Cellular Life Flashcards
(252 cards)
1
Q
What are biomolecules?
A
Chemicals made inside a living thing that is involved in the maintenance and metabolic processes of living organisms
2
Q
What element do all biomolecules contain?
A
Carbon
3
Q
What are the four major types of biomolecules?
A
Carbohydrates.
Lipids.
Proteins.
Nucleic acids.
4
Q
List two nucleic acids
A
DNA and RNA
5
Q
What are nucleic acids?
A
Long polymers made of repeating units of nucleotides
6
Q
What are the main functions of nucleic acids?
A
To store and transfer genetic information
To use the genetic information to synthesize new protein
RNA such as m-RNA takes genetic message from RNA
7
Q
Why are proteins important on a cellular level?
A
(Products of genes)
- Catalysts to promote replication (Enzymes)
8
Q
Why are lipids important on a cellular level?
A
Give structure
9
Q
Why are carbohydrates important on a cellular level?
A
Provide energy for growth & replication
10
Q
What are the Properties of Life
A
Order/Organization Adaptation Responsiveness Reproduction & Heredity Growth Obtain/Use Energy Control/Regulation
11
Q
What are the molecular processes which aid the common features of living organisms
A
Metabolism
Replication
12
Q
What is metabolism?
A
The total sum of all chemical reactions in the body – the balance of anabolism and catabolism
13
Q
What is the purpose of metabolism?
A
Converts the fuel in the food we eat into the energy needed to power everything we do, from moving to thinking to growing.
It maintains the living state of the cells and the organism
14
Q
What is replication?
A
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance.
15
Q
What is the purpose/significance of DNA replication?
A
If DNA never replicated, meiosis and mitosis would slowly halve the size of the genome until each cell would die.Therefore, it is important that DNA doubles itself to account for the cells splitting during mitosis/meiosis.
16
Q
What is life?
A
The capacity for growth and self-replication
17
Q
What are the processes which allow growth?
A
Metabolism
Maintainance of order
Response to stimuli
18
Q
What is the process which allows for self-replication?
A
Inheritence of genetic material
19
Q
What biomolecules are involved in the growth of an organism
A
Proteins
Carbohydrates
Lipids
20
Q
What biomolecules are involved in the self-replication of DNA in an organism?
A
Nucleic Acids - DNA and RNA
21
Q
What is the central dogma of molecular biology?
A
It describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein
22
Q
What are the catalytic events supporting the transmission of genetic information?
A
Metabolism
Growth
Response to Stimuli
23
Q
What facilitates the transmission of genetic information and processes to support it
A
Cell structure
24
Q
What are the three common features of cells?
A
Nuclear Region
Plasma Membrane
Cytoplasm
25
What is the nuclear region and what is it's function
Area of a cell where most of its genetic material is found (DNA)
Allows DNA Replication & DNA Transcription
26
What is the Plasma Membrane and what is it's function
Separates cell from outside
Maintains order
Allows transport
27
What is the Cytoplasm and what is it's function?
It contains multiple organelles & sites of catalytic action to support metabolic activities required for growth & replication
28
What biomolecules are present in the nuclear region?
DNA + RNA + Protein
29
What biomolecules are present in the cytoplasm?
Lipid and Protein
30
Give a function of the nucleus
Contains, decides & sends out the instructions for cell behaviour
Controls gene expression and mediate the replication of DNA during the cell cycle
31
Where is the genetic information contained in bacteria?
Cytoplasm
32
Where is the genetic information contained in Eukaryotes?
Genetic information (DNA) contained within nuclear membrane separated from cytoplasm
33
What are the three domains in the three domain system?
Bacteria
Eukarya
Archaea
34
List five differences between Prokaryotes and Eukaryotes
```
P =
no true nucleus and no membrane bound organelles –
metabolism in cytoplasm
nuclear region called “nucleoid”
no membrane separating it
cell Wall gives structure & rigidity
smaller cells
E =
true nucleus
within nucleus, nucleolus region
no Cell Wall – more fluidic shape
contain organelles (Mitochondria)
larger cells
```
35
What is the nuclear envelope?
It is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells
36
What is the nucleolus?
Area rich in ribosomal RNA
| obvious under microscope
37
How is chromosome made visible
Only visible in replicating cells
38
What are the structures in the the Nucleus/Nuclear Region
Nuclear Envelope, Nucleolus, Chromosomes
39
What is the nuclear envelope made of?
Phospholipid bi-layer forms a Nuclear Membrane studded with Nuclear Pores
40
What is the function of the nuclear envelope?
Allows transport of RNA, proteins, carbohydrates
41
What is the function of the nucleolus?
