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Bio > Cell Structure > Flashcards

Cell Structure Flashcards

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Biology 101 flashcards
1
Q

Outline how a student could prepare a temporary mount of tissue for a light microscope

A
  • Obtain a thin section of tissue
  • Place tissue in a drop of water
  • Stain tissue on a slide
  • Add cover slip using mounted needle at 45 degree angle to avoid trapping air bubbles
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2
Q

Describe how light microscopes work

A
  • Lenses focus rays of light and magnify the view of a thin slice of specimen
  • Different structures absorb different amount and wavelengths of light
  • Reflected light is transmitted to the observer via the objective lens and eyepiece
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3
Q

Describe how TEM’s work

A
  • Pass a high energy beam of electrons through a thin slice of specimen
  • More dense structures appear darker since they absorb more electrons
  • Focus image onto florescent screen or photographic plate using magnetic lenses
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4
Q

Describe how a SEM works

A
  • Focus a beam of electrons onto a specimens surface using electromagnetic lenses
  • ## Reflected electrons hit a collecting device and are ampilfied to produce an image on a photographic plate
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5
Q

Describe how a laser scanning confocal microscope works

A
  • Focus a laser beam onto a small area of a sample’s surface using objective lenses
  • This causes flourescence from the components labelled with a dye
  • The specimens emitted light is filtered through a pinhole aperture
  • Only light radiated from very close to the focal plane is detected
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6
Q

Why do samples need to be stained for light microscopes?

A
  • Coloured dye binds to the structures
  • Facilitates absorption of wavelengths of light to produce image
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7
Q

What is differential staining?

A

Contrast between heavily and lightly stained areas distinguishes structures

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8
Q

What is the magnification and resolution of a light microscope and SEM ?

A

Light - x200, 200nm
SEM - x500 000, 0.5nm

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9
Q

Describe the structure of the nucleus

A
  • Surrounded by a nuclear envelope, a semipermeable double membrane
  • Nuclear pores allow substances to enter/leave
  • Dense nucleolus made up of RNA and proteins assemble ribosomes
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10
Q

Describe the structure and function of the golgi apparatus

A
  • Stack of membrane bound, flattened sacs aligning with rER
  • Modifies and packages proteins for export
  • Synthesises glycoproteins
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11
Q

Describe the structure and function of ribosomes

A
  • Formed of protein and rRNA
  • Have large subunit which joins amino acids
  • Small subunit with mRNA binding site
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12
Q

Describe the relationship between the organelles involved in the production and secretion of proteins

A
  • Ribosomes synthesis proteins and are attached to rER
  • Golgi apparatus modifies proteins for secretion and is aligned with rER
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13
Q

Describe the function of a lysosome

A
  • Digests contents of phagosome
  • Exocytosis/carrying of digestive enzymes
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14
Q

Describe the structure and function of a plant cell wall

A
  • Made of cellulose microfibrils for mechanical support
  • Plasmodesmata form part of apoplast pathway to allow molecules to pass between cells
  • Middle lamella separates adjacent cell walls
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15
Q

What are bacterial and fungal cell walls made of?

A

Bacteria - Peptidoglycan
Fungi - Chitin

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16
Q

Describe the structure and function of centrioles

A
  • Spherical group of 9 microtubules arranged in triplets
  • Located in centrosomes
  • Migrate to opposite poles of a cell during prophase and spindle fibres form between them
17
Q

Describe the structure and function of the plasma membrane

A
  • Fluid mosaic phospholipid bilayer with extrinsic and intrinsic proteins embedded
  • Isolates ctyoplasm from extracellular environment
  • Selectively permeable to regulate transport of substances
  • Involved in cell signalling/recognition
18
Q

Explain the role of cholesterol, glycoproteins and glycolipids in the plasma mebrane

A

Cholesterol - Connects phospholipids and reduces fluidity
Glycoproteins - Cell signalling, cell recognition (antigens) and binding cells together
Glycolipids - Cell signalling and cell recognition

19
Q

Describe the structure and function of the flagella

A
  • Hollow helical tube made of the protein flagellin
  • Rotates to propel organism
20
Q

Why is the cytoskeleton important?

A
  • Provides mechanical strength
  • Aids transport within cells
  • Enables cell movement
21
Q

Describe microfilaments

A
  • Formed from actin
  • Responsible for cell movement and cell contraction during cytokineses
22
Q

Describe microtubules

A
  • Act as tracks for movement of organelles, including vesicles
  • Spindle fibres are composed of microtubules
23
Q

Describe intermediate fibres

A
  • Give mechanical strength to cells and help maintain their integrity

Bio (19 decks)

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