The Cell and Its Components Flashcards

1
Q

Describe the structure and function of the nucleus

A
  • Stores and replicates the genetic information of the cell
  • Is surrounded by a nuclear envelope which consists of 2 phospholipid bilayers to separate the nucleus from the rest of the cell
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2
Q

What is the importance of the nuclear envelope?

A
  • Studded with thousands of nuclear pore complexes, which form openings in the envelope
  • Allows ions, water, and other small particles though the openings
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3
Q

Describe the structure and function of the endoplasmic reticulum

A
  • The surface is devoted to synthesizing proteins which are studded by ribosomes
  • Molecular aggregates of protein and RNA
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4
Q

What is the function of the smooth ER?

A
  • Synthesizes and metabolizes lipids and other lipid-containing molecules like phospholipids
  • Can perform other functions, depending on the type of cell
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5
Q

Describe the structure and function of the vesicles

A
  • Pieces off of the smooth ER which pinch off and form
    -Used for transport and storage
  • A membrane-enclosed sac
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6
Q

Describe the structure and function of the Golgi apparatus

A
  • A curved stack of membrane sacs
  • Packages, processes, sorts, and distributes proteins, lipids, and other substances within the cell
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7
Q

Describe the structure and function of lysosomes

A
  • A membrane-enclosed sac
  • Contains enzymes that catalyze the hydrolysis of reactions by breaking down macromolecules
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8
Q

Describe the structure and function of peroxisomes

A
  • A membrane-enclosed sac
  • Contains an oxidative enzyme that breaks down excess fatty acids and hydrogen peroxide
  • Can help produce bile and cholesterol
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9
Q

Describe the structure and function of the vacuole

A
  • A large membrane-bound sac
  • Only found in plants
  • Stores amino acids, sugars, macromolecules, water, and ions
  • Determines the turgor pressure of the plant depending on the plants water intake
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10
Q

Describe the structure and function of the mitochondria

A

Breaks down high-energy molecules to break them down to convert stored energy into usable energy

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11
Q

Describe the structure and function of chloroplast

A
  • Contains photosynthetic pigment
  • Absorbs light energy which converts carbon dioxide and water through redox reactions
  • Stores glucose
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12
Q

Describe the structure and function of the cell wall

A
  • Used for protection and support
  • Only found in plant cells
  • Around the outside of the cell
  • Composed of polysaccharides, glycoproteins, or both
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13
Q

Describe the structure and function of the cytoskeleton

A
  • A network of protein fibres which extends throughout the cytosol
  • Provides the cell with structure, shape, support and mobility
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14
Q

What are the 3 structures in the endomembrane system?

A
  1. Vesicles
  2. Golgi Apparatus
  3. Lysosomes
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15
Q

What is the structure and function of cilia and flagella? How is their structure slightly different?

A
  • A long, thin appendage which allows cells to move themselves or move substances over their surface
  • Cilia: Small hair-like projections
  • Flagella- Has a long, whip-like tail
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16
Q

What does the fluid mosaic model depict?

A
  • A model of the basic framework of a semi-fluid phospholipid bilayer
  • Represents the proteins and substances that are able to pass through
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17
Q

What are the important features of the fluid mosaic model?

A
  • The mosaic section depicts proteins and other macromolecules
  • The fluid section depicts the membranes in the molecule that can move freely
  • Contains the phospholipid bilayer
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18
Q

Explain the structure and components of the phospholipid bilayer

A
  • Composed of one glycerol and 2 fatty acids, and a highly polar phosphate group
    Head: Polar, hydrophilic
    Tail: Non-polar, hydrophobic
  • Held together by intermolecular interactions
  • Polar heads face out, toward the aqueous environment
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19
Q

What are the 4 main factors that affect the fluidity of the phospholipid bilayer?

A
  1. Temperature
  2. % of Unsaturated Fatty Acids in Phospholipids
  3. Fatty Acid Tail Length
  4. Cholesterol in Membrane
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20
Q

What is the difference between peripheral and integral proteins?

A

Integral: Embedded in the membrane
Peripheral: Loosely and temporarily attached to outer regions of the membrane, or to integral proteins

21
Q

How do peripheral and integral proteins work?

A

-Help stabilize membranes
- Holding them in place by linking them to the cytoskeleton of the cell

22
Q

What is the difference between passive and active transport?

A

Passive: The movement of ions/molecules across a cell membrane from a region of higher to lower concentration without energy
Active: The transport of a solute across its membrane with the use of energy (ATP)

23
Q

What is the difference between diffusion and osmosis?