The nucleolus primary function is to assemble ribosomes
42
How does the double helix structure aid the DNA processes DNA replication and DNA transcription
- DNA REPLICATION – whole genome unwinding & copying chromosomes
- DNA TRANSCRIPTION – regulated unwinding of specific genomes, creation
of “RNA” copy
43
What is a nucleosome and what is it made up of?
- The smallest DNA bundle
| - DNA + Histone Protein
44
What is the chromatin made up of?
Nucleosomes (DNA + Histone)
45
What are chromosomes made up of?
Chromosomes are made up of a DNA-protein complex called chromatin that is organized into subunits called nucleosomes.
46
What is the template, Catalyst and Product of Transcription
Template : DNA (Gene)
Catalyst : RNA polymerase (protein enzyme)
Product : messenger RNA (mRNA)
47
Give four differences between DNA and RNA
```
DNA : double stranded
SUGAR COMPONENT – Deoxyribose
Thymine as base
Stable Structure
RNA : single strand
SUGAR COMPONENT – Ribose
URACIL as base
Unstable, short-lived
```
48
Does all RNA get turned/translated into Proteins?
No
49
Why doesn't DNA directly translate into protein?
If DNA would directly have to translate into protein, there is a high risk of the loss of genetic material. Also DNA is very tightly packed, so unwinding it every now and then will not be energy efficient
50
What are the fates of RNA?
mRNA : Exported from Nucleus to sites of Protein synthesis (Ribosomes)
rRNA : Forms a complex with proteins - Ribosomes
tRNA : RNA species that links up with Amino acids -> proteins
Found in Ribosomes
51
Where are ribosomes found (both eukaryotic and prokaryotic?)
Found in Pro and Euk
52
Why are ribosomes important?
They are central in flow of genetic information
53
What are the functions of ribosomes?
Translate mRNA into PROTEINS
| Forms complex of rRNA, proteins, tRNA & mRNA
54
Where are ribosomes found in the cell
Ribosomes are found 'free' in the cytoplasm or bound to the endoplasmic reticulum (ER) to form rough ER
55
Where are ribosomes found in a prokaryotic cell?
Since there are no membrane-bound organelles in prokaryotes, the ribosomes float free in the cytosol
56
What is the template, catalyst and product of translation?
Template : mRNA (Nucleotides)
Catalyst : RIBOSOME (protein & RNA
complex)
Product : Protein (Amino Acids)
57
What is the fate of the protein produced by DNA
Enzymes
Hormones
Antibodies
58
What occurs in the nucleus during protein synthesis?
DNA resides
| mRNA made
59
What occurs in the cytoplasm during protein sythesis?
(Ribosome) mRNA translated into protein
60
Where do the proteins go?
The Cytoplasm
The Endomembrane System
The Plasma Membrane
Organelles with a Prokaryotic Origin
61
What does the cytoplasm consist of?
Includes the fluid known as cytosol, the supportive structure known as the cytoskeleton and membrane bound organelles
62
What is the cytosol and what is it mainly made up of?
Intracellular fluid inside the cell (transparent) and Mainly water, ions, biomolecules/metabolites & proteins
63
Is the cytosol and cytoplasm the same thing?
The cytoplasm is made up of the cytosol and insoluble suspended particles. The cytosol refers to the water and anything that is soluble and dissolved in it such as ions and soluble proteins. The insoluble suspended particles could be things like ribosomes. Together, they make up the cytoplasm
64
What are the functions of the cytosol?
Metabolic function - Concentration Gradients of Biomolecules
Contains Protein Complexes (Inflammasomes/Apoptosomes/Centrosomes)
used in cell signalling/division
Contains cytoskeleton proteins - Shape, Structure & Motility
65
What are the three Cytoskeletal proteins?
Microfilaments, microtubules, intermediate filaments
66
What's another name for Actin filaments?
Microfilaments
67
What is the function of the cytoskeleton?
It provides structure and shape to cells
Intracellular transport - The movement of vesicles and substances within the cell. Intracellular transport heavily relies on microtubules for movement
68
Actin filaments are the ____ cytoskeletal filaments in eukaryotic cells
smallest
69
Give an example of microfilaments
Actin
70
Example of microtubules
Tubulin
71
Example of intermediate filaments
Keratin
72
A Role of Cytoskeleton: Serves as a scaffold providing _______ ______ and maintaining ______ _____
structural support; cell shape
73
What is the shape of microtubules
Hollow, cylindrical structures.
74
The distribution of which cytoskeleton protein determines the shape of the cell and how?
