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OAT- Biology > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

the nucleus

A

contains genome enveloped by the nuclear membrane. Where replication, transcription and splicing occur

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2
Q

the genome

A

organized into linear molecules of dsDNA in eukaryotes and sDNA in prokaryotes

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3
Q

the nucleolus

A

“little nucleus” functions as a ribosome factory, not separated from the nucleus.

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4
Q

nucleolus is composed of

A

loops of DNA, RNA, polymerase, rRNA and the protein components of the ribosome

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5
Q

the nucleolus is largest in cells that are producing large amounts of proteins (T/F)

A

True, the bigger the size the more synthesis of ribosomes

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6
Q

Site of transcription of rRNA byRNA pol I

A

nucleolus

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7
Q

where does all translation take place?

A

cytoplasm

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8
Q

nuclear envelopes is composed of

A

Two lipid bilayers, the inner nuclear membrane and the outer nuclear membrane

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9
Q

orientation of the nuclear envelope

A

the inner nuclear membrane faces the nuclear interior. Outer nuclear membrane faces the cytoplasm and is contiguous “sharing a common border” with the ER lumen

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10
Q

Nuclear envelope structure

A

punctuated w large nuclear pores to allow passage of materials in out of the nucleus. Molecules < 60 kilodaltons can freely diffuse

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11
Q

How do molecules larger than 60 kilodaltons enter the nucleus

A

if they contain the nuclear localization sequence (lysine rich)

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12
Q

mitochondria

A

site of oxidative phosphorylation. Singular circular DNA molecule, exhibits maternal inheritance

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13
Q

the matrix

A

interior of the mitochondria bounded by the inner and outer mitochondrial membrane. Contains pyruvate dehydrogenase and enzymes of the Krebs cycle

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14
Q

Krebs Cycle

A

location of the electron transport chain and ATP synthase

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15
Q

Endoplasmic reticulum (ER)

A

large system of folded membrane accounting for over half of the membrane of some cells

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16
Q

Plays a role in directing traffic to different parts of the cell

A

endoplasmic reticulum

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17
Q

Rough ER

A

site of protein synthesis for proteins targeted to enter the secretory pathway

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18
Q

Smooth ER

A

contains enzymes involved in steroid hormone biosynthesis (gonads) or degradation of environmental toxins (liver)

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19
Q

The two sites of proteins synthesis in eukaryotic cells

A

(1) ribosomes free in the cytoplasm (2) ribosomes bound to the surface of the rough ER

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20
Q

Destinations of ribosomes bound to the surface of the rough ER

A

(1) are secreted into extra cellular environment (2) integral membrane proteins (3) membrane interior of ER, Golgi or Lysosomes

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21
Q

the interior of the ER, Golgi apparatus, lysosomes and the extra cellular environment are not continuous (T/F)

A

false

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22
Q

Proteins start translation

A

in the cytoplasm

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23
Q

Signal recognition particle (SRP)

A

ER has SRP receptors which doc the complex and is pushed through the ER lumen and moved through the Golgi to the plasma and released by exocytosis

removed after translation and at the N-terminus

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24
Q

Transmembrane domains

A

sections of hydrophobic amino acid residues. threaded through the ER lumen during translation and undergoes secretory pathways.

not at the N-terminus and not removed after translations

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25
Q

ER functions

A

(1) initial post translational modification of proteins (2) some glycosylation (3) disulfide bond formation

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26
Q

glycosylation

A

addition of saccharides to proteins (usually in the Golgi)

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27
Q

Golgi Apparatus

A

(1) modification of proteins in the RER (2) sorting; sending proteins to their correct destinations (3) synthesizes certain macromolecules to secrete

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28
Q

the route taken by a protein once it leaves the trams face is determined by

A

signals within the protein

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29
Q

exocytosis

A

vesicles move from the Tran’s Golgi towards the cell surface, then fuses w/ the cell membrane and dumps its contents into the extracellular environment.

