The cell Flashcards
1
Q
Who was the first to look through a microscope?
A
Robert Hooke in 1665 (looked at a piece of cork)
2
Q
Who was the first to view a living cell under a microscope?
A
Anton Van Leewenhock in 1674
3
Q
Who was the first to say diseased cells came from normal cells?
A
Rudolph Virchow in 1850
4
Q
What are the concepts of cell theory?
A
1- All living cells are composed of cells
2- The cell is the basic unit of live
3- Cell arise only from preexisting cells
4-Cells carry genetic info by DNA and is passed on from parent to daughter cell
5
Q
What is the point of membrane-bound organelles?
A
Compartmentalization of functions
6
Q
What is the cell membrane made of
A
Phospholipid bilayer (hydrophilic surface and hydrophobic interior)
7
Q
What is the role of the cytosol
A
Allow diffusion of molecules throughout the cell
8
Q
What is the nucleus?
A
Contains all genetic material for replication
9
Q
What’s surrounding the nucleus?
A
Double membrane nuclear membrane/envelope with nuclear pores
10
Q
What is the role of nuclear pores?
A
Allows selective two-way exchange of material for the nucleus and the cytoplasm
11
Q
What is called linear DNA
A
Histones
12
Q
What is called linear DNA wound into linear strands?
A
Chromosomes
13
Q
What is the nucleolus?
A
Where the rRNA (ribosomal) is synthesized (is about 25% of the nucleus)
14
Q
What is the roles of the mitochondria?
A
Provide energy, could also kill the cell
15
Q
How could the mitochondria kill the cell? What is this action called?
A
By releasing the enzymes in the electron transport chains. It is called apoptosis
16
Q
How many layers are in the mitochondria?
A
2
17
Q
What are the 2 layers of the mitochondria and what do they do?
A
Outer and inner layer. The outer layer is a barrier with the cytosol. The inner barrier contains molecules and enzymes of the electron transport chain
18
Q
What is the matrix?
A
Space into the inner membrane
19
Q
What makes the mitochondria special?
A
It is semi-autonomous
20
Q
What does being semi-autonomous means?
A
Contain some of their own genes and can replication independently
21
Q
How could a mitochondria replicate independently?
A
Binary fission
22
Q
What is extranuclear inheritance?
A
Transmission of genetic material independently of the nucleous (can also be called cytoplasmic)
23
Q
What are lysosomes?
A
Sacs containing hydrolytic enzymes that can break down substrates
24
Q
What can endosomes do?
A
Transport, package and sort cell material travelling to and from the membrane
25
Where can endosomes transport cellular material?
Transgolgi, cell membrane or the lysosomal pathway for degradation
26
What are the 2 organelles that can cause apoptosis?
Mitochondria and lysosomes
27
How could Lysosomes cause apoptosis?
Releasing of its enzymes, causing autolysis resulting in apoptosis
28
What is the definition of autolysis?
Degradation of cellular components
29
What are the 2 types of endoplasmic retinaculum?
Smooth and rough
30
What is the relation between the endoplasmic retinaculum contiguous with?
The nuclear envelope
31
What is the endoplasmic retinaculum?
A double membrane folded in numerous invaginations creating complex structures with a central lumen
32
What is the main difference between SER and RER other than their function?
RER had ribosomes
33
What is the RER function?
Translation of protein for secretion directly into its lumen
34
What is the SER function?
Lipid synthesis and transports proteins from RER to the Golgi apparatus
35
What can the SER synthesize?
Phospholipid membrane, drugs, poison
36
In what are the proteins transported from the RER to the Golgi apparatus?
Vesicules
37
What are the functions of the Golgi apparatus?
Modify and sort (and signal sequences)
38
What modification can the Golgi apparatus do?
Adding groups of carbohydrates, phosphates and sulfates
39
What is signal sequence?
Direct delivery of the product to a specific location
40
What can perixosomes do?
Break down long chains of fatty acids with beta-oxydation, participate in synthesis of phospholipids.
41
What perixosomes contains?
Hydrogen peroxide and some of the enzymes for the pentose phosphate pathway
42
What are the main functions of the cytoskeleton?
Structure and help the cell maintains its shape
Provide a conduit for transport around the cell
43
What are the components of cytoskeleton?
Microfilaments, microtubules and intermediate filaments
44
What are the microfilaments?
Solid polymerized rod of actin
45
What is the role of the microfilaments in mitosis?
Forms the cleavage furrow
46
What are microtubules?
