UNIT 2 - A 2.2 - Cell Structure Flashcards
(226 cards)
1
Q
What is cytology?
A
the branch of biology that studies all aspects of the cell
2
Q
how many micrometers are in a millimeter?
A
1000
3
Q
How many nanometers are in a millimeter?
A
1 000 000
4
Q
How many nanometers are in a micrometer?
A
1000
5
Q
what do microscopes need in order to observe cells and especially their subunits?
A
high magnification and resolution
6
Q
What is magnification ?
A
the increase in an object’s image size compared to its actual size
7
Q
What is resolution?
A
the minimal distance between two points/objects at which they can still be distinguished as two
8
Q
What happens when the resolution of a microscope increases?
A
the microscope will reveal greater detail
9
Q
How do light microscopes form an image?
A
they use light which passes through the specimens
10
Q
What are stains used for in a light microscope?
A
to improve the visibility of structures
11
Q
What do electron microscopes (EMs) use to create an image?
A
electrons passing through a specimen
12
Q
What is the order (from largest to smallest) of cells/subunits?
A
cells, bacteria, viruses, membranes, molecules
13
Q
What is the field of view/vision?
A
total area visible when looking through a microscope’s ocular/eyepiece
14
Q
What are the two general types of micrometers?
A
ocular and stage
15
Q
where is the graticule (ocular micrometer) located?
A
in the eyepiece
16
Q
How are the units on the graticule calibrated?
A
using a stage micrometer
17
Q
How can the size of the image being examined under a microscope be determined?
A
By comparing the units of the graticule to the know unit size of the stage micrometer
18
Q
What is the formula to calculate magnification?
A
measured size of image/actual size of specimen
19
Q
What benefits do electron microscopes have over light microscopes?
A
Because electrons have much shorter wave lengths, the EM has a 1000x greater resolving power than a light microscope and the ability to magnify objects over 500000x
20
Q
What are the two general types of EMs?
A
scanning electron microscope (SEM) and transmission electron microscope (TEM)
21
Q
How do SEMs work?
A
They use a beam of electrons to scan the surface of a specimen
22
Q
How do TEMs work?
A
They aim a beam of electrons through a very thin section of specimen which allows its inner structure to be viewed
23
Q
What are two techniques used when working with an EM?
A
freeze fracture and cryogenic electron microscopy
24
Q
What is freeze fracture?
A
The process of preparing a sample for observation with an EM, involves rapid freezing of specimen, then breaking the specimen apart
25
What is enabled with the use of cryogenic electron microscopy?
an image to be formed using computers showing the 3D framework of proteins involved with the function of a cell
26
What are some examples of how our knowledge has been enhanced using cryogenic electron microscopy?
virus composition and structure, cell membrane components and their arrangement, cellular protein synthesis, hereditary expression and regulation
27
What are the cons of electron microscopes?
They are expensive, require extensive training to operate, and require non-living specimens
28
What are two preparation techniques developed recently for the study of cells using light microscopy?
fluorescent stains and immunofluorescence
29
What are fluorescent stains?
substances/dyes that combine with specific cellular components
30
Why are fluorescent stains used?
They are accepted by certain parts of the specimen after being exposed to UV light and those parts start to fluoresce and assorted colours are produced, allowing for more detailed visibility
31
What does immunofluorescence allow?
greater visibility of living tissue
32
How does immunofluorescence work?
because it involves antibodies already combined with dyes, specific antibodies combined with unique coloured dyes recognize and combine with target molecules
33
What is the technique of immunofluorescence often used for?
Detecting viral proteins that have infected cells
34
What is the condenser on a light microscope?
Located between the stage and the light source, it has a lens that directs light rays from the light source through the specimen
35
What is a brightfield microscope?
it uses visible light so the specimen is viewed against a light background
36
What is a darkfield microscope?
An opaque lens is used in the condenser which blocks direct light, specimen is viewed against a dark background
37
What is a phase-contrast microscope?
A special condenser is used to show detailed images of a specimen without staining
38
What structures do all cells contain?
DNA as genetic material, cytoplasm composed of mainly water, plasma membrane composed of lipids surrounding the cytoplasm
39
What is a cell's means of storing and transferring information?
DNA
40
What allows the production of the exact proteins needed for passing distinctive characteristics from cell-cell and organism-organism?
The four different nucleotides making up DNA and their sequences as well as their ability to form big chains
41
What sort of role do enzymes serve in chemical reactions?
Controlling
42
What controls the production of enzymes?
