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The cell Flashcards

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1
Q

Who was the first to look through a microscope?

A

Robert Hooke in 1665 (looked at a piece of cork)

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2
Q

Who was the first to view a living cell under a microscope?

A

Anton Van Leewenhock in 1674

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3
Q

Who was the first to say diseased cells came from normal cells?

A

Rudolph Virchow in 1850

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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

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5
Q

What is the point of membrane-bound organelles?

A

Compartmentalization of functions

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6
Q

What is the cell membrane made of

A

Phospholipid bilayer (hydrophilic surface and hydrophobic interior)

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7
Q

What is the role of the cytosol

A

Allow diffusion of molecules throughout the cell

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8
Q

What is the nucleus?

A

Contains all genetic material for replication

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9
Q

What’s surrounding the nucleus?

A

Double membrane nuclear membrane/envelope with nuclear pores

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10
Q

What is the role of nuclear pores?

A

Allows selective two-way exchange of material for the nucleus and the cytoplasm

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11
Q

What is called linear DNA

A

Histones

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12
Q

What is called linear DNA wound into linear strands?

A

Chromosomes

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13
Q

What is the nucleolus?

A

Where the rRNA (ribosomal) is synthesized (is about 25% of the nucleus)

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14
Q

What is the roles of the mitochondria?

A

Provide energy, could also kill the cell

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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

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16
Q

How many layers are in the mitochondria?

A

2

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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

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18
Q

What is the matrix?

A

Space into the inner membrane

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19
Q

What makes the mitochondria special?

A

It is semi-autonomous

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20
Q

What does being semi-autonomous means?

A

Contain some of their own genes and can replication independently

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21
Q

How could a mitochondria replicate independently?

A

Binary fission

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22
Q

What is extranuclear inheritance?

A

Transmission of genetic material independently of the nucleous (can also be called cytoplasmic)

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23
Q

What are lysosomes?

A

Sacs containing hydrolytic enzymes that can break down substrates

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24
Q

What can endosomes do?

A

Transport, package and sort cell material travelling to and from the membrane

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25
Q

Where can endosomes transport cellular material?

A

Transgolgi, cell membrane or the lysosomal pathway for degradation

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26
Q

What are the 2 organelles that can cause apoptosis?

A

Mitochondria and lysosomes

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27
Q

How could Lysosomes cause apoptosis?

A

Releasing of its enzymes, causing autolysis resulting in apoptosis

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28
Q

What is the definition of autolysis?

A

Degradation of cellular components

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29
Q

What are the 2 types of endoplasmic retinaculum?

A

Smooth and rough

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30
Q

What is the relation between the endoplasmic retinaculum contiguous with?

A

The nuclear envelope

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31
Q

What is the endoplasmic retinaculum?

A

A double membrane folded in numerous invaginations creating complex structures with a central lumen

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32
Q

What is the main difference between SER and RER other than their function?

A

RER had ribosomes

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33
Q

What is the RER function?

A

Translation of protein for secretion directly into its lumen

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34
Q

What is the SER function?

A

Lipid synthesis and transports proteins from RER to the Golgi apparatus

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35
Q

What can the SER synthesize?

A

Phospholipid membrane, drugs, poison

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36
Q

In what are the proteins transported from the RER to the Golgi apparatus?

A

Vesicules

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37
Q

What are the functions of the Golgi apparatus?

A

Modify and sort (and signal sequences)

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38
Q

What modification can the Golgi apparatus do?

A

Adding groups of carbohydrates, phosphates and sulfates

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39
Q

What is signal sequence?

A

Direct delivery of the product to a specific location

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40
Q

What can perixosomes do?

A

Break down long chains of fatty acids with beta-oxydation, participate in synthesis of phospholipids.

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41
Q

What perixosomes contains?

A

Hydrogen peroxide and some of the enzymes for the pentose phosphate pathway

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42
Q

What are the main functions of the cytoskeleton?

A

Structure and help the cell maintains its shape
Provide a conduit for transport around the cell

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43
Q

What are the components of cytoskeleton?

A

Microfilaments, microtubules and intermediate filaments

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44
Q

What are the microfilaments?