Hollow polymers of tubular proteins
47
What are the 2 components of microtubules?
Cilia and flagella
48
What is the difference between cilia and flagella?
Cilia helps with movements throughout the surface of the cell while flagella helps with the cell mouvement itself
49
What are the 2 proteins that carry vesicles in microtubules?
kinesin and dynein
50
What is the primary pathway for kinesin and dynein to carry vesicles?
microtubules (radiate through the cell)
51
What is the name of the structure of cilia and flagella?
9+2 structure
52
What is the 9+2 structure
Structure of the flagella and the cilia
53
How are the cilia and flagella structured?
9 pairs of microtubules forming an outer ring with 2 microtubules in the center
54
What are the centrioles?
Organizing centers of microtubules
55
Where are the centrioles situated?
In the centrosome
56
What is the process of separating 2 sister chromatids?
Kinetochores
57
What can make kinetochores
Centrioles
58
What are intermediate filaments?
Diverse groups of filamentous proteins
59
What are the proteins in the intermediate filaments?
keratin, desmin, vimentin and lamins
60
What is the role of the intermediate filaments?
Help cell on cell adhesion, maintenance of the cytoskeleton and anchoring other organelles
61
What are the types of tissue?
Epithelial, connective, muscle and nervous
62
Where do you find epithelial tissue?
In the body cavities
63
What could be the roles of epithelial tissue?
Protection agains pathogen invasion, absorption, secretion and sensation
64
What is a basement membrane?
The underlying membrane out of which the epithelial tissue cells are all tightly joined together
65
What does the epithelial cells constitute in most organs?
Parenchyma or the functional part of the organ
66
What does it mean for an epithelial cell to be polarized?
One side faces a lumen and the other faces outside (i.e. underlying blood vessels and structural cells)
67
What are the types of epithelial cells according to their number of layers?
Simple epithelia (1 layer), stratified epithelia (multiple layers), pseudostratified epithelia (one layer of different sizes)
68
What are the types of epithelial cells according to their shapes?
Cuboidal, columnar (long and thin) and squamous (flat)
69
What is the function of connective tissue?
Supports (provide a framework for the epithelial cells to carry out their functions)
70
What connective tissue contributes as in an organ usually?
The stroma or the support structure
71
What are examples of connective tissue?
Bone, cartilage, tendons, ligaments, adipose tissue, blood
72
What does most connective tissue cells produce and secrete?
collagen and elastin
73
What is the extracellular matrix made of?
Collagen and elastin produced and secrete from connective tissue cells
74
Where does the prokaryotes store their DNA and as what?
The nucleic region. It's stored as a singular circular molecule of DNA
75
What are the 2 types of prokaryotes?
Archaea and Bacteria
76
What does is means to be extremophiles?
Found in extreme environment like extreme temperature, high salinity or no light
77
What are archaea notable for?
Using alternate sources of energy (photosynthesis, chemosynthesis)
78
What does it mean to be chemosynthetic?
Generate energy from inorganic compound
79
What are 3 similarities between the Achaea and the eukaryotes?
Both starts translation with methionine, have a similar RNA polymerase and associate their DNA with histones
80
Why could it be difficult to develop medicine that targets only bacteria?
Because bacteria and eukaryotes still share analogous structures
81
What are the 2 types of bacteria according to their interactions with us?
Mutualistic symbiotes and pathogens/parasites
82
What does it mean to be in a mutualistic symbiote?
The relationship is beneficial for both parties
83
Pathogenic bacteria lives intra ou extracellularly?
They can be both
84
What are the 3 shapes of bacteria?
Cocci, bacilli, spirilli
85
What are the types of relations a bacteria can have with oxygen?
1- Obligate aerobe (requires oxygen to live)
2- Obligate anaerobe (dies if there's oxygen
3- Facultative anaerobe (can switch from using or not using oxygen)
4- Aerotolerant anaerobe (won't die if there's oxygen, but won't use it either)
86
What does prokaryotes being single celled organisms invokes?
Each cell must be able to perform every function on its own
87
What is made of the envelope of a prokaryote?
The cell wall (outer barrier) and the cell membrane (or plasma membrane composed of phospholipids)
88
What are the function of the cell wall?
Structure and controls of mouvements from inside to outside the cell
89
What are the types of cell wall?
Gram + and Gram -
90
What are the coloration of different cell walls in a gran staining process?
Gram + is mauve and Gram - is pink
91
What are the differences between Gram + and Gram - cell walls?
