CH 7 Flashcards
(129 cards)
1
Q
proteins
A
- perform most of cell’s functions
2
Q
nucleic acids
A
- store, transmit, and process info
3
Q
carbohydrates
A
- provide chemical energy, carbon, support, & identity
4
Q
plasma membrane
A
- serves as a selectively permeable barrier
- membrane: single; contains transport & receptor proteins
- components: phospholipid bilayer w/transport & receptor proteins
- function: selective permeability- maintains intracellular environment
5
Q
Morphology
A
the overall shape & appearance of an organism & its component parts
- 2 fundamental types of cells; eukaryotes & prokaryotes
6
Q
Eukaryotes
A
- membrane-bound compartment (NUCLEUS)
- e.g. protists, fungi, plants, & animals
- much larger than bacteria & archaea
- 5 -100 microm in diameter (allows them to ingest bacteria & archaea whole)
7
Q
Prokaryotes
A
- NO nucleus
- Bacteria & Archaea
8
Q
phylogeny
A
the evolutionary history of a group of organisms
- organisms are divided into bacteria, archaea, & euukarya
9
Q
transmission electron microscope
A
microscope that produces images by passing a focused beam of electrons through extremely thin sections of a specimen stained with heavy metals
10
Q
parts of a prokaryotic cell
A
plasmid, ribosomes, cell wall, plasma membrane, chromosome, cytoplasm
- at least 1 chromosome & many protein-synthesizing ribosomes enclosed in plasma membrane
11
Q
bacterial membranes
A
phospholipids consist of fatty acids bound to glycerol
12
Q
archaeal membranes
A
phospholipids use highly branched isoprenoid chains bound to glycerol
- more stable in extreme environments
13
Q
cytoplasm
A
all the contents of a cell bounded by the plasma membrane, excluding the nucleus
- contains high concentration of solutes, therefore it is HYPERTONIC relative to the surrounding environment in most habitats (cause water to enter via osmosis= volume expand)
14
Q
Chromosome
A
- most prominent structure inside prokaryotic cell
- bacterial & archaeal species contain single, circular chromosome
- gene-carrying structure consisting of a single long molecule of DNA & associated proteins
15
Q
DNA molecule
A
- contains in formation
- structural support given by proteins
- encoded in its sequence of nitrogenous bases
16
Q
genes
A
segments of DNA that contain info for building function RNAs, some of which may be used to make polypeptides
17
Q
central dogma
A
describes the flow of genetic info in cells
18
Q
1st step of central dogma
A
- the synthesis of RNA based on info stored in DNA
- takes place in nucleus
19
Q
relation of chromosomes, DNA, & RNA
A
chromosomes contain DNA, which contains genes that code for RNA
20
Q
DNA in prokaryotes
A
- DNA double helix coils on itself w/the aid of enzymes to form a compact, “supercoiled” structure
21
Q
Nucleoid
A
- in prokaryotic cells, a dense, centrally located region that contains DNA but is not surrounded by a membrane
- where circular chromosome is located
- genetic material often organized by clustering loops of DNA into distinct domains
22
Q
plasmid
A
small, usually, circular, supercoiled DNA molecule that exists independently of the cell’s main chromosomes in prokaryotes and SOME eukaryotes
- not required under normal conditions but help cells ADAPT in UNUSUAL circumstances, such as the sudden presence of poison in the environment
- AUXILIARY GENETIC ELEMENTS
23
Q
Ribosome
A
large macromolecular machine that synthesizes proteins by using the genetic info encoded in mRNA
- consists of 2 subunits, each composed of rRNA & proteins
- observed in all prokaryotic cells in interior
- not compartments inside a cell, so they are NOT ORGANELLES
- also associated w/surface of ER
24
Q
2nd step of cnetral dogma
A
Information stored in the RNA may be used to direct the synthesis of protein by RIBOSOMES
25
Cytoskeleton
- in EUkaryotic cells, a network of protein fibers in the cytoplasm that are involved in cell SHAPE, support, locomotion, & transport of materials within the cell
- in PROkaryotic cells, similar but much less extensive network of fibers
- membrane: none
- components: actin filaments, intermediate filaments, microtubules
- function: structural support; movement of materials; in some species, movement of whole cell
- dynamic structure; fibrous proteins move & change to alter cell's shape & shift its contents
26
Photosynthesis
set of chemical reactions responsible for converting energy in sunlight into chemical energy stored in sugars
26
Photosynthesis
set of chemical reactions responsible for converting energy in sunlight into chemical energy stored in sugars
27
photosynthetic membranes in bacteria