A

Solid polymerized rod of actin

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45
Q

What is the role of the microfilaments in mitosis?

A

Forms the cleavage furrow

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46
Q

What are microtubules?

A

Hollow polymers of tubular proteins

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47
Q

What are the 2 components of microtubules?

A

Cilia and flagella

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48
Q

What is the difference between cilia and flagella?

A

Cilia helps with movements throughout the surface of the cell while flagella helps with the cell mouvement itself

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49
Q

What are the 2 proteins that carry vesicles in microtubules?

A

kinesin and dynein

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50
Q

What is the primary pathway for kinesin and dynein to carry vesicles?

A

microtubules (radiate through the cell)

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51
Q

What is the name of the structure of cilia and flagella?

A

9+2 structure

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52
Q

What is the 9+2 structure

A

Structure of the flagella and the cilia

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53
Q

How are the cilia and flagella structured?

A

9 pairs of microtubules forming an outer ring with 2 microtubules in the center

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54
Q

What are the centrioles?

A

Organizing centers of microtubules

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55
Q

Where are the centrioles situated?

A

In the centrosome

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56
Q

What is the process of separating 2 sister chromatids?

A

Kinetochores

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57
Q

What can make kinetochores

A

Centrioles

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58
Q

What are intermediate filaments?

A

Diverse groups of filamentous proteins

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59
Q

What are the proteins in the intermediate filaments?

A

keratin, desmin, vimentin and lamins

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60
Q

What is the role of the intermediate filaments?

A

Help cell on cell adhesion, maintenance of the cytoskeleton and anchoring other organelles

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61
Q

What are the types of tissue?

A

Epithelial, connective, muscle and nervous

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62
Q

Where do you find epithelial tissue?

A

In the body cavities

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63
Q

What could be the roles of epithelial tissue?

A

Protection agains pathogen invasion, absorption, secretion and sensation

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64
Q

What is a basement membrane?

A

The underlying membrane out of which the epithelial tissue cells are all tightly joined together

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65
Q

What does the epithelial cells constitute in most organs?

A

Parenchyma or the functional part of the organ

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66
Q

What does it mean for an epithelial cell to be polarized?

A

One side faces a lumen and the other faces outside (i.e. underlying blood vessels and structural cells)

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67
Q

What are the types of epithelial cells according to their number of layers?

A

Simple epithelia (1 layer), stratified epithelia (multiple layers), pseudostratified epithelia (one layer of different sizes)

68
Q

What are the types of epithelial cells according to their shapes?

A

Cuboidal, columnar (long and thin) and squamous (flat)

69
Q

What is the function of connective tissue?

A

Supports (provide a framework for the epithelial cells to carry out their functions)

70
Q

What connective tissue contributes as in an organ usually?

A

The stroma or the support structure

71
Q

What are examples of connective tissue?

A

Bone, cartilage, tendons, ligaments, adipose tissue, blood

72
Q

What does most connective tissue cells produce and secrete?

A

collagen and elastin

73
Q

What is the extracellular matrix made of?

A

Collagen and elastin produced and secrete from connective tissue cells

74
Q

Where does the prokaryotes store their DNA and as what?

A

The nucleic region. It’s stored as a singular circular molecule of DNA

75
Q

What are the 2 types of prokaryotes?

A

Archaea and Bacteria

76
Q

What does is means to be extremophiles?

A

Found in extreme environment like extreme temperature, high salinity or no light

77
Q

What are archaea notable for?

A

Using alternate sources of energy (photosynthesis, chemosynthesis)

78
Q

What does it mean to be chemosynthetic?

A

Generate energy from inorganic compound

79
Q

What are 3 similarities between the Achaea and the eukaryotes?

A

Both starts translation with methionine, have a similar RNA polymerase and associate their DNA with histones

80
Q

Why could it be difficult to develop medicine that targets only bacteria?

A

Because bacteria and eukaryotes still share analogous structures

81
Q

What are the 2 types of bacteria according to their interactions with us?

A

Mutualistic symbiotes and pathogens/parasites

82
Q

What does it mean to be in a mutualistic symbiote?