Microtubules
75
Microtubules facilitate movement of ____ between compartments.
vesicles
76
What is the function of microtubules
Involved in cellular organization
Centrosome - In mitosis the nuclear membrane breaks down and the centrosome nucleated microtubules can interact with the chromosomes to build the mitotic spindle.
77
What is the function of Intermediate filaments?
Anchor organelles & organize 3-D shape
78
What is the function of the microfilaments?
Cellular growth as actin filaments polymerizes
| & depolymerizes at opposite ends
79
What is the Endoplasmic Reticulum?
A network of membranes found throughout the cell and connected to the nucleus
80
The endoplasmic reticulum consist of folds, what are they called and what are their function
Cisternae, Pack and modify proteins and polysaccharides
Package the proteins and then send them to transport carriers.
Package polysaccharides that are synthesized in the Golgi apparatus.
81
Is the Endoplasmic Reticulum found in eukaryotic or prokaryotic cells?
Eukaryotic
82
What are the two types of Endoplasmic Reticulum?
Rough and Smooth Endoplasmic Reticulum
83
What is the difference between rough ER and smooth ER?
Rough ER – studded with Ribosomes, series of flattened sacs.
| Smooth ER – no Ribosomes, tubule network
84
What is the function of rough ER?
sites of protein synthesis
85
What is the function of smooth ER?
important in lipid synthesis & detoxification
86
The ER doesnt reach the plasma membrane directly, how does it do this?
Vesicles bud off – (membrane bound) &
| transport contents around & out of cell
87
What is the function of the Golgi Apparatus?
Directs/Sorts traffic inside the cell
88
The New membrane-bound organelles bud off golgi, but where do they go?
Lysosome
Plasma membrane
Secretory Vesicles
89
Why do the new membrane- bound organelles bud off golgi and go to lysosome?
for recycling
90
Why do the new membrane- bound organelles bud off golgi and go to Plasma membrane?
For Transport Functions
91
Why do the new membrane- bound organelles bud off golgi and go to Secretory Vesicles
For secretion/export (eg - Exosomes - extracellular vesicles)
92
What is the function of smooth er in relation to the Golgi Aparatus?
Traffics lipid to Golgi
93
What is the function of rough er in relation to the Golgi Aparatus?
Delivers protein cargo to Golgi
94
What is the function of the Golgi Aparatus?
It is another packaging organelle like the endoplasmic reticulum (ER).
It directs & sorts trafficking of
proteins within & out of the cell via the Plasma Membrane
95
What is the Cis face of the Golgi Aparatus?
Nuclear side
96
What is the Trans face of the Golgi Aparatus?
Plasma membrane side
97
What is Endocytosis?
Endocytosis occurs when the cell membrane engulfs particles outside the cell, draws the contents in, and forms an intracellular vesicle called an endosome.
98
What is an endosome?
Endosomes are a heterogeneous collection of organelles that function in the sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole.
99
Why is Endocytosis crucial to the survival of a cell?
Since most molecules important to the cell cannot normally pass through the cell's hydrophobic plasma membrane, endocytosis is needed
100
What needs to occur in order for endocytosis to happen?
Substances must be enclosed within a vesicle formed from the cell (plasma) membrane
101
What organelle builds lysosomes?
Golgi Aparatus
102
Where is the golgi aparatus found?
They are located very near the rough endoplasmic reticulum and hence near the nucleus.
103
What transports lipids and proteins to the Golgi Aparatus?
Transport Vesicles
104
Is the Lysosome highly acidic or basic and why?
Highly Acidic - Contains degradative enzymes (work at
| acidic pH)
105
Why do the substances entering in vesciles enter the lysome?
For degredation - Lysosomes contain a wide variety of acidic enzymes that break down macromolecules such as nucleic acids, proteins, and polysaccharides.
106
What is the lysosome made up of?
Enzymes and a membrane
107
What are the other functions of the lysosome?
Important in response to pathogens (PHAGOCYTOSIS)
| Important in recycling old organelles (AUTOPHAGY)
108
What is the problem that arises in the cytoplasm in terms of seperation of organelles.
Cytoplasm – mainly water,
Proteins
Some nucleic acids (RNA)
(Hydrophilic environment)
109
What does Hydrophilic mean?
Water soluble
110
How do you chemically achieve the seperation in the cytoplasm
Need something that won’t mix with these polar molecules to provide separation (NON-POLAR)
(Hydrophobic environment)
111
What is Hydrophobic?
Hydrophobes are nonpolar molecules and do not interact with water molecules.
112
What biomolecule provides the solution to this seperation crisis in the cytoplasm and why?