develop as infoldings of the plasma membrane & contain the enzyme & pigment molecules required for photosynthesis to occur
- in some cases, membrane-bound vesicles pinch off as the plasma membrane folds in
- in other cases, plattened stacks remain connected to plasma membrane
- internal membranes provide extensive SA that allows more photosynthetic reactions to occur = increase cell's ability to make food
28
organelle
A discrete compartment inside the cell- often bounded by a membrane- that contains enzymes/structures specialized to:
- store calcium ions
- hold crystals of the mineral magnetite, which function like compass needles to help cells swim in a directed way
- concentrate enzymes responsible for synthesizing complex carbon compounds from CO2
29
cell wall
fibrous layer found outside plasma membrane of most bacteria & archaea & many eukaryotes
- pressure of cell's volume expanding due to osmotic pressure resisted by cell wall
- protects the organisms & gives them shape & rigidity
30
bacteria cell walls
primary structural component is modified polysaccharide peptidoglycan
- some are also surrounded by an outer membrane consisting of glycolipids
31
archaeal cell walls
highly variable among the different species, but peptidoglycan is markedly absent
32
flagellum
long, cellular projection that undulates (in eukaryotes) or rotates (in prokaryotes) to move the cell through an aqueous environment
- assembled from many diff proteins at cell surface of certain species
33
molecular motor embedded in plasma membrane
- common to both archaeal & bacterial flagella
- proteins that make up these motors & filaments differ btwn the 2 groups
- functions are the same; to rotate a long rigid filament that propels the cell through the water
34
fimbria
long, needlike projection that extends form the plasma membrane of some bacteria & promotes attachment to other cells or surfaces
- more numerous than flagella & are often distributed over the cell's entire surface
- ability to glue bacteria to the surface tissues makes them crucial in establishing many infections
35
what structure in archaea are similar to the fimbria in bacteria
appendages
36
as cell increases in diameter, its volume increase ______ than its surface area
more
- this causes a decrease in rate of exchange
37
Diffusion only allows for rapid movement across _________ distances
very small
38
cytosol
the fluid portion between the plasma membrane of organelles, excluding the contents of membrane-enclosed organelles.
- only a fraction of the total cell volume
39
Advantages of compartmentalization by organelles in eukaryotic cells
1. incompatible chem rxns can be separated
2. chem rxns become more efficient
- substrates required for particular rxns can be localized & maintained @ high concs within organelles. when substrates are used up in a particular part of the organelle, they can be replaced by substrates that have only a short distance to diffuse
- groups of enzymes that work together can be clustered within or don't the membranes of the organelles instead of free floating (increase speed & efficiency)
40
nucleus
- membrane: double ('envelope') openings called nuclear pores
- components: chromosomes, nucleolus, nuclear lamina
- function: INFO storage & transmission, ribosome subunit assembly, structural support
- confine eukaryotic chromosomes
- chromosomes densely packed at periphery & loose towards interior
41
ribosomes
- membrane: none
- components: complex of RNA & proteins
- function: protein synthesis
42
endomembrane system
- endoplasmic reticulum: smooth & rough
- Golgi apparatus
- lysosomes
- center for producing, processing, & transporting proteins, carbs, & lipids in eukaryotic cells
43
Rough endoplasmic reticulum
- membrane: single; contains receptors for entry of selected proteins
- components: network of branching sacs, ribosomes associated
- function: protein synthesis & processing
44
smooth endoplasmic reticulum
- membrane: singular, contains enzymes for synthesizing phospholipids
- components: network of branching sacs, enzymes for synthesizing or modifying lipids
- function: lipid synthesis & processing
- free of ribosomes
- reservoir for calcium ions
45
golgi apparatus
- membrane: single; contains transporters for selected molecules & proton pumps
- components: distinct cisternae, often as stack of flattened vesicles
- function: protein, lipid & carb processing
- most of proteins that leave the rough ER must pass through here
46
vacuoles
- membrane: single; contains transporters for selected molecules
- components: varies- carbs, water, pigments, oils, toxins, hydrolases
