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BIOL 3011 > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

What year were microscopes invented?

A

1590 and further refined during the 1600s

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2
Q

Cell walls were first seen by…

A

Robert Hook in 1665
-They were from the bark of an oak tree

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3
Q

Light Microscope (LM)

A

In a LM, visible light is passed through the specimen and then through glass lenses.

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4
Q

Three important parameters in microscopy:

A

Magnification
Resolution
Contrast

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5
Q

Magnification

A

Is the ratio of an object’s image size to its real size.

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6
Q

Light microscopes can magnify effectively to about _____ times the actual size of the specimen

A

1,000

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7
Q

Resolution

A

-Is a measure of the clarity of the image
- It is the minimum distance two points can be separated and still be distinguished as separate points.

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8
Q

The light microscope cannot resolve detail finer than about _____________ or ___________

A

0.2 micrometer, 200 nanometers

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9
Q

Contrast

A

Is the difference in brightness between the light and dark areas of an image.

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10
Q

Methods for enhancing contrast

A

Staining or labeling cell components to stand out visually.

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11
Q

Organelles

A

The membrane-enclosed structures within eukaryotic cells.

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12
Q

When was the electron microscope introduced to biology?

A

1950s

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13
Q

Electron microscope (EM)

A

The EM focuses a beam of electrons through the specimen or onto its surface.

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14
Q

Resolution is inversely related to…

A

The wavelength of the light (or electrons) a microscope uses for imaging.

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15
Q

Electron beams have much shorter wave lengths than visible light.

A

True

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16
Q

Modern electron microscopes can theoretically achieve a resolution of about _____

A

0.002 nm (nanometers)

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17
Q

The scanning electron microscope (SEM) is especially useful for…

A

Detailed study of the topography of a specimen.

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18
Q

How does a SEM work?

A

-The electron beam scans the surface of the sample, usually coated with a thin film of gold.
- The beam excites the electrons on the surface.
- The patterns of electrons are translated into an electronic signal sent to a video screen
- An image of the specimen’s surface appears in 3-dimensions.

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19
Q

The transmission electron microscope (TEM) is used to…

A

Study the internal structure of cells.

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20
Q

How does a TEM work?

A

-The specimen is stained with heavy metals, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cell.
- The electron beam is scattered in the denser regions.
- The image displays the pattern of transmitted electrons.

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21
Q

Instead of using glass lenses, the SEM and TEM use…

A

Electromagnets

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22
Q

Disadvantage of electron microscopy

A

The methods used to prepare the specimen kill the cells.

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23
Q

Super-resolution microscopy

A

Technique that allows LM to break the limit of resolution.

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24
Q

Cytology

A

The study of cell structure.

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25
Q

Biochemistry

A

The study of chemical processes (metabolism) of cells.

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26
Q

Cell fractionation

A

Takes cells apart and separates major organelles and other subcellular structures from one another.

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27
Q

Centrifuge

A

-Used for cell fractionation
-Spins test tubes holding mixtures of cells at a series of increasing speeds.

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28
Q

A pellet

A

Subset of cell components at the bottom of the tube in a centrifuge.

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29
Q

At lower speeds, the pellet consists of …

A

Larger components

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30
Q

At higher speeds, the pellet consists of …

A

Smaller components

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31
Q

All cells share certain basic features:

A

-Are all bounded by a selective barrier, the plasma membrane
-Inside all cells is a semifluid substance, the cytosol
-All contain chromosomes
-All have ribosomes

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32
Q

Where is the DNA of a eukaryotic cell?

A

In the nucleus.

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33
Q

Where is the DNA of a prokaryotic cell?

A

In a region called the nucleoid.

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34
Q

Cytoplasm in eukaryotic cells

A

The region between the nucleus and the plasma membrane.
-Is suspended in cytosol

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35
Q

Mycoplasmas

A

Bacteria with diameters between 0.1 and 1.0 micrometers

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36
Q

Eukaryotic cells are typically _____________ in diameter.

A

10-100 micrometers

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37
Q

Prokaryotic cytoplasm appears to be organized into different regions.

A

True

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38
Q

Plasma membrane

A

Functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell.

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39
Q

Why is the ratio of surface area to volume critical?

A

Because for each square micrometer of membrane, only a limited amount of a particular substance can cross per second.

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40
Q

As a cell increases in size,…

A

It’s surface area grows proportionately less than its volume.

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41
Q

A smaller object has a greater ratio of surface area to volume.

A

True

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42
Q

Total surface area =

A

Sum of the surface areas of all box sides X number of boxes

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43
Q

Surface area =

A

Height X Width

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44
Q

Total volume =

A

Height X Width X Length X Number of boxes

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45
Q

Microvilli

A

Projections that increase surface area without an appreciable increase in volume.