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30
Q

Endocytosis

A

materials are taken into the cell by an invagination of a piece of the cell membrane to form a vesicles (endosome)

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31
Q

three types of endocystosis

A

phagocytosis, pinocytosis, and receptor mediated endocytosis

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32
Q

phagocytosis

A

macrophages of the immune system

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33
Q

pinocytosis

A

cell drinking; nonspecific uptake of small molecules and extracellular fluid via vagination

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34
Q

receptor mediated endocytosis

A

very specific; the site is marked with clathrin (inside cell) and with receptors (outside cell)

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35
Q

constitutive secretory pathways

A

proteins sent in vesicles from the Golgi immediately to the cell surface through unregulated membrane fusion

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36
Q

regulated secretory pathways

A

specialized secretory cells (pancreatic cells, B- cells of the immune system) store secretory proteins in secretory vesicles and release them only at certain times, usually in response to change in the extracellular environment

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37
Q

lysosomes

A

membrane bound organelle that degradates biological molecules.

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38
Q

lysosomal proteins are made in the

A

RER and modified in the Golgi and releases from the trans face of the Golgi

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39
Q

Autophagy

A

self eating; organelles are degraded in lysosomes

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40
Q

phagocytosis

A

cell eating; degradation of large particulate matter engulfed by the cell

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41
Q

macrophages

A

from the immune system, engulf bacteria and viruses

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42
Q

crinophagy

A

lysosomal digestion of unneeded (excess) secretory products

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43
Q

after hydrolysis the lysosomes will

A

release molecular building blocks into the cytoplasm for reuse

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44
Q

degradation in lysosomes occurs due

A

to acid hydrolysis

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45
Q

acid hydrolysis

A

enzymes only hydrolyze substances when they are in an acidic environment

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46
Q

peroxisomes

A

contain enzymes that produce H2O2 which is converted into H2O + O2. Detoxify drugs and chemicals in the liver, protects the rest of the cell from damage by peroxides or oxygen radical

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47
Q

membrane structure

A

all membranes are composed of lipid bilayers. The 3 most found lipids are phospholipids, glycolipids, and cholesterol

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48
Q

fatty acid arrangement

A

hydrophilic head is facing outward and the hydrophobic tails facing inwards, away from the water

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49
Q

fatty acids arrrange in a lipid bilayer due to

A

steric hindrance. this arrangement allows them to reseal or repair any ruptured areas of the membrane

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50
Q

what molecules are not soluble in the plasma membrane

A

hydrophilic molecules (ions, carbohydrates & amino acids). This makes the membrane a barrier to these molecules

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51
Q

which molecules can cross the plasma membrane easily

A

non polar molecules ( CO2, O2 and steroid hormones)

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52
Q

how does water pass through the plasma membrane

A

through membrane specialized protein channels

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53
Q

what are big components of the membrane

A

proteins; they act to mediate interactions of the cell with other cells

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54
Q

cell- surface receptors

A

bind extracellular signaling molecules such as hormones and relay signals into the cell

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55
Q

channel proteins

A

selectively allow ions or molecules to cross the membrane

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56
Q

membrane proteins are classified as

A

either peripheral or integral

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57
Q

integral membrane proteins

A

are embedded in the membrane and held by hydrophobic interactions

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58
Q

membrane crossing regions are

A

transmembrane domains

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59
Q

peripheral membrane proteins

A

are not embedded in the membrane. They are stuck to integral membrane proteins, held by hydrogen bonding and electrostatic interactions

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60
Q

Fluid Mosaic model

A

lipids and proteins are free to diffuse laterally, in 2D but are not free to flip flop

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61
Q

what is a major determinante of plasma membrane fluidity

A

Van der Waals interactions between fatty acid side chains on the membrane

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62
Q

cholesterol plays a key role in

A

maintaining optimal membrane fluidity by fitting into the membrane interior

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63
Q

transmembrane transport

A

integral membrane proteins transport material through membranes that cannot diffuse on their own.

