Exam 2 Flashcards
(305 cards)
1
Q
cells
A
- were discovered in 1665 by Robert Hooke
- Early studies of cells were conducted by
Mathias Schleiden (1838)
Theodor Schwann (1839) - Schleiden and Schwann proposed the Cell Theory
2
Q
early studies of cells were conducted by __ and __
A
Mathias Schleiden (1838); Theodor Schwann (1839)
3
Q
Schleiden and Schwann proposed the __ __
A
cell theory
4
Q
cell theory
A
- All organisms are composed of cells
- Cells are the smallest living things
- Cells arise only from pre-existing cells
- All cells today represent a continuous line of descent from the first living cells
5
Q
Most cells are relatively __ due reliance on diffusion of substances in and out of cells
A
small
6
Q
rate of diffusion affect by
A
- Surface area available
- Temperature
- Concentration gradient
- Distance
7
Q
the smaller the cell, the more __it is for movement
A
efficient
8
Q
__ cells are smaller than __ cells
A
prokaryotic; eukaryotic
9
Q
surface area-to-volume ratio
A
- Organism made of many small cells has an advantage over an organism composed of fewer, larger cells
- As a cell’s size increases, its volume increases much more rapidly than its surface area
- Some cells overcome limitation by being long and skinny( like neurons)
- Smaller cell has a higher SA/volume ratio than a bigger cell
- Higher SA-volume ratio = more efficient the cell will be = smaller the cell
10
Q
resolution
A
minimum distance two points can be apart and still be distinguished as two separate points
11
Q
Objects must be __ μm apart for naked eye to resolve them as two objects rather than one
A
100
12
Q
what are the 2 types of microscopes?
A
- light
2. e-
13
Q
light microscopes
A
- Use magnifying lenses with visible light
- Resolve structures that are 200 nm apart
- Limit to resolution using light
14
Q
e- microscopes
A
- Use beam of e-
- Resolve structures that are 0.2 nm apart
- Transmission electron microscopes transmit e- thru the material
- Scanning electron microscopes beam e- onto the specimen surface
15
Q
scanning e- microscopes
A
beam electrons onto the specimen surface
16
Q
transmission e- microscopes (TEM)
A
- Shows inside cells
- E- pass thru specimen
- Shows great detail of internal structure
- Magnifies up to 1,000,000 times
17
Q
basic structural similarities
A
- Nucleoid or nucleus where DNA is located
- Cytoplasm
a) Semifluid matrix of organelles and cytosol - Ribosomes
a) Synthesize proteins - Plasma membrane
a) Phospholipid bilayer
18
Q
prokaryotic cells
A
- Simplest organisms
- Lack a membrane-bound nucleus
- DNA is present in the nucleoid
- Cell wall outside of plasma membrane
- Do contain ribosomes (not membrane-
bound organelles) - Two domains of prokaryotes
a) Archaea
b) Bacteria
19
Q
bacterial cell walls
A
- Most bacterial cells are encased by a strong cell wall
a) composed of peptidoglycan
b) Cell walls of plants, fungi, and most protists different - Protect the cell, maintain its shape, and prevent excessive uptake or loss of water
- Susceptibility of bacteria to antibiotics often depends on the structure of their cell walls
- Archaea lack peptidoglycan
20
Q
flagella
A
- Present in some prokaryotic cells
a) May be one or more or none - Used for locomotion
- Rotary motion propels the cell
- Mobility
- Slender, rigid, helical structures
- Composed of protein flagellin
- Spin like propeller
- *Usually gram-negative bacteria
21
Q
eukaryotic cells
A
- Possess a membrane-bound nucleus
- More complex than prokaryotic cells
- Hallmark is compartmentalization
a) Achieved through use of membrane-bound organelles and endomembrane system - Possess a cytoskeleton for support and to maintain cellular structure
22
Q
nucleus
A
- Repository of the genetic information
- Most eukaryotic cells possess a single nucleus
- Nucleolus
- Nuclear envelope
- In eukaryotes, the DNA is divided into multiple linear chromosomes
- Chromatin
23
Q
nucleolus
A
region where ribosomal RNA
synthesis takes place
24
Q
nuclear envelope
A
a) 2 phospholipid bilayers
b) Nuclear pores: control passage in and out
25
chromatin
chromosomes plus protein
26
ribosomes
- Cell’s protein synthesis machinery
- Found in all cell types in all 3 domains
- Ribosomal RNA (rRNA)-protein complex
- Protein synthesis also requires messenger
- RNA (mRNA) and transfer RNA (tRNA)
- Ribosomes may be free in cytoplasm or associated with internal membranes
27
endomembrane system
- Series of membranes throughout the cytoplasm
- Divides cell into compartments where different cellular functions occur
- One of the fundamental distinctions between eukaryotes and prokaryotes
28
Rough endoplasmic reticulum (RER)
- Attachment of ribosomes to the membrane gives a rough appearance
- Synthesis of proteins to be secreted, sent to lysosomes or plasma membrane
29
Smooth endoplasmic reticulum (SER)
- Relatively few bound ribosomes
- Lipid synthesis
- Variety of functions: synthesis, store Ca2+, detoxification
30
Ratio of RER to SER depends on cell ___
function
31
Golgi apparatus
- Flattened stacks of interconnected membranes (Golgi bodies)
- Functions in packaging and distribution of molecules synthesized at one location and used at another within the cell or even outside of it
- Has cis and trans faces
- Vesicles transport molecules to destination
32
lysosomes
- Membrane-bounded digestive vesicles
- Arise from Golgi apparatus
- Enzymes catalyze breakdown of macromolecules
- Destroy cells or foreign matter that the cell has engulfed by phagocytosis
33
microbodies
- Variety of enzyme-bearing, membrane-enclosed vesicles
| - Peroxisomes
34
peroxisomes
- Contain enzymes involved in the oxidation of fatty acids
| - Hydrogen peroxide produced as by-product – rendered harmless by catalase
35
vacuoles
- Membrane-bound structures in plants
- Various functions depending on the cell type
- There are different types of vacuoles
36
what are the different types of vacuoles
- Central vacuole in plant cells
- Contractile vacuole (pumps water out of cell) of some fungi and protists
- Storage vacuoles
37
mitochondria
- Found in all types of eukaryotic cells
- Generate e in the cell
- Bound by membranes
- On the surface of the inner membrane, and also embedded within it, are proteins that carry out oxidative metabolism
- Have their own DNA
38
what are the membranes that the mito is bound to?
