Chapter 4 And 5 Flashcards
(149 cards)
1
Q
Small cells related to diffusion:
A
•small for reasons related to diffusion, into and out of cells
•affected by: surface area, temperature, concentration gradient of diffusing substance, the distance it must occur
More control over cell contents
2
Q
Big cell related to diffusion:
A
- size increase= time increase for diffusion into a cell
- synthesize more macromolecules
- higher energy requirements
- produce greater waste
3
Q
The advantage for small cells:
A
• surface area-to-volume ratio
- as cell size increases volume increases
- more rapidly than its surface area
4
Q
In a spherical cell, Surface area is proportional to
A
The square of the radius
5
Q
In a spherical cell the volume is proportional to
A
The cube of the radius
6
Q
The membrane surrounding a cell plays a key roll in
A
Controlling cell function
7
Q
Do smaller cells have greater or less control over contents?
A
Greater
8
Q
How did large cells overcome the surface area to volume problem?
A
Adaptive mechanisms
Ex: more than one nucleus
•long and skinny, keeping all points close to plasma membrane
•allows diffusion from outside to inside to be rapid
9
Q
What are cells visible to the naked eye?
A
Egg cells
10
Q
Why can humans see cells?
A
Limited resolution of the human eye
11
Q
Resolution is
A
The minimum distance two points can be apart and still be distinguished as two separate parts
12
Q
Light microscopes
A
- visible light
* two lenses
13
Q
Compound microscope
A
- magnify in stages
* using several lenses
14
Q
Scanning electron microscope
A
Beams electrons onto the surface of the specimen
15
Q
Immunohistochemistry
A
- stains that bind to specific molecules
- uses antibodies that bind to particular protein
- generated in animals
16
Q
Basically similarities of cells
A
- nucleoid or nucleus
- cytoplasm
- ribosomes
- plasma membrane
17
Q
In prokaryotes genetic material lies
A
Within a single cellular molecule of
DNA
•near center of cell in area called nucleoid
18
Q
DNA in eukaryotes
A
- contained in nucleus
* surrounded by double membrane structure= nuclear envelope
19
Q
Cytoplasm
A
- semifluid matrix
- fills interior of cell
- sugars, amino acids, proteins (used to carry out everyday activities)
- contains organelles
20
Q
Organelles
A
- macromolecule structure in the cytoplasm
* specialized for specific function
21
Q
Cytosol
A
•part of cytoplasm that contains organic molecules and ions in solution
22
Q
Plasma membrane
A
- phospholipid bilayer
- separates contents from its surroundings
- embedded proteins
23
Q
Transport proteins
A
- help molecules and ions move across membrane
* environment to inside or vise versa
24
Q
Receptor proteins
A
- induce changes within the cell when they come into contact with specific molecules in environment
- ex hormones
- markers
25
Two divisions of cells
* eukaryotic
| * prokaryotes
26
What lack a nucleus and do not have an internal membrane system? Also don't have membrane bound organelles?
Prokaryotes
27
The simplest organisms are
Prokaryotes
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Prokaryotes consist of
* cytoplasm surrounded by a plasma membrane
* encased within rigid cell wall
* no interior compartments
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Prokaryotes are able to perform
Photosynthesis
| •also break down dead organisms
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Two main domains under prokaryote:
Archaea
| Bacteria
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What do prokaryotes lack?
Membrane bound organelles
•cytoskeleton
•strength of cell comes from rigid cell wall
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Bacteria includes
* peptidoglycan cell wall (carbohydrate matrix cross linked)
| * cell walls determine susceptibility of bacteria
33
Archaea contain
* cell walls made of polysaccharides and proteins
* inorganic molecules
* different lipids than bacteria, hydrocarbons attached to a glycerol at each end
* can't adapt to changing environmental temperatures
* DNA syntheses closer to that of eukaryotes
34
Flagella
* for locomotion
* made of proteins
* uses energy stored in a gradient
35
Eukaryotes are
* conpartmentalized
| * achieved by endomembrane system, weaves through cell interior
36
Central vacuole
* large membrane bound sac
| * stores proteins pigments and waste materials
37
What cells contain vesicles?