64
Q

two types of transport

A

passive (does not require cellular energy) and active (requires cellular energy)

65
Q

hypertonic solution

A

has more total dissolved solutes than the cell

66
Q

hypotonic

A

solution has less total dissolved solutes in the cell

67
Q

forms of passive transport

A

(1) simple diffusion (2) facilitated diffusion

68
Q

simple diffusion

A

diffusion of a solute through a membrane without help from a protein

69
Q

facilitated diffusion

A

movement of a solute across a membrane, down a concentration gradient with the help of a protein when the membrane is otherwise impermeable to solute

70
Q

two types of proteins involved in facilitated diffusion

A

channel and carrier proteins

71
Q

channel proteins

A

allow for facilitated diffusion by forming a narrow opening in the membrane surrounded by the protein. Channels are very selective

72
Q

ion channels

A

Are gated if the channel is open in response to specific environmental stimuli. Only involved in facilitated diffusion

73
Q

voltage- gated channel

A

opens in response to a change in the electrical potential accross the memebrane

74
Q

ligand-gated channel

A

opens in response to the binding of a specific molecule like a neurotransmitter

75
Q

Carriers

A

bind the molecule to be transported at one side of the membrane

76
Q

Uniports

A

Carry only one molecule

77
Q

Symports

A

Carry two molecules

78
Q

Antiports

A

Carry two molecules in opposite directions

79
Q

Pore

A

Tube through the membrane, large and non selective. All molecules below a certain size can pass through. Pores are formed by polypeptides known as porins.

80
Q

Which membrane does not contain pores

A

Eukaryotic plasma membrane. Pores destroy the barrier function.

81
Q

Active Transport

A

Movement of molecules through the plasma membrane against the gradient. Requires energy input usually thermodynamically favorable.

82
Q

Primary Active Transport

A

transport of a molecule coupled to ATP hydrolysis (release of ATP)

83
Q

Secondary active transport

A

Not coupled to ATP hydrolysis. ATP released in primary active transport is used to create a gradient an then the potential energy in the gradient is used to drive the transport of other molecules across the membrane.

84
Q

NaK/ATPase and the resting membrane

A

Transmembrane proteins in the plasma membrane of all cells in the body. Pumps out 3+ Na ; 2K+ in and hydrolyses one ATP to drive the pumping of these ions against their concentration gradients. Some potassium ions leak out of the cell through potassium leak channels.

85
Q

Resting membrane potential

A

As potassium leaves the cell the movement of positive charge out of the cells creates an electric potential across the plasma membrane with a net (-) charge on the inside of the cell

86
Q

Driving force behind secondary active transport of different molecules (sugars, amino acids)

A

Concentration gradient of high sodium outside the cell

87
Q

Catalytic receptors

A

have an enzymatic active site on the cytoplasmic side of the membrane. When a ligand binds at the extra cellular surface enzyme activity is initiated.

Usually behaves similar to a protein kinase; enzymes that covalently attach phosphate groups to proteins. (serine, threonine, tyrosine)

88
Q

G-protein linked receptor

A

does not directly transduce a signal. It transmit it into the cell with the aid of a second messenger

89
Q

The second messenger

A

relays instructions from the cell surface to enzymes in the cytoplasm

90
Q

The cytoskeleton

A

provides structural support. Allows for movement of the cells and its appendages (cilia & filaments).

91
Q

Animal cell’s internal cytoskeleton is composed of these proteins

A

Microtubules, Intermediate filaments & microfilaments

(all are composed of no covalently polymerized proteins)

92
Q

Microtubules

A

Hollow rod composed of gobular proteins: alpha tubulin and beta tubulin. Once formed the Microtubules can elongate by adding alpha-beta tubulin dimers to one end.

The other end cannot elongate because its anchored to the MTOC (nicrotubulue organizing center)

93
Q

Microtubules mediate what

A

transport of substances within the cell. Transport is driven by proteins that hydrolysis ATP and act as molecular motors along the Microtubules.

94
Q

Cilia and Flagella

A

Cilia are small hairs on the cell surface that move fluids past the cell surface.

Flagellum is a large tail which moves the cell by wiggling (the only human one is the sperm)

Both have 9+2 arrangement of Microtubules. Prokaryotic flagellum is different in structure and its motion is driven by a different mechanism.