- Outer membrane
- Intermembrane space
- Inner membrane has cristae
- Matrix
39
chloroplasts
- Organelles present in cells of plants and some other eukaryotes
- Contain chlorophyll for photosynthesis
- Surrounded by 2 membranes (internal and external)
- Thylakoids
a) Grana
- Have their own DNA
40
thylakoids
membranous sacs within the inner membrane of chloroplast
41
grana
stacks of thylakoids
42
endosymbiosis
- Proposes that some of today’s eukaryotic organelles evolved by a symbiosis arising between two cells that were each free-living
- One cell, a prokaryote, was engulfed by and became part of another cell, which was the precursor of modern eukaryotes
- Mitochondria and chloroplasts
43
cytoskeleton
- Network of protein fibers found in all eukaryotic cells
a) Supports the shape of the cell
b) Keeps organelles in fixed locations
- Dynamic system
44
dynamic system
constantly forming and disassembling
45
what are the 3 types of fibers?
1. microfilaments (actin filaments)
2. intermediate filaments
3. microtubules
46
microfilaments
aka actin filaments
- smallest of fibers
- Two protein chains loosely twined together
- Movements like contraction, crawling, “pinching”
47
microtubules
- Largest of the cytoskeletal elements
- Dimers of α- and β-tubulin subunits
- Facilitate movement of cell and materials within cell
48
intermediate filaments
- Between the size of actin filaments and microtubules
| - Very stable – usually not broken down
49
centrioles
- Region surrounding centrioles in almost all animal cells
- Microtubule-organizing center
a) Can nucleate the assembly of microtubules
- Animal cells and most protists have centrioles
- Plants and fungi usually lack centrioles
50
centrioles
pair of organelles
51
plants and fungi usually lack __
centrioles
52
cell movement
- Essentially all cell motion is tied to the movement of actin filaments, microtubules, or both
- Some cells crawl using actin microfilaments
- Flagella and cilia have 9 + 2 arrangement of microtubules
a) Not like prokaryotic flagella
b) Cilia are shorter and more numerous
53
eukaryotic cell walls
- Plants, fungi, and many protists
- Different from prokaryotes
- Plants and protists – cellulose
- Fungi – chitin
- Plants – primary and secondary cell walls
54
cell wall of plants are protists
cellulose
55
cell wall of fungi
chitin
56
extracellular matrix (ECM)
- Animal cells lack cell walls
- Secrete an elaborate mixture of glycoproteins into the space around them
- Collagen may be abundant
- Form a protective layer over the cell surface
- Integrins
57
integrins
link ECM to cell’s cytoskeleton
| - influence cell behavior
58
cell-to-cell interactions
- Surface proteins give cells identity
- Cells make contact, “read” each other, and react
- Glycolipids
- MHC proteins
59
glycolipids
most tissue-specific cell surface markers
60
MHC proteins
recognition of “self” and “nonself” cells by the immune system
61
cell connections
1) adhesive junctions
2) separate, or tight, junctions
3) communicating junctions
62
adhesive junctions
Mechanically attaches cytoskeletons of neighboring cells or to the ECM (adherens junctions, desmosomes)
63
separate, or tight, junctions
Connect the plasma membranes of adjacent cells in a sheet – no leakage
64
communicating junctions
Chemical or electrical signal passes directly from one cell to an adjacent one (gap junction, plasmodesmata)
65
plasmodesmata
Plant cells
Plasmodesmata
- Specialized openings in their cell walls
- Cytoplasm of adjoining cells are connected
- Function similar to gap junctions in animal cells
- Plant cells have Cell wall, chloroplast, central vacuoles
66
unlike animal cells, plant cells have __, __, and __
Cell wall, chloroplast, central vacuoles
67
which of the following statements is NOT part of the cell theory?
eukaryotic cells have evolved from prokaryotic cells
68
all cells have all of the following except
a) plasma membrane
b) genetic material
c) cytoplasm
d) cell wall
cell wall
69
eukaryotic cells are more complex than prokaryotic cells. which of the following are found only in a eukaryotic cell?a) cell wall
b) plasma membrane
c) ER
d) ribosomes
ER
70
which of the following are differences between bacteria and archaea?
the molecular architecture of their cell walls
71
the cytoskeleton includes
intermediate filaments made of twisted fibers of vimentin and keratin
72
the smooth ER is
the site of lipid and membrane synthesis
73
plasmodesmata in plants and gap junctions in animals are functionally similar in that
they form channels between cells that allow diffusion of small molecules
74
the most important factor that limits the size of a cells is the
surface area-to-volume ratio of the cell
75
all eukaryotic cells possess each of the following except
a) mitochondria
b) cell wall
c) cytoskeleton
d) nucleus
cell wall
76
adherens junctions, which contain cadherin, are found in all animals. Given this, which of the following predictions is most likely?
