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DAT Bio > 2- Cell Membranes > Flashcards

2- Cell Membranes Flashcards

(116 cards)

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1
Q

What is characteristic of phospholipid regions?

A

They are amphipathic, meaning they have hydrophobic and hydrophilic regions.

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2
Q

What are the constituents of a phospholipid?

A

A glycerol backbone, phosphate group, and two fatty acid tails.

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3
Q

What parts of the phospholipid are hydrophilic and hydrophobic, respectively?

A

Hydrophilic head and hydrophobic tail

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4
Q

______ is a precursor to the steroid hormone and makes 50% of eukaryotic membranes.

A

Cholesterol

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5
Q

Cholesterol is ______.

A

Amphipathic

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6
Q

What are membrane proteins divided into?

A

Integral and Peripheral

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7
Q

Describe important things about Integral Proteins

A

Cross the ENTIRE lipid bilayer, they are amphipathic, and their functions are to act as receptor and transport proteins.

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8
Q

Describe important things about peripheral proteins.

A

Do NOT cross the entire lipid bilayer, they are POLAR, and their functions are to act as adhesion proteins and cellular recognition proteins.

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9
Q

What are the 3 determinants for the fluidity of the membrane?

A

Temperature, Cholesterol, and Fatty Acid Saturation

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10
Q

How does temperature affect fluidity of the membrane?

A

When the temperature is hot, the membrane is loose. When it is cold, the membrane is more compact.

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11
Q

What is the function of cholesterol within the bilayer?

A

Maintains the distance between the layer when it is cold and holds hem together when the temperature is warm.

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12
Q

How does the saturation of the fatty acids come into play with respect to membrane fluidity?

A

When there is cis unsaturation, there are kinks in the chain, meaning that there will be increased distancing within the membrane. When they are trans, however, the case is opposite and they behave normally.

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13
Q

Are fatty acids amphipathic?

A

NO

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14
Q

How is transport regulated throughout the cell (2 mechanisms)?

A

Active and Passive

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15
Q

Describe Important things about Passive Transport

A

Utilize passive diffusion (diffusion down the concentration gradient)- moving from high to low concentration. THERE IS NO ENERGY REQUIRED.

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16
Q

______ is the currency of the cell.

A

ATP

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17
Q

What are the types of passive transport?

A

Facilitated and Simple

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18
Q

Describe Simple Diffusion

A

Small, uncharged molecules. Molecules include water and CO2.

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19
Q

What is the direction of flow in OSMOSIS?

A

Down the concentration gradient.

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20
Q

Describe Facilitated Diffusion

A

Large, hydrophilic, or charged molecules. Utilizes integral proteins, examples are glucose and sodium.

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21
Q

What are the directions possible in facilitated diffusion?

A

Uniporter, Symporter, and Antiporter

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22
Q

Define Channel Proteins

A

Connect extra and intracellular environments. Allow for the passage of small polar molecules.

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23
Q

Define Carrier Proteins

A

Changes shape. Only faces one side at a time.

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24
Q

What is a division of channel proteins called?

A

Porins. They are not specific and normally allow any hydrophilic molecule to pass.