- function: STORAGE, digestion, & recycling
- large in plant & fungal cells
- some contain hydrolases to digest & recycle macromolecules
- stores water & pushes cytoplasm & plasma membrane against cell wall
47
peroxisomes
- membrane: single; contains transporters for selected macromolecules
- components: enzymes that catalyze oxidation reactions, catalase (process peroxide)
- function: oxidation of fatty acids, ethanol or other compounds
- originate when empty vesicles form the ER are loaded with peroxisome-specific enzymes from the cytosol
- CENTER OF REDOX (reduction-oxidation) RXNS
48
mitochondria
- membrane: double; inner contains enzymes for ATP production
- components: enzymes that harvest energy from molecules to make ATP
- function: ATP production
- 2 membranes
- outer = surface; inner = forms cristae
- prone to fusion & fission
49
chloroplasts
- membrane: double; plus membrane-bound sacs in interior
- components: pigments, enzymes that use light energy to make sugars
- function: production of sugars via photosynthesis
- sunlight is converted to chemical energy during photosynthesis
- surrounded by a double membrane
- no cristae
- has 3rd membrane that forms an independent network of hundreds of thylakoids
50
cell wall & extracellular matrix
- membrane: none
- components: fibers running through carbohydrate or protein matrix
- function: protection, structural support
51
nuclear envelope
double-layered membrane enclosing the nucleus of a eukaryotic cell
- studded w/pore-like openings
- inside surface is linked to fibrous proteins that form a lattice-like sheet called the nuclear lamina
52
nuclear lamina
lattice-like sheet of fibrous nuclear lamins, which are one type of intermediate filament.
- lines inner membrane of nuclear envelope, stiffening the envelope & helping to organize the chromosomes & maintain organelle shape
53
nucleolus
in eukaryotic cells, a specialized structure in the nucleus where the manufacturing & processing of the RNA molecules occurs, assembling them into large & small ribosomal subunits
54
what happens to proteins manufactured by free ribosomes
they either remain in the cytosol or are imported into other organelles, such as the nucleus
55
the ER membrane is continuous with the...
nuclear envelope
56
lumen
the interior space of any hollow structure (e.g., the rough ER) or organ (e.g., the stomach)
57
What are the roles of the proteins produced by the rough ER
- carry messages to other cells
- act as membrane transport proteins or pumps
- catalyze reactions
58
cisternae
flattened, membranebound compartments that make up the golgi apparatus
59
cis
surface of the golgi apparatus closes to the nucleus
- receives vesicles containing rough ER products aka cargo
60
trans
surface of the golgi apparatus oriented toward the plasma membrane
- ships cargo out to other organelles or the cell surface
61
lysosomes
- membrane: single; contains transporters for selected molecules & proton pumps
- compartments: acid hydrolases (catalyze hydrolysis reactions)
- function: digestion & RECYCLING
- 40 diff enzymes to hydrolyze diff macromolecules (proteins, nucleic acids, lipids, carbs)
62
what is the pH in cystosol in the eukaryotic cell
7.2
63
how does in the lumen of the lysosome remain acidic
proton pumps in the lysosomal membrane maintain an acidic pH by importing hydrogen ions
64
glyoxysomes
specialized type of peroxisome found in plant cells & packed w/enzymes for processing the products of photosynthesis
- packed with enzymes that oxidize fatty acids to form a compound that can be used to store energy for the cell
65
mitochondrial matrix
central compartment of a mitochondrion, lined by inner membrane
- contains mitochondrial DNA, ribosomes, & enzymes for pyruvate processing & citric acid cycle
66
mitochondrial DNA
small circular, linear chromosome that contains some of the genes to encode proteins & functional RNA molecules within mitochondria
- independent of nuclear chromosomes
- contains only small fraction of genes responsible for the function of the organelle- other genes reside in nuclear DNA
67
thylakoids
membrane-bound network of flattened sac-like structures inside a plant chloroplast that functions in converting light energy to chem energy
- make up grana
- many pigments, enzymes, & macromolecular machines responsible for conversion are embedded in this membrane
68
grana
stacks of flattened thylakoid discs in chloroplasts where the light reactions of photosynthesis occur
69
stroma
fluid matrix of a chloroplast, enclosed inside a double-membrane envelope in which the thylakoids are embedded.