A

The relationship is beneficial for both parties

83
Q

Pathogenic bacteria lives intra ou extracellularly?

A

They can be both

84
Q

What are the 3 shapes of bacteria?

A

Cocci, bacilli, spirilli

85
Q

What are the types of relations a bacteria can have with oxygen?

A

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
Q

What does prokaryotes being single celled organisms invokes?

A

Each cell must be able to perform every function on its own

87
Q

What is made of the envelope of a prokaryote?

A

The cell wall (outer barrier) and the cell membrane (or plasma membrane composed of phospholipids)

88
Q

What are the function of the cell wall?

A

Structure and controls of mouvements from inside to outside the cell

89
Q

What are the types of cell wall?

A

Gram + and Gram -

90
Q

What are the coloration of different cell walls in a gran staining process?

A

Gram + is mauve and Gram - is pink

91
Q

What are the differences between Gram + and Gram - cell walls?

A

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
Q

What separates both the 2 barriers of the Gram - cell wall?

A

The periplasmic space

93
Q

Which Gram cell wall creates the bigger immune system reaction to the human?

A

Lipopolysaccharides

94
Q

What is the function of the flagella?

A

Propulsion

95
Q

What is a particularity of the prokaryote’s cell flagella?

A

Is chemotaxis, which means it has the ability to detect chemical stimuli and move towards or away them

96
Q

What is chemotaxis?

A

Having the ability to detect chemical stimuli and move towards or away them

97
Q

What are the parts of the flagella of a prokaryotes?

A

The filament, the basal body and the hook

98
Q

What is compose the filament in the flagella?

A

Flagellin

99
Q

Which of the flagella parts is the motor?

A

Basal body

100
Q

What is the hook role in the flagella?

A

It connects the filament to the basal body making them move together

101
Q

What is a plasmid?

A

Small and circular structure where DNA acquired from external sources that is kept

102
Q

What is the advantage for prokaryotes in having a plasmid?

A

Antibiotic resistance

103
Q

How does the prokaryote live without a mitochondria?

A

The electron transport chain and the generation of ATP is made from the cell membrane

104
Q

Does the prokaryotes have a cytoskeleton?

A

It has a primitive cytoskeleton, but not as advance as the eukaryotes

105
Q

Do prokaryotes have ribosomes?

A

Yes

106
Q

What is the difference between the prokaryotes and eukaryotes ribosomes?

A

The size (prokaryotes = 30S and 50S subunits and eukaryotes = 40S and 60S subunits)

107
Q

Do the prokaryotes has a cytoplasm?

A

Yes

108
Q

How does prokaryotes reproduces?

A

Via binary fission, an asexual reproduction

109
Q

What is the process of binary fission?

A

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
Q

What is the subset of plasmids?

A

Episomes

111
Q

What are episomes?

A

A subset of plasmids that can integrate into the genome of the bacteria

112
Q

What are the 3 recombination processes?

A

Transformation, conjugation and transduction

113
Q

What advantage brings genetic recombination to bacterias?

A

Helps increase bacteria diversity and permits evolution

114
Q

What is the process of transformation?

A

Integration of foreign genetic material into the host genome

115
Q

What type of bacteria are usually able to do transformation?

A

Gram -

116
Q

What is the process of conjugation?

A

Bacterial form of sexual reproduction, in which a conjugation bridge is formed between 2 cells to facilitate transfer of genetic material

117
Q

What is the direction ofconjugeation?

A

Unidirectional, from the male donor (+) to the recipient female (-)

118
Q

What is the sex factor in conjugation?

A

Plasmids

119
Q

What is the conjugation bridge made from?

A

Sex pili from the male donor

120
Q

What happens if the plasmid gets integrated in the host genome for conjugation?

A

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
Q

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?

A

Hfr for High Frequency of Recombination

122
Q

What is transduction and its process?

A

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
Q

What are transposons?

A

Genetic elements that are capable of inserting and removing themselves from the genome

124
Q

Are transposons limited to prokaryotes?

A

No, it has been seen in eukaryotes as well

125
Q

What is the bacterial growth in a new environment like?

