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BIOL 115 Final > Cell evolution > Flashcards

Cell evolution Flashcards

1
Q

Cell theory

A
  1. All living organisms are composed of one or more cells
  2. The cell is the basic unit of structure and organization in organisms
  3. Cells arise from pre-existing cells
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2
Q

Relative sizes of different cells

A

Cell are measure in micro meters (um) - one one-thousandth of a mm

  • 0.1 nm - Atoms
  • 1nm - Lipids
  • 5-10nm - Potein
  • 100 nm - Flu virus (similar to Ribosome)
  • 1um - Bacteria (Prokaryote cell), Mitochondria, Chloroplasts
  • 10-100um - Plant & Animal cells
  • 100um and a bit - Human egg
  • 1mm - Frog egg
  • 10mm and a bit - Chicken egg
  • 100mm - ostridge egg
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3
Q

Advantages of cell being small

A
  • ions & organic molecules in the environment efficiently enter the cell and rapidly diffuse throughout its volume
  • This is important: cell is an open system (thermodynamics) and must transform energy from its environment into stored chemical energy that can be used for building and breaking down macromolecules (sucrose/glucose)
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3
Q

What happens if the cell grows too large

A

Surface area will be insufficient to support the rate of diffusion required for the increased volume

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3
Q

Prokaryotic cell size

A
  • Relatively small
  • Surface area-to-volume ration of 3:1
    -> plenty of surface to absorb and can rapidly diffuse
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4
Q

Eukaryotic cell size

A
  • Cells are 10-fold larger than Prokaryotic
  • Surface area-to-volume ration of 0.3: 1
    -> once something gets inside of the cell, it takes longer to diffuse throughout the entire volume
    -> Solution: making compartments (used for specific purposes) within the cell help organize smaller spaces for chemical reactions to occur
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5
Q

Prokaryotic & Eukaryotic share 6 common components

A
  1. Macromolecules - Proteins, lipids, carbs
  2. Plasma membrane - Separates cell’s interior from its surrounding environment
  3. Cytoplasm - Consists of a jelly-like cytosol within the cell (watery)
  4. DNA and RNAs
  5. Ribosomes
  6. Enzymes
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6
Q

Prokaryotes: Bacteria

A
  • Bacteria Cell wall: composed of proteins and sugars
  • Bacteria Capsule: gives it shape and resilience, determines how things will enter the cell, protect the cell against toxins
  • Bacteria Chromosome: molecule of double stranded DNA
  • Ability of bacteria to resist freezing and remain in a fluid state bc it’s hard to freeze cytoplasm: quickly or slowly freeze it but it remains fluid. When temperature gets warmer, bacteria wake up
  • Bacteria are so small that molecules can enter and diffuse across the cell in seconds
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7
Q

Eukaryotes: Animal cells

A
  • Reduced S/V ratio selected for adaptations in animals cells. SO:
  • Folding of membranes to increase surface area (minimize size/volume)
  • Intracellular transport
  • Organelles specialized for specific chemical reactions
  • Everything in animal cells are dynamic at room temp.
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8
Q

Microfilaments and Microtubules (Animal Cells)

A

Rod-like structures composed of polymers similar to the polymers that make up the flagella in bacteria
- Related, have diff proteins
- Both: use energy stored in ATP or GTP to do chemical reactions

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9
Q

Eukaryotes: Plant cells

A

Plant cells are adapted for life in one place

  • A rigid cell wall
  • A central vacuole
    -> Stores watery substances so plants can survive in drought (why you don’t need to water plants everyday)
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10
Q

The plasma membrane (all cells)

A

Barrier between the cell and the environment

  • Barrier = permeable (allows things to come in)
    -> Small uncharged molecules can diffuse across membrane
  • Integral membrane proteins: form a channel on their own or w another protein. They allow big molecules to be pumped into the cell across membrane barriers
  • Cholesterol: makes membrane more fluid
  • Glycoproteins (proteins mixed w sugars): form structures that are unique to you
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11
Q

Ribosomes (all cells)