cadherins would be found in the ancestor to all animals
77
different motor proteins like kinesin and myosin are similar in that they can
use e from ATP to produce movement
78
the protein sorting pathway involves the following organelles/compartments in order
RER, transport vesicle, Golgi, final destination
79
chloroplasts and mitochondria have many common features bc both
arose by endosymbiosis
80
eukaryotic cells are composed of 3 types of cytoskeletal filaments. How are these 3 filaments similar?
they contribute to the shape of the cell
81
Girolamo Fracastoro
1546 Italian physician
| suggested that disease was caused by unseen organisms
82
Antony van Leeuwenhoek
was 1st to observe and accurately describe microbial life
| Modern e- microscopes allows the study of cell substructure
83
Louis Pasteur
refutes idea of spontaneous generation (idea that living things arise spontaneously from other living things)
84
Robert Koch
studied anthrax; proposed four postulates to prove a causal relationship between a microorganism and a disease
85
Koch's four postulates
1) The microorganism must be present in every case of the disease and absent from healthy individuals
2) The putative causative agent must be isolated and grown in pure culture
3) The same disease must result when the cultured microorganism is used to infect a healthy host
4) The same microorganism must be isolated again from the diseased host
86
prokaryotic diversity
- Oldest, structurally simplest, and most abundant forms of life
- Abundant for over a billion years before eukaryotes appeared
- 90-99% unknown and undescribed
- Fall into 2 domains:
a) Bacteria
b) Archaea
- Many archaea are extremophiles
87
characteristics of prokaryotes #1
1) Unicellularity
- Most are single-celled
- May stick together to form associations and biofilms
2) Cell size
- Size varies tremendously
- Most are less than 1 μm in diameter
3) Nucleoid
- Chromosome is single circular double-stranded DNA
- Found in the nucleoid region of cell
- Often have plasmids
4) Cell division
- Most divide by binary fission
88
characteristics of prokaryotes #2
1) Genetic recombination
- Exchange genetic material extensively thru horizontal gene transfer; not a form of reproduction
2) Internal compartmentalization
- No membrane-bounded organelles
- No internal compartment
- Plasma membrane can be extensively infolded
3) Flagella
- Simple in structure
- Diff from eukaryotic flagella
4) Metabolic diversity
- Oxygenic and anoxygenic psyn
- Chemolithotrophic
89
4 key areas bacteria and archaea differ
1) Plasma membranes
2) Cell walls
3) DNA rep
4) Gene expression
90
bacteria vs archaea #1
- Plasma membrane
a) All prokaryotes have a plasma membrane
b) Membranes of archaea differ from bacteria and eukaryotes
c) Archaean membranes are formed of glycerol linked to hydrocarbon chains by ether linkages
- Hydrocarbons may be branched
- Tetraethers
91
tetraethers
form a monolayer instead of a bilayer; allows extremophiles to withstand high temps
92
bacteria vs archaea #2
1) Cell wall
- All prokaryotes have cell walls
- Bacteria have peptidoglycan
- Archaea lack peptidoglycan
2) DNA rep
- Both have single rep origin; nature of origin and proteins used are diff
- Archaeal DNA rep is more similar to that of eukaryotes
3) Gene expression
- Archaeal transcription and translation are more similar to those of eukaryotes
* the 3 domains - bacteria, archaea, and eukarya- share a common ancestor
93
Early Classification Characteristics
- Prokaryotes not easily classified according to forms
- Early systems relied on staining characteristics and observable phenotypes
1) Photosynthetic or non-photosynthetic
2) Motile or non-motile
3) Unicellular, colony-forming, or filamentous
4) Formation of spores or division by transverse binary fission
5) Importance as human pathogens or not
94
__ have peptidoglycan
bacteria
95
which of the following would be an example of a biomarker?
a hydrocarbon found in an ancient rock layer
96
a cell that can use e from the sun, and CO2 as a carbon source is a
photoautotroph
97
gram positive (+) and gram (-) bacteria are characterized by differences in
the cell wall: gram + have a thick layer of peptidoglycan and gram - have an outer membrane
98
which of the following characteristics is unique to the archaea?
ether-linked phosolipids
99
the horizontal transfer of DNA using a plasmid is an example of
conjugation
100
the disease tuberculosis is
caused by a bacterial pathogen
101
prokaryotes participate in the global cycling of
carbon and nitrogen
102
which of the following is typically NOT associated with a prokaryote?
multiple, linear chromosomes
103
the mechanisms of DNA exchange in prokaryotes share the feature of
horizontal transfer of info
104
the cell wall in both gram-positive and gram-negative cells is
a target for antibiotics that affect peptidoglycan synthesis
105
the three domains of life
consist of three different basic cell types
106
ulcers and tooth decay do not appear related, but in fact both
can be due to bacterial infection
107
bacteria lack independent internal membrane systems, but are able to perform psyn and resp, both of which use membranes. they are able to perform these functions bc
invaginations of the plasma membrane can provide an internal membrane surface
108
plants cannot fix nitrogen, yet some plants do NOT need nitrogen from the soil. This is because...