Plants and animal cells
| •small sacs that store and transport a variety of material
38
Inside the nucleus of a eukaryotic cell
•DNA is wound around proteins and packaged into proteins
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Eukaryotic cells are supported by an internal protein scaffolding called
The cytoskeleton
40
Plants cell wall is made of
Cellulose
41
What does the nucleus do?
* largest organelle
* contains genetic synthesis
* many contain nucleolus
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Nucleolus
* in nucleus
* dark staining zone
* where ribosomal RNA is synthesized
43
Nuclear envelope
* surface of the nucleus
* bound by two phospholipid bilayer membranes
* together make up envelope
* outer membrane is continuous with the cytoplasms interior membrane system aka endoplasmic reticulum
44
Nuclear pores
* shallow depressions on nuclear envelope
* made with proteins
* where two membranes pinch together
* allows small molecules to diffuse between nucleoplasm and cytoplasm
* also controls protein and RNA passage
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Nuclear pours allow two kinds of particle
•proteins moving in to be incorporated into the nuclear structure or catalyze activities
Or
•RNA and RNA protein complexes being exported to cytoplasm
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Inside nuclear envelope
* network of fibers that make up nuclear lamina
* made of intermediate fibers call nuclear lamins
* gives shape
* involved in deconstruction and reconstruction
47
Chromatin
* prokaryotes: single circular chromosome - no chromatin
* eukaryotes: multiple linear chromosomes
* DNA is organized with proteins into complex structure called chromatin
* regulates gene expression
* aid in direction of DNA day to day activities
48
Ribosomes
* protein syntheses machinery
* most complex molecular assemblies
* made of two sub units
* each subunit composed of proteins and ribosomal RNA
* found free in cytoplasm or associated with internal membranes
* universal organelles
49
Distinction between prokaryotes and eukaryotes (inside of cell)
The endomembrane system in eukaryotes
50
Endoplasmic reticulum
* largest internal membrane
* made of phospholipid bilayer
* weaves in sheets, creating folds
* inner ER is one if largest compartments
* called the cisternal space
51
Two largest compartments in a cell
•inner region of ER- cisternal space
•region exterior to that, cytosol
- fluid component of cytoplasm
- contains dissolved organic molecules proteins and ions
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Rough ER
* protein synthesis
* surface, pebbly due to ribosomes
* proteins either, sent to lysosomes or vacuoles, or embedded in plasma membrane
53
Glycoproteins
* modified proteins, by addition of short chain carbohydrates
* destined for secretion
54
ER
* manufactures membranes
| * produces phospholipid molecules and membrane proteins
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Smooth ER
* few bound ribosomes
* network of tubes
* membranes of SER contain embedded enzymes
* steroids synthesized in the SER
* membrane lipids assembled here
* stores ca2+, signals muscle contraction
* makes foreign substances less toxic
56
Golgi body
flattened stacks if membranes
•aka Golgi apparatus
•collection packaging and distribution of molecules synthesized at one location
•ER synthesizes molecules then go to lumen if Golgi apparatus
•Modifies membranes as they pass through
•synthesize cell wall components
57
Cisternae
* newly formed altered glycoproteins or lipids collect here
* in flat stacked membrane folds called cisternae
* pinch off small secretory vesicles
58
Lysosomes
```
Membrane bound digestive vesicles
•components of endomembrane system
•arise from Golgi apparatus
•contain degrading enzyme- catalyze rapid breakdown of proteins, nucleic acids, carbs and lipids
•breaks down old cells
```
59
Microbodies
* found in: plants animals fungi and protists
* enzyme bearing
* way eukaryotes organize metabolism
60
Peroxisome
* type of Microbody
* oxidize fatty acids
* if they weren't isolated in microbodies, would short circuit the metabolism of the cytoplasm
* forms from ER vesicles
* PBD- disorder caused by mutations in genes
* produce hydrogen peroxide
61
Vacuoles
* in plants
* ex: central vacuole
* used for storage and water balance
* surrounded by tonoplast
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Tonoplast
