Biology Chapter 1 Flashcards
(145 cards)
1
Q
Robert Hooke
A
first compound microscope
2
Q
Anton van Leeuwenhoek
A
first to view living cell
3
Q
Rudolph Virchow
A
demonstrated that diseased cells could arise from cells
4
Q
4 tenets of cell theory
A
- all living things are composed of cells
- the cell is the basic functional unit of life
- cells arise only from preexisting cells
- cells carry genetic information in the form of DNA. this genetic material is passed on from parent to daughter cell
5
Q
are viruses living organisms?
A
no, because violates 3rd and 4th tenets of cell theory
- unable to reproduce on their own
6
Q
prokaryotic cell characteristics
A
- always single-celled
- do not contain a nucleus
7
Q
eukaryotic cell characteristics
A
- can be unicellular or multicellular
- contains a true nucleus enclosed in a membrane
8
Q
nucleus
A
- contains all of the genetic material necessary for cell replication
- surrounded by nuclear membrane/envelope (double membrane) containing nuclear pores
- nucleoulus
9
Q
nuclear pores
A
allow selective two-way exchange of material between cytoplasm and nucleus
10
Q
nucleolus
A
- subsection of nucleus
- synthesizes RNA
- takes up 25% of nucleus
- darker spot in nucleus is identifier
11
Q
mitochondria
A
- performs important metabolic functions
- semi-autonomous
- can initiate apoptosis
12
Q
two layers of the mitochondria
A
- outer membrane
- inner membrane
13
Q
how is the inner membrane arranged?
A
into cristae formation
14
Q
intermembrane space
A
space between inner and outer membranes
15
Q
mitochondrial matrix
A
space inside inner membrane
16
Q
lysosomes
A
- contains hydrolytic enzymes capable of breaking down substrates
- functions in conjunction with endosomes
- when releasing endosomes, initiates autolysis/apoptosis
17
Q
endosome
A
transports, packages, and sorts cell material traveling to and from membrane
18
Q
endoplasmic reticulum (ER)
A
series of interconnected membranes that are in sequence with the nuclear envelope
19
Q
rough ER functions
A
permits translation of proteins directly into lumen
20
Q
smooth ER
A
- primarily used for lipid synthesis
- detoxifies certain drugs and poisons
- transports proteins from RER to golgi apparatus
21
Q
golgi apparatus
A
- consists of stacked membrane-bound sacs
- modifies materials by addition of groups
- also modifies cellular products through introduction of signal sequences
22
Q
peroxisomes
A
- contain hydrogen peroxide
- primarily breaks down very long chain fatty acids via beta-oxidation
- participates in synthesis of phospholipids
- contains some of the enzymes involved in the pentose phosphate pathway
23
Q
cytoskeleton
A
- provides structure to cells and helps cells maintain shape
- provides conduit for transport of materials around cells
24
Q
3 components of cytoskeleton
A
- microfilaments
- microtubules
- intermediate filaments
25
microfilaments
- made up of solid polymerized rods of actin
26
actin filaments
- organized into bundles and networks
- resistant to both compression and fracture (provides protection to cell)
- can also use ATP to generate force for movement by interacting with myosin
27
How do actin filaments play a role in cytokinesis?
cleavage furrow is formed from microfilaments
28
microtubules
- hollow polymers of tubulin proteins
- provides primary pathways along which motor proteins carry vesicles
- contained inside motile structures (ex: cilia, flagella)
29
cilia
primarily involved in the movement of materials along the surface of the cell
30
flagella
involved in the movement of the cell itself
31
What structure do microtubules form within cilia and flagella?