Lipids - Lipids can have hydrophobic & hydrophilic
| portions (amphipathic) which is ideal for use in membranes
113
What is amphipathic?
It has both hydrophilic and hydrophobic parts.
114
What is a phospholipid?
It contains a phosphate head – water soluble/hydrophilic/polar
2 Fatty Acids (C/H chain) tails – hydrophobic/non-polar, insoluble
115
Give an example of a phospholipid
```
Phosphatidylcholine
Choline
Phosphate
Glycerol
Two fatty acids
```
116
Why are phospholipids important?
Due to its hydrophobic and hydrophilic parts, they play a key role in determining what enters and exits every cell. They make up your cell membranes and is critical to a cell's ability to function
117
What is a micelle structure?
Circular arrangement of phospholipids where the hydrophilic tails are attracted to each other & mix with external soluble environment
Hydrophobic tails are attracted to each other
118
What is a bilayer structure?
Flat-sheet containing 2 layers of phospholipids
Hydrophobic tails attracted to each other
Exposing the Hydrophilic Heads to the external and internal water soluble environment
119
What is the function of the Hydrophobic tails?
Provide separation
120
What is the function of the Hydrophilic heads?
Allow mixing with the environment
121
Why does the phospholipid bilayer want to form a ''circular/enclosed'' shape?
Linear shape with exposed ends will not work - energetically unfavourable and is ideal for cell shape
122
What is the advantage of the aphilic nature of phospholipids?
Allows Fluidity - permits Growth, Expansion, Transport
123
Why do phospholipids move laterally?
Fatty acid chains in the phospholipids are often unsaturated, so that they don't pack together tightly
124
How do phospholipids in the cell membrane move?
Individual phospholipids can rotate and move laterally within a bilayer
125
Which hydrophobic lipid can become embedded in the plasma membrane and what does it do?
Cholesterol - provide extra stability
126
How does Cholesterol provide extra stability?
It slightly immobilizes the outer surface of the membrane and makes it less soluble to very small water-soluble molecules that could otherwise pass through more easily. Without cholesterol, cell membranes would be too fluid, not firm enough, and too permeable to some molecules
127
How does water transport across the Lipid bi-layer?
Osmosis
128
Why is it difficult for polar molecules to cross the bi-layer?
Because of the hydrophobic centre
129
Out of the three - water, polar moleules and non polar molecules- which can pass through the membrane the easiest
Non-polar small molecules - because of the hydrophobic core
130
What is the function of Protein Transporters in cell membrane?
Protein Transporters assist the transport process in cell membranes:
Ion Channels/Transporters – permit entry
Receptors – detect substances and initiate cellular responses
Some allow passive diffusion through Carrier
Some requires energy/stimulation
131
How does the Cellular Transport System facilitate transport?
Production of Vesicles from Golgi to transport proteins out (Secretion & Exocytosis)
Substances can enter via Endocytosis (Pinocytosis - nutrients)
132
What does the Bacterial Cell Wall consist of?
Lipid, lipoprotein, carbohydrate/sugar species
133
Some bacteria have second “plasma membrane” outside their cell wall, what is the benefit of this?
Allows more specificity/selectivity
134
Why are the Cell Wall & Membrane components of bacteria often targeted by antibiotics
Associated with immunogenicity and
| pathogenicity
135
Some bacteria possess polysaccharide outside cell wall, what is it called?
Capsule - protect the bacteria cells from environmental dangers such as antibiotics and desiccation
136
Bacterial kingdom divided into 2 Groups based on what?
Cell Wall Structure
| How they stain under biochemical assays (Gram stain)
137
List three differences between a gram positive and gram negative bacteria
```
Gram negative :
- Outer membrane with lipids/lipoprotein & transport proteins
- Thin cell wall of peptidoglycan
(stain negative)
- Contains periplasmic space
Gram positive :
- No outer membrane
- Major Peptidoglycan (carbohydrate
polymer) cell wall (Stain positive – retain counterstain)
- Smaller periplasmic space
```
138
Plants cells have a thick cell wall, what is it made of and what is its function?
Cellulose cell wall (carbohydrate polymer)
Confers stability & protection
Survives high osmotic pressure
139
Plants have a three layer structure, what is it made up of?
- Plasma membrane (inside)
- 3 layers of cellulose “primary wall”
- Outer “middle lamella”, forms the
division/border with neighbouring cell
140
What is the function of mitochondria and how does it do this?
Allows cellular respiration,
Breakdown of Glucose (cytoplasm) &
other intermediates (matrix) to generate
energy via oxidative phosphorylation
141
What is the function of the christae?
Contain proteins and molecules that participate in cellular respiration.