Gram + has a thick layer of peptidoglycan and also contains lipoteichoic acid
Gram - has a thin layer of peptidoglycan. Has an outer barrier containing phospholipids and lipopolysaccharides.
92
What separates both the 2 barriers of the Gram - cell wall?
The periplasmic space
93
Which Gram cell wall creates the bigger immune system reaction to the human?
Lipopolysaccharides
94
What is the function of the flagella?
Propulsion
95
What is a particularity of the prokaryote's cell flagella?
Is chemotaxis, which means it has the ability to detect chemical stimuli and move towards or away them
96
What is chemotaxis?
Having the ability to detect chemical stimuli and move towards or away them
97
What are the parts of the flagella of a prokaryotes?
The filament, the basal body and the hook
98
What is compose the filament in the flagella?
Flagellin
99
Which of the flagella parts is the motor?
Basal body
100
What is the hook role in the flagella?
It connects the filament to the basal body making them move together
101
What is a plasmid?
Small and circular structure where DNA acquired from external sources that is kept
102
What is the advantage for prokaryotes in having a plasmid?
Antibiotic resistance
103
How does the prokaryote live without a mitochondria?
The electron transport chain and the generation of ATP is made from the cell membrane
104
Does the prokaryotes have a cytoskeleton?
It has a primitive cytoskeleton, but not as advance as the eukaryotes
105
Do prokaryotes have ribosomes?
Yes
106
What is the difference between the prokaryotes and eukaryotes ribosomes?
The size (prokaryotes = 30S and 50S subunits and eukaryotes = 40S and 60S subunits)
107
Do the prokaryotes has a cytoplasm?
Yes
108
How does prokaryotes reproduces?
Via binary fission, an asexual reproduction
109
What is the process of binary fission?
The circular chromosome attaches to the cell wall and replicates. While the cell grows in size, the plasma membrane and the cell wall will grow inward (invagination), which will create 2 daughter cells
110
What is the subset of plasmids?
Episomes
111
What are episomes?
A subset of plasmids that can integrate into the genome of the bacteria
112
What are the 3 recombination processes?
Transformation, conjugation and transduction
113
What advantage brings genetic recombination to bacterias?
Helps increase bacteria diversity and permits evolution
114
What is the process of transformation?
Integration of foreign genetic material into the host genome
115
What type of bacteria are usually able to do transformation?
Gram -
116
What is the process of conjugation?
Bacterial form of sexual reproduction, in which a conjugation bridge is formed between 2 cells to facilitate transfer of genetic material
117
What is the direction ofconjugeation?
Unidirectional, from the male donor (+) to the recipient female (-)
118
What is the sex factor in conjugation?
Plasmids
119
What is the conjugation bridge made from?
Sex pili from the male donor
120
What happens if the plasmid gets integrated in the host genome for conjugation?
The whole genome will then be replicated, but usually the bridge will close before the whole genome will get the chance to be replicated
121
How do you call cell that haven't been able to transfer all of their DNA sequence to the other bacteria before the conjugation bridge was closed?
Hfr for High Frequency of Recombination
122
What is transduction and its process?
Genetic recombination that requires a vector (usually virus, such as bacteriophages). A virus would have accidentally incorporate a segment of host DNA during assembly and will then release the trapped DNA into the new cell it'll try to infest
123
What are transposons?
Genetic elements that are capable of inserting and removing themselves from the genome
124
Are transposons limited to prokaryotes?
No, it has been seen in eukaryotes as well
125
What is the bacterial growth in a new environment like?
1- Lag phase, in which the bacteria gets used to the new habitat
2- Exponential phase (or log phase), in which the rate of bacteria's division increases
3- Stationary phase, in which with the higher number of bacterias, the ressources become limited, so they slow the division rate
4- Death phase, in which the number of bacteria exceeded the ability of the environment, so they die, marking the depletion of resources
126
What are viruses composed of?
Genetic material, a protein coat (capsid) and sometimes an envelope containing lipids. Can also have a tail sheath and a tail fiber (if its a bacteriophage)
127
How are genetic information stored as in a virus?
Can be circular or linear, can be single or double stranded and composed of CNA or RNA
128
How come viruses with an envelope are usually easier to kill?
Because the envelope is very sensitive to heat, detergents and dessication
129
What do we call viruses since they can't reproduce independently?
Obligate intra-cellular parasites
130
Why are viruses obligate intra-cellular parasites?
Because they lack ribosomes to carry out protein syntheses, so they need to express and replicate their genetic information within a host cell
131
What are virions?