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46
Q

Nucleus

A

Contains most of the genes in the eukaryotic cell.

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47
Q

Average diameter of a nucleus

A

About 5 micrometers

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48
Q

Nuclear envelope

A

Encloses the nucleus, separating its contents from the cytoplasm.

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49
Q

The nuclear envelope is a double membrane

A

True

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50
Q

The two membranes of a nuclear envelope are separated by a space of…

A

20-40 nm (nanometers)

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51
Q

Pore structures in the nuclear envelope have a diameter of…

A

100 nm

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52
Q

Pore complex

A

A protein structure that lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNAs, as well as large complexes of macromolecules.

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53
Q

Nuclear lamina

A

A netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
(Does not affect pores)

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54
Q

Nuclear matrix

A

A framework of protein fibers extending throughout the nuclear interior.

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55
Q

Chromatin

A

The complex of DNA and proteins making up chromosomes.

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56
Q

Nucleolus

A

A prominent structure within the non dividing nucleus.

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57
Q

Where is ribosomal RNA (rRNA) synthesized?

A

In the nucleolus from instruction in the DNA.

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58
Q

How are ribosomes formed?

A

In the nucleolus, proteins imported from the cytoplasm are assembled with rRNA into a large and a small subunit of ribosomes.
- The large and small subunits layer assemble into a ribosome after they exit through the nuclear pores to the cytoplasm.

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59
Q

Ribosomes

A

Are the cellular complexes that carry out protein synthesis.
-Not membrane bound, thus not considered organelles.

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60
Q

Free ribosomes

A

Are suspended in the cytosol.

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61
Q

Bound ribosomes

A

Are attached to the outside of the endoplasmic reticulum or nuclear envelope.

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62
Q

Ribosomes can alternate between free and bound

A

True

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63
Q

Bound ribosomes generally make proteins that are destined for…

A

Insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell (secretion).

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64
Q

Endomembrane system includes:

A

Nuclear Envelope
Endoplasmic Reticulum
Golgi apparatus
Lysosomes
Various kinds of vesicles and vacuoles
Plasma membrane

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65
Q

Endomembrane system functions

A

Synthesis of proteins
Transport of proteins
Metabolism and movement of lipids
Detoxification of poisons

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66
Q

Vesicles

A

Sacs made of membrane

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67
Q

How are the organelles in the Endomembrane system related?

A

Through direct physical continuity or by the transfer of membrane segments as tiny vesicles.

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68
Q

The endoplasmic reticulum is such an extensive network of membranes that it accounts for more than half the total membranes in many eukaryotic cells.

A

True

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69
Q

Cisternae

A

A network of membranous tubules and sacs.

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70
Q

ER Lumen / cisternal space

A

The internal compartment of the ER
-Is separated from the cytosol

71
Q

Two regions of the ER

A

Smooth ER
Rough ER

72
Q

Smooth ER is so named because…

A

Its outer surface lacks ribosomes.

73
Q

Rough ER is so named because…

A

It is studded with ribosomes on the outer surface of the membrane and thus appears rough through the electron microscope.

74
Q

Functions of smooth ER

A

Synthesis of lipids
Metabolism of carbohydrates
Detoxification of drugs and poisons
Storage of calcium ions

75
Q

Steroids produced by smooth ER

A

Sex hormones
Steroid hormones secreted by the adrenal glands

76
Q

Detoxification usually involves…

A

Adding hydroxyl groups to drug molecules, making them more soluble and easier to flush from the body.

77
Q

Smooth ER helps detoxify drugs and poisons, especially in…

A

Liver cells

78
Q

Smooth ER stores calcium, particularly in what cells?

A

Muscle cells

79
Q

Glycoproteins

A

Proteins with carbohydrates covalently bonded to them.
-Secretory proteins

80
Q

How are glycoproteins made?

A

Polypeptide chain is threaded into the ER lumen.

81
Q

Secretory proteins are separated from proteins that will remain in the cytosol by the ER membrane.

A

True

82
Q

Secretory proteins depart from the ER wrapped the membranes of _________ from a specialized region called _______

A

vesicles, transitional ER

83
Q

Transport vesicles

A

Vesicles in transit from one part of the cell to another.

84
Q

In addition to making secretory proteins, rough ER is a membrane factory for the cell.

A

True

85
Q

After leaving the ER, many transport vesicles travel to the _______

A

Golgi apparatus

86
Q

What happens in the Golgi apparatus?

A

Products of the ER, such as proteins, are modified and stored and then sent to other destinations.

