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BIOL 110 > Exam 2 > Flashcards

Exam 2 Flashcards

Lectures 7-12

1
Q

What are the 5 characteristics of life?

A
  1. Organization and complexity (uses energy to maintain both actively)
  2. Respond to the environment:
    - Actively maintain internal conditions within idea ranges (homeostasis ex. body temp)
  3. Growth and metabolism
  4. Reproduction/heredity
  5. Evolve
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2
Q

What are the 2 types of cells?

A
  1. prokaryotes - bacteria & archaea
    - dominant forms of life in terms of biomass (if you weighed all the prokaryotes on earth and all eukaryotes, prokaryotes would weigh way more) and diversity (more species)
  2. eukaryotes - (everything else that’s not bacteria and archaea) animals, plants, fungi, and protists (protists are everything that isn’t animals, plants, and fungi)
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3
Q

What is the major difference between eukaryotes and prokaryotes?

A

Eukaryotic cells can be up to 1000x larger than prokaryotic cells

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4
Q

What are the economics of cell size?

A
  • Cell volume represents DEMAND - lots of metabolism occurring to keep cell alive (greater volume of cell = greater demand)
  • Cell surface area represents SUPPLY - everything that enters/exits the cell must go through its surface area
  • To survive: SUPPLY ≥ DEMAND
  • As cell size increases, cell volume (demand) increases faster than the cell’s surface area (supply), so at some point, demand exceeds supply
  • So remaining small allows cells to maintain a workable surface area to volume ratio
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5
Q

Prokaryotes’ differences with eukaryotes

A
  • No nucleus, DNA is in the nucleoid
  • No internal membrane system
  • Have a cell wall (a protective outer barrier) composed of peptidoglycans
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6
Q

Prokaryotes’ similarities with eukaryotes

A
  • Both use DNA as their genetic material
  • Both have an outer plasma membrane (phospholipid bilayer)
  • Both have cytoplasm: a semi-solid substance that contains the cell’s internal components
  • Both have ribosomes, the universal organelle, responsible for synthesizing proteins
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7
Q

Prokaryotic cell structure (some vs all)

A
  • structures all prokaryotes have: cell wall, phospholipid bilayer, cytoplasm, ribosome, DNA, nucleoid
  • structures only some prokaryotes have: capsule, pili, flagellum
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8
Q

What is a distinctive feature of eukaryotic cells?

A

internal compartmentalization
- Possible b/c of an internal membrane system
- Internal membrane-bound compartments are called organelles which means little organs

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9
Q

What is the one organelle prokaryotes have?

A

ribosomes (exception to the rule that organelles needs membranes)

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10
Q

What are the functions (3) of the nucleus?

A
  • Stores genetic information (like a suitcase 🧳)
  • Ribosomes are assembled here
  • RNA is produced (transcription) here
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11
Q

What is the structure of the nucleus?

A
  • Nuclear envelope: a double lipid bilayer membrane that defines the nucleus (has an inner and outer lipid bilayer) (bilayer that surrounds cell is single)
  • Outer lipid bilayer is connected to the smooth and rough ER
  • Nuclear pores: passages through the nuclear envelope that regulate nuclear transport
  • Nucleus contains chromatin: chromosomal DNA bound to DNA-binding proteins
  • Nucleolus: an area inside the nucleus where ribosomes are assembled
    (not an organelle
    On tests, don’t read too fast and read it as nucleus)
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12
Q

Function of ribosomes

A

synthesize proteins

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13
Q

Structure of ribosomes

A
  • Made of ribosomal proteins and ribosomal RNAs (rRNAs)
  • Some rRNAs have enzymatic function: ribozymes
  • Ribosomes are assembled at the nucleolus
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14
Q

Endomembrane system definition and components (3)

definition and what it includes

A

a network of internal (lipid bilayer) membranes that include
* Endoplasmic reticulum (ER)
- Smooth (SER): no ribosomes
- Rough (RER): ribosomes on surface
* Golgi apparatus - like Amazon distributor system of the cell, go in and shipped out
* Vesicles (like a balloon but walls are made of lipid bilayer membrane)
- Amazon trucks - delivering content

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15
Q

Endoplasmic Reticulum (ER) Structure

tubules, lumen definition

A
  • Network of interconnect tubules (tiny tubes)
  • Walls of tubules made of lipid bilayer
  • Lumen: space inside tubes
  • Smooth and rough ER are interconnected with each other and the outer lipid bilayer of the nuclear envelope
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16
Q

SER Specialized Functions (4)

A
  • Site of lipid synthesis (phospholipids made here)
  • Site of fatty acid desaturation (fatty acid made saturated then can become unsaturated)
  • Site of cholesterol synthesis
  • Some carbohydrate synthesis occurs
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17
Q

RER specialized functions

A

A site for synthesis of some proteins that are
1. bound for export out of the cell
or
2. for use in the endomembrane system