142
Where is the mitochondria's DNA (Plasmid-like) & Ribosome found?
in the “Mitochondrial matrix''
143
What does the mitochondrion consist of structurally?
Outer membrane
Inner membrane
Gel-like material called the matrix
144
How many membranes are present in the mitochondria?
Two - Double membrane system (sim to prokaryotic system)
145
Where are mitochondria found?
All free-living eukaryotes
146
Where are chloroplasts found?
Plant & Algae only
147
How many membranes are present in chloroplasts?
Two - Double membrane system
148
Where is chlorophyll found in chloroplasts?
Chemical found in internal membrane network “Thylakoids”
149
What are thylakoids?
A thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis
150
Where are the chloroplasts own DNA (Plasmid-like) & Ribosomes found?
In the “Stroma”, colorless fluid surrounding the grana within the chloroplast
151
Function of chloroplasts
Allows Photosynthesis, Captures light energy, fuel enzymatic formation of Glucose (req CO2/H20)
152
What is the mitochondrial eve and why is it possible?
The Mitochondrial Eve is the matrilineal most recent common ancestor of all currently living humans. Fertilized Egg - Cytoplasm & its contents solely from Mother
All Mitochondria travel through maternal line
153
What two factors lead to different types of cell division arising in living things?
- Different Cells have different structures
| - DNA is organized very differently in different cells
154
What are the three types of cell division?
Binary Fission
Budding
Mitosis
155
In what living things does Binary Fission occur?
Bacteria
156
What are the key factors of living things who divide by binary fission?
- No nucleus
- 1 “bacterial chromosome”
- Duplicates by replication
157
In what organisms does budding occur?
Diatoms and some yeasts
158
What are Diatoms?
Diatoms are a major group of algae, specifically microalgae, found in the oceans, waterways and soils of the world.
159
What are the key features of organisms which divide by budding?
- Have nuclei & chromosome (s)
- Cell Walls
- Nuclear envelope remains intact
- Chromosomes duplicates & separate
160
What are the key features of organisms which divide by mitosis?
- Have nuclei & multiple chromosomes
- No Cell Wall
- Nuclear envelope dissolves
- Chromosomes duplicates & separate
- Nuclear envelope reforms
161
In what organisms does mitosis occur?
Most eukaryotes
162
In what type of cells does mitosis only occur?
Somatic cells
163
What is DNA replication?
Duplication & separation of the chromosome(s)
164
What is Cytokinesis?
Cytoplasmic events required to separate chromosomes & divide the cytoplasm
165
Where does DNA replication occur in eukaryotic cells?
DNA replication occurs in the nucleus of eukaryotic cell.
166
Where does DNA replication occur in prokaryotic cells?
Because prokaryotic cells do not have nuclei, DNA replication occurs in the cytoplasm of a prokaryotic cell.
167
What is the result of mitosis?
- 1 cell gives rise to 2 daughter cells with identical genetic complement
168
What is the cell cycle?
The cell cycle, or cell-division cycle, is the series of events that take place in a cell leading to its division and duplication of its DNA to produce two daughter cells
169
What is mitosis refered to in the cell cycle?
M-phase
170
What is the Non Mitotic phase of cell?
Interphase
171
What is Interphase broken up into?
- G1
- S
- G2
172
In which part of interphase does DNA replication occur?
S
173
What is the mitotic phase broken up into?
Cytokinesis
| Mitosis
174
What are the different phases in mitosis?
- Prophase
- Pro-Metaphase
- Metaphase
- Anaphase
- Telophase
175
What is interphase and what occurs in interphase in
a) Nucleus
b) Cytoplasm
```
Preparatory events for mitosis
NUCLEUS:
- DNA Replication
CYTOPLASM:
- Centrosome duplication
```
176
What occurs in G1 of interphase?
The cell synthesizes mRNA and proteins (increases the amount of cytosol in the cell)
177
What is the importance of interphase?
Without the time to grow and carry out DNA replication during interphase, eukaryotic cells would be unable to successfully carry out cell division
178
What is the cell cycle composed of?
G1 phase, S phase, G2 phase and M phase
179
How is the cell cycle regulated?
Cell cycle is regulated at three checkpoints to ensure that the cells are ready to proceed through the process of division
At each of these checkpoints, the cell waits to receive signals on whether or not it has carried out the functions that should have been completed.If the cell receives the correct signals, it will allow itself to continue through the cell cycle, if not it either waits for the necessary tasks to be carried out or stops the cell cycle completely
180
What are the three key checkpoints of the cell cycle?
(G1) , (G2), (M)
181
When does the G1 Phase occur?