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25
Define Active Transport
Molecules travel against the concentration gradient and a lot of energy is required. RELIES HEAVILY on carrier proteins.
26
What are the types of Active Transport?
Primary, Secondary, Cytosis
27
What is an example of primary active transport?
Sodium-Potassium Pump 3-SOPI (3 Sodiums Out and 2 Potassiums In) Uses energy from ATP hydrolysis and pumps ions AGAINST the concentration gradient.
28
What goes on with Secondary Active Transport?
Relies on other energy sources besides ATP, transports molecules AGAINST their concentration gradient.
29
Define Cytosis
Facilitate bulk transport (large polar molecules).
30
What are the types of cytosis?
Endocytosis (Pinocytosis, Phagocytosis, Receptor-Mediated Endocytosis) and Exocytosis
31
Define Endocytosis
Formation of a vesicle around something extracellular (plasma membrane package).
32
Define Phagocytosis
Cellular Eating (undissolved MATERIAL)
33
Define Pinocytosis
Cellular drinking (dissolved materials)
34
Define Receptor-Mediated Endocytosis
Specific molecule binds to the peripheral membrane protein (some non-steroidal hormone)
35
Define Exocytosis
The opposite of endocytosis.
36
Define Organelles
Rooms of the cell
37
What is the difference between Eukaryotes and Prokaryotes in terms of organelles?
Eukaryotes have membrane bound organelles while prokaryotes do not.
38
What is the difference between the cytoplasm and the cytosol?
Cytoplasm is everything in the cell and cytosol is the intracellular fluid.
39
Where is DNA located in prokaryotes and eukaryotes?
Its in the nucleoid for prokaryotes and nucleus for eukaryotes.
40
Define Perinuclear Space
the space between the inner and outer envelopes of the membrane.
41
Define Nucleolus
Most dense part of the nucleus. Responsible for rRNA production
42
______ are the passageway to the nucleus.
Nuclear Pores
43
What is the function of ribosomes?
Protein Translation
44
Are ribosomes considered to be organelles?
No
45
Both eukaryotes and prokaryotes have ______ subunits for their ribosomes.
2. Eukaryotes have 60S and 40S while prokaryotes have 50S and 30S.
46
______ are assembled in the nucleoid region in prokaryotes.
Ribosomes
47
Describe Important things about the Rough ER
CONT. with the outer nuclear membrane. It is called rough because it has ribosomes bound to the surface.
48
What happens in the ER Lumen
Protein modification (glycosylation). Protein moves towards the Golgi Apparatus
49
What are the Rough ER Protein Fates?
1) Becomes part of the membrane 2) Leaves cell- EXOCYTOSIS
50
Describe Important things about the Smooth ER
No ribosomes attached, synthesize lipids, steroid hormones, detoxify cells, and store ions.
51
Describe the Golgi Apparatus
Flattened Sacs called cisternae (looks like stacks on a pancake) There is a cis face and a trans face (cis is closer to nucleus) Mail Room ER Product Modification (Phosphorylation)
52
Describe Important things about Lysosomes
Break down things. Function at low pH. Use acidic and hydrolytic enzymes.
53
When are lysosomes used?
For endocytosis, autophagy, and apoptosis.
54
What is the distribution of vacuoles in different cells?
Plant and Fungal- ALL Animal- Some Bacterial- RARE
55
What are the type of vacuoles?
Transport-Food-Central-Contractile (TFCC)
56
What is the function of food vacuole?
to store food until it is merged with lysosome.
57
What types of vacuoles are only found in plant cells?
Central
58
What is the function of the central vacuole?
Maintains the cell shape and acts as storage places for the plants.
59
What is the function of the contractile vacuole?
To pump out excess water through ACTIVE transport.
60
Define Endomembrane System
A group of organelles that modify, package, and transport proteins and lipids entering or exiting the cell.
61
What are important things about Peroxisomes?
Not in the EM system. Break down fatty acids Detoxification May break down proteins.W
62
What is a concern with peroxisomes?
Releases hydrogen peroxide, which is a reactive oxidative species (ROS): excess cause damage to DNA and potentially leads to cancer. The enzyme CATALASE breaks it down to oxygen and water.
63
What is the function of the chloroplast?
Photosynthesis
64
What are important things about centrosomes?
Found near the nucleus, contains a pair of centrioles, and serves as a microtubule organizing center.
65
Where does transcription occur in Eukaryotes?
Nucleus
66
Define Cytoskeleton
Lies within the cytoplasm of eukaryotes and prokaryotes.
67
What are the functions of the cytoskeleton?
Structural Support, Movement, and transport.
68
What are the different constituents of the cytoskeleton?
Microtubule, Microfilament, and Intermediate Filament
69
What are important things about microfilaments?
Smallest diameter, double helix, assemble/disassemble rapidly. Aids in cell movement through cyclosis (cytoplasmic movement) and cytokinesis. Has directionality, which means its a one way street for myosin.
70
What are important things about intermediate filaments?
Intermediate diameter, many different proteins make this up. MOST COMMON IS KERATIN
71
What are 3 structures that allow for structural support?