A

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
Q

What are viruses composed of?

A

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
Q

How are genetic information stored as in a virus?

A

Can be circular or linear, can be single or double stranded and composed of CNA or RNA

128
Q

How come viruses with an envelope are usually easier to kill?

A

Because the envelope is very sensitive to heat, detergents and dessication

129
Q

What do we call viruses since they can’t reproduce independently?

A

Obligate intra-cellular parasites

130
Q

Why are viruses obligate intra-cellular parasites?

A

Because they lack ribosomes to carry out protein syntheses, so they need to express and replicate their genetic information within a host cell

131
Q

What are virions?

A

Viral progeny produced by a virus once it has hijack a cell’s machinery

132
Q

How does bacteriophage infect bacteria?

A

They stay on the outside and inject their genetic material

133
Q

What are the tail sheath and the tail fibers?

A

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
Q

What are the 2 types of singele-stranded ARN viruses? What does they mean?

A

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
Q

What are retroviruses?

A

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
Q

What makes the retroviruses so hard to treat?

A

Since they have integrated the host genome, the only way to remove the infection is to kill the cell

137
Q

Name an example of retrovirus?

A

HIV

138
Q

What are the 2 proteins to which the HIV must bind to on the surface of the cell?

A

CD4 or CCR5

139
Q

Which viral enzyme inserts the DNA just made into the host DNA in a viral infection?

A

Integrase

140
Q

Can viruses infect any cell they want?

A

No they need to bind to a specific receptor on the surface of the cell

141
Q

What are ways a virus can enter a host cell during infection?

A

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
Q

What can a tail fibre with an enzymatic activity could do to the bacteria membrane?

A

Allow penetration and formation of pores in the cell membrane also

143
Q

What must be done in order for reproduction of the viruses?

A

Translation of viral genetic material

144
Q

Where are virus DNA transcribed in a host cell?

A

In the nucleus

145
Q

What happens to positive-sense RNA in the host cell?

A

It stays in the cytoplasm and can be directly translated into protein by the ribosomes

146
Q

What happens to negative-sense RNA in the host cell?

A

Needs synthesis of a complimentary RNA strand via RNA replicase which can then be translated to form proteins

147
Q

What are used to translate viral RNA into protein?

A

Ribosomes, tRNA, amino acids and enzymes of the host cell

148
Q

What are usually the proteins translated from viral RNA?

A

Structural capsid proteins, which allows the creation of new virions in the cytoplasm of the host cell

149
Q

What needs to be done to the viral genome to be packed within the virions capsids?

A

It needs to be returned to its original form

150
Q

How can the viral progeny (virions) be released from the host cell?

A

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
Q

What is extrusion?

A

When a virus leaves the host cell by fusing with the plasma membrane

152
Q

What is a virus in a productive cycle?

A

When the host cell is still alive and allows for the continued use of the host cell by the virus

153
Q

What are the 2 life cycle a bacteriophage may enter?

A

Lytic or lysogenic cycle

154
Q

What is the lytic cycle?

A

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
Q

What is the lysogenic life cycle?

A

When a virus will integrate a host cell genome as a provirus or prophage

156
Q

What is a provirus or a prophage?

A

When a virus integrates the host cell genome, which is starting a lysogenic cycle

157
Q

What are virus in the lytic life cycle called?

A

Virulent

158
Q

What can cause the provirus to leave the genome and revert to a lytic cycle?

A

Environmental factors (radiation, light, chemicals)

159
Q

What is an advantage of the lysogenic cycle?

A

The virus will be replicated as the bacteria reproduce

160
Q

What could be the advantage for a bacteria to be in a lysogenic cycle?

A

The bacteria will be less susceptible to superinfection (simultaneous infections). The provirus will be relatively innocuous, this may confer an evolutionary advantage

161
Q

What are sub viral particles that can cause diseases under certain circumstances?

A

Prions and viroids

162
Q

What are prions?

A

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
Q

What are Viroids?

A

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
Q

Name an example of prions and of viroids?

A

Prions = mad cow disease
Viroids = hepatitis D virus

165
Q
A

MCAT - Biology (12 decks)

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