Right after cells have divided
182
What occurs in G2 Phase?
G2 phase is when the organelles of the cell need to duplicate.
183
What is the order of the phases?
G1, S, G2, M
184
What occurs in Prophase in
a) Nucleus
b) Cytoplasm
NUCLEUS:
- Sister Chromatids appear
CYTOPLASM:
- Early Spindle formation
185
What occurs in Pro-meta-phase in
a) Nucleus
b) Cytoplasm
```
NUCLEUS:
- Membrane dissolves
(Fragments remain)
CYTOPLASM:
- Microtubules extend
- Attachment to Kinetochore
```
186
What occurs in Metaphase in
a) Nucleus
b) Cytoplasm
“NUCLEUS”:
- Attached chromosomes align on “Metaphase Plate”
CYTOPLASM:
- Extension of Spindle forms symmetry & plate formation
187
What occurs in Anaphase in
a) Nucleus
b) Cytoplasm
```
“NUCLEUS”:
Separation of sister
chromatids
CYTOPLASM:
De-polymerization of
Microtubules & Migration of
Chromatids
```
188
What occurs in Telophase in
a) Nucleus
b) Cytoplasm
```
“NUCLEUS”:
Reformation of nuclear
membrane (from remnants
of old envelope)
CYTOPLASM:
Cytokinesis & Cleavage
Dissolution of Spindle
```
189
After mitosis, what does each daughter cell have?
Each daughter cell:
- Correct chromosome number
- 1 centrosome
190
What does too much Profileration cause?
can form cancer (unregulated growth of cells)
191
What is it known as when a cell must die
APOPTOSIS, “Programmed Cell Death” - cells that are no longer needed or are a threat
192
What is the failure of the first two checkpoints (G1, G2/M) caused by?
Mostly occurs upon DNA damage
193
When does G1 checkpoint occur?
Before DNA Replication
194
What occurs if there is no progression signal in G1 checkpoint?
Cell Cyle Arrest -> G0 phase
195
Which checkpoint is the most important and why?
The G1 checkpoint is the most important because it is there where the cell "decides" whether or not to divide
196
What happens if a cell fails a checkpoint?
If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted and the cell attempts to either complete DNA replication or repair the damaged DNA
197
```
Which of the following is the simplest collection of matter that can live?
tissue
cell
organ
molecules
```
cell
198
A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should she choose and why is it the best choice?
- light microscope, because of its high resolving power
- scanning electron microscope, because of its ability to visualize the surface of subcellular objects
- light microscope, because the specimen is alive
- transmission electron microscope, because of its high magnifying power
- transmission electron microscope, because of its high resolving power
light microscope, because the specimen is alive
Although the resolution of the light microscope is far less than that of electron microscopes, light microscopy is the only technique that permits one to observe living cells.
199
Why can't an electron microscope be used to view living cells?
The beam of electrons used to illuminate a specimen also destroys the samples, meaning that electron microscopes can't be used to image living cells.
200
Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to __________.
be involved in the rapid uptake of compounds from the cell's environment
201
What limits the maximum size of a cell?
- the shape of the cell
- the cell's surface-to-volume ratio
- the time it takes a molecule to diffuse across a cell
202
Which of the following structures is found in eukaryotic but NOT prokaryotic cells?
- mitochondria
- plasma membrane
- ribosomes
- cytosol
- DNA
Mitochondria, only eukaryotic cells have membrane-bound organelles such as mitochondria
203
A substance moving from outside the cell into the cytoplasm must pass through what?
Plasma membrane. The plasma membrane defines the boundary between the cytoplasm and the outside of the cell.
204
In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?
Eukaryotic cells are compartmentalized, which allows for specialization.
205
What features do prokaryotes and eukaryotes have in common?
Ribosomes, plasma membrane, and cytoplasm
206
A particular cell has a nucleus and chloroplasts in addition to the fundamental structures required by all cells. Based on this information, this cell could be
- a cell from a pine tree
- a photosynthetic protist cell or a plant cell
- a cell from the intestinal lining of a cow
- a bacterium
- a yeast (fungus) cell
```
-a photosynthetic protist cell or plant cell
Some protists (such as algae) can photosynthesize, and so can plants. As both the protists and plants are eukaryotes, they contain organelles.
```
207
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?
Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.
208
A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure or structures would you predict the majority of the radioactive phosphorous to accumulate?
- the nucleus
- the Golgi apparatus
- rough endoplasmic reticulum
- rough endoplasmic reticulum and Golgi apparatus
- the Golgi apparatus and the nucleus
- nucleus
| Large numbers of nucleotides would be used to make new DNA as the cells grew, and the DNA is housed in the nucleus.