9+2 structure (seen only in eukaryotic organelles of motility)
32
bacterial flagella have a different structure with a different chemical composition than eukaryotic flagella
True
33
____ are the organizing centers for microtubules
centrioles
34
Where are centrioles found?
in the centrosome regin of the cell
35
intermediate filaments
- diverse grou pof filamentous proteins
- involved in cell-cell adhesion or maintenance of overall itegrity of cytoskeleton
- able to withstand a tremendous amount of tension
- helps anchor other organelles
36
identity of the intermediate filament proteins within a cell is specific to the cell and tissue type
True
37
prokaryotic cells are unique in the formation of tissues with division of labor
False, eukaryotic cells are
38
4 types of tissues
- epithelial
- connective
- muscle
- nervous
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epithelial tissue locations
- covers the body and lines its cavities
- tightly joined to each other and to an underlying layer of connective tissue to remain as one cohesive unit
- in most organs, epithelial cells constitute the parenchyma
- often polarized
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epithelial tissue functions
- provides protection against pathogen invasion and desiccation
- in certain organs, involved in absorption, secretion, and sensation
- highly diverse and serve numerous functions depending on organ in which they are foun
41
epithelial tissue layer classification
- simple epithelia: have one layer
- stratified epithelia: have multiple layers
- pseudostratified epithelial: appear to have multiple layers due to cell height different but actually one
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epithelial tissue shape classification
- cuboidal cells: cube-shaped
- columnar cells: long and thin
- squamous cells: flat and scale-like
43
parenchyma
functional parts of the organ
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polarized
one side faces lumen while other side interacts with underlying blood vessels and structural cells
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connective tissue
- supports body
- provides framework for the epithelial cells to carry out their functions
- main contributors to stoma or support structure
- most cells produce and secrete materials to form the extracellular matrix
46
prokaryotes
- simplest of all organisms
- includes all bacteria
- does not contain any membrane-bound organelles
47
How does the genetic material for prokaryotes look like?
organized into a single circular molecule of DNA concentrated in nucleoid region
48
3 overarching domains into which all life is classified
- archaea
- bacteria
- eukarya
49
archaea
- single-celled organisms that are visually similar to bacteria but mechanically more similar to eukaryotes
- considered extremophiles but found in a greater variety of habitats
- are resistant to many antibiotics
50
Ways archaea is similar to eukaryotes
- start translation with methionine
- contain similar RNA polymerases
- associate their DNA with histones
51
Ways that archaea is different from eukaryotes
- contain a single circular chromosome
- divide by binary fission or budding
- share a similar overall structure to bacteria
52
All bacteria contain
- cell membrane
- cytoplasm
- flagella
- fimbriae (similar to cilia)
53
Why can it be difficult ot develop medicines that target only bacteria?
bacteria and eukaryotes often share analogous structures
54
Bacteria relationships to humans
- some are mutualistic
- others are pathogens, parasites
55
3 shapes of bacteria
- cocci: spherical
- bacilli: rod-shaped
- spirilli: spiral-shaped
56
obligate aerobes
bacteria that require oxygen for survival
57
anaerobes
bacteria that use fermentation or some other form of cellular metabolism that does not require oxygen
58
obligate anaerobes
anaerobes that cannot survive in an oxygen-containing environment
59
facultative anaerobes
bacteria that, when there is oxygen, use aerobic metabolism
- if not, then use anaerobic metabolism
60
aerotolerant anaerobes
bacteria that are unable to use oxygen for metabolism but are not harmed by its presence in the environment
61
envelope (in terms of prokaryotes)
contain a cell wall then a cell membrane
62
cell wall
- provides both structure and controls the movement of solutes into and out of bacterium
- aids bacterial pathogens by providing protection from host organism's immune system
63
How are the 2 main types of cell wall classified?
determined by Gram staining process
- if envelope absorbs the crystal violet stain, it will appear deep purple (gram positive)
- if envelope does not absorb the crystal violet stain but rather the safranin counterstain, the cell wall will appear pink-red (gram negative)
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2 main types of cell wall
- gram positive
- gram negative
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gram positive cell wall
- consists of a thick layer of peptidoglycan
- also contains lipoteichoic acid
66
Gram negative
- cell walls are very thin and also contain peptidoglycan but in smaller amounts
- contains outer membranes containing phospholipids and lipopolysaccharides
67
lipopolysaccharides
part of gram-negative bacteria that triggers an immune response in human beings
- much stronger inflammatory response than to lipoteichoic acid
68
flagella
- long, whip-like structures that can be used for propulsion
- can be used to move toward food or away from toxins or immune cells
- bacteria may have one or multiple
69
chemotaxis
ability of a cell to detect chemical stimuli and move towards or away from them
70
What do flagellas consist of?
