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BIO 1140 - Introduction to Cell & Molecular Biology > BIO 1140 - Cell Structure & Varieties > Flashcards

BIO 1140 - Cell Structure & Varieties Flashcards

1
Q

What is a Cell?

A

a small membrane bound unit filled with a concentrated aqueous solution of chemicals with reproduction capacity

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2
Q

What is the Cell Size difference of Prokaryotes and Eukaryotes?

A
  • Prokaryotic cells range from 0.2 to 2.0 µm in diameter
  • Eukaryotic cells range from 10-100 µm in diameter
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3
Q

Why are cells small and large organisms made of many small cells?

A
  • The cell surface area determines the amount of substances entering and exiting the cell
  • To function, cells must maintain a large surface area to volume ratio
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4
Q

What are the different Nutritional Requirements of Organisms?

A

Energy Source:
- Phototroph = Light
- Chemotroph = Chemical Compounds (Lithotroph & organotroph)

Carbon Source:
- Photoautotroph = Inorganic
- Photoheterotroph = Organic
- Chemoautotroph = Inorganic
- Chemoheterotroph = Organic

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5
Q

Who built the first Compound Microscope?

A

Robert Hooke (1665) built the first compound microscope
- two converging lenses
- coined the term ‘cell’

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6
Q

Who first observed living microorganisms?

A

Anton Van Leeuwenhoek (1670) observed living microorganisms
- Called them animalcules
- 200x magnification

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7
Q

What is the Cell Theory?

A
  • Cells are the fundamental units of life
  • All living organisms are composed of cells
  • All cells come from preexisting cells
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8
Q

What can we add to the Cell Theory?

A
  • Modern cells evolved from a common ancestor
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9
Q

What is Bright-Field Microscopy?

A

Unless natural pigments are present, there is little contrast and details are not distinguished
- light passes directly through the cells

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10
Q

What is Phase-Contrast Microscopy?

A

contrast is increased by emphasizing differences in refractive index (the capacity to bend light)
- enhances light and dark regions in the cell

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11
Q

What is Differential Interference-Contrast Microscopy?

A

The combined images look as if the cell is casting a shadow on one side
- two beams of polarized light are used

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12
Q

What is Stained Bright-Field Microscopy?

A

Stains differ greatly in their chemistry and their capacity to bind to cell materials.
- A stain enhances contrast and reveals details not otherwise visible

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13
Q

What is Fluorescence Microscopy?

A

a natural substance in the cell or a fluorescent dye that binds to a specific cell material is stimulated by a beam of light
- the longer wavelength florescent light is observed coming directly from the dye

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14
Q

What is Confocal Microscopy?

A
  • fluorescent materials are used
  • adds a system of focusing both the stimulating and emitted light so that a single plane through the cell is seen
  • The result is a sharper two-dimensional image than with standard fluorescence microscopy
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15
Q

When was Electron Microscopy Invented?

A
  • 1931
  • Max Knoll and Ernst Ruska invented electron microscope
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16
Q

How does an Electron Microscopy work?

A

The electron microscope directs electrons through a vacuum at a fluorescent screen or digital camera to create a visible image

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17
Q

What is the Resolution of an Electron Microscopy?

A

The resolution of electron microscopes is about 2nm (100,000x greater than the eye).

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18
Q

What are the Two Main Types of Electron Microscopy?

A
  1. Transmission Electron Microscope (TEM)
  2. Scanning Electron Microscope (SEM)
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19
Q

What is Transmission Electron Microscopy?

A
  • a beam of electrons is focused on the object by magnets
  • Objects appear darker if they absorb the electrons
  • If the electrons pass through they are detected on a fluorescent screen
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20
Q

What is Scanning Electron Microscopy?

A
  • electrons aredirected to the surface of the sample where they causeother electrons to be emitted
  • These electrons are viewedon a screen
  • The tree-dimensionalsurface of the samplecan be seen
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21
Q

What is the Cytoplasm?

A

Everything inside the cell, except for the nucleus of the cell has one, is termed the cytoplasm

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22
Q

What is the Cytosol?

A

The cytosol is the fluid cytoplasm not contained inside another compartment

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23
Q

What is the Difference between Prokaryotes and Eukaryotes?

A
  • A prokaryotic cell does not have a nucleus or any other membrane-enclosed internal compartments
  • Eukaryotic cells contain membrane-enclosed compartments called organelles
  • Nucleus is the most noticeable organelle in eukaryotes
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24
Q

What do all Prokaryotes have?

A
  • A cell membrane
  • A nucleoid
  • A cytoplasm
  • Ribosomes (25 nm in diameter)
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25
Q

What is a Cell Membrane?

A

The cell membrane encloses the cell, regulating the traffic of materials into and out of the cell, and separating its
interior from the external environment.

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26
Q

What is the Nucleoid?