Viral progeny produced by a virus once it has hijack a cell's machinery
132
How does bacteriophage infect bacteria?
They stay on the outside and inject their genetic material
133
What are the tail sheath and the tail fibers?
The tail sheath is the syringe injecting the genetic material inside the bacteria and the tail fibers help the virus to recognize and connect to the correct cell
134
What are the 2 types of singele-stranded ARN viruses? What does they mean?
Positive and negative
Positive = can be directly translated to functional proteins by the cell's ribosomes
Negative = act as a template. So they need to carry RNA replicase with them, to synthesize the RNA which then could be used for protein synthesis
135
What are retroviruses?
Enveloped, single-stranded RNA. They carry RNA transcriptase which synthesizes RNA into double-stranded DNA which can integrate the host cell genome in the nucleus.
136
What makes the retroviruses so hard to treat?
Since they have integrated the host genome, the only way to remove the infection is to kill the cell
137
Name an example of retrovirus?
HIV
138
What are the 2 proteins to which the HIV must bind to on the surface of the cell?
CD4 or CCR5
139
Which viral enzyme inserts the DNA just made into the host DNA in a viral infection?
Integrase
140
Can viruses infect any cell they want?
No they need to bind to a specific receptor on the surface of the cell
141
What are ways a virus can enter a host cell during infection?
If it's enveloped, it can fuse with the cell membrane to enter.
A cell could mistake the virus for nutrients and make the virus enter via endocytosis
Bacteriophages will inject their genome into the cell
142
What can a tail fibre with an enzymatic activity could do to the bacteria membrane?
Allow penetration and formation of pores in the cell membrane also
143
What must be done in order for reproduction of the viruses?
Translation of viral genetic material
144
Where are virus DNA transcribed in a host cell?
In the nucleus
145
What happens to positive-sense RNA in the host cell?
It stays in the cytoplasm and can be directly translated into protein by the ribosomes
146
What happens to negative-sense RNA in the host cell?
Needs synthesis of a complimentary RNA strand via RNA replicase which can then be translated to form proteins
147
What are used to translate viral RNA into protein?
Ribosomes, tRNA, amino acids and enzymes of the host cell
148
What are usually the proteins translated from viral RNA?
Structural capsid proteins, which allows the creation of new virions in the cytoplasm of the host cell
149
What needs to be done to the viral genome to be packed within the virions capsids?
It needs to be returned to its original form
150
How can the viral progeny (virions) be released from the host cell?
By cell death (results in spilling of the progeny)
Host cell may lyse (disadvantage to the virus)
Can leave the cell by fusion with the membrane (extrusion)
151
What is extrusion?
When a virus leaves the host cell by fusing with the plasma membrane
152
What is a virus in a productive cycle?
When the host cell is still alive and allows for the continued use of the host cell by the virus
153
What are the 2 life cycle a bacteriophage may enter?
Lytic or lysogenic cycle
154
What is the lytic cycle?
When the virus will maximize the use of a host cell with no or little regards to the host cell survival. The cell will become swollen and will eventually lyse
155
What is the lysogenic life cycle?
When a virus will integrate a host cell genome as a provirus or prophage
156
What is a provirus or a prophage?
When a virus integrates the host cell genome, which is starting a lysogenic cycle
157
What are virus in the lytic life cycle called?
Virulent
158
What can cause the provirus to leave the genome and revert to a lytic cycle?
Environmental factors (radiation, light, chemicals)
159
What is an advantage of the lysogenic cycle?
The virus will be replicated as the bacteria reproduce
160
What could be the advantage for a bacteria to be in a lysogenic cycle?
The bacteria will be less susceptible to superinfection (simultaneous infections). The provirus will be relatively innocuous, this may confer an evolutionary advantage
161
What are sub viral particles that can cause diseases under certain circumstances?
Prions and viroids
162
What are prions?
Infectious proteins
They can cause disease by triggering misfiling of other proteins (usually through the conversion of alpha-helical structures to beta-pleated sheets.
This drastically reduces the proteins solubility and the ability of the cell to degrade the protein
The proteins will the aggragate interfering with the cell functioN
163
What are Viroids?
Viroids are short circular single-stranded RNA
They bind to a large number of RNA sequences and can silence genes, this prevents synthesis of necessary proteins
Can cause metabolic disruption and structural damage to the cell
164
Name an example of prions and of viroids?
Prions = mad cow disease
Viroids = hepatitis D virus
165
