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concept 2b Flashcards

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1
Q

cell theory

A
  1. all living things are composed of cells
  2. the cell is the basic functional unit of life
  3. cells arise only from preexisting cells
  4. cells carry genetic information in the form of DNA. this genetic material is passed on from patron to daughter cell
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2
Q

eukaryotic cells

A

contain a true nucleus enclosed in a membrane
organisms can be unicellular or multicellular
contain many organelles in the cells
reproduce by mitosis allowing the formation of 2 identical daughter cells

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3
Q

prokaryotic cells

A

do not contain a nucleus

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4
Q

nucleus

A

control center of the cells
contains genetic material encoded in DNA, organized into chromosomes
surrounded by the nuclear membrane (envelope)

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5
Q

nuclear pores

A

in the nuclear membrane

allow for selective 2-way exchange of material b/w the cytoplasm and the nucleus

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6
Q

nucleolus

A

subsection of the nucleus
synthesizes rRNA
about 25% of the volume of the entire nucleus and can often be identified as a darker spot in the nucleus

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7
Q

mitochondria

A

power plants of the cell
important in metabolic functions
contains 2 membranes, inner and outer
contain some of their own genes and replicate independently of nucleus via binary fission
capable of killing cell by release of enzymes from ETC to kickstart apoptosis

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8
Q

mitochondrial matrix

A

space inside the inner membrane
pumping of protons from the matrix to the inter membrane space (out of the matrix) establishes the proton-motive force, protons then flow through ATP synthase to generate ATP during oxidative phosphorylation

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9
Q

lysosomes

A

membrane-bound organelle

contain hydrolytic enzymes that are capable of breaking down many different substrates

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10
Q

autolysis

A

process of release of lysosome enzymes
results in apoptosis
release of enzymes directly lead to degradation of cellular components

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11
Q

endoplasmic reticulum

A

interconnected membranes that are continuous with the nuclear envelope
folded into numbers invaginations creating complex structures w/ a central lumen
2 varieties: smooth and rough

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12
Q

rough ER

A

studded with ribosomes

site of protein translation that are destined for secretion directly into lumen

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13
Q

smooth ER

A

lacks ribosomes
utilized for lipid synthesis and detoxification of certain drugs and poisons
transports proteins from the RER to the Golgi apparatus

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14
Q

Golgi apparatus

A

consists of stacked membrane-bound sacs
modifies, sorts, and repackages, and transferred to correct cellular location in vesicles
materials are transferred from the ER to the Golgi and vesicles

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15
Q

peroxisomes

A

contain hydrogen peroxide
primary function is the breakdown of long chain fatty acids via beta-oxidation
participate in the synthesis of phospholipids and contain some of the enzymes involved in pentose phosphate pathway

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16
Q

cytoskeleton

A

provides structure to the cell and help it to maintain its shape
provides a pathway for the transport of material around the cell
3 components: microfilaments, microtubules, and intermediate filaments

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17
Q

microfilaments

A

made up of polymerized rods of actin
actin filaments are organized in bundles and networks that provide protection for the cell
role in cytokinesis, division of materials b/w daughter cells, during mitosis the cleavage furrow is formed from microfilaments

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18
Q

microtubules

A

hollow polymers of tubular proteins
provide primary pathway along witch motor proteins like chines and dyne carry vesicles
cilia and flagella are motile structures composed of microtubules

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19
Q

cilia

A

projections from a cell that are primarily involved in moment of materials along the surface of the cell
one projection
made up of microtubules

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20
Q

flagella

A

structures involved in movement of the cell itself
multiple small, hairlike projections
made up of microtubules

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21
Q

centrioles

A

found in centrosome
organizing centers for microtubules
structured as 9 triplets of microtubules with hollow center
migrate to opposite poles of dividing cell in mitosis and microtubules originate from these and attach to chromosomes at the kinetochores

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22
Q

intermediate filaments

A

diverse group of filamentous proteins, including keratin and desmin
involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton
able to withstand a lot of tension making the cell structure more rigid
help to anchor other organelles

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23
Q

tissue types

A

epithelial tissue
connective tissue
muscle tissue
nervous tissue

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24
Q

epithelial tissue

A

cover the body and line its cavities
means for protection against pathogen invasion and desiccation
involved in absorption, secretion, and sensation
tightly joined to each other and to an underlying layer of connective tissue
tissues are diverse and serve numerous functions depending on the identity of the organ
often polarized, one side faces a lumen or outside world and other interacts w/ blood vessels and structural cells