209
Which of the following groups is primarily involved in synthesizing molecules needed by the cell?
smooth endoplasmic reticulum, ribosome, vacuole
- lysosome, vacuole, ribosome
- ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum
- vacuole, rough endoplasmic reticulum, smooth endoplasmic reticulum
- rough endoplasmic reticulum, lysosome, vacuole
-ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum
Each of these structures is capable of synthesizing molecules needed by cells (vacuole cant)
210
Which of the following categories best describes the function of the rough endoplasmic reticulum?
- information storage
- manufacturing
- energy processing
- breakdown of complex foods
- structural support of cells
-manufacturing
| The rough endoplasmic reticulum is involved in the manufacture of proteins for the endomembrane system.
211
You would expect a cell with an extensive Golgi apparatus to __________.
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move rapidly
store large quantities of ions
secrete large amounts of protein
make large amounts of ATP
absorb nutrients in the GI tract
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The Golgi apparatus modifies and sorts the lipids and proteins produced in the ER. Cells that secrete large amounts of material require an extensive Golgi apparatus.
212
A researcher made an interesting observation about a protein made by the rough endoplasmic reticulum and eventually found in a cell's plasma membrane. The protein in the plasma membrane was actually slightly different from the protein made in the ER. Where was the protein probably altered?
Golgi Appartatus
| Vesicles carrying proteins from the rough ER fuse with the Golgi apparatus, where the proteins may be altered.
213
What is the flow of materials through the endomembrane system?
Rough ER +Smooth ER
The Golgi Apparatus (Cis then Trans)
Lysosome
Plasma Membrane
214
Which of the following sequences represents the order in which a protein made in the rough endoplasmic reticulum might move through the endomembrane system?
```
plasma membrane → nuclear envelope
Golgi apparatus → mitochondria
nuclear envelope → lysosome
Golgi apparatus → lysosome
lysosome → plasma membrane
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Golgi apparatus → lysosome
Proteins of the endomembrane system are synthesized in the rough ER, modified and sorted in the Golgi, and then transported to other organelles of the endomembrane system such as vacuoles.
215
A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized where?
All of the membrane proteins of the endomembrane systems are made in the rough ER.
216
Which of the following five membranes is most likely to have a lipid composition that is distinct from those of the other four?
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endoplasmic reticulum
Golgi apparatus
plasma membrane
mitochondrial outer membrane
lysosome membrane
```
mitochondrial outer membrane
The mitochondria are not part of the endomembrane system and must synthesize their own lipids.
217
Which of the following statements about chloroplasts and mitochondria is true?
Mitochondria, but not chloroplasts, contain a small amount of DNA.
Chloroplasts and mitochondria have three sets of membranes.
Chloroplasts and mitochondria are components of the endomembrane system.
Chloroplasts, but not mitochondria, are completely independent of the cell of which they are a part.
Chloroplasts and mitochondria synthesize some of their own proteins.
Chloroplasts and mitochondria synthesize some of their own proteins - because they contain DNA and ribosomes
218
Which type of cell is most likely to have the largest number of mitochondria?
- bacterial cells that are growing on sugars
- photosynthetic cells in the leaves of a tree
- muscle cells in the legs of a marathon runner
- inactive yeast cells that are stored for future use
- nondividing cells in the skin on your finger
Cellular respiration releases energy that cells need in order to carry out their functions. Active muscle cells need large amounts of energy.
219
Where are the ribosomes of mitochondria found?
The ribosomes in the mitochondria are found in the matrix of the mitochondria, not in the intermembrane space
220
Which of the following organelles might be found inside other organelles?
```
mitochondria
transport vesicles
the nucleolus
ribosomes
No organelles are found inside of other organelles.
```
ribosomes
| Ribosomes are nonmembranous organelles that are found in the cytoplasm but also in mitochondria and chloroplasts.
221
Microtubules and microfilaments commonly work with what to perform many of their functions?
Golgi Apparatus
222
Which of the following structures is found in animal cells but NOT in plant cells?
```
mitochondria
rough endoplasmic reticulum
plasma membrane
Golgi apparatus
centrioles
```
-centrioles
| Although plant cells have a microtubule organizing center, they lack a pair of centrioles.
223
Cilia and flagella move due to the interaction of the cytoskeleton with what?
Motor proteins, such as dynein, use energy to move parts of the cytoskeleton.
224
What is a a common characteristic of a plant cell wall and an animal cell extracellular matrix?
Both plant cell walls and the ECM of animal cells allow movement of water and small solutes.
225
The plasma membrane is referred to as a "fluid mosaic" structure. Why?