Membrane surrounding vacuole
•contains channels for water
•helps maintain it's osmotic balance
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Vacuoles 2
* helps maintain it's osmotic balance
* allows cell to expand or contract in certain conditions
* maintains toxicity of cell
* plants grow by expanding vacuole, not increasing cytoplasm
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Vacuoles in fungi and protists
* contractile vacuole- protists
| * used to maintain water balance
65
Mitochondria
* eukaryotes
* two membranes, one outer and one inside and folded, called cristae
* metabolize sugar and generate ATP
* have own DNA
* divide in two when a new cell is made
* genes in the nucleus make up the mitochondrion, which means it could not be made on its own without nucleus
66
Cristae partition mitochondrion into two compartments
* matrix: inside inner membrane
| * intermembrane space: between the two mitochondrial membranes
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Chloroplasts
* make own food
* contain photosynthetic pigment chlorophyll
* has its own DNA
* most genes that make up chloroplasts are in nucleus
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Leucoplasts
* lack pigment
* complex internally
* contains DNA
* leucoplasts that store starch: termed amyloplast
69
Plastids
* chloroplasts, leucoplasts, amyloplast
| * former by other existing plastids
70
Symbiosis
Close relationship between organisms of different species that live together
71
Endosymbiosis
•some eukaryotic organelles evolve by symbiosis
- arise by two cells that were each free living
•one prokaryote cell engulfed by and became part of another cell
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Three types of fiber that compose the cytoskeleton
* actin filaments
* microtubules
* intermediate filaments
73
Actin filaments
* two protein chains loosely twined together
* exhibit polarity (have plus and minus end)
* cellular movements responsible for: crawling, pinching, formation of cellular extensions
74
Microtubules
* largest of cytoskeleton elements
* in a constant state of flux
* facilitate cellular movement
* organize cytoplasm
* responsible for moving materials within the cell itself
75
Intermediate filaments
* most durable fibers in animal cells
* do not break down
* ex keratin
76
Four components used to move material along microtubules
* a vesicles or organelle that is being transported
* motor energy that provides energy driven motion
* connector molecule that connect the vesicles to the motor molecule
* microtubules on which the vesicle will ride like a train
77
What filament allows a cell to crawl?
* actin
* allow: inflammation, clotting, wound healing, spread of cancer
* myosin: main protein, muscle contraction
78
Myosin
* protein filament that causes muscle to contract
| * through crawling
79
9+2
* eukaryote flagellum
* consists of a circle of nine microtubule pairs surrounding two central micro tubules
* flagellum ungulates
80
Basal body
* microtubules of flagellum arise from this
| * point where flagellum protrudes from surface of the cell
81
Cilia
* similar organization to 9+2
* short projections
* organized in rows
* can move water over surface
* eukaryotes
82
Fungi cell walls are made of?
Chitin
83
Plants and protists cell walls are made of?
Cellulose
84
Animal cells secret what
* an extracellular matrix
* made of glycoproteins
* and collagen
85
Integrins
* integral part of plasma membrane in animal cells
* extending into cytoplasm
* where attached to microfilaments
86
Prokaryote cells include
* cell wall(protein/polysaccharide)
* cell membrane
* flagella maybe
* Ribosomes
* chromosomes (single circle of DNA)
87
Animal cells have
* cell membrane
* flagellum (9+2 structure)
* ER
* ribosomes
* microtubules
* centrioles
* Golgi apparatus
* nucleus
* mitochondria
* chromosomes (multiple)
* lysosomes
88
Plants cells have
•cell wall with cellulose
•everything except
-centrioles
•also have flagellum and cilia in very few species
89
Four components of cellular membranes
* phospholipid bilayer
* transmembrane proteins
* interior protein network
* cell-surface markers
90
The ER adds adds chains of sugar molecules to membrane proteins and lipids converting them into
Glycoproteins
| And glycolipids
91
Glycoproteins and glycolipids
Act as cell identity markers
92
Saturated fats make the membrane more or less fluid?