DNA
43
Where is cytoplasm found?
WIthin the boudary of a cell
44
What is cytosol?
Matrix composed mainly of water which is located in cytoplasm
45
What does cytosol contain?
Everything necessary for a cell to conduct its day-to-day activities: includes different carbon compounds, ions and other inorganic molecules
46
Where do most chemical reactions within a cell take place?
Within the cytoplasm
47
What is the major component of the plasma membrane surrounding a cell?
two layers of lipids combined as a bilayer
48
What does the membrane of a cell control the interactions between?
a cell's contents and the exterior
49
What do membrane proteins provide?
identity properties to the cell
50
What is the diameter of most prokaryotic cells?
less than 1 micrometre
51
What are two examples of prokaryotic organisms?
bacteria and archaea
52
What are different factors differentiating prokaryotes?
nutritional requirements, sources of energy, chemical composition and morphology (shape)
53
What are the features of a prokaryotic cell?
cell wall, plasma membrane, flagella, pili, ribosomes, nucleoid
54
What does the cell wall of a prokaryotic cell do?
protects and maintains shape, keeps bacterial cell from rupturing when water pressure is greater inside than outside
55
What is the cell wall of a prokaryote made from?
peptidoglycan
56
What is peptidoglycan?
a carbohydrate-protein complex
57
What is the capsule on some prokaryotes?
and additional layer of a type of polysaccharide
58
What does the capsule do?
makes it possible for some bacteria to adhere to structures such as teeth, skin, and food
59
What is one major way to classify bacteria?
by their ability to retain a dye called crystal violet
60
What happens to the cell wall of a "Gram-positive" bacteria when it is exposed to crystal violet?
it takes a violet/blue appearance
61
What's the difference between "Gram-positive" and "Gram-negative" bacteria?
"Gram-negative" bacteria don't retain crystal violet and don't appear blue/violet when exposed to the dye
62
What are two examples of Gram-positive bacteria?
Bacillus and Staphylococcus
63
What are pili?
The hair-like growths on the outside of some bacteria cell walls
64
What are the functions of pili?
attatchment and sexual reproduction
65
What is the pili's function in sexual reproduction?
joining bacterial cells in preparation for the transfer of DNA from one cell to another
66
What does a prokaryote's flagella/flagellum do?
Allow a cell to move
67
Where is the flagellum anchored?
to the cell wall and plasma membrane
68
Why are there no specialized areas within the cytoplasm of a prokaryote?
Because there are no internal membranes
69
Where do all cellular processes within a prokaryotic cell occur?
Within the cytoplasm
70
What are the two subunits of making up ribosomes?
a protein and ribosomal RNA
71
What does the nucleoid region of a bacterial cell contain?
a single, long, continuous, circular thread of DNA (the bacterial chromosome)
72
Why are bacterial chromosomes described as naked loops?
Because the DNA of a prokaryotic cell is not associated with histones
73
What is the nucleoid region of a prokaryotic cell involved with?
cell control and reproduction
74
What are plasmids?
small, circular, DNA molecules contained in prokaryotes
75
Though it is not required under normal conditions, what can plasmids help a prokaryotic cell to do?
adapt to unusual circumstances
76
How do prokaryotic cells divide?
binary fission
77
What occurs during the process of binary fission?
the DNA is copied, resulting in two daughter chromosomes which become attached to different regions on the plasma membrane and the cell divides into two genetically identical daughter cells
78
What does binary fission include the use of specialized fibres for?
lengthening of the cell and the newly produced DNA dividing into parts
79
What do eukaryotic cells occur in?
organisms such as algae, protozoa, fungi, plants, and animals
80
What are organelles?
non-cellular structures that carry out specific functions
81
What do organelles allow for in eukaryotic cells which is not a characteristic of prokaryotic cells?
compartmentalization
82
What does compartmentalization do?
Enables different chemical reactions to be separated and allows chemicals for specific reactions to be isolated which results in increased efficiency
83
When is compartmentalization especially important?
When adjacent chemical reactions are incompatible
84
Where does cytoplasm occur?
inside the plasma membrane and outside the nucleus of all eukaryotic cells
85
What is the fluid portion of the cytoplasm around the organelles called?
Cytosol
86
What is a cytoskeleton?
small fibres and rods within eukaryotic cytoplasm
87
What does the cytoskeleton create?
A complex internal structure
88
What is the difference between eukaryotic and prokaryotic cytoplasm?