87
Q

The Golgi apparatus consists of…

A

Cisternae

88
Q

Vesicles in the vicinity of the Golgi apparatus are enhanced in…

A

The transfer of material between parts of the Golgi and other structures.

89
Q

The two sides of a Golgi stack

A

Cis face “on the same side”
Trans face “on the opposite side”

90
Q

The cis face is usually located

A

Near the ER

91
Q

The trans face gives rise to…

A

Vesicles that pinch off and travel to other sites.

92
Q

Products of the ER are usually modified during their transit from the ________ to the _______ of the Golgi apparatus.

A

cis region, trans region

93
Q

Golgi apparatus also manufactures some macromolecules

A

True

94
Q

What does the cisternal maturation model state about the Golgi apparatus?

A

The cisternae of the Golgi actually progress forward from the cis to the trans face, carrying and modifying their cargo as they move.

95
Q

A Golgi stack dispatches its products by budding vesicles from the trans face. Before this, it sorts these products and targets them for various parts of the cell using ________

A

Molecular identification tags, such as phosphate groups

96
Q

Lysosome

A

Is a membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules.

97
Q

Lysosomal enzymes work best in…

A

The acidic environment found in lysosomes.

98
Q

Phagocytosis

A

A type of endocytosis in which large substances or small organisms are taken up by a cell.

99
Q

How is a food vacuole made?

A

Through phagocytosis.

100
Q

How does a food vacuole digest food?

A

The food vacuole fuses with a lysosome, whose enzymes digest the food.

101
Q

Autophagy

A

A process where lysosomes use their hydrolytic enzymes to recycle the cell’s own organic material.

102
Q

Vacuoles

A

Are large vesicles derived form the endoplasmic reticulum and Golgi apparatus.

103
Q

Types of vacuoles

A

Food vacuoles
Contractile vacuoles
Central vacuole

104
Q

Contractile vacuole

A

Pumps excess water out of the cell.

105
Q

How does a central vacuole develop?

A

By the coalescence of smaller vacuoles.

106
Q

Cell sap

A

Solution inside the central vacuole

107
Q

Mitochondria

A

Are the sites of cellular respiration, the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels.

108
Q

Chloroplasts

A

Are the sites of photosynthesis. The process that converts solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from carbon dioxide and water.

109
Q

Endosymbiont

A

A cell living within another cell.

110
Q

Endosymbiont theory

A

This theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell. Eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an endosymbiont.

111
Q

Cristae

A

Foldings in the inner membrane of the mitochondria.

112
Q

Each of the two membranes enclosing a mitochondrion is a _________

A

Phospholipid bilayer

113
Q

Intermembrane space

A

The narrow region between the inner and outer membrane

114
Q

The inner membrane divides the mitochondrion into two internal compartments:

A

Intermembrane space
Mitochondrial matrix

115
Q

Mitochondrial matrix

A

Is enclosed by the inner membrane. Contains many different enzymes as well as the mitochondrial DNA and ribosomes.

116
Q

How long is a mitochondrion?

A

1-10 micrometers long

117
Q

Mitochondria in a living cell form a branched tubular network

A

True

118
Q

Length of chloroplast

A

3-6 micrometers

119
Q

Thylakoids

A

Membranous system in the form of flattened, interconnected sacs

120
Q

Granum (plural grana)

A

Stack of thylakoids

121
Q

Stroma

A

Fluid outside the thylakoids. Contains the chloroplast DNA and ribosomes as well as many enzymes.

122
Q

The membranes of the chloroplast divide the chloroplast space into three compartments:

A

The Intermembrane space
The stroma
The thylakoid space

123
Q

The chloroplast is a specialized member of a family of closely related plant organelles called______

A

Plastids

124
Q

Examples of plastids

A

Chloroplast
Amyloplast
Chromoplast

125
Q

Peroxisome

A

Is a specialized metabolic compartment bounded by a single membrane.

126
Q

What does a peroxisome do?

A

Peroxisomes contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen (O2), producing hydrogen peroxide (H2O2) as a by-product (from which the organelle derives its name).

127
Q

Functions of peroxisomes

A

Break down fatty acids
Detoxify alcohol / other harmful compounds

128
Q

Glyoxysomes

A

Specialized peroxisomes found in fat-storing tissues of plant seeds

129
Q

Cytoskeleton

A

A network of fibers extending throughout the cytoplasm.

130
Q

The eukaryotic cytoskeleton is composed of three types of molecular structures:

A

Microtubules
Microfilaments
Intermediate filaments

131
Q

Primary function of the cytoskeleton

A

Give mechanical support to the cell and maintain its shape.