of a symbiotic association with a bacterium that can fix nitrogen
109
molecular classification #1
- Amino acid sequences of key proteins
- Percent guanine- cytosine content
- Nucleic acid hybridization
- Closely related species will have more base pairing
- Gene and RNA sequencing (Especially rRNA)
- Whole-genome sequencing
110
molecular classification #2
- Several prokaryotic groupings have been proposed
- huge book in microbio: Bergey’s Manual of Systematic Bacteriology, 2nd edition
- Large scale sequencing of random samples indicates vast majority of bacteria have never been cultured or studied in detail
111
prokaryotic cell structure
3 basic shapes
1) Bacillus: rod-shaped 0.5 µm
2) Coccus: spherical 2 µm
3) Spirillum: helical-shaped 3 µm
112
prokaryotic cell characteristics
- Cell Wall
- Gram Stain
a) Gram-positive (+) bacteria
b) Gram-negative (-) bacteria
113
prokaryotic cell characteristics: cell wall
Peptidoglycan forms a rigid network
- Maintain shape
- Withstands hypotonic environments
- Archaea have a similar molecule (pseudomurein)
114
Gram-positive (+) bacteria
have thicker peptidoglycan wall and stain a PURPLE color - complex network of peptidoglycan
- Also contains lipoteichoic and teichoic acid
115
Gram-negative (-) bacteria
contain less peptidoglycan and don’t retain purple color, they look PINK
- Thin layer of peptidoglycan
- Second outer membrane with lipopolysaccharide
- Resistant to many antibiotics
116
prokaryotic cell walls: S-layer
- Rigid paracrystalline layer found in some bacteria and archaea
- Outside of peptidoglycan or outer membrane layers in gram-negative and gram-positive bacteria
- Diverse functions: often involves adhesion
117
prokaryotic cell walls: capsule
Wax coating surround bacteria
- Gelatinous layer found in some bacteria
- Aids in attachment
- Protects from immune system
118
pili
- Short, hairlike structures
- Found in gram-negative bacteria
- Aid in attachment and conjugation
- Anchor
*Specialized pili called sex pili, which allow transfer of genetic material in horizontal transfer of bacteria to bacteria
119
endospores
- Develop a thick wall around their genome and a small portion of the cytoplasm when exposed to environmental stress
- Highly resistant to environmental stress
a) Especially heat
- When conditions improve can germinate and return to normal cell division
- Bacteria causing tetanus, botulism, and anthrax
120
Prokaryotic cells often have complex internal membranes
- Invaginated regions of plasma membrane
| - Function in respiration or psyn
121
organization of prokaryotic cells
- Nucleoid region
a) Contains single, circular chromosome
b) May also contain plasmids
c) Plasmids: exhiliery genes
- Ribosomes
a) Smaller than those of eukaryotes
b) Differ in protein and RNA content
c) Targeted by some antibiotics
122
prokaryotic genetics
- Prokaryotes don’t reproduce sexually
- 3 types of horizontal gene transfer
1) Conjugation
2) Transduction
3) Transformation
123
conjugation
cell to cell contact
- Plasmids may encode functions not necessary to the organism, but may provide a selective advantage
- In E. coli, conjugation is based on the presence of the F plasmid (fertility factor)
a) F(+) cells contain plasmid
b) F(-) cells don’t
ex: sex pili
124
F plasmid transfer
- F(+) cell produces F pilus that connects it to the F(-) cell
- Transfer of F plasmid occurs thru conjugation bridge
- F plasmid copied thru rolling circle replication
- The end result is two F(+) cells
- F(+) is donor cell, F(-) is recipient cell
125
F plasmid recombination
- F plasmid can integrate into the bacterial chromosome
a) Events similar to crossing over in eukaryotes
b) Homologous recombination
- Hfr cell (high frequency of recombination)
a) F plasmid integrated into chromosome
b) Replicated every host divides
- The F plasmid can also excise itself by reversing the integration process
a) An inaccurate excision may occur picking up some chromosomal DNA- F’ plasmid
b) Hfr cell has integrated plasmid, F(+) cell has external plasmid
126
F plasmid recombination #2
- During conjugation in Hfr strains, the transfer of genes is progressive- genes farther from the origin of transfer will be transferred later
- Gene order can be mapped based on entry time
127
transduction
by viruses
Occurs when u use a virus that’s been modified to transfer genetic material into a bacterial cell
- U can have either generalized or specialized transduction
128
generalized transduction
- Virtually any gene can be transferred
- Occurs via accidents in the lytic cycle
- Viruses package bacterial DNA and transfer it in a subsequent infection
129
specialized transduction
- Occurs via accidents in the lysogenic cycle
- Imprecise excision of prophage DNA
- These phage carry both phage genes and chromosomal genes
130
natural transformation
from environment
- Cell dies and releases its DNA and is taken up
- Occurs in many bacterial species, including streptococcus which was studied by Griffith
- DNA that is released from a dead cell is picked up by another live cell
- Proteins involved in natural transformation encoded by bacterial chromosome
a) Not an accident of plasmid or phage biology
131
artificial transformation
- Some species do not naturally undergo transformation
- Accomplished in the lab
- Used to transform E. coli for molecular cloning
- Do it in the lab w specific DNA ur trying to get into an E.coli cell
132
antibiotic resistance
- R (resistance) plasmids
- Genes from pathogenic species transferred by plasmids or transduction
- Encode genes for pathogenic traits
- Enterobacteriaceae
- E. coli O157:H7 strain evolved by acquiring genes for pathogenic traits
133
R (resistance) plasmids
- Encode antibiotic resistance genes
- Acquire genes through transposable elements
- Important factor in appearance of antibiotic resistant strains of Staphylococcus aureus
134