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18
Q

Golgi apparatus structure

A
  • Series of flattened tubes (sacs)
  • Walls of tubes are a lipid bilayer
  • Not connected to other structures
  • Cis face: receives transport vesicles from ER
  • Trans face: transport vesicles exit
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19
Q

Golgi Appartus Function (amazon center)

A
  • Proteins and other molecules may be modified
  • Molecules are sorted by eventual destination
  • Molecules are released in vesicles
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20
Q

Exocytosis

A

process by which material is exported out of the cell

ex. production and export of insulin

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21
Q

Endocytosis

A

material is taken into a cell

  • Plasma membrane surrounded material from outside the cell, trapping it in an endocytic vesicle
  • Can be a:
  • specific process using receptors on cell
  • non-specific taking up water and nutrients
  • The endocytic vesicle then fuses w/ a digestive vesicle: a lysosome
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22
Q

Lysosome definition

A

membrane-bound vesicles with a low internal pH (4.5-5.0 b/c proton pumps) that contain digestive enzymes
* like a floating stomach
* Bud off from the trans face of Golgi

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23
Q

Lysosome function

A

to digest material from outside or inside the cell (worn-out organelles that need to be destroyed and recycled)

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24
Q

Primary lysosome

A

not fused to anything yet

25
Q

secondary lysosome

A

fuse with an endocytic vesicle or cellular organelle; after fused, it is a secondary lysosome where the material that is going to be digested meets the enzyme that is going to break the bacteria down

26
Q

What does tuberculosis bacterium do

A
  • Can prevent fusion of endocytic vesicle and primary lysosome so TB avoids destruction and lives in cell
  • Multiplies inside macrophage cell
  • Kills it
  • Spreads to infect more cells
27
Q

Mitochondria structure

A
  • double lipid bilayer membrane
  • Outer membrane: covered entire organelle
  • Inner membrane: extensively infolded
  • Folds are called cristae
  • Liquid center called the matrix
28
Q

Mitochondria function

A

energy metabolism (ATP production)

29
Q

Mitochondria and endosymbiotic theory

A

one time mitochondria were free-living prokaryotes and developed an endosymbiotic relationship with current-day eukaryotic cells

only arise from pre-existing mitochondria (reproduce themselves)

30
Q

Chloroplast structure

A
  • double lipid bilayer (DLB) membrane
  • Outer and inner LB membranes cover the entire organelle
  • Within DLB is an internal membrane into multiple stacks of disks
  • Thylakoid: single membrane disk
  • Granum: a stack of thylakoids
  • Stroma: liquid substance surrounding grana
31
Q

Chloroplast function

A

Site of photosynthesis in plant cells
Light energy converted into usable chemical energy

32
Q

Chloroplast and endosymbiotic theory

A

applies

33
Q

Cytoskeleton structure

not an organelle

A

Network of multiple types of proteins inside cells

34
Q

cytoskeleton functions (3)

A
  • Provides structural support within cells (can make cells change shape for when cells need to get into tight spaces)
  • Has a role in transport within cells (motor proteins attached to vesicles and CS motor proteins walk vesicles along and take them where they need to go)
  • Help mobile cells move ex. flagellum
35
Q

Extracellular Matrix structure

not an organelle

A

Network of multiple types of proteins outside of cells

36
Q

Extracellular Matrix functions (3)

A
  • Structural support outside cells
  • Glues cells into higher-order structures, like organs
  • Has a role in cell-cell communication (signaling molecules along ECM)
37
Q

Plasma Membrane

A
  • Defines the inside and outside of a cell; it’s a barrier
  • Are ‘selective barriers’
  • Regulates transport into/out of the cells
  • PM is dynamic (always changing) and cells can adjust the…
  • chemistry of the pH
  • molecules associated with the PM
38
Q

Method and results of discovering membrane structure

A
  • Obtain and count red blood cells
  • Calculated the total surface area of the RBCs (multiplied SA of 1 cell by total # of cells)
  • Destroyed the cells and collected the membrane phospholipids (through chemical separation)
  • Placed the phospholipids into a chamber of liquid buffer where they formed a floating monolayer (all tails pointed up)
  • Measured the total SA of the phospholipids in the chamber and compared it to the total SA of the RBCs

Results: he found that the SA of the monolayer was double the SA of the cells (2:1 ratio)

39
Q

Why did Garter use red blood cells?