95
Q

Intermediate Filaments

A

heterogeneous, composed of a wide range of polypeptides. They are more permanent and involved in providing strong cell structure, such as in resisting mechanical stress.

96
Q

Microfilaments

A

Rods formed in the cytoplasm from polymerization of the globular protein actin. Responsible for gross movements of the entire cell such as pinching the dividing parent cell into two daughters during cell division and amoeboid movement.

97
Q

Changes in the cytoplasmic structure which cause cytoplasm & the rest of the cell to flow in one direction.

A

Amoeboid movement

98
Q

Tight Junctions

A

form tight seal preventing items from moving freely between the intestinal lumen and the body

99
Q

Desmosomes

A

Intercellular junctions that provide strong adhesion between cells.

Do not form a seal, but merely hold cells together

100
Q

Gap Junctions

A

form pore-like connections between adjacent cells, allowing the two cells’ cytoplasma to mix. Permits exchange of solutes such as ions, amino acids and carbohydrates. NOT polypetides and organelles.

101
Q

Cells reproduce themselves by

A

first doubling everything in the cytoplasm and the genome and then split it in half

102
Q

S Phase (synthesis)

A

when the cell actively replicates its genome

103
Q

M Phase

A

Mitosis is the partitioning of cellular components into two halves.

104
Q

Prophase

A

genome becomes visible upon condensing into densely packed chromosomes. Nucleolus disappears, spindle & kinetochore fibers appear.

Centriole pairs begin to move to opposite ends of the cell. At the end of prophase the nuclear envelope converts itself into many tiny vesicles

105
Q

Metaphase

A

All the chromosomes line up at the center of the cell, forming the metaphase plate. They are pushed and pulled by the mitotic spindle.

106
Q

Anaphase

A

spindle fibers shorten, and the centromeres of each sister chromatid pair are pulled apart.

The cell elongates, and cytokinesis beings with the formation of a cleavage furrow.

107
Q

Telophase

A

nuclear membrane forms around the bunch of chromosomes at each end of the cell.

Chromosomes decondense and nucleolus becomes visible within each new daughter nucleus. Each daughter has n chromosomes

108
Q

Cytokines

A

physical process of cell division

109
Q

Interphase is made by

A

Gap phase and S phase

110
Q

The cell spends most its time in

A

Interphase. Some cells become permanently stuck in interphase (Go)

111
Q

During Interphase

A

the genome is spread out and is not visible. DNA is accessible to the enzymes replication.

112
Q

The more specialized the cell becomes

A

the less likely it is to remain capable of reproducing itself.

113
Q

Oncogenes

A

Inappropriate cell division and unregulated cell growth can cause disastrous consequences; like inducing cancer.

114
Q

Sister Chromatids

A

identical copies of chromosomes, attached to each other at the centromere.

115
Q

Homologous chromosomes

A

are equivalent but non identical and do not come anywhere near each other during mitosis.

116
Q

Karyotype

A

display of an organism’s genome

117
Q

Prokaryotes

A

do not contain membrane bound organelles. “before the nucleus”

Posses all the machinery required for life (unlike viruses).

True cells and true living organisms, bacteria, archea & blue-green algae

118
Q

Prokaryotic Genome is a

A

single-double stranded circular DNA chromosome

119
Q

What processes occur in the same pace in bacteria

A

transcription and translation. Ribosomes begin to translate mRNA before it’s completely transcribed.

elongation of mRNA proceeds 5’ to 3’

120
Q

Polyribosome

A

many ribosomes translating. Bacterial ribosome is structurally different from the eukaryotic ribosome, but both function in the same way.

121
Q

Plasmid

A

extra chromosomal genetic elements.

Encode gene products which may confer an advantage upon bacterium carrying the plasmid (antibiotic resistance)

Orchestrate bacterial exchange of genetic information; conjugation (allows for exchange of genetic information).

122
Q

The bacterial cell wall is composed of

A

peptidoglycan (a complex polymer unique to prokaryotes). Contains amino acid D-alanine which is not found in animal cells.