mutations in bacteria
- Mutations can arise spontaneously in bacteria as with any organism
a) Radiation and chemicals increase likelihood
- Auxotrophs are nutritional mutants
a) Can no longer survive on minimal medium
- Mutations (and plasmids) can spread rapidly in a population
a) Methicilin-resistant Staphylococcus aureus (MRSA)
b) Vancomycin-resistant Staphylococcus aureus (VRSA)
135
CRISPR systems provide adaptive immunity
Screens of prokaryotic genomes revealed repeated sequences with spacer regions called CRISPR (clustered regularly interspaced short palindromic repeats)
- Adaptive immunity to viral infection
- Prokaryotes integrate short segments of viral nucleic acid into CRISPR loci, produce RNA that degrades viral nucleic acid
- Useful for gene editing in the lab
136
prokaryotic metabolism
Acquisition of carbon
- Autotrophs
- Heterotrophs
137
autotrophs
from inorganic CO2
- Photoautotrophs
- Chemolithoautotrophs
138
Photoautotrophs
e from the sun
139
chemolithoautotrophs
e from oxidizing inorganic substances
140
heterotrophs
from organic molecules
- photoheterotrophs
- Chemoheterotrophs
141
Photoheterotrophs
light as e source but obtain organic carbon made by other organisms
142
Chemoheterotrophs
both carbon atoms and e from organic molecules
| ex: humans
143
Some bacteria can attack other cells directly
Type III secretion system
- Found in many gram-negative bacteria
- Molecular syringe to inject virulence proteins into host cell cytoplasm
- Yersinia pestis (bubonic plague), Salmonella, Shigella
144
common human diseases
- Lyme disease
- Peptic ulcers
- Plague
- Pneumonia
- Tuberculosis
- Typhoid fever
- Typhus
145
human bacterial disease
- In the early 20th century, infectious diseases killed 20% of children before the age of 5
a) Sanitation and antibiotics improved this situation
- In recent years, however, many bacterial diseases have appeared and reappeared
146
tuberculosis (TB)
- Respiratory disease
- Scourge for thousands of years
- Mycobacterium tuberculosis
- Afflicts the respiratory system
- Easily transferred from person to person thru the air
- Multidrug-resistant (MDR) strains are very alarming
147
dental caries
aka tooth decay
- Plaque consists of bacterial biofilms
- Streptococcus sobrinus and S. mutans ferment sugar to lactic acid
- Tooth enamel degenerates
148
peptic ulcers
- Helicobacter pylori is the main cause of these peptic ulcers
- Treated w antibiotics
149
gonorrhea
- One of the most prevalent communicable disease in North America
- Neisseria gonorrhoeae
- Transmitted thru exchange of body fluids
- Can pass from mom to baby thru birth canal
150
chlamydia
- Chlamydia trachomatis
- Silent STD
- incidents have skyrocketed
- Can cause pelvic inflammatory disease and heart disease
151
syphilis
treponema pallidum
- Transmitted through sex or contact with open chancre
- Can pass from mom to baby via birth canal
Four distinct stages
1) Primary: Chancre – highly infectious
2) Secondary: Rash-infectious
3) Tertiary: Latency – no longer infectious but attacking internal organs
4) Quaternary: Damage now evident – heart disease, mental deficiency, nerve damage
152
beneficial prokaryotes
- Decomposers release a dead organism’s atoms to the environment
- Fixation
153
fixation
a) Photosynthesizers fix C into sugars
- Ancient cyanobacteria added O to air
b) Nitrogen fixers reduce N2 to NH3 (ammonia)
- Anabaena in aquatic environments
- Rhizobium in soil
154
symbiosis
the ecological relationship between different species that live in direct contact with each other
155
mutualism
both parties benefit
- Nitrogen-fixing bacteria on plant roots
- Cellulase-producing bacteria in animals
Ex: goats, sheep, cows
156
commensalism
one organism benefits, the other is unaffected
157
parasitism
one organism benefits, the other is harmed
158
bacteria in genetic engineering and bioremediation
- Bacteria are used in genetic engineering
a) “Biofactories”
- Bacteria are used for bioremediation
a) Remove pollutants from water, air, and soil
b) Biostimulation
159
biostimulation
adds nutrients to encourage growth of naturally occurring microbes
-Exxon valdez oil spill
160
biofactories
produce various chemicals, including insulin and antibiotics
161
Vertical transfer
from the original parent to the offspring
162
Horizontal transfer
from one parent to another parent cell thru conjugation of the sex pilus (a tube)
163
the fluid mosaic model of the membrane describes the membrane as
made up of proteins and lipids that can freely move
164
what chemical property characterizes the interior of the phospholipid bilayer
it is hydrophobic
165
the transmembrane domain of an integral membrane protein
is composed of hydrophobic amino acids, often forms an a-helical structure, can cross the membrane multiple times
166
the specific function of a membrane within a cell is determined by the
type and number of membrane proteins
167
the movement of water across a membrane is dependent on
the solute concentration
168
if a cell is in an isotonic environment, then
osmosis still occurs, but there is no net gain or loss of cell volume
169
which of the following is NOT a mechanism for bringing material into a cell
exocytosis
170
a bacteria cell that can alter the composition of saturated and unsaturated fatty acids in its membrane lipids is adapted to a cold environment. If this cell is shifted to a warmer environment, it will react by
increasing the degree of saturated fatty acids in its membrane
171
what variable(s) influence(s) whether a non polar molecule can move across a membrane by passive diffusion?
the difference in conc of the molecule across the membrane
172
which of the following does NOT contribute to the selective permeability of a biological membrane?
hydrogen bond formation between water and phosphate groups
173
how are active transport and coupled transport related?