A
  • In cytoplasm
  • Large and small subunits
  • E, A, P sites
  • Enzyme
  • Essential for protein synthesis
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12
Q

Cytoplasm (and nucleoplasm)

A
  • The aqueous environment of a cell
  • Densely packed with molecules and macromolecules (Glycogen)
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13
Q

Organelles (Eukaryotes)

A
  • Organelles: a collection of factories and assembly lines
    -> Have their own membrane barriers
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14
Q

Organelle membranes

A
  • Isolate chemical reactions
    OR
  • Ensure that metabolic pathways involving many chemical reactions are efficient
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15
Q

Organelles: Nucleus

A
  • Nucleus: a membrane compartment that holds the DNA
    -> Huge surface area
  • Inside the nucleus: RNA polymerase is working on the DNA at the genes to produce mRNA
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16
Q

Organelles: Nuclear Pore

A

Allows mRNA has to leave the nucleus, and proteins need to move back and forth across through

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17
Q

Organelles: Nucleolus

A
  • Specialized region of DNA
  • Where the specialized mRNA required for ribosomes to function is synthesized.
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18
Q

Organelles: Nucleoplasm

A
  • The aqueous environment within the nucleus
  • Special chemical reactions needed for transcription occur in the nucleoplasm

NOTE: For translation, chemical reactions occur in the cytoplasm.

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19
Q

Organelles: Mitochondria

A
  • Specialized for the synthesis of ATP
  • Folded membranes with many different compartments
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20
Q

Micro-environments

A
  • Membranes form Microenvironment that allow chemical reactions to occur without affecting the rest of the cell
    -> Breaking down polysaccharides
    -> Eliminating waste via Phagocytosis: lysosome containing digestive enzymes break down food vacuole
21
Q

Intracellular transport system in Eukaryotes

A

Transport system: makes the diffusion of things linear through by restricting what things can diffuse in

  • Nucleus, Rough Endoplasmic Reticulum and Golgi are connected
  • These organelles are a combined protein synthesis and transport system
22
Q

The Cytoskeleton (All cells)

A

Composed of specialized rods (Microfilaments and Microtubules) that grow and shrink

23
Q

Cytoskeleton Functions

A
  • Cell shape and cell movement
  • Transport within cells
  • Exerts force to move chromosome or cleave membranes
24
Q

Microfilaments

A
  • Actin = subunit of a microfilament/enzyme
  • Actin are monomers, when bound to/collide w ATP or ADP (nucleotide) changes length of the microfilament
25
Q

How do microfilaments increase in length

A

Concentration Actin-ATP high = increase in length

  • Actin-ATP subunits can polymerize (join together) to form a microfilament. The energy stored in ATP helps drive this polymerization process,
26
Q

How do microfilaments decrease in length (shrink to microfili)

A

Concentration Actin-ADP high = decrease in length

  • As the microfilament grows, ATP is hydrolyzed (loses a phosphate group and releases energy) to form ADP.
  • Actin-ADP subunits tend to depolymerize (break apart), causing the microfilament to shrink or decrease in length.
27
Q

How do cells control their shape and size

A

By controlling how much ATP/ADP actin is coming in and out

  • Growing actin helps cells change shape, move around, or perform specific tasks.
  • Shrinkage assists in splitting or cutting the cell’s plasma membrane.
28
Q

Microtubules

A
  • Are composed of 13 rods/subunits that form a tube
  • Concentration of tubulin-GTP and tubulin-GDP effects the length of the microtubule
29
Q

How microtubules increase in length

A

Concentration tubulin-GTP high

30
Q

How microtubules decrease in length

A

Concentration tubulin-GDP high

31
Q

Example of Catastrophe

A
  • When Tubulin starts to undergo hydrolysis, there is a mix of GDP and GTP-bound tubulin.
  • When this happens: tubulin structures decompress, and the whole cellular structure collapses or falls apart.
32
Q

Actin is necessary for cell divison

A
  • Actin helps split the cell into two parts during cell division.
  • Microtubules attach to chromosomes and pull them apart, allowing them to move to different parts of the cell.
  • Cancer: when chromosomes don’t move properly during cell division causing uncontrolled cell division
33
Q

Cells as bio machines

A
  • Cells create large structures, like “bio-machines,” to do specific jobs.