The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.
226
Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?
in the interior of the membrane
in the interior and on the inside surface, but not on the outside surface
on the outside (external) surface of the membrane
on the inside (cytoplasmic) surface
on either surface of the membrane, but not in the interior of the membrane
interior of the membrane
The steroid cholesterol, wedged between phospholipid molecules in the plasma membranes of animals, helps stabilize the membrane.
227
What is meiosis?
a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell
228
Meiosis I
PMAT I: The first cell division of meiosis when the homologous pairs are split up into two separate cells.
229
Meiosis II
PMAT II: The second cell division of meiosis. This is when the sister chromatids are split up into two separate cells.
230
Does DNA replication occur in meiosis 1 or 2?
Meiosis II :No DNA replication during this division
| Meiosis I :There IS DNA replication during this division
231
What is The Mitotic Spindle?
A structure composed of microtubules which segregates chromosomes into the daughter cells during mitosis.
232
What is the centosome?
They are made from two centrioles. the centrosome is an organelle that is the main place where cell microtubules are organized (MTOC – Micro-Tubule Organizing Center)
233
What are the functions of the centrosome?
The main purpose of a centrosome is to organize microtubules and provide structure for the cell, as well as work to pull chromatids apart during cell division.
234
What is a centriole?
a centriole is a cylindrical cellular organelle composed mainly of a protein called tubulin
235
What are the functions of centrioles?
The centrioles help in the formation of the spindle fibers that separate the chromosomes during cell division (mitosis)
236
Describe the centrosome cycle
- 2 subunits of 1 centriole exist “perpendicular” – held by linkages
- They Move apart & new centriole microtubules begin to get laid down perpendicularly
- Old linkages break -> 2 centrioles (with 2 subunits @ 90*)
- Oppose each other & migration to opposite poles begins….
237
Describe the Spindle Formation
- Microtubule proteins form from the CENTROSOME & extend into cytoplasm
- More “tubulin” subunits added on -> Expansion of the Microtubules
- Short Microtubules – “Aster”
- Longer Microtubules – “Spindle Microtubules”
238
What are the short spindle fibres (microtubules) known as?
Short Microtubules – “Aster”
239
What are the long spindle fibres (microtubules) known as?
Longer Microtubules – “Spindle Microtubules”
240
Why is the spindle fiber necessary?
The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells
241
What is the kinetochore?
The kinetochore forms in eukaryotes, assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis
242
Seperation in mitosis is assisted by what enzyme?
Enzyme assisted “Separase” – breaks down connections btw sister chromatids
243
Describe the seperation during mitosis
- Sister Chromatids migrate away
- Moving along kinetochore microtubules – toward centriole,
- Move along the network
- Kinetochores shorten – depolymerization, Chromatids move on as they do
244
Describe the division of the cytoplasm in cytokinesis
Opposing Centrosomes give “Polarity”
- Short “Aster” microtubules give push in opposite direction – away from centre
- Before separation, “Non-kinetochore microtubules” play important role;
- > Elongating the cytoplasm by extending in opposing directions
245
What is the cleavage furrow?
the cleavage furrow is the indentation of the cell's surface that begins the progression of cleavage, by which animal and some algal cells undergo cytokinesis, the final splitting of the membrane, in the process of cell division. In a typical animal mitosis, a cleavage furrow forms at the equatorial cortex after anaphase. This furrow then advances inwards to separate the two daughter cells.
246
What does each chromosome contain?
Each chromosome contains one long DNA molecule associated with many proteins.
247
How can a protein outside the cell cause events to happen inside the cell?
A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell
248
What effect does phosphorylating a protein have on that protein?
Protein phosphorylation causes a shape change in the phosphorylated protein. The shape change results from the interaction of the newly added phosphate groups with charged or polar amino acids on the protein being phosphorylated. The shape change alters the function of the protein, most often activating it, but in some cases phosphorylation instead decreases the activity of the protein.
249
What is the function of the mitotic cell cycle?
To produce daughter cells that are genetically identical to the parent cell (assuming no mutation has occurred)
250
When are sister chromatids created?
When DNA is replicated, during S-phase.
251
When are sister chromatids seperated?
Sister chromatids are separated during mitosis prior to cytokinesis.
252
Which of the following is FALSE regarding sister chromatids?
a) Sister chromatids are created when DNA is replicated.
b) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
c) Sister chromatids are separated during mitosis.
d) Sister chromatids form in the S-phase stage of the cell cycle.
e) Sister chromatids are attached to one another at the centromere.
b) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
This statement is false. Each of the sisters ends up in a different cell after cell division.
