A

Differentiation is the gradual appearance of characteristic cellular specializations during development. It results from gene activation or repression

286
Q

The process that transports solid objects such as bacteria into the cell is called…?

A

phagocytosis

287
Q

Plasma membranes are said to be…

A

SELECTIVELY permeable

288
Q

In a resting transmembrane potential, the inside of the cell is _____ and the cell exterior is ______

A

inside is slightly negative, exterior is slightly positive

289
Q

Our somatic nuclei contains ____PAIRS of chromosomes

A

23

290
Q

What is osmosis?

A

The movement of water across a membrane from an area of low solute concentration to an area of higher solute concentration

291
Q

The interphase of the cell life cycle is divided into:

A

G0, G1, S, G2

292
Q

List the 4 basic concepts that make up the modern day cell theory.

A
  1. cells are produced from the division of pre existing cells
  2. Cells are the building blocks of all plants and animals
  3. Cells are the smallest units that perform all vital physiological functions
  4. Each cell maintains homeostasis at the cellular level
293
Q

What are the 4 general functions of the plasma membrane?

A
  1. Physical isolation
  2. Regulation of exchange with the environment
  3. Sensitivity
  4. Structural support
294
Q

By what THREE major transport mechanisms do substances get into and out of cells?

A
  1. Diffusion
  2. Carrier-mediated transport
  3. Vesicular transport
295
Q

Diffusion is important in body fluids because it…..

A

eliminates local concentration gradients

296
Q

Microvilli are found…

A

in cells that are actively engaged in absorption

297
Q

The sodium-potassium exchange pump is composed of…..

A

a carrier protein located in the plasma membrane

298
Q

If a cell lacked ribosomes, it would not be able to—

A

synthesize proteins

299
Q

List the phases of the interphase stage and briefly describe what happens in each

A

G0: normal cell functions
G1: cell growth, duplication of organelles, protein synthesis
S: DNA replication and synthesis of histones
G2: protein synthesis

300
Q

What is cytokinesis?

A

Cytoplasmic movement that separates 2 daughter cells

301
Q

What is the role of cytokinesis in the cell cycle?

A

completes cell division

302
Q

In facilitated diffusion….

A

-energy is not required
-substances move in the direction of their concentration gradient
-at concentrations above a given level, rate of diffusion does not increase

303
Q

Solutions A and B are separated by a selectively permeable barrier. Over time, the level of fluid on side A increases. Which solution initially had the higher concentration of SOLUTE

A

A

304
Q

What is the benefit of having some of the organelles enclosed by a membrane similar to that of the plasma membrane

A

-the isolation allows them to make and store secretions, enzymes, or toxins that would otherwise adversely affect the cytoplasm
-increased efficiency of having specialized enzyme systems concentrated in one place
-

A&P Exam 1 (19 decks)

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