Less fluid
| •because they pack together tightly
93
Saturated fats make the membrane more or less fluid?
* more fluid
| * kinks made by double bonds keep from packing tightly
94
Cholesterol effect on a membrane
* is a sterol
| * can increase or decrease membrane fluidity depending on the temperature
95
What is special about bacteria and the what they can do with their membrane?
* can maintain constant membrane fluidity
| * despite temperature
96
Proteins and protein complexes key functions
* transporters
* enzymes
* cell surface receptors
* cell surface identity markers
* cell to cell adhesion proteins
* attachment to cytoskeleton
97
Transmembrane proteins differ in the way they
Transverse the lipid bilayer
•difference lies in how many times they span the membrane
•each membrane spanning region is called transmembrane domain
98
Transmembrane domain
* each membrane spanning region of a transmembrane protein is called transmembrane domain
* made if hydrophobic amino acids
* need only a single protein to be anchored in the membrane
99
Biologists classify some types of receptors based on
* number of transmembrane domains they have
| * ex: G protein coupled receptors with 7 membrane spanning domains
100
Pores that open up a plasma membrane
* beta sheets form motif
* folding back and forth ini cylinder
* arranged like a pipe through membrane
* allow molecules to pass through the membrane
101
Passive transport
* substance can move in and out of the cell without energy
| * ions and molecules can move freely and easily due to concentration gradients
102
Diffusion
* movement from high concentration to low concentration
| * continues until gradient is the same in all regions
103
What two molecules can move across the membrane if there is a gradient?
* O2
| * nonpolar organic molecules: steroid hormones
104
Facilitated diffusion
* diffusion mediated by a membrane
| * no need for ATP
105
Channel proteins
* have hydrophilic interior
* provides and aqueous channel
* through with polar molecules can pass
* when channel is open
106
Carrier proteins
* no ATP
* bind to specific molecule
* assists through channel
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Selectively permeable
* channels and carriers are usually selective to one type of molecule
* makes membrane selectively permeable
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Ion channels
* ions can't pass due to their polar nature
| * ion channels possess hydrated interior that spans the membrane
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Gated channels
* open or close in response to stimuli
| * stimulus can be electrical or chemical
110
Gated channels: three conditions that determine direction of net movement of ions
* relative concentration of net movement on either side of membrane
* voltage across the membrane
* state of gate, open or closed
111
Membrane potential
A voltage difference is an electrical potential across the membrane
•changes in this are basis for transmission of signals in the nervous system
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Carrier proteins carry:
•transport ions
•solutes
•sugars
•amino acids
** still transport by diffusion, concentration difference required
**carriers can exhibit saturation, where all carriers are taken
113
When all carriers are taken carriers exhibit
* saturation
* rate of transport becomes constant
* ex: crowd passive through gates of a stadium
* if all gates are filled, becomes constant
114
RBC trick to keep glucose inside the membrane
* as glucose enters, phosphate is immediately added to it
* converting to glucose phosphate
* highly charged
* making unable to bind to glucose transported
* not allowing is to pass through the membrane
115
Aqueous solution
* cytoplasm of a cell
| * that contains: ions, molecules that dissolve in water
116
Solvent
* water
| * substances dissolve in it
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Solutes
•substances that dissolve in water
118
Solutes and solvents tent to
* diffuse from high to low concentration
| * down concentration gradient
119
Hydration shells form when
* water molecules interact with dissolved solutes
| * form around charged solute molecules
120
Water and solutes separated by semipermeable membrane:
* the side with higher solute concentration has tied up more water molecules in hydration shells