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25
parenchyma
the functional parts of the organ | in most organs this constitutes as epithelial cells
26
classes of epithelial cells by # of layers
simple epithelia: single layer of cells stratified epithelia: multiple layers of cells pseudo-stratified epithelia: appear to have multiple layers due to differences in cell height but only have one layer
27
classes of epithelia cells by shape
cuboidal: cells are cube shaped columnar: cells are long and thin squamous: cells are flat and scalelike
28
connective tissue
supports the body and provides framework for the epithelial cells to carry out their functions main contributors to the stroma (support structure) most cells produce and secrete materials to form the extracellular matrix, like collagen and elastin exp of connective tissues: bone, cartilage, tendons, ligaments, adipose tissue, and blood
29
binary fission
simple form of asexual reproduction seen in prokaryotes circular chromosome attaches to the cell wall and replicates while cell grows in size plasma membrane and cell wall grow inward at midline to produce 2 daughter cells requires fewer steps than mitosis and is more rapid
30
plasmids
extrachromosomal material in bacteria carry genes that impart some benefit to bacterium, antibiotic resistance may also carry virulence factors
31
virulence factors
traits that increase how pathogenic a bacterium is toxin production, projections that allow the bacterium to attach to certain kinds of cells, or evasion of the host's immune system contained in plasmids
32
episomes
subset of plasmids | capable of integrating into the genome of the bacterium
33
bacterial genetic recombination
helps increase bacterial diversity permits evolution of a bacterial species over time process includes transformation, conjugation, and transduction
34
transformation
results from integration of foreign genetic material into the host genome foreign genetic material comes from other bacteria that spills their contents in the vicinity of a bacterium capable of transformation
35
conjugation
bacterial form of mating (sexual reproduction) 2 cells form a conjugation bridge that allows for the transfer of genetic material transfer is unidirectional from the donor male (+) to the recipient female (-) made from sex pili found in donor male
36
transduction
only genetic recombination process that requires a vector | transposition of genetic material from one organism to another by a virus
37
vector
a virus that carries genetic material from one bacterium to another
38
transposons
genetic elements capable of inserting and removing themselves from the genome not limited to prokaryotes, has been seen in eukaryotes if transposon is inserted within a coding region of the gene it may be disrupted
39
growth of bacteria
reproduce via binary fission | growth in a series of phases: lag phase, exponential (log) phase, stationary phase, and death phase
40
lag phase
in new environment bacteria first adapt to new local conditions during this phase
41
exponential phase
as bacteria adapt, growth increases, causing an exponential increase in the number of bacteria in the colony aka log phase
42
stationary phase
as # of bacteria in colony grows, resources are often reduced reduction of resources slows reproduction and this phase results no more growth in bacteria
43
death phase
occurs as resources in the environment have been depleted | after bacteria have exceeded the ability of the environment to support the number of bacteria
44
virus structure
composed of genetic material, a protein coat, and sometimes an envelope w/ lipids have a tail sheath and tail fibers
45
virus genetic information
may be circular or linear single or double stranded composed of DNA or RNA
46
capsid
the protein coat surrounding a virus
47
lipid envelope of a virus
it surrounds the capsid and composed of phospholipids and virus-specific proteins very sensitive to heat, detergents, and desiccation enveloped viruses are easier to kill viruses w/out and envelope are more resistant to sterilization and likely to persist on surfaces for extended periods of time
48
virus reproduction
cannot reproduce independently, considered obligate intracellular parasites must express and replicate genetic info within a host cells bc they lack ribosomes to carryout protein synthesis once they take of cell's machinery the virus will replicate and produce viral progeny (virions) which can be released to infect additional cells
49
virus structure
composed of genetic material, a protein coat, and sometimes an envelope w/ lipids
50
bacteriophages
viruses that specifically target bacteria do not enter bacteria but inject their genetic material in addition to a capsid they have a tail sheath and tail fibers
51
tail sheath
can act like a syringe | injects genetic material into a bacterium
52
tail fibers
help the bacteriophage to recognize and connect to the correct host cell
53
single-stranded RNA viruses
may be positive sense or negative sense | virus genetic information is single stranded RNA
54
positive sense
implies that the genome may be directly translated to functional proteins by the ribosomes of the host cells
55
negative sense
more complicated than positive sense these viruses require synthesis of an RNA strand complementary to the negative-sense RNA strand this strand can be used as a template for protein synthesis may carry RNA replicase in the virion to ensure that the complementary strand is synthesized
56
retroviruses
enveloped, single stranded RNA viruses virion contains 2 identical RNA molecules carry enzyme reverse transcriptase which synthesizes DNA from single stranded RNA DNA then integrates into the host cell genome where is is replicated and transcribed mechanism of the integration of genetic material into the host cell genome allows for cell to be infected indefinitely only way to cure the infection is to kill the infect cell itself exp. is human immunodeficiency virus (HIV)
57
viral life cycle
infection translation and progeny assembly progeny release lytic and lysogenic cycles
58
infection
to infect a cell the virus has to bind to specific receptors on the host cell once they are bound they are brought in close proximity to permit additional interactions depending on virus, different portions of the virion will be inserted into the host cells enveloped viruses fuse w/ membrane and enter the cell to interact bacteriophages only insert their genetic material
59
translation
must occur for virus reproduction translocation of genetic material to the correct location in the cell using ribosomes, tRNA, amino acids, and enzymes of the host cell, the viral RNA is translated into protein most of these proteins are structural capsid proteins and allow for creation of new virions
60
progeny assembly
once viral genome is replicated it is packaged within the capsid viral genome must be returned to its original form before packaging
61
progeny release
may be released in multiple ways 1. viral invasion may initiate cell death which results in spilling of the viral progeny 2. host cell may lyse as a result of being filled with extremely large numbers of virions, lysis is a disadvantage bc virus can no longer use the cell to carry outs its life cycle 3. virus can leave the cell by fusing with its plasma membrane in a process known as extrusion, allows for survival of host cell and continued use of host cell by virus, this is called a productive cycle
62
lytic cycle
bacteriophage makes maximal use of cells machinery w/ little regard for survival of host cell host swells w/ new virion, cell lyses, and other bacteria can be infected bacteria in this phase are termed virulent
63
lysogenic cycle
virus does not lyse the bacterium and may integrate into the host genome as a provirus or prophage virus is replicated as bacterium reprocess bc it is now part of host genome environmental factor will cause provirus to leave the genome and revert to lytic cycle
64
prions
very small (subviral) particles infectious proteins and nonliving things cause disease by triggering misfiling of other proteins, usually involve conversion from alpha-helix to beta-sheets this reduces the solubility of proteins protein aggregates form and function of the cell is reduced
65
viroids
small plant pathogens consisting of very short circular single stranded RNA bind to a large # of RNA sequences and silence genes in the plant genome this prevents synthesis of proteins and cause metabolic and structural derangements hepatitis D is an example of this in humans and alone is innocuous but when coinfected with hepatitis B is able to silence functioning on human hepatocytes

MCAT (18 decks)

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