- filament
- basal body
- hook
71
filament
hollow, helical structure composed of flagellin
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basal body
complex structure that anchors flagellum to cytoplasmic membrane
- also motor of flagellum
73
hook
connects filament to basal body so as basal body rotates, it exerts torque on filament
- spins and propels basal body forward
74
plasmids
smaller circular structures that carry DNA that is not necessary for survival of prokaryotes but can offer advantages such as antibiotic resistance
75
prokaryotes lack several key organelles
True
- so the cell membrane is used for the ETC and generation of ATP
76
prokaryotes have a more complex cytoskeleton than eukaryotes
False, eukaryotes are more complex
77
Do prokaryotes also contain ribosomes?
Yes, but they are different sizes from eukaryotic ribosomes
78
binary fission
- simple form of asexual reproduction seen in prokaryotes
- proceeds more rapidly than mitosis
79
How does binary fission work?
- circular chromosome attaches to cell wall and replicates while cell continues to grow in size
- plasma membrane and cell wall begin to grow inward along midline of cell to produce two identical daughter cells
80
genetic recombination
- helps increase bacterial diversity and permits evolution of a bacterial species over time
- can be through plasmids, virulence factors, episomes
81
virulence factor
traits that increase pathogenicity
82
episomes
subset of plasmids that are capable of integrating into the genome of bacterium
83
3 examples of genetic recombination
- transformation
- conjugation
- transduction
84
transformation
- results from integration of foreign genetic material into the host genome
- material mostly comes from other bacteria -> upon breaking -> spilling contents into vicinity of a bacterium capable of transformaiton
- many gram-negative rods are able to carry out process
85
conjugation
- bacterial form of mating
- involves two cells forming a conjugation bridge between them
- transfer is unidirectional (from donor male (+) to recipient female (-)
86
conjugation bridge
- made from appendages called sex pili (found on donor male)
- to form pilus, bacteria must contain plasmids known as sex factors (contain necessary genes)
87
best studied sex factor
F (fertility) factor
- bacteria possessing plasmid are termed F+ cells; those without are termed F- cells
88
F factor during conjugation
- F+ cell replicates its F factor and donates copy to F- cell, converting it to an F+ cell
- allows cell obtaining the new plasmid to then transfer copies to other cells
89
Hfr (high frequency of recombination)
- through transformation, ex factor plasmid can become integrated into host genome
- when conjugation occurs, entire genome replicates because it now contains sex factor
- donor cell will then attempt to transfer entire copy of its genome into recipient but bridge usually breaks before full DNA is moved
90
transduction
only genetic recombination process that requires a vector
- viruses are obligate intracellular pathogens; because of this, bacteriophages can accidentally incorporate a segment of host DNA during assembly
- when bacteriophage infects another bacterium, can release this trapped DNA into new host cell
- this transferred DNA can then integrate into the genome, giving new host additional genes
91
vector
virs that carries genetic material from one bacterium to another
92
obligate intracellular pathogens
cannot reproduce outside of a host cell
93
bacteriophage
viruses that infect bacteria
94
transposons
- genetic elements capable of inserting and removing themselves from the genome
- if a transposon is inserted within a coding region of a gene, that gene may be disrupted
95
transposons are limited to prokaryotes
False, also seen in eukaryotes
96
All bacteria are exactly the same in a local colony due to binary fission reproduction
True, assuming no mutations, genetic recombination, or that no bacteria are dividing faster than others
97
phases of bacteria growth
- lag phase
- exponential phase/log phase
- stationary phase
- death phase
98
lag p ahse
in a new environment, bacteria first adapt to the new local conditions
99
exponential phase/log phase
as bacteria adapt, the rate of division increases, causing exponential increase in number of bacteria in colony
100
stationary pahse
as number of bacteria in colony grows, resources are often reduced, which slows reproduction
101
death phase
after bacteria have exceeded ability of environment ot support number of bacteria, phase occurs, marking depletion of resources
102
What do viruses lack?
organelles and a nucleus
103
What do viruses consist of?