A

The nucleoid is a region in the cell where the DNA is located.

DNA is the hereditary material that controls cell growth, maintenance, and reproduction

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27
Q

What are Ribosomes?

A

Ribosomes are complexes of RNA and proteins in the cytoplasm that are about 25 nanometers (nm) in diameter

  • Sites of protein synthesis, where information coded for in nucleic acids directs the sequential linking of amino acids to form proteins
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28
Q

What are some Specialized Features of Prokaryotes?

A
  • A cell wall and capsule
  • Internal membranes
  • Cytoskeleton (filamentous proteins, FtsZ, MreB)
  • Flagella (motility, adhesion, invasion)
  • Pili (motility, contact, adhesion, genetic exchange)
  • Fimbriae (contact and adhesion)
29
Q

What is a Cell Wall composed of?

A

The cell wall is composed of:
- Peptidoglycan
- outer membrane (absent in some bacteria)

30
Q

What is a Capsule?

A

The capsule is made mostly of polysaccharides.

  • protect the bacteria from attack by white blood cells
  • Keep them from drying out
  • help bacteria attach to other cells
31
Q

What is the difference between Gram Positive and Negative Bacteria?

A

Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane.

Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane.

32
Q

What does the Wall Structure of a Bacteria affect?

A

The wall structure affects the cell’s ability to retain the crystal violet stain used in the Gram staining procedure which can then be visualized under a light microscope.

33
Q

What are Cytoskeletons of Prokaryotes?

A
  • Some prokaryotic cells have filamentous proteins (FtsZ, MreB)
  • These proteins are homologous to the ones found in eukaryotic cells
  • Bacterial cytoskeleton is involved in cell division, movement and shape maintenance.
34
Q

What are Flagella, Pili and Fimbriae of Prokaryotes?

A
  • Flagella (motility, adhesion, invasion)
  • Pili (motility, contact, adhesion, genetic exchange)
  • Fimbriae (contact and adhesion)
35
Q

How do some Prokaryotes Swim?

A

Some prokaryotes swim using their flagella
- Flagellum (singular), Flagella (plural): hair like helical structures
- Responsible for the motility of bacteria
-15-20nm in diameter
- Composed of Flagellin protein

Three parts: basal body, hook and filament

36
Q

What do Eukaryotic Cells contain?

A

Eukaryotic cells contain organelles

  • Membrane-enclosed organelles process information, transform energy, form internal compartments for transporting proteins, and carry out intracellular digestion
  • An internal cytoskeleton plays several structural roles
37
Q

What is the most Prominent Organelle in a Eukaryotic Cell?

A

Nucleus

38
Q

What are the Functions of a Nucleus?

A
  • It is the location of most of the cell’s DNA and the site of DNA replication
  • It is the site where gene transcription is turned on or off
  • A region within the nucleus, the nucleolus, is where ribosomes (see the previous section) begin to be assembled from RNA and proteins
  • The contents of the nucleus, aside from the nucleolus, are referred to as the nucleoplasm
39
Q

What are the different Features of a Nucleus?

A
  • Nucleolus
  • Nucleoplasm
  • Nuclear Envelope
  • Nuclear pores
  • Nuclear lamina
  • Chromatin
  • Chromosomes
40
Q

What is a Nucleolus?

A

Nucleolus is a small dense spherical structure in thenucleusof a cell duringinterphase
- Ribosomal RNA synthesis
-bRibogenesis (ribosome assembly)

41
Q

What are Nuclear Pores?

A

Nuclear pores are protein-lined channel in the nuclear envelope that regulate the transportation ofmolecules between the nucleus and the cytoplasm.

42
Q

What is the Nuclear Lamina?

A

Nuclear lamina is involved in most nuclear activities including:
- DNA replication
- RNA transcription
- nuclear and chromatin organization
- cell cycle regulation
- cell development
- cell differentiation
- apoptosis

43
Q

What is Hutchinson-Gilford Progeria Syndrome?

A
  • Rare genetic condition
  • Rapid aging in children
  • Signs such as balding and wrinkled skin.
  • Average lifespan of 14 years
44
Q

What does the Endomembrane System include?

A
  • Cell membrane
  • Nuclear envelope
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
45
Q

What is the Role of Vesicles in the Endomembrane System?

A

Vesicles transport substances between the various components of the endomembrane system.

46
Q

What is Rough ER?

A

Rough ER (RER) is the site of protein synthesis

47
Q

What is Smooth ER?

A

Smooth ER (SER) is the site of glycogen degradation, lipid and steroid synthesis, calcium ion storage.

48
Q

What is the Golgi Apparatus?

A

site of protein modification and sorting
- receives protein-containing vesicles from the RER
- Adds carbohydrates to proteins
- Modifies carbohydrates attached to proteins in the RER
- Sort proteins to their destination
- It is where some polysaccharides for the plant cell wall are synthesized
- It cuts certain large precursor proteins transferred from the RER into smaller, functional fragments

49
Q

What are Lysosomes?