123
Q

Protoplast

A

a wall less vulnerable cell whose peptidoglycan has been destroyed by lysozyme

124
Q

Gram- Positive

A

stain strongly (dark purple) and have a thick peptidoglycan layer outside the cell membrane and no other layer

125
Q

Gram-Negative

A

stain weakly (light pink) have a thinner layer of peptidoglycan in the cell wall but have an additional layer containing lipopolysaccharides

126
Q

Capsule/Glycocalyx

A

sticky layer of polysaccharide surrounding the bacterial cell and often surrounding an entire colony of bacteria.

Makes bacteria more resistant to eradication from the immune system. Allows bacteria to adhere to smooth surfaces

127
Q

Flagella

A

involved in motility, only in bacteria. Can be either monotrichous (only located at one end) or amphitrichous (located at both ends) or peritrichous (have multiple flagella)

128
Q

Chemotaxis

A

Motion can be directed towards attractants, such as food, or away from toxins, such as acid.

129
Q

Chemoreceptors

A

bind attractants repellents and transmit a signal which influences the direction of flagellar motion.

This is not dependent on an absolute concentrations but to a change in the concentration over time

130
Q

Pili

A

Long projections on the bacterial surface involved in attaching to different surfaces

131
Q

Sex Pilus

A

special Pilus attaching F+ (male) and F- (female) bacteria that facilitates the formation of conjugation bridges.

132
Q

Fimbraie

A

smaller structures that are not involved in locomotion or conjugation but are involved in adhering to surfaces

133
Q

Mesophiles

A

moderate temperature lover (30C)

134
Q

Thermophiles

A

heat lovers (100C)

135
Q

Pyschrophiles

A

cold lovers (0C)

136
Q

Chemoautotrophs

A

build organic macromolecules from CO2 using energy of chemicals.

They obtain energy by oxidizing inorganic molecules like H2S.

137
Q

Chemo Heterotrophs

A

require organic molecules such as glucose made by other organisms as thei carbon source and for energy.

Humans are chemo heterotrophs

138
Q

Photoautotrophs

A

use only CO2 as a carbon source and obtain their energy from the sun (Plants)

139
Q

Photoheterotrophs

A

are odd in that they get their energy from the Sun, like plants, but require an organic molecule made by another organism as their carbon source

140
Q

Auxotroph

A

cannot survive on minimal medium because it can’t synthesize a molecule it needs to live. Requires an auxiliary trophies substance to live

141
Q

Obligate aerobes

A

bacteria that requires oxygen

142
Q

Anaerobes

A

bacteria that does not require oxygen

143
Q

Facultative anaerobes

A

will use oxygen when it’s around but don’t need it

144
Q

Tolerant anaerobes

A

can grow in the presence or absence of oxygen but do not use it in their metabolism

145
Q

Obligate anaerobes

A

are poisoned by oxygen. (commonly infect wounds)

146
Q

Binary Fission

A

Bacteria reproduce asexually. Each bacterium grows in size until it has synthesized enough cellular components for two cells rather than one|it then replicates it genome, then divides into two

147
Q

Log phase

A

bacteria grow exponentially

148
Q

Lag phase

A

bacteria that were not previously growing enter this phase and cell division does not occur even if the growth condition is ideal

149
Q

Stationary Phase

A

Once the medium is depleted the cells cease to divide and go into this phase

150
Q

if the environment is isotonic to the cell

A

the solute concentration is the same inside and outside

151
Q

Endospores

A

Have a though, thick external shell compromised of peptidoglycan.

152
Q

Germination

A

reactivation of an endospore

153
Q

How do bacteria aquire new genetic material

A

Transduction, transformation and conjugation

154
Q

Transduction

A

transfer of genomic DNA from one bacterium to another by lysogenis phase

155
Q

Transformation

A

if pure DNA is added to a bacterial culture, the bacteria internalize the DNA in certain conditions and gain genetic information in the DNA.

156
Q

Conjugation

A

bacteria make physical contact and form a bridge between cells.

157
Q

Hfr cell

A

a cell with the F factor integrated into its genome is considered a high frequency of recombination cell

OAT- Biology (10 decks)

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