Prokaryotic cytoplasm does not have a cytoskeleton
89
What is the cytoskeleton made of?
protein
90
What are the functions of the cytoskeleton?
maintaining cell shape, anchoring some organelles, helping cellular movements, providing a means for some organelles to move within the cell
91
Which fibres do cytoskeletons contain?
actin filaments, intermediate filaments, and microtubules
92
How can a eukaryotic cell respond to changes in both internal and external environments?
The fibres of the cytoskeleton can rearrange their protein components
93
What are actin filaments also called?
microfilaments
94
What do microfilaments function in?
cell division and cell movement, especially involving contractions in muscle cells
95
What do intermediate filaments do?
reinforce cell shape, anchor some organelles and function as movement paths throught the cell for some organelles
96
Where are intermediate filaments found?
Most animal cells
97
What is the endoplasmic reticulum?
a network of tubulus/channels extending from the nucleus to the plasma membrane
98
What is the function of the endoplasmic reticulum?
To transport materials throughout the inside of the cell
99
What is the main difference between smooth ER and rough ER?
smooth ER does not have any ribosomes on its surface, rough ER does
100
What are the functions of smooth ER?
production of membrane phospholipids and cellular lipids, production of sex hormones, detoxification of drugs in the liver, storage of calcium ions in muscle cells, transportation of lipid-based compounds, helping the liver to release glucose into the bloodstream when needed
101
What does the rough ER engage in?
Protein development and transportation
102
What may the proteins synthesized on the rough ER become?
Parts of the membrane, enzymes, or messengers between cells
103
Which type of ER is closer to the nuclear membrane?
rough ER
104
Where may ribosomes be found?
Free within the cytoplasm or attached to the rough ER
105
What are ribosomes always composed of?
a type of RNA and protein
106
What do the two subunits of ribosomes in prokaryotic cells equal?
70S
107
What do the two subunits of ribosomes in eukaryotic cells equal?
80S
108
What are lysosomes?
intracellular digestive centres which are vesicles (sacs)
109
What are lysosomes bounded by?
a single membrane that contains as many as 40 different enzymes
110
Why do lysosomes fuse with old/damaged organelles?
to break them down so that recycling of the components may occur
111
What is phagocytosis?
a type of endocytosis, a means by which material can enter a cell
112
Why is the interior environment of a functioning lysosome acidic?
Because acidic conditions are necessary for enzymes to hydrolyse large molecules
113
What does the golgi apparatus consist of?
flattened sacs called cisternae, which are stacked one on top of another
114
What does the golgi apparatus function in?
collection, packaging, modification, and distribution of materials synthesized in the cell
115
Where is the cis side of the golgi apparatus?
The side close to the rough ER
116
What does the cis side of the golgi apparatus receive?
products from the rough ER
117
Where do the products received from the ER to the cis side of the golgi apparatus go?
into the cisternae of the golgi apparatus
118
Which side of the golgi apparatus is the discharging side/opposite of the cis side?
the trans side
119
What happens after the products from the ER move through the cisternae and to the trans side of the golgi apparatus?
vesicles can be seen coming out of the trans side
120
What is one example of a vesicle produced by the golgi apparatus?
lysosomes
121
What do vesicles carry?
modified materials wherever they are needed inside or outside the cell
122
Where are golgi apparatuses found in particular?
in glandular cells such as those in the pancreas
123
What allows mitochondria to have some of their own independence within the cell?
they have their own DNA
124
What are the two membranes of mitochondria like?
the outer membrane is smooth while the inner membrane is folded into cristae
125
What is found inside the inner membrane of mitochondria?
a semi-fluid substance called the matrix
126
What lies between the two membranes of mitochondria?
the inner membrane space
127
What does the cristae of a mitochondrion provide?
a large surface area within which the chemical reactions of the mitochondrion occur
128
What do most mitochondrial reactions involve the production of?
adenosine triphosphate (ATP)
129
What type of ribosomes are produced and contained within mitochondria?
70S ribosomes
130
Which types of cells have large numbers of mitochondria?
Cells that have high energy requirements like muscle cells
131
What is the nucleus of eukaryotic cells?
an isolated region where DNA resides
132
What is the nuclear envelope?
a double membrane bordering the nucleus
133
Why is it important that the nuclear envelope allows compartmentalization of the eukaryotic DNA?
Because it provides an area where DNA can conduct its functions without being affected by processes occurring in other parts of the cell
134
Why does the nuclear membrane not result in complete isolation?