coupled transport uses the conc gradient established by active transport
174
a cell can use the process of facilitated diffusion to
move ions or large polar molecules from a region of high conc to a region of low conc
175
4 Structures of Prokaryotic and Eukaryotic Cells
1. DNA
2. Cell membrane
3. Cytoplasm
4. Ribosomes
176
4 major macromolecules
1. proteins
2. carbohydrates
3. lipids
4. nucleic acids
177
membrane structure
- Phospholipids arranged in a bilayer
- Globular proteins inserted in the lipid bilayer
- Fluid mosaic model
- 3 types of phospholipid structures
178
Fluid mosaic model
mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond
179
3 types of phospholipid structures
1. formula
2. space-filling model
3. icon
180
4 components of cellular membranes
1. Phospholipid bilayer
2. Transmembrane proteins
3. Interior protein network
4. Cell surface markers
181
phospholipid bilayer
Flexible matrix, barrier to permeability
182
transmembrane proteins
Integral membrane proteins
183
interior protein network
Peripheral or intracellular membrane proteins
184
cell surface markers
Glycoproteins and glycolipids
| 3 blood types: A, B, O
185
studying the cell membrane
- Both transmission e- microscope (TEM) and scanning (SEM) use to study membranes
- One method to embed specimen in epoxy
a) 1 µm shavings
b) TEM shows layers
186
Freeze-fracture microscopy visualizes inside of membrane
- Take it
- Freeze it
- Crack it
- Separate the components
- Part of cell membrane remains, other part comes out
187
phospholipid structure consists of
- glycerol: 3C polyalcohol
- 2 fatty acids attached to glycerol
a) Nonpolar and hydrophobic
- Phosphate group attached to glycerol
a) Polar and hydrophilic
- Spontaneously forms a bilayer
a) Hydrophobic hydrocarbon tails are on inside
b) Polar head groups are on outside towards water
188
bilayers are __
fluid
189
_ bonding of water holds the 2 layers together
hydrogen
190
Individual phospholipids and unanchored proteins can move thru the ___
membrane
191
__ fatty acids make the membrane less fluid than __ fatty acids
saturated; unsaturated
192
__ temps make the membrane more fluid than __ temp
warm; cold
193
membrane proteins
1) Transporters
2) Enzymes
3) Cell-surface receptors
4) Cell-surface identity markers
5) Cell-to-cell adhesion proteins
6) Attachments to the cytoskeleton
7) Integral membrane proteins
194
structure relates to __
function
195
Cell-surface receptors
- Specific ligand binds to specific receptor molecule
| - Transduces signal
196
Cell-to-cell adhesion proteins
Single cells bind to form tissues
197
attachments to the cytoskeleton
- Actin filaments present
| - Actin can relax to allow the change of shape in the protein
198
peripheral proteins
anchoring molecules attach membrane protein to surface
199
anchoring molecules
Anchoring molecules are modified lipids with
1) Nonpolar regions that insert into the internal portion of the lipid bilayer
2) Chemical bonding domains that link directly to proteins
200
Integral membrane proteins
- Span the lipid bilayer (transmembrane proteins)
a) Nonpolar regions of the protein are embedded in the interior of the bilayer
b) Polar regions of the protein protrude from both sides of the bilayer
- Transmembrane domain
201
transmembrane domains
- Spans the lipid bilayer
- Hydrophobic amino acids arranged in α helices
- Proteins need only a single transmembrane domain to be anchored in the membrane but they often have more than one such domain
202
pores
- Extensive nonpolar regions within transmembrane protein can create a pore thru the membrane
- Cylinder of ß sheets in the protein secondary structure called a ß-barrel
203
ß-barrel
- Interior is polar and allows water and small polar molecules to pass thru the membrane
- Larger diameter
- Allows for free movement of water molecules to come in and out of the cell
204
passive transport
movement of molecules thru the membrane in which
- No e is required
- Molecules move in response to a concentration gradient
- diffusion
205
diffusion
movement of molecules from high conc to low conc
| - Will continue until the conc is the same in all regions
206
transport across membranes #1
- Major barrier to crossing a biological membrane is the hydrophobic interior that repels polar molecules but not nonpolar molecules
a) Nonpolar molecules will move until the conc is equal on both sides
b) Limited permeability to small polar molecules
c) Very limited permeability to larger polar molecules and ions
207
facilitated diffusion
Molecules that can’t cross membrane easily may move thru proteins
- Move from higher to lower conc
- Channel proteins
- Carrier proteins
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channel proteins
Hydrophilic channel when open
| -ion channels
209
carrier proteins
- Bind specifically to molecules they assist
- Can help transport both ions and other solutes, such as some sugars and other solutes, such as some sugars and amino acids
- Requires a concentration difference across the membrane
- Must bind to the molecule they transport
210
membrane is selectively __
permeable
211
Ion channels
- Allow the passage of ions
- Gated channels
- 3 conditions determine direction
212
gated channels
open/close in response to stimulus (chemical or electrical)
213
ion channels: 3 conditions that determine direction
1) Relative conc on either side of membrane
2) Voltage differences across membrane
3) Gated channels
214
osmosis
net diffusion of water across a membrane toward a higher solute conc
- Cytoplasm of the cell is an aqueous solution
- Water is solvent
- Dissolved substances are solutes
215
osmotic concentration
When 2 solutions have diff osmotic concentrations
- Hypertonic solution
- Hypotonic solution
- Aquaporins
216
hypertonic solution
has a higher solute conc (water mol move out, cells shrivel)
217
hypotonic solution
has a lower solute conc (water mol move in, cells swell)
218
When 2 solutions have the same osmotic conc, the solutions are __
isotonic
219
aquaporins
facilitate osmosis
220
osmotic pressure
Force needed to stop osmotic flow
- Cell in a hypotonic solution gains water causing cell to swell, creates pressure
- If membrane strong enough, cell reaches counterbalance of osmotic pressure driving water in with hydrostatic pressure driving water out
a) Cell wall of prokaryotes, fungi, plants, protists
- If membrane is not strong, may burst
a) Animal cells must be in isotonic environments
221
maintaining osmotic balance
- Some cells use extrusion in which water is ejected thru contractile vacuoles
- Isosmotic regulation
- Plant cells use turgor pressure to push the cell membrane against the cell wall and keep the cell rigid
222
contractile vacuoles
contract and relax water out the cell to maintain osmotic pressure outside the cell
223
isosmotic regulation
involves keeping cells isotonic w their environment
- Marine organisms adjust internal conc to match sea water
- Terrestrial animals circulate isotonic fluid
224
Plant cells use __ ___ to push the cell membrane against the cell wall and keep the cell rigid
turgor pressure
225
active transport
- Requires e
- ATP is used directly or indirectly to fuel active transport
- Moves substances from LOW to HIGH conc
- Requires use of highly selective carrier proteins
- Goes AGAINST conc gradient
- Active process
226
Carrier proteins used in active transport are..