* has fewer free water molecules
* water moves towards higher solutes concentration
* free water molecules move down concentration gradient
121
Osmosis
•net diffusion of water across a membrane toward s a higher solute concentration
122
Osmotic concentration
•convention of all solutes in a solution
123
Hypertonic
* solution with the higher osmotic concentration
| * ex: cells in this environment would shrivel
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Hypotonic
* the solution with the lower osmotic concentration
| * ex:cells would swell
125
Isotonic
* same osmotic concentration
| * ex:normal cell
126
A cell in any environment can be thought of as a plasma membrane
•separating two solutions
•cytoplasm and extracellular fluid
•the direction and extent of any diffusion across plasma membrane
- determined by the osmotic strength
127
Aquaporins
* specialized channels for water
| * two kinds: water only, other allows small hydrophilic molecules (glycerol and urea) to cross as well
128
Osmotic pressure
•the force needed to stop osmotic flow
•amt of water that enters the cell depends on the
- difference in solute concentration between the cell and extracellular fluid
129
What cells can withstand high internal pressure
•prokaryotes, fungi, plants and protists
130
Three developed strategies solving dilemma posed by being hypertonic to their environment
- therefore having a stead influx of water by osmosis
* extrusion
* isosomotic regulation
* turgor
131
Extrusion
•single celled eukaryotes use contractile vacuoles to remove water through pore
132
Isosomotic regulation
* organisms that live in salt water
* adjust internal concentration of solutes to match surroundings
* no net flow occurs into or out of cells
133
Turgor
•most plant cells are hypertonic to environment, containing high concentration of solutes in central vacuoles
•turgor pressure presses plasma membrane firmly against interior of the cell wall
-making it rigid
134
Turgor pressure
* in plants
* internal hydrostatic pressure
* presses plasma membrane firmly against the cell wall
* making it rigid
* allows plant to maintain shape
135
Active transport
* requires the expenditure of energy
* ATP
* across cell membrane up concentration gradient
136
Uniporters
* transport a single kind of molecule
* molecule or ion specific carrier protein
* can also be used to describe facilitated transporters
137
Symporters
* two molecules in same direction
| * can also be used to describe facilitated transporters
138
Antiporters
* transport two molecules in opposite directions
| * can also be used to describe facilitated transporters
139
Sodium potassium pump
* maintain by concentration by pumping Na+ out and K+ in
* from low to high concentrations
* na binds
* ATP phosphorylates protein with sodium
* na diffuse out
* k binds to site
* k binding causes se phosphorylation of protein
* k diffuse into cell
140
Coupled transport
•molecules moved against their concentration gradient by using the energy stored in a gradient of different molecule
•ex: active glucose transporter uses na gradient produced by pump to move glucose into the cell
- transporter would be a symporter, two molecules same direction
141
Bulk transport
* transports large polar molecules into cell
* substances cells require for growth
* two types: endocytosis and exocytosis
* required energy
142
Endocytosis
•plasma membrane envelops food particles and fluids
| -three types of endocytosis: phagocytosis, pinocytosis, receptor mediated endocytosis
143
Phagocytosis
•takes in particulate or multiple particles
144
Pinocytosis
•if material cell takes in is liquid
145
Receptor mediated endocytosis:
* mostly in eukaryotes
* molecules bind to receptors
* clathrin acts as mouse trap
* forms internal vesicles
146
Exocytosis
* discharge of material from vesicles
| * plants is important: exports materials needed to make cell wall through the cell membrane
147
Type or molecule taken up my receptor mediated proteins: LDL
* brings cholesterol into the cell where it is incorporated into the membrane
* plays key roll in determining stiffness of the body's membrane
148
Passive transport
* facilitated diffusion
* carrier proteins
* ion channels
* osmosis
149
Active transport
```
•requires ATP
•sodium potassium pump
•coupled transport
•bulk transport
-pinocytosis, phagocytosis, receptor mediated endocytosis, exocytosis
```