132
Q

The cytoskeleton can be quickly dismantled in one part of the cell and reassembled in a new location, changing the shape of the cell

A

True

133
Q

All eukaryotic cells have microtubules

A

True

134
Q

Microtubules

A

Hollow rods constructed from a globular protein called tubilin.

135
Q

What is a dimer?

A

A molecule made up of two subunits.

136
Q

Microtubules grow in length by adding ______

A

Tubulin dimers

137
Q

Two types of tubulin dimers

A

Alpha tubulin
Beta tubulin

138
Q

The two ends of a microtubule are slightly different

A

True

139
Q

“Plus end”

A

The end of the microtubule that can accumulate or release tubulin dimers rapidly

140
Q

Function of microtubules

A

Shape and support the cell
-Serve as tracts where organelles with motor proteins can move
-Guide vesicles from the ER to the Golgi apparatus
-Involved in cell division

141
Q

Centrosomes

A

The region where Microtubules grow out of in animal cells.
-Located near the nucleus

142
Q

Centrioles

A

Within the centrosome is a pair of centrioles, each composed of nine sets of triplet microtubules arranged in a ring.

143
Q

Primary cilium

A

Cilium that act as a signal-receiving “antenna” for the cell.

144
Q

Specialized arrangement of Microtubules responsible for movement (beating)

A

Flagella
Cilia

145
Q

Common structure between motile cilia and flagella

A

The “9+2” pattern
Nine doublets of microtubules are arranged in a ring, with two single microtubules in its center.

146
Q

Nonmotile primary cilia have a “9+0” pattern

A

True

147
Q

The microtubule assembly of a cilium or flagellum is anchored in the cell by a _________

A

Basal body

148
Q

The basal body is structurally very similar to a centriole

A

True

149
Q

Bending involves large motor proteins called _________

A

Dyneins

150
Q

Microfilaments

A

Are thin solid rods. Is a twisted double chain of actin subunits.
AKA actin filaments.
-Present in all eukaryotic cells.

151
Q

Structural role of microfilaments

A

To bear tension (pulling forces).

152
Q

Cortex

A

The outer cytoplasmic layer of a cell.

153
Q

Cortical microfilaments

A

Helps support the cell’s shape and gives the cortex the semisolid consistency of a gel.

154
Q

The cell crawls along a surface by extending cellular extensions called _________

A

Pseudopodia

155
Q

Cytoplasmic streaming

A

A circular flow of cytoplasm within cells.

156
Q

Intermediate filaments are named for their…

A

Diameter, which is larger than the diameter of Microfilaments but smaller than that of microtubules.

157
Q

Intermediate filaments are only found in the cells of some animals, including vertebrates.

A

True

158
Q

Intermediate filaments are specialized for…

A

Bearing tension (like Microfilaments)

159
Q

Even after cells die, intermediate filament networks often persist.

A

True

160
Q

Cell wall

A

Protects the plant cell, maintains its shape, and prevents excessive uptake of water.

161
Q

Plant cell wall thickness

A

0.1 micrometers to several micrometers

162
Q

Structure of cell wall

A

Microfibrils made of cellulose embedded in a matrix of other polysaccharides and proteins.

163
Q

Primary cell wall

A

A relatively thin and flexible wall. Secreted by young plant cells.

164
Q

Middle lamella

A

A thin layer rich in sticky polysaccharides called pectins. The middle lamella glues adjacent cells together.

165
Q

Secondary cell wall

A

A wall between the plasma membrane and the primary wall.
-Offers protection and support to the cell.

166
Q

Ingredients of an animal cell’s extracellular matrix (ECM)

A

Glycoproteins and other carbohydrate-containing molecules secreted by the cells.

167
Q

Most abundant glycoprotein in the ECM

A

Collagen, which forms strong fibers outside the cells.

168
Q

Proteoglycans

A

A proteoglycan molecule consists of a small core protein with many carbohydrate chains covalently attached, so that it may be up to 95% carbohydrate.

169
Q

Integrins

A

Are cell-surface receptor proteins that are built into the plasma membrane

170
Q

Plasmodesmata

A

Channels that connect cells.

171
Q

Three main types of cell junctions

A

Tight junctions
Desmosomes
Gap junctions

172
Q

Tight junctions

A

Establish a barrier that prevents leakage of extracellular fluid across a layer of epithelial cells.

173
Q

Desmosomes

A

Fasten cells together into strong sheets. For example, some “muscle tears” involve the rupture of Desmosomes.

174
Q

Gap junctions (communicating junctions)

A

Provide cytoplasmic channels from one cell to an adjacent cell.

BIOL 3011 (15 decks)

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