- Uniporters
- Symporters
- Antiporters
- Terms
227
uniporters
moves 1 molecule at a time
228
symporters
move 2 molecules in the same direction
229
antiporters
move 2 molecules in opposite directions
| -something’s going out while another is going in
230
terms
can be used to describe facilitated diffusion carriers
231
Sodium-potassium (Na+ - K+) pump
- Direct use of ATP for active transport
- Uses an antiporter to move 3 Na+ ions out of cell and 2 K+ ions into the cell
- Against their concentration gradient
- ATP e is used to change the conformation of the carrier protein
- Affinity of the carrier protein for either Na+ or K+ changes so the ions can be carried across the membrane
232
coupled transport
- Uses ATP indirectly
- Uses the e released when a molecule moves by diffusion to supply e to active transport of a diff molecule
- Symporter is used
- glucose-Na+ symporter captures the e from Na+ diffusion to move glucose against a conc gradient
233
bulk transport
- endocytosis
| - exocytosis
234
endocytosis
movement of substances INTO the cell
- 3 types:
1) phagocytosis
2) Pinocytosis
3) Receptor-mediated endocytosis
235
Phagocytosis
cell takes in particulate matter
236
Pinocytosis
cell takes in only fluid
237
Receptor-mediated endocytosis
specific molecules are taken in after they bind to a receptor
In the human genetic disease familial hypercholesterolemia, the LDL receptors lack tails, so they are never fastened in the clathrin-coated pits and as a result, do not trigger vesicle formation. The cholesterol stays in the bloodstream of affected individuals, accumulating as plaques inside arteries and leading to heart attacks
238
exocytosis
movement of substances OUT of cell
- Requires e
- Discharge of materials out of cell
- Used in plants to export cell wall material
- Used in animals to secrete hormones, neurotransmitters, digestive enzymes
239
bacillus
rod shaped
240
coccus
sphere shaped
241
spirillum
spiral shaped
242
gram positive bacteria color
violet
243
gram negative bacteria color
pink
244
Plasma membrane
a phospholipid bilayer w/ embedded proteins
| - Regulates what passes into and out of cell; cell- to-cell recognition; connection and adhesion; cell communication
245
nucleus
Structure (usually spherical) that contains chromosomes and is surrounded by double membrane
-Instructions for protein synthesis and cell reproduction; contains genetic information
246
chromosomes
Long threads of DNA that form a complex with protein
| -Contain hereditary information used to direct synthesis of proteins
247
nucleolus
Site of genes for rRNA synthesis
| -synthesis of rRNA and ribosome assembly
248
ribosomes
Small, complex assemblies of protein and RNA, often bound to ER
-sites of protein synthesis
249
endoplasmic reticulum (ER)
network of internal membranes
-Intracellular compartment forms transport vesicles; participates in lipid synthesis and synthesis of membrane or secreted proteins
250
Golgi apparatus
stacks of flattened vesicles
| -packages proteins for export from cell; forms secretory vesicles
251
lysosomes
Vesicles derived from Golgi apparatus that contain hydrolytic digestive enzymes
-Digest worn-out organelles and cell debris; digest material taken up by endocytosis
252
microbodies
Vesicles that are formed from incorporation of lipids and proteins and that contain oxidative and other enzymes
-isolate particular chemical activities from rest of cell
253
mitochondria
bacteria-like elements w double membrane
- power plants of the cell
- site of oxidative metabolism
254
chloroplasts
Bacteria-like elements with double membrane surrounding a third, thylakoid membrane containing chlorophyll, a photosynthetic pigment
-sight of psyn
255
cytoskeleton
Network of protein filaments
- structural support
- cell movement
- movement of vesicles within cells
256
flagella (cilia)
cellular extensions with 9+2 arrangement of pairs of microtubules
-motility or moving fluids over surfaces
257
cell wall
outer layer of cellulose or chitin; or absent
- protection
- support
258
what do prokaryotes lack?
- ER
- microtubules
- centrioles
- golgi
- nucleus
- mitochondria
- chloroplasts
- lysosomes
- vacuoles
259
what do eukaryotes lack?
- cell wall
- chloroplasts
- vacuoles (or small)
260
what do plant cells lack?