A

Diffusion: The net movement of ions/ molecules from an area of high to low concentration
Osmosis: The movement of water from an area of high to low concentration across a semi-permeable membrane

24
Q

Explain the passive transport by diffusion

A
  • The net movement of ions/molecules from an area of high to low concentration
  • Its goal is to meet an equilibrium on both sides of the membrane
25
Q

Explain the passive transport by osmosis

A
  • The movement of water from an area of high to low concentration across a semi-permeable membrane
  • Water molecules move in and out of the cell until both sides reach an equilibrium
26
Q

Explain the structure and condition of a cell in an isotonic solution

A
  • Animal cell is immersed in mild salt solution
  • Cell is flaccid
  • No net diffusion of water
27
Q

Explain the structure and condition of a cell in a hypertonic solution

A
  • Cell is in salt water
  • Cell is plasmolyzed/shriveled
  • If plant cells are plasmolyzed, they wilt
28
Q

Explain the structure and condition of a cell in a hypotonic solution

A
  • A cell in freshwater
  • Cell is turgid
  • Can potentially burst (lysis)
29
Q

Explain the passive transport by facilitated diffusion

A

The transport of ions or molecules across a membrane using a membrane protein along the concentration gradient for that ion or molecule

30
Q

What is a channel protein and what is its function?

A
  • Diffuses through protein channels
  • Allows specific ions or molecules to cross the membrane along their concentration gradients
31
Q

Explain the process of primary active transport

A
  • Uses ATP to transport molecules or ions from one side of the membrane to the other
  • Use carrier proteins instead of channel proteins
  • Ion pumps are carrier proteins that use ATP to “pump” ions across the membrane against a concentration gradient
32
Q

What is a carrier protein and what is its function?

A
  • Binds to specific molecules and transports them across the membrane, which is released on the other side
  • Changes shape while transporting molecules
33
Q

Explain the process of secondary active transport

A
  • Uses an existing gradient to actively transport another substance
  • As an ion pump functions, a concentration gradient forms across the membrane
  • A difference in charge or electric potential builds up across the membrane
  • The electrochemical gradient created by primary active transport via an ion pump is used by a different protein to transport other molecules across a cell membrane
34
Q

Explain the structure and hydrolysis of ATP

A
  • A source of energy used in active transport
  • Composed of an adenosine nucleotide, with a triple phosphate group
  • ATP hydrolyzes to form ADP, which releases energy
35
Q

What is endocytosis?

A
  • Cell membrane engulfs extracellular material to bring it inside the cell
  • Pinches off to form vesicles inside the cell
36
Q

What is exocytosis?

A
  • Vesicles fuse with the cell membrane and empty its contents into the extracellular environment
  • Vesicle becomes part of the cell membrane
  • In animal cells, exocytosis is used to release substances such as hormones, neurotransmitters, and digestive enzymes
37
Q

What is phagocytosis

A
  • Endocytosis involving solid particles
  • Known as cell eating
  • Forms large vesicles or vacuoles
38
Q

What is pinocytosis?

A
  • Endocytosis involving liquid particles
  • Known as cell drinking
  • Forms small pinocytic vesicles
39
Q

Explain the process of the sodium-potassium pump

A
  1. 3 cytoplasmic sodium binds to the Na/K pump
  2. The sodium bind stimulates phosphorylation by ATP
  3. Phosphorylation causes the protein to lose its original conformation, expelling the sodium outside
  4. 2 extracellular potassiums bind to the protein, causing a release of a phosphate group
  5. The loss of a phosphate group results in the protein regaining its original conformation
  6. Potassium is expelled and sodium sites are receptive, repeating the cycle again
40
Q

What kind of transport is endocytosis and exocytosis?

A

Membrane-assisted transport

41
Q

Explain the permeability of the phospholipid bilayer

A
  • Impermeable to macromolecules
  • Slightly permeable to ions
  • Quite permeable to small, lipid-containing molecules
  • Permeable to CO2 and O2
  • Larger molecules pass through the membrane using carrier proteins
42
Q

Explain how temperature affects the fluidity of the phospholipid bilayer

A
  • Increased temperature, increased fluidity
  • Decreased temperature, decreased fluidity, forming a gel-like state
43
Q

Explain how the % of unsaturated fatty acids in phospholipids affects the fluidity of the phospholipid bilayer

A
  • Double bonds create kinks in the fatty acid tail
  • More double bonds cause fatty acids to be more fluid
44
Q

Explain how fatty acid tail length affects the fluidity of the phospholipid bilayer

A
  • Longer fatty acid tails have more intermolecular attractions
  • They hold tightly together, decreasing fluidity
45
Q

Explain how the cholesterol of the membrane affects the fluidity of the phospholipid bilayer

A
  • Acts as a “mortar” that fills in small gaps in the phospholipid structure, improves membrane impermeability to small water molecules like glucose
  • Acts as a membrane “antifreeze gel”, decreases fluidity at high temperatures and increases fluidity at low temperatures
46
Q

What is the difference between what channel and carrier proteins transport?

A

Channel: Transports ions or small polar molecules across the membrane
Carrier: Tansports large molecules-glucose, amino acids

47
Q

What are aquaporins?

A
  • Water moves rapidly in and out of the cell
  • Water movement through aquaporins is a passive process that follows the direction of osmotic pressure across the membrane
48
Q

The sodium-potassium pump is an example of what kind of transport?

A

Primary active transport