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MBB 201 > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

Visualizing cells became possible following the invention of the _________?

A

Light microscope

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2
Q

What did Robert Hooke do?

A
  • described the appearance of plants and insects underneath a microscope
  • coined the term “cell”
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3
Q

What is the most common type of light microscope used today?

A
  • a compound microscope that is a microscope with multiple lenses
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4
Q

How does a light microscope show an image of a cell?

A

light passes through an unstained, living cell undergoes very little changes in amplitude, but the phase of light is changed and small phase differences can be made visual by using special lenses

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5
Q

What is the advantage of staining a sample under a light microscope?

A
  • The stained portions of a cell reduce the amplitude of light waves of particular wavelength passing through them and a coloured image of the cell is obtained
  • some stains can localize different cellular compartments
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6
Q

what is fluorescence microscopy

A
  • can be used to localize and quantify specific molecules in fixed and live cells
  • light is absorbed at one wavelength and emitted at a longer wavelength (example: DAPI has an absorption maximum of 358 and an emission maximum of 461nm)
  • fluorescent dyes are used for staining cells
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7
Q

Fluorescence microscopes have two filters

A
  1. filters lights before hitting the specimen, allowing only the wavelength of light that excites the fluorescent dye
  2. blocks all light except the wavelength of light emitted by the excited fluorescent dye
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8
Q

DAPI

A

visualizes nuclear DNA in both fixed and living cells by forming complexes with double stranded DNA to enhance fluorescence

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9
Q

Conjugation of Fluorochromes to antibodies

A
  • fluorochromes (fluorescent dyes) can attach to specific antibodies to perform immunofluorescent microscopy
  • these antibodies will only bind to your target of interest
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10
Q

What is confocal microscopy

A
  • a specialized type of fluorescence microscopy. Preventing blurry images resulting from the presence of fluorescent structure above and below the plane of focus
    A few key features:
    –> a beam is focused on a single point
    –> a small hole allows light from the in focus point through to hit the detector
    –> out of focus light is excluded from the detector
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11
Q

Can confocal microscopes produce 3D images?

A

not directly 3D confocal images can be constructed using multiple 2D confocal images taken at different planes of focus

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12
Q

Define resolving power

A
  • the ability of an imaging device to separate points of an object located at a small angular distance
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13
Q

Compare transmission electron microscopy and scanning electron microscopy.

A

Transmission electron microscopy (TEM): operates under similar principle light microscopy except uses a beam of electrons intends of light (2D image)

Sanning electron microscopy (SEM): scatters electrons off the surface of the sample (3D image)

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14
Q

what are the 3 main features of a cell

A
  • Nucleus
  • Cytoplasm
  • Plasma membrane
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15
Q

Nucleoid

A
  • region of the cell which contains most of the cells genetic material
  • it is not surrounded by a membrane
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16
Q

Nucleus

A
  • membrane-enclosed organelle which contains the cells genetic material
17
Q

What does the presence or absence of a nucleus define?

A
  • it defines which organisms are prokaryotes and which are eukaryotes
18
Q

Compare prokaryotes and eukaryotes.

A

Prokaryotes –> no membrane bound organelle, nucleoid, smaller, singular circular chromosome, cytoplasm bound by plasma membrane

Eukaryotes–> membrane bound organelles, nucleus, larger, multiple linear chromosome, cytoplasm bound by plasma membrane and nuclear membrane

19
Q

Name 3 prokaryotes

A
  • archaea
  • photosynthetic bacteria
  • non photosynthetic bacteria
20
Q

Outline the main features of the nucleus

A
  1. Nuclear envelop has 2 membranes:
    - inner nuclear membrane and outer nuclear membrane (note that the outer membrane in contact w/ the ER)
  2. Nucleolus: large structure in nucleus where ribosomal RNA is transcribed and and ribosomal subunits are assembled
  3. Had nuclear pores
21
Q

Why do we have nuclear pores?

A

to allow passage of molecules in and out of nucleus (transport of proteins)

22
Q

Outline the main features of the mitochondria

A
  • contain there own DNA and reproduce by division
  • contains an inner and outer membrane
  • contribute to cellular respiration (generates the energy currency of the cell) –> electron transport from oxidation of food, oxidative phosphorylation
23
Q

What are the most probable origins of mitochondria and chloroplasts?

A
  • chloroplast (most certainly) and mitochondria (most likely) evolved from engulfed bacteria
24
Q

Endoplasmic reticulum

A
  • major site of proteins, membrane lipid and oblisaccaride synthesis
  • ribosomes attached to the ER translate RNA into proteins
25
Q

Golgi apparatus

A
  • stacks of flattened membrane enclosed sacs that modifies and packages molecules made in the ER destined to be secreted or sent to another compartment
  • exchange is mediated by secretory vesicles
26
Q

secretory vesicles

A

membrane vesicles that transport materials to and from compartments

27
Q

Lysosomes

A
  • contain hydrolytic enzyme which are activated by proteolytic cleavage in an acidic environment
28
Q

What do lysosome membranes contain?

A
  • they contain transport molecules which carry the products of macromolecules (sugars, nucleotides, amino acids) to the cytosine for reuse (or excretion)
29
Q

Peroximes

A
  • membrane enclosed vesicle where carry out oxidation reaction leading to the production of hydrogen peroxide (H2O2)
  • H2O2 is used to inactivate toxic molecules
  • found in all animal cells except RBCs and in many plant cell
  • used to breakdown non toxic molecules (fatty acids into acetyl coA)
    Or biosynthetic reactions (production of plasmalogen)
30
Q

Does cytosol = cytoplasm

A

No cytosol is the aqueous portion of the cytoplasm. The cytoplasm include the aqueous portion, the suspended particle and the organelles

31
Q

The cytoplasm of a cell is ___________

A

Crowded

32
Q

What is the cytoskeleton?

A

network of protein filaments in the cytoplasm involved in strength, movement, shape, cell division and organization
–> involves actin filaments, microtubules and intermediate filaments

33
Q

What are the major components of the cell membrane

A
  • lipids
  • carbohydrates
  • proteins
34
Q

What are the membrane functions

A
  • maintain the integrity of cells and organelles
  • provides a highly selective permeability barrier
  • control flow of information between organelles and surrounding environment: contain receptors for chemical stimuli, some membranes generate electrical and chemical signals
  • sites of energy transformation: mitochondrial membrane performs oxidative phosphorylation

MBB 201 (28 decks)

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