Microscopy Example in Mammal Cells:

  • To see things in a mammal cell under a microscope, we use the fact that chromosomes (structures in the cell) have different densities.
  • Bc of diff densities, light bends differently when passing through chromosomes compared to other cell parts.
  • This bending of light helps us see and study objects in the cell using a microscope.
34
Q

Primary cilium

A

Sensory structure on every cell

35
Q

Cilia

A

Cilia on cells that line lungs: Helps move things so that mucus does not pile up in lungs

36
Q

Flagella

A

In bacteria, flagella are moving the cells around in single cell eukaryotic organisms

37
Q

Cilia and Flagella are built from

A

Microtubules and motor proteins that use ATP to apply force

38
Q

Plants have special organelles

A
  • Central vacuole: stores watery sap
  • Mitochondria
  • Chloroplasts: where light radiant energy can be transformed into ATP
39
Q

Evolution of the cell

A
  • Inorganic molecules + water + heat = radiant energy
    -> CO2 on early Earth absorbed energy from sunlight that was released as radiant energy
    -> When this energy condenses and particles collide, it triggers chemical reactions that led to the formation of organic molecules
  • Organic molecules = building bocks of the macromolecules in living organisms
40
Q

Evolution of the cell: DNA and RNA

A
  • RNA before DNA
  • RNA is how molecules remember info
  • RNA can be translated into Proteins which can catalyze its own replication (DNA can’t do this)
41
Q

Phospholipid membrane

A
  • Acts as a barrier
  • Forms watery environment that is suitable for chemical reactions such as:
    -> RNA passed on through auto-catalyzed duplication
    -> Cells increasing in number through fission
42
Q

Evolution for Mitochondria and Chloroplasts

A

Endosymbiosis
- Host cells engulfed aerobic (needs oxygen) or photosynthetic (uses sunlight) bacteria
- Aerobic bacteria became mitochondria
- Autotrophic (Photosynthetic) bacteria became chloroplasts

NOTE:
- Mitochondria and Chloroplasts have their own DNA, Ribosomes, and RNAs
- Both similar size to bacteria

43
Q

Models for evolution of Eukaryotes

A
  • Nucleus first
  • Mitochondria first
  • Eukaryote first
44
Q
A
  • The idea that bacteria, animals, and plants share a common ancestor.
  • Archaea (type of microorganism) have the ability to perform photosynthesis.
    -> Suggests that the common ancestor of bacteria, animals, and plants might have also had the potential for photosynthesis.
45
Q

Web of life hypothesis

A
  • Ancestral community of primitive cells gave rise to bacteria, archaea, and eukarya
46
Q

Electron microscopes

A
  • Nanometer resolution 1x10-9 m - individual molecules are visible
    -> Ex. To understand microtubule structure:
    -> Slice through frozen cell that had been treated with a dye that binds to proteins in a particular way and is very dense
    -> so when the electrons hit it, they are either absorbed or scatter
47
Q

Super-resolution light microscope

A
  • Chromosome Segregation during mitosis
  • Chromosomes are denser than the Cytoplasm and Membranes
  • Can be detected by their refraction (contrast) of white light
48
Q

Light microscopes: How can we detect cellular components in living cells?

A

Bioluminescent organisms such as jellyfish gave us a tool that changed the life sciences: GFP protein

49
Q

Fluorescent Microscopy

A
  • Because of the degeneracy of the genetic code, the GFP protein can be produced by many types of cells
  • Blue light excites protein and will produce green light which represents GFP protein
50
Q

Protein engineering

A

By introducing a series of amino acid mutations into jellyfish GFP, scientists created a colour palette for cells
- Blue to Yellow = GFP (Eukaryotic)
- Yellow to Red = RFP (Prokaryotic)

51
Q

Super-resolution fluorescence microscopy

A
  • 60 nanometer resolution
  • Can see dynamic growth and shrinkage of microtubules by tracking the movement of the green

BIOL 115 Final (5 decks)

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