- surrounds grana & contains enzymes that use chemical energy to produce sugars
70
what do biologists propose about the mitochondria & chloroplasts
they were once free-living bacteria
71
endosymbiosis theory
theory that mitochondria & chloroplasts evolved from prokaryotes that were engulfed by host cells & took up a symbiotic existence in those cells
- in some eukaryotes, chloroplasts may have originated by secondary endosymbiosis
72
do animal cells have a cell wall
no
73
extracellular matrix
-ECM
- complex fiber composite in which animal cells are embedded, consisting of proteins (e.g. collagen, proteoglycan, & laminin) and polysaccharides produced by the cells
74
cardiac muscles cells
- long & tapered
- filled w/protein fibers that slide past one another as muscle flexes or relaxes to generate the heartbeat
- packed w/mitochondria, which produce ATP required for sliding motion to occur
75
fat cells
- rounded, globular structures that store lipids
- consist of plasma membrane, nucleus, & fat droplet
76
pancreatic cell
exports digestive enzymes
- packed w/rough ER that manufacture & secretes digestive enzymes
77
testis cell
exports lipid-soluble signals
- dominated by smooth ER that synthesizes lipids like testosterone- a steroid hormone
78
leaf cell
manufactures ATP & sugar
- has many chloroplasts that are specialized for absorbing light & manufacturing sugar
79
differential centrifugation
procedure for separating cellular components according to their size & density by spinning a cell homogenate in a series of centrifuge runs
80
nuclear pore complex
large complex of about 30 proteins that form an opening in the nuclear envelope connecting the inside of the nucleus with the cytosol & allowing the free diffusion of small molecules & ions
- also regulates transport of RNA & proteins
- serves as a dynamic gate to control passage through the envelope, not a filter
81
ribosomal RNAs
an RNA molecule that forms part of the ribosome
- manufactured in the nucleolus, where they bind to proteins to form the large & small subunits of ribosomes
82
messenger RNAs
an RNA molecule transcribed from DNA that carries info (in codons) that specifies the amino acid sequence of a polypeptide
- must be transported from nucleus to cytosol
83
nucleoside triphosphates
building blocks for DNA & RNA
84
nuclear localization signal
short amino acid sequence that marks a protein for delivery to the nucleus
85
Places in the cell where cargo moves in a regulated & energy-demanding fashion
nuclear membrane, peroxisomes, mitochondria, chloroplasts
86
pulse-chase experiment
type of experiment that involves using a labeled molecule (pulse) to mark a population of cells or molecules at a particular moment and then following their fate over time (chase)
- PULSE: expose experimental cells to a hi conc of a modified amino acid for a short time. proteins synthesized during period will be radiolabeled
- CHASE: end pulse by washing away the modified amino acid & replacing w/normal version of same molecule. The time following the end of the pulse. proteins synthesized during period will NOT be radiolabeled
- revealed that proteins are trafficked through the secretory pathway in a highly organized & directed manner
87
signal hypothesis
predicts that proteins bound for the endomembrane system have a molecular zip code that serves a similar role to the nuclear localization signal in nucleoplasmin
- 1st amino acid residues of the growing protein act as a signal that marks the ribosome for transport to the ER membrane
88
ER signal sequence
short maino acid sequence tha tmarks a polypeptide (growing protein) for transport to the ER, where the synthesis of the polypeptide chain is completed & the signal sequence removed
89
signal recognition particle
an RNA-protein complex that binds to the ER signal sequence in a polypeptide as it emerges from a ribosome & participates in transport of the ribosome-polypeptide complex to the ER membrane, where synthesis of the polypeptide is completed
90
what happens to proteins once they are inside the rough ER or inserted into its membrane?