A
  • Easy to obtain and count
  • Uniform in size across all animals and people
  • Was perfect b/c eukaryotes have a nuclear membrane w/ phospholipids which would have messed up the results; mature red blood cells eject all other membranes except for the plasma membrane so it worked perfectly
40
Q

Fluid mosaic model

A
  • plasma membranes are fluid structures
  • The phospholipid bilayer is like a lake
  • Molecules are ‘floating’ around in it
41
Q

Cell fusion experiment

A
  • The membrane proteins of cells were stained with fluorescent dyes (human cell membrane proteins w/ red dye and mouse cell membrane proteins w/ green dye)
  • The cells were fused together
  • Conclusion: proteins diffuse around the membrane which means they’re fluid
  • if it was static, it red and green would stay on their respective side
42
Q

Photo-bleaching experiment

A

demonstrated fluidity of plasma membranes

  • Labeling membrane associated proteins w/ fluorescent dye so it glows under fluorescent light
  • Exposed specific area of cell to laser which destroys the fluorescent dye
  • Proteins are still there
  • Dye is not there
  • If membranes are static, bleached out area will stay in same place
  • Membranes are fluid so bleached out area got filled back up with fluorescence
43
Q

What is the importance of maintaining fluidity level?

A
  • If the membrane is too fluid, it will not serve as a barrier and will fall apart
  • If the membrane is too solid, transmembrane proteins (in phospholipid bilayer) won’t be able to flex (change their shape) and carry out their functions
  • Ex. transport and signaling proteins
44
Q

How do membranes regulate fluidity?

A
  • Cells regulate fluidity of their membranes by changing the fatty acid chains of phospholipids in 2 ways
    1. Cell can generate phospholipids that have more or fewer unsaturations in the fatty acid chains
    2. Cell can generate phospholipids that have longer or shorter fatty acid chains

  • If it’s too liquid, phospholipids will become more unsaturated and shorter at the same time, not at different times
45
Q

How does the plasma membrane respond to lower temperatures? ex. fridge

A
  • plasma membrane becomes less fluid (too solid) → cell makes phospholipids with fatty acid chains that are
  • Shorter
  • More unsaturated
46
Q

How does the plasma membrane respond to higher temperatures?

A
  • plasma membrane becomes too liquidy → cells make phospholipids with fatty acid chains that are
  • Longer
  • More saturated
47
Q

What is the major barrier for molecules crossing a plasma membrane?

A

the hydrophobic interior

48
Q

hydrophobic interior permeability levels

A
  • Permeable to nonpolar molecules (size doesn’t matter as long as they’re nonpolar)
  • Less permeable to small polar molecules w/ no electric charge
  • Ex. H2O
  • Not permeable to large polar molecules and ions
  • Ex. glucose
49
Q

What are the types of membrane transport

A
  1. passive transport (diffusion): movement of molecules across the membrane from high concentration to low concentration
    Does NOT require cellular energy
  2. active transport: movement of molecules across the membrane from low concentration to high concentration
    DOES require cellular energy
50
Q

What are the types of passive transport?

A
  1. simple diffusion: IF the PM is permeable to a molecule
    AND there is a difference in concentration of that molecule across the membrane
    THEN the molecule will diffuse across the membrane by simple diffusion
    * No energy input from cell required
    * No transport proteins required
  2. facilitated diffusion: diffusion of molecules that can’t cross the membrane on their own must be facilitated
    * No energy required
    * Requires transport proteins are selective
    - Channel proteins
    - Carrier proteins
51
Q

How do cells regulate facilitated diffusion

A
  1. Regulating the concentration of particular transport proteins in the membrane
    - The cell can make more or less of a type of transport protein to increase/decrease a protein
  2. Regulating the activity of transport proteins
    - Some proteins are always on, so always transporting
    - Some have an on-and-off switch
52
Q

Channel proteins in FD

5 points

A
  • Like tunnels
  • Don’t bind to the molecules they transport
  • Direction of moment depends on concentration
  • Movement doesn’t require energy input from cell
  • Channels can be
  • Always open (molecules always going through them)
  • Gated: opened or closed
53
Q

Carrier proteins

3 points

A
  • Must bind to molecules they transport
  • Direction of movement depends on concentration (remember it’s in facilitated diffusion, not active transport)
  • Movement doesn’t require energy input from cell
54
Q

What are the 3 types of carrier proteins in FD?

A
  1. Uniporters: carrier proteins that only transport 1 type of molecule
  2. Symporters: carrier proteins that transport 2 types of molecules, in the same direction, at the same time
  3. Antiporters: carrier proteins that transport 2 types of molecules, in opposite directions, at the same time
55
Q

Kinetics of channel vs carrier proteins

A
  • Channel proteins display linear kinetics (no speed limit)
  • Carrier proteins display saturation kinetics (carrier proteins have binding sites, so at high concentrations, binding sites will eventually run out)
56
Q

Active transport

A
  • Used by cells to go against the concentration gradient of a molecule across a plasma membrane
  • b/c concentration gradients are critical for some biological processes
  • Moving molecules against a concentration gradient requires:
    Carrier proteins
    Energy input from cell
57
Q

peripheral proteins

A

attached to surface of lipid layer

58
Q

integral proteins

A

integrated into the lipid bilayer in whole or part

BIOL 110 (9 decks)

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