- flagella/cilia
| - centrioles
261
surface markers
- structure: Variable, integral proteins or glycolipids in plasma membrane
- function: identify the cell
- ex: MHC complexes, blood groups, antibodies
262
septate/tight junctions
- structure: Tightly bound, leakproof, fibrous claudin protein seal that surrounds cell
- function: Hold cells together such that materials pass through but not between the cells
- ex: junctions between epithelial cells in the gut
263
adhesive junction (desmosome)
- structure: Variant cadherins, desmocollins, bind to intermediate filaments of cytoskeleton
- function: creates strong flexible connections between cells. Found in vertebrates
- ex: epithelium
264
adhesive junction
| adherens junction
- structure: Classical cadherins, bind to microfilaments of cytoskeleton
- function: Connects cells together. Oldest form of cell junction, found in all multicellular organisms
- ex: tissues w high mechanical stress, such as the skin
265
adhesive junction (hemidesmosome, focal adhesion)
- structure: integrin proteins bind cell to extracellular matrix
- function: provides attachment to a substrate
- ex: involved in cell movement and important during development
266
communicating junction (gap junction)
- structure: six transmembrane connexon/pannexin proteins creating a pore that connects cells
- function: allows passage of small molecules from cell to cell in a tissue
- ex: excitable tissue such as heart muscle
267
communicating junction (plasmodesmata)
- structure: cytoplasmic connections between gaps in adjoining plant cell walls
- function: communicating junctions between plant cells
- ex: plant tissues
268
solution w high conc is __
hypertonic
269
solution w low conc is __
hypotonic
270
when 2 solutions have the same osmotic conc the solution is __
isotonic
271
phospholipid bilayer
- composed of phospholipid molecules
- allows permeability barrier, matrix for proteins
- excludes water-soluble molecules from non polar interior of bilayer and cell
- ex: glucose cannot enter bc it is a large water-soluble molecule
272
what are the transmembrane proteins
- carriers
- channels
- receptors
273
carriers
actively or passively transport molecules across membrane
- move specific molecules through the membrane in a series of conformational changes
- ex: Glycophorin carrier for sugar transport; sodium–potassium pump
274
channels
passively transport molecules across membrane
- create a selective tunnel that acts as a passage thru membrane
- ex: Sodium and potassium channels in nerve, heart, and muscle cells
275
receptors
transmit info into cell
- Signal molecules bind to cell- surface portion of the receptor protein. This alters the portion of the receptor protein within the cell, inducing activity
- ex: Specific receptors bind peptide hormones and neurotransmitters
276
interior protein network composed of..
- spectrins
| - clathrins
277
spectrins
determine shape of cell
- Form supporting scaffold beneath membrane, anchored to both membrane and cytoskeleton
- ex: red blood cell
278
clathrins
Anchor certain proteins to specific sites, especially on the exterior plasma membrane in receptor- mediated endocytosis
- Proteins line coated pits and facilitate binding to specific molecules
- ex: Localization of LDL receptor within coated pits
279
what are the cell-surface markers?
- glycoproteins
| - glycolipid
280
glycoproteins
- "self" recognition
- Create a protein/carbohydrate chain shape characteristic
of individual
- ex: Major histocompatibility complex protein recognized by immune system
281
glycolipid
- tissue recognition
- Create a lipid/carbohydrate chain shape characteristic of tissue
- ex: A, B, O blood group markers
282
transporters
Membranes are very selective, allowing only certain solutes to enter or leave the cell, either through channels or carriers composed of proteins.
283
enzymes
Cells carry out many chemical reactions on the interior surface of the plasma membrane, using enzymes attached to the membrane.
284
cell-surface receptors
Membranes are exquisitely sensitive to chemical messages, which are detected by receptor proteins on their surfaces.
285
cell-surface identity markers
Membranes carry cell-surface markers that identify them to other cells.
Most cell types carry their own ID tags, specific combinations of cell-surface proteins and protein complexes such as glycoproteins that are characteristic of that cell type.
286
cell-to-cell adhesion proteins
Cells use specific proteins to glue themselves to one another. Some act by forming temporary interactions, and others form a more permanent bond.
287
attachments to the cytoskeleton
Surface proteins that interact with other cells are often anchored to the cytoskeleton by linking proteins.
288
passive processes
- diffusion
- facilitate diffusion
- osmosis
289
diffusion
random molecular motion produces net migration of nonpolar molecules toward region of lower concentration
ex: movement of O2 into cells
290
facilitated diffusion
- protein channel
| - protein carrier
291
protein channel
Polar molecules or ions move through a protein channel; net movement is toward region of lower concentration
ex: Movement of ions in or out of cell
292
protein carrier
Molecule binds to carrier protein in membrane and is transported across; net movement is toward region of lower concentration
ex: movement of glucose into cell
293
osmosis
- aquaporins
- Diffusion of water across the membrane via osmosis; requires osmotic gradient
- Movement of water into cells placed in a hypotonic solution
294
active processes
- active transport
a) Na+/K+ pump
b) coupled transport
- endocytosis
- exocytosis
295
Na+/K+ pump
Carrier uses energy to move a substance across a membrane against its concentration gradient
- ex: Na+ and K+ against their concentration gradients
* 3 Na+ leave, 2 K+ enter
296
coupled transport
Molecules are transported across a membrane against their concentration gradients by the cotransport of sodium ions or protons down their concentration gradients
-ex: Coupled uptake of glucose into cells against its concentration gradient using a Na+ gradient
297
endocytosis: 3 components
1) phagocytosis
2) pinocytosis
3) receptor-mediated endocytosis
298
phagocytosis
Particle is engulfed by membrane, which folds around it and forms a vesicle
- ex: Ingestion of bacteria by white blood cells
299
pinocytosis
Fluid droplets are engulfed by membrane, which forms vesicles around them
- ex: “Nursing” of human egg cells
300
receptor-mediated endocytosis
Endocytosis triggered by a specific receptor, forming clathrin-coated vesicles
- ex: cholesterol uptake
301
exocytosis: membrane vesicle
Vesicles fuse with plasma membrane and eject contents
| -ex: Secretion of mucus; release of neurotransmitters
302
F plasmid transfer
1) the F plasmid binds to a site on the interior of the F+ cell just beneath the pilus/conjugation bridge
2) by a process called rolling-circle replication, the F plasmid begins to copy its DNA at the binding point
3) As it is replicated, the dis- placed single strand of the plasmid passes into the other cell
4) a complementary strand is added, creating a new, stable F plasmid
303
hypertonic solution
one where the concentration of solutes is greater outside the cell than inside it.
*cell shrivels bc water is going out
304
hypotonic solution
one in which the concentration of solutes is greater inside the cell than outside of it
*cell bursts bc water is going in
305
Griffith
was the first to conduct experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.