they FOLD into their 3D shape w/ the help of chaperone proteins
- for proteins that enter the ER lumen, they interact w/enzymes that catalyze the addition of carbohydrate side chains
90
what happens to proteins once they are inside the rough ER or inserted into its membrane?
they FOLD into their 3D shape w/ the help of chaperone proteins
- for proteins that enter the ER lumen, they interact w/enzymes that catalyze the addition of carbohydrate side chains
91
carbohydrates are ______ of sugar ______
polymers; monomers
92
glycosylation
addition of a carbohydrate group to a molecule
93
glycoprotein
any protein w 1+ covalently bonded carbohydrates, typically oligosaccharides
- structure of carbs changes proteins as they're folded, serving as an indicator for shipment to Golgi apparatus
94
how do proteins move from the ER to the Golgi apparatus
a distinctive type of veicle ensures that only appropriate cargo is loaded & carries these proteins from the rough ER to the cis face of the Golgi apparatus
95
How do cisternae act in the golgi apparatus
new cisternae constantly form at the cis face of the GA, while old cisternae break apart at the trans face
96
how is cargo from the GA put into the right shipping containers, & how are the containers addressed for transport to different locations
- For those shipped to lysosomes, lysosome-bound proteins have a phosphate group attached to a specific sugar on their surface, forming the compound mannose-6-phosphate (serves as zip code)
97
exocytosis
secretion of intracellular molecules, contained within membrane-bound vesicles, to the outside of the cell by fusion of vesicles to the plasma membrane
- vesicle membrane & plasma membrane make contact, causes interior of vesicle to be exposed to outside the cell
98
endocytosis
pinching off of plasma membrane that results in the uptake of material form outside the cell
- e.g. phagocytosis, pinocytosis, & receptor-mediated endocytosis
99
receptor-mediated endocytosis
uptake by a cell of certain extracellular macromolecules bound to specific receptors in the plasma membrane, by pinching off the membrane to form small membrane-bound vesicles
- begins when particles outside the cell bind to receptors on the plasma membrane
100
early endosome
a small transient organelle that is formed by the accumulation of vesicles from receptor-mediated endocytosis & is an early stage in the formation of a lysosome
101
What causes cargo to be released from their receptors in receptor-mediated endocytosis
the activity of proton pumps in the membrane of the early endosome that acidified its lumen
102
late endosome
a membrane-bound vesicle that arises form an early endosome, accepts lysosomal enzymes form the Golgi, & matures into lysosome
103
phagocytosis
uptake by a cell of small particles or cells by invagination & pinching off of the plasma membrane to form small, membrane-bound vesicles
- type of endocytosis
- surrounds a smaller cell of food particle & engulfs it, forming phagosome
- recycle material brought in from outside of cell
104
autophagy
the process by which damaged organelles & other cytoplasmic components are surrounded by a membrane & delivered to a lysosome to be recycled
105
What do the 3 pathways of recycling material have in common
molecules are hydrolyzed & the products are transported across the lysosomal membrane into the cytosol for recycling
106
actin filaments
- aka microfilaments
- made of globular protein subunits called actin
- maintain cell shape by resisting tension (pull)
- move cells via muscle contraction or cell crawling (myosin)
- divide animal cells in 2
- move organelles & cytoplasm in plants, fungi, & animals
- 5-10% of protein in cell
- made of noncovalent bonds
- non-symmetrical= head-to-tail arrangement = distinct polarity = two diff ends (+-); reflect differences btwn rates of assembly
107
motor protein
class of proteins whose major function is to convert the chemical energy of ATP into motion