Because it has pores allowing for communication with the cell's cytoplasm
135
What does the DNA of eukaryotic cells occur in the form of?
chromosomes
136
What do chromosomes carry allowing an organism to survive?
all the information necessary for the cell to exist
137
When is the cell's DNA in the form of chromatin?
during the phase when the cell is not in the process of dividing and the chromosomes are not visible structures
138
What is chromatin formed of?
stands of DNA and histones
139
What structures are the result of the combination of DNA and histones?
nucleosomes
140
What do nucleosomes consist of?
a strand of DNA wrapped around 8 histones, with a ninth securing the structure
141
What is a chromosome?
a highly coiled structure of many nucleosomes
142
What can't cells do without a nucleus?
reproduce
143
What would a cell that cannot reproduce likely have?
increased specialization to carry out certain functions
144
What is an example of a type of cell that does not have nuclei?
human red blood cells
145
What are nucleoli?
dark areas included in nuclei
146
What type of molecule are manufactured in nucleoli?
ribosome molecules
147
What do ribosome molecules do before assembling as ribosomes?
they pass through the nuclear envelope
148
Where do chloroplasts occur?
only in algae and plant cells
149
How are chloroplasts similar to mitochondria?
They contain their own DNA and 70S ribosomes
150
Other than DNA and ribosomes, what do chloroplasts have within their interior?
grana, thylakoids and the stroma
151
What is a granum made up of?
numerous thylakoids stacked like a pile of coins
152
What are thylakoids?
flattened membrane sacs with the components necessary for the absorption of light
153
What is the first step of photosynthesis?
the absorption of light
154
What is photosynthesis?
a process that converts light energy into chemical energy
155
What is the stroma compared to?
they cytoplasm of the cell
156
Where does stroma occur?
outside the grana but within the double membrane
157
How is reproduction similar between chloroplasts and mitochondria?
they can reproduce independently of the cell
158
Where does centrosome occur?
in all eukaryotic cells
159
What does a centrosome in an animal cells consist of?
A pair of centrioles, often at right angles to one another
160
What are centrioles involved in the assembly of?
microtubules
161
Why are microtubules important to a cell?
Because they provide structure, allow movement and they are important for cell division
162
Which cells do not have centrioles?
plant and fungal cells
163
Why may centrioles not be necessary for the production of microtubules?
Because plants and fungal cells still produce microtubules from their centrosome-like regions
164
Where are centrosomes located?
at one end of the cell close to the nucleus
165
What are basal bodies?
structures related to the centrosome of eukaryotic cells
166
Why don't all eukaryotic cells have basal bodies?
Because basal bodies are located at the base of cilia and flagella and not all eukaryotic cells have cilia or flagella
167
What are basal bodies thought to direct the assembly of?
microtubules within the associated cilia or flagella
168
What appears to produce basal bodies when present?
centrioles
169
What are vacuoles?
storage organelles
170
What are vacuoles usually formed from?
the golgi apparatus
171
What are some examples of substances stored within vacuoles?
potential food, metabolic waste, toxins and water
172
What does the vacuole in plant cells allow which provides rigidity to the organism?
an uptake of water
173
What is a central vacuole?
The large singular vacuole in plants
174
What are the main similarities between prokaryotic and eukaryotic cells?
both have some outside boundary which always involves a plasma membrane, both conduct all the functions of life, DNA is present in both
175
What are the functions of life?
metabolism, growth, reproduction, response to stimuli, homeostasis, nutrition, excretion, and movement
176
What is metabolism?
sum of all chemical reactions occuring within an organism
177
What is nutrition?
The ability to acquire the energy necessary to maintain life
178
What is growth?
Development of an organism
179
What is reproduction?
Ability to reproduce offspring
180
What is response to stimuli?
the organism adapts as the environment changes
181
What is homeostasis?
maintenance of a constant internal environment
182
What is excretion?
the ability to release materials not needed/harmful into surrounding environment
183
What is movement?
ability to change position
184
How do unicellular organisms maintaine homeostasis?
The cell membrane controls movement of materials in and out of cell
185
How do unicellular organims conduct excretion?
vacuoles isolate and store waste
186
What allows unicellular organisms to move in response to changes in the environment?
cilia and flagella
187
What allows for nutrition in unicellular organisms?
Vacuoles carry out digestion
188
What allows energy production in unicellular organisms?
mitochondria or areas of enzymes
189
What provides the building blocks for growth and repair?
ribosomes
190
What allows multicellular organisms to carry out the functions of life compared to unicellular organisms?