A

sites of macromolecules digestion
- Primary lysosomes bud from the Golgi apparatus
- They contain digestive enzymes to digest proteins, polysaccharides, nucleic acids, and lipids and even old cell organelles (autophagy)
- The interior of the lysosome is acidic (pH=5)

50
Q

What is the Mitochondria?

A

sites of energy transformation
- The number of mitochondria depends on the energetical needs of the cells (>1,000/livre cell)

51
Q

What are the Different components to the Mitochondria?

A
  1. Cristae: key molecules for generation of ATP from fuel molecules
  2. Matrix: ribosomes, DNA, Enzymes for energy conversion
  3. The Inner Membrane: Primary barrier between the cytosol and mitochondrial enzymes
  4. Outer Membrane: permeable to small molecules and ions
52
Q

What are Chloroplasts?

A

sites of photosynthesis in plants

53
Q

What are the different components to a Chloroplast?

A
  1. Stroma: area outside thylakoid membrane; chemical energy used to convert CO2 and H2O to carbohydrates
  2. Thylakoid Membrane: sites where light energy is harvested by green pigmented chlorophylls and converted into chemical energy
  3. Granum: a stack of Thylakoids
54
Q

What are the other types of Plastids?

A
  1. Chromoplasts: make and store red, yellow, and orange pigments, especially in flowers and fruits
  2. Leucoplasts: store starch
55
Q

What are Peroxisomes?

A

a single-membrane oxidative organelle that contains enzymes
- removes hydrogen atoms from substrates and transfer them to oxygen (O2)
- Peroxisomes accumulate toxic peroxides, such as hydrogen peroxide (H2O2)

56
Q

What are the Roles of Peroxisomes?

A
  • Break fatty acids down into smaller molecules for cellular respiration (mitochondria)
  • Detoxification by oxidizing alcohol and other harmful compounds
57
Q

Where are Peroxides Safely Broken Down?

A

Peroxides are safely broken down inside the peroxisomes

RH2+O2→R+H2O2 (cellular reactions)
2 H2O2→2 H2O+O2 (inside peroxisome

58
Q

What are Glyoxysomes?

A

Glyoxysomes are similar to peroxisomes and are found only in plants.
- allow seedlings to grow by breaking down the stored fatty acids
- allows growth before photosynthesis

59
Q

What are Vacuoles?

A

a storage compartment in plants
- Founds in plants, fungi and protists
- 90% of the cell volume
- Increase in water pressure (called turgor) stiffens the cell

60
Q

What are Plant Vacuoles involved in?

A

Plant vacuols are involved in:
- supports the plant body
- Reproduction (contain pigments)
- Digestion (hydrolyze stored proteins)
- Storage (toxic molecules and waste)

61
Q

What is the Role of the Cytoskeleton?

A
  • Cell support and shape maintenance
  • Positioning of cell organelles and other particles within the cell
  • Organelles and other particles movement around in the cell
  • Cytoplasm movements (cytoplasmic streaming)
  • Anchoring the cell in place by interacting with extracellular structures
62
Q

Where does Protein Synthesis take place?

A

Protein synthesis takes place at cell structures called ribosomes

63
Q

What is the Hypothetical Evolution of the ER?

A
  1. Prokaryotes had no internal membranes
  2. cell membrane folds inwards
  3. further infoldings begin the formation of ER to create a segregated compartment
  4. ER surrounds the nucleoid and forms the nuclear envelope
64
Q

What is a possible cause for the Evolution of Nuclear Membranes and ER?

A

Nuclear membranes and the ER may have evolved through invagination of the plasma membrane
- In bacteria, the single DNA molecule is typically attached to the plasma membrane
- The plasma membrane invagination at the site of DNA attachment could have been at the origin of nucleus formation

65
Q

Where did the Mitochondria originate from?

A

Mitochondria are thought to have originated when a pre-eukaryotic cell engulfed an aerobic prokaryote

66
Q

Where did the Chloroplast originate from?

A

Chloroplasts are thought to have originated when a eukaryotic cell with mitochondria engulfed a photosynthetic prokaryote

67
Q

What is the Theory responsible for the appearance of Mitochondria and Chloroplast?

A

Endosymbiosis is probably responsible for the appearance of mitochondria and chloroplasts.

68
Q

What are the Evolutionary Advantages of Compartmentalization?

A
  1. Chemicals could be concentrated in particular regions of the cell, allowing chemical reactions to proceed more efficiently
  2. A biochemical process could be segregated within an organelle with, for example, a different pH from the rest of the cell, creating more favorable conditions for that process
  3. DNA transcription could be separated from translation, providing more opportunities for separate control of these steps in gene expression

BIO 1140 - Introduction to Cell & Molecular Biology (7 decks)

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