- genetic material
- protein coat
- sometimes envelope containing lipids
104
There's a diversity to the genetic information viruses contain
True, genetic material can be circular or linear, single- or double-stranded, DNA or RNA
105
capsid
the protein coat of viruses
106
What are the envelopes that sometimes surround the capsid composed of?
composed of phospholipids and virus-specific proteins
107
Viruses with envelopes are often easier to kill
True, because they are sensitive to heat, detergents, and desiccation
108
Viruses are considered ____ _______ ______ because they cannot reproduce on its own
obligate intracellular parasites
109
virions
viral progeny
110
What do bacteriophages have additionally in terms of structure?
- tail sheath
- tail fibers
111
tail sheath
acts like a syringe and injects genetic material into bacterium
112
tail fibers
helps bacteriophages recognize and connect to correct host cell
113
How do bacteriophages infect bacteria?
inject genetic material with structure outside bacteria
- does not enter
114
Two types of single-stranded RNA viruses
- positive sense
- negative sense
115
positive sense single-stranded RNA viruses
genome may be directly translated to functional proteins by the ribosomes of the host cell
116
negative sense single-stranded rNA viruses
- act as a template for synthesis of a complementary strand (then can be used as a template for protein synthesis)
- must carry rNA replicase in the virion to synthesize complementary strands
117
retroviruses
- enveloped, single-stranded RNA viruses that allow cell to be infected indefinitely
118
Why do retroviruses cause indefinite infection?
- viruses carry enzymes known as reverse transcriptase which synthesizes DNA from single-stranded RNA
- DNA is then integrated into host cell genome where it is replicated and transcribed as if it were host cell's own DNA
119
What is an example of a retrovirus?
HIV
120
The virion of a retrovirus has two identical RNA molecules
True
121
viruses can only infect a specific set of cells
True
122
enveloped viruses ____ host cell
enter
123
bacteriophages enter host cell
False, just inject
124
What must occur after viral infection for viruses to reproduce?
translation of viral genetic material
125
where do DNA viruses enter to be transcribed to mRNA?
nucleus
126
Where does the viral mRNA go to be translated into protein?
cytoplasm
127
Where does genetic material from positive-sense RNA viruses go?
stays in cytoplasm
128
Where does DNA formed from retroviruses go?
nucleus to be incorporated into host genome
129
What enzyme is needed to form complementary viral RNA strands?
RNA replicase
130
Viral genome must be returned to its original form before packaging
True
131
ways that viral progeny may be released
1. viral invasion may initiate cell death -> spilling of viral progeny
2. host cell may lyse (disadvantage for viruses)
3. extrusion
132
extrusion
virus leaving cell by fusing with cell's plasma membrane
133
productive cycle
virus in state after extrusinon
- host cell is alive
134
lytic cycle
bacteriophage maximized use of cell's machinery with little regard for survival of host cell
- cell lyses and other bacteria can be infected
135
virulent
viruses in the lytic phase
136
lysogenic cycle
virus may integrate int o host genome as a provirus or prophage (now part of host's genome)
- does not lyse bacterium
137
Integration of phage into host genome may actually benefit the bacterium
True, less susceptible to superinfection
138
superinfection
simultaneous infection with other phages
139
prions and viroids are subviral particles
true
140
prions
infectious proteins that cause disease by triggering misfolding of other proteins
141
what do prions do
convert alpha-helical structures of proteins to beta-pleated sheets
142
what is caused by prions?
reduces solubility of protein as well as ability of cell to degrade proteins
- proteins then aggregate and interferes with cell function
143
viroids
small pathogens consisting of very short circular single-stranded RNA that infect plants
144
what do viroids do?
bind to a large number of rNA sequences and silences genes in the plant genome
- prevents synthesis of necessary proteins
145
what is caused by viroids?
metabolic disruption and structural damage to the cell