They have organs carrying out all the functions of life
191
What are the three types of organisms with eukaryotic cells?
plants, animals, and fungi
192
What are believed to be the first eukaryotes to live on land?
Fungi
193
How do the three eukaryotic organisms differ in terms of cell wall?
plants= cellulose cell wall
animals= no cell wall
fungi= chitin cell wall
194
How do the three eukaryotic organisms differ in terms of chloroplasts?
plants= present
animals= not present
fungi= not present
195
How do the three eukaryotic organisms differ in terms of vacuoles?
plants= one large vacuole
animals= small and numerous
fungi= small and numerous
196
How do the three eukaryotic organisms differ in terms of their storage of carbohydrates?
plants= stored as starch
animals= stored as glycogen
fungi= stored as glycogen
197
How do the three eukaryotic organisms differ in terms of cilia and flagella?
plants= usually not present
animals= may be present
fungi= may be present
198
How do the three eukaryotic organisms differ in terms of shape?
plants= fixed, angular shape
animals= rounded shape
fungi= varying shape
199
How do the three eukaryotic organisms differ in terms of centrosomes and centrioles?
plants= centrosomes present but not centrioles
animals= both present
fungi= centrosomes present but not centrioles
200
What allows some eukaryotic cells carry out special functions?
a unique/atypical structure
201
What is hyphae?
filaments produced by fungi
202
What does most hyphae consist of?
chains sperated by cross-walls that have pores allowing various organelles and cytoplasm to flow from cell to cell
203
What is the result of hyphae that do not have cross-walls?
a single mass of cytoplasm (one cell) with more than one nucleus
204
What does phloem sieve tube elements' specialized functions allow for?
transportation within a multicellular plant
205
What is minimal in the cells of phoem slieve tube?
nuclei, ribosomes, cytoskeleton, and cytoplasm
206
What is needed for ploem sieve tube cells to stay alive?
companion cells
207
What do red blood cells contain a lot of which combines easily with oxygen?
haemoglobin
208
What does the shape of red blood cells have a large surface area?
for the absorption and release of oxygen
209
Why don't red blood cells have a nucleus?
because it allows them to carry more oxygen
210
How can skeletal muscle have the specialized function of body movement?
It has specialized proteins arranged in bands that contract and relax
211
What allows skeletal muscle to have more coordinated protein molecules?
There is limited cell membrane, so the shape is large and tubular and the cells also have multiple nuclei
212
What does the long and thin structure, along with branched connections allow nerve cells to do?
transmit electrical impulses
213
What are the specializations of sperm cells?
many mitochondria, tail allowing for movement, head with a tip producing an enzyme allowing for egg penetration
214
What specializations do the cells in the lungs have to help move mucus and other particles up and out of the airways?
they have cilia (little hairs) which work in unison
215
What are the key points of the endosymbiotic theory?
1. 2 billion years ago, large cell with nucleus and able to sexually reproduce engulfed small prokaryote that could produce energy
2. a mutual beneficial (symbiotic) relationship developed forming one organism
3. smaller cell went through changes to become a mitochondrion
216
How did the larger cell help the bacteria prokaryote in the endosymbiotic theory?
it provided protection and carbon compounds
217
How did the smaller cell end up helping the larger cell (after changes) in the endosymbiotic theory?
It provided ATP
218
What evicence supports the endosymbiotic theory involving mitochondria compared to bacteria?
roughly same size, and divide by binary fission
219
What evidence supports the endosymbiotic theory involving mitochondria compared to prokaryotes?
they have their own 70S ribosomes, they have their own DNA which occurs in aw circular ring, inner membrane composition is similar, and RNA present in mitochondrial ribosomes resembles to prokaryote ribosomes
220
What evidence supports the endosymbiotic theory with mitochondria by itself?
they divide independently of host cell, they produce their own proteins with their 70S ribosomes, and they have two membranes consistant with engulfing process
221
Other than mitochondria, which organelle also provides evidence to the endosymbiotic theory?
chloroplasts
222
Other then endosymbiosis, what other process helped the development of the cell?
compartmentalization
223
What does compartmentalization result in?
specializations within the cell
224
How is the nucleus an example of compartmentalization?
it has a protective membrane which enables DNA molecules to function without interference from other reactions in the cytoplasm
225
How is the mitochondrion an example of compartmentalization?
it produces the energy necessary for the cell to carry out the functions of life
226
What alters gene expression in the cells of multicellular organisms?
differing environments