Nuclear Lamina, Cell Junctions, and web throughout the cytoplasm.
72
What are some important things about microtubules?
They have the LARGEST diameter, are hollow tubes, grow/shrink rapidly, and have directionality.
73
What are some of the roles of microtubules?
Beating of the cilia and flagella, structural support, and cell division.
74
What are examples of motor proteins?
Kinesins and Dyneins
75
What is the main job of motor proteins?
To transport cargo through ATP hydrolysis.
76
What are some important things about Kinesins?
Anterograde transport, end up on the + end of the microtubule (EDGES)
77
What are some important things about Dyneins?
Retrograde transport, end up on the - end of the tubules (center)
78
What is the function of axonemal dyneins?
Propagates the beating of the cilia and flagella
79
What is the function of microtubule organizing centers? What is another function?
Create, organize, and extend micotubules. Formation of the spindle apparatus.
80
What are the types of Spindle Apparatus Microtubules?
KPA: Kinetochores, Polar Microtubules, and Astral Microtubules
81
How can centrosomes be classified?
As microtubule organizing centers.
82
Where are centrosomes present/not present?
They are present in animal cells but NOT present in plant and fungal cells.
83
How many centrosomes are needed per cell?
One per daughter cell
84
What are some important things about Centrioles?
there are 2 per centrosome (one mother and one daughter) and they are hollow microtubule cylinders. Form the cilia and flagella
85
What is the process of the formation of cilia and flagella with centrioles?
Mother centriole attaches to the membrane, basal body forms, and the cilia or flagella is made.
86
What is the difference between prokaryotes and eukaryotes with respect to the dimers they use?
Prokaryotes use flagellin and Eukaryotes use tubulin.
87
What is the function of the Pericentriolar Matrix
Perform the nucleation of microtubules, several tubulin dimers form microtubule, and the microtubule is secured to the centrosome.
88
What is the ECM and what are its functions?
Carbs, Adhesion Proteins, and fibrous structural proteins. The function is mechanical support between the cells.
89
______ make collagen.
Fibroblasts (related to fibrous structural proteins)
90
What are the functions of fibrous structural proteins?
Strength and rigidity
91
What are some important things about Integrin?
It's a transmembrane protein and its function is to alert the cell about the outside environment (GDDA): grow, divide, differentiate, apoptosis.
92
What is the function of fibronectin?
Connects integrin to collagen or proteoglycans and assist in the transduction of cells.
93
What are the functions of Laminin?
Similar to fibronectin.
94
What are the functions of the cell wall?
Structural Support, Filtration, and Protection SPF
95
What are the different walls of different types of organisms?
Plants: Cellulose Fungi: Chitin Bacteria: Peptidoglycan Archaea: Polysaccharide
96
What can be said about the wall of bacteria?
It's a peptidoglycan wall (glycocalyx) which is a coat of glycoproteins and lipids.
97
What are the functions of glycocalyx?
Adhesion, Protection, Cell-Cell Recognition APC
98
What is the function of cell matrix junctions?
connect the ECM to cytoskeleton.
99
What are the main types of matrix junctions and what is the difference?
Focal Adhesions and Hemidesmosomes Focal Adhesion is ECM to actin whereas hemidesmosome is ECM to keratin.
100
What are the types of cell-cell junctions?
TDAG Tight, Desmosomes, Adherens Junction, and Gap Junction
101
What can be said about the tight junction?
Found in the gut and functions are being water tight. (no fluid passage between the cells)
102
What can be said about desmosomes?
Staples Extend across cell membranes-keratin Robust mechanical stability Connect to cytoskeleton
103
What can be said about Adherens Junction?
It is the EXACT same as desmosomes but it uses ACTIN
104
What can be said about Gap Junctions?
Made up of connexons which are made of connexins (channel protein that allows for the transport of fluid)
105
Define Connexin
Channel protein that allows for the passage of fluid.
106
What can be said about the Middle Lamina?
It is like sticky cement but makes transport of large molecules difficult.
107
Define Tonicity
Relative solute concentration of 2 solutions (semipermeable membrane separating them).
108
How do you determine the direction of solvent flow?
Side with lower concentration gets lower and side with higher gets higher.
109
How are you going to determine the direction of flow with osmosis?
Water goes to side with MORE solute.
110
Define Isotonic
Extracellular and Intracellular environments are the same.
111
Define Hypertonic
outside concentrations are higher (water leaves the cell)
112
Define Hypotonic
inside concentrations are higher (water enters the cell)
113
Plant cells prefer _____ environments.
Hypotonic
114
Define Brownian Motion
Random motion due to kinetic energy
115
Define Cytoplasmic Streaming
Cyclosis Transportation of nutrients, proteins, and organelles. Uses actin filaments as the road
116

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