- e.g. dynein, kinesin, myosin
108
Myosin
with actin filaments, it binds & hydrolyzes ATP to ADP, undergoes a series of shape changes that extends the
head" region, attaches to actin, & contracts to pull itself along the actin filament
109
cytokinesis
final stage in cell division where the cytoplasm forms 2 daughter cells
- in animals; accomplished by actin filaments connected to plasma membrane & arranged in ring (caused by myosin)
110
cytoplasmic streaming
the directed flow of cytosol & organelles that facilitates distribution of materials within some large plant & fungal cells
- occurs along actin filaments & powered by myosin
111
cell crawling
form of cellular movement along actin filaments in which the cell produces bulges in the membrane that stick to the substrate & are used to pull the cell forward
112
intermediate filament
long fiber composed of 1 of various proteins; 1 of 3 types of cytoskeletal fibers
- used to form networks that help maintain cell shape & hold the nucleus in place
- do not exhibit filament polarity; identical ends & serve a structural role in eukaryotic cells
- e.g. keratins & lamins
113
keratin
- most familiar intermediate filaments
- make up skin, hair
- intermediate filaments provide mechanical strength to resist pressure & abrasion
114
nuclear lamins
dense mesh inside the nuclear envelope that anchors chromosomes, defines the shape of the nucleus, and stabilizes the envelope
115
microtubules
long tubular fiber (longest of 3 cytoskeletal filaments) formed by polymerization of tubulin protein dimers (alpha tubulin & beta tubulin)
- involved in cell structure, movement, transport of materials within cell
- Tubulin dimers polymerize in a polar head-to-tail fashion via noncovalent bonds to form thin chains called protofilaments; form hollow tubes
- exhibit polarity
- separate chromosomes during mitosis & meiosis
116
dimers
an association of 2 molecules that may be identical or different
117
Microtubule-organizing center
general term for any structure where new microtubules originate in cells
118
centrosome
structure that serves as a microtubule-organizing center for the cell's cytoskeleton & for the spindle apparatus during cell division
- MTOC in animal cells
119
centrioles
1 of 2 small cylindrical structures contained within the centrosome near the nucleus of a eukaryotic cell
- found in animals
120
kinesin
class of motor proteins that uses the chem energy of ATP to "walk" toward the plus end of a microtubule
- used to transport vesicles, particles, organelles, & chromosomes
121
prokaryotic flagellum
- consists of single helical rod made of flagellin (in bacteria) or other types of proteins (in archaea)
- move the cell by rotating like a ship's propeller
122
eukaryotic flagellum
- microtubules constructed from tubulin dimers
- move the cell by undulating- whip back & forth
- surrounded by plasma membrane
123
cilium
short, filamentous projects of some eukaryotic cells, contains core of microtubules
- used to move the cell & circulate fluid or particles around the surface of the stationary cell
124
axoneme
- characteristic of most cilia & flagella
- axle-thread
- nine microtubule pairs, or doublets, surrounds 2 central microtubules
125
basal body
microtubule-organizing center for cilia & flagella in eukaryotic cells
- consists of 9 triplets of microtubules arranged in a circle
- establishes structure of axonemes
125
basal body
microtubule-organizing center for cilia & flagella in eukaryotic cells
- consists of 9 triplets of microtubules arranged in a circle
- establishes structure of axonemes
126
dynein
class of motor proteins that uses the chem energy of ATP to "walk" toward the MINUS end of a microtubule
- responsible for bending cilia & flagella, play role in chromosome movement during mitosis, & can transport vesicles & organelles
- walking is constrained- if one doublet slides, it transmits force to the rest of axoneme
