Chapter 2 - PPT Flashcards by Katie Davidson

4 different types of light microscopy

Bright-field
Phase-contrast
Dark-field
Fluorescence

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uses visible light to illuminate cells

Compound light microscope

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Specimens are visualized because of differences in contrast (density) between specimen and surroundings

Two sets of lenses form the image
Objective lens and ocular lens
Total magnification = objective magnification  ocular magnification

Bright-field scope

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Bright-field scope

Specimens are visualized because of differences in contrast (density) between specimen and surroundings

Two sets of lenses form the image
Objective lens and ocular lens
Total magnification = objective magnification  ocular magnification

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Compound light microscope

uses visible light to illuminate cells

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Microsocpe

Ocular lenses
objective lense
Stage
Condenser
Focusing nobs
Light Source

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Light Path

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Ocular lenses
objective lense
Stage
Condenser
Focusing nobs
Light Source

Microsocpe

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Define Resolution

The ability to distinguish two adjecent objects as seperate and distinct.

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What is resolution determined by?

The wavelength of light used, and the numerical aperture of lens

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Why is it important to improve contrast?

Improving contrast results in a better final image

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What are dyes?

Dyes are organic compounds that bind to specific cellular materials

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Preparing a smear:

Spread culture in thin film over slide –> dry in air

Heat fixing and staining:

Heat fix,–> flood slide with stian, rinse and dry

Microscopy

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What are the colors of a gram stain, and what do they mean?

Gram-Positive bacteria appear purple

Gram-Nevative appear Red

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What are the steps of Gram Staining?

Cristal violet -Flood the heat fixed smear with cristal violet for 1 min (Result all the cells are purple)
Iodine - Add iodine solution for 1 min (Result all cells remain purple)
Alcohol - Decolorize with alcohol breifly, about 20 sec (gram positive cells are puple, gram negative are colorless)
Safranin - Counter stain with safranin for 1-2 minutes, Result : G+ are purples, G- are pink/red

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Which cells are G+ and Which are G-

G+ are Purple

G- Are Pink/Red

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Phase-Contrast Microscopy

Phase ring amplifies differences in the refractive index of cell and surroundings
Improves the contrast of a sample without the use of a stain
Allows for the visualization of live samples
Resulting image is dark cells on a light background

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Phase-Contrast Microscopy

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What type of microscopy is being used here?

Phase-Contrast Microscopy

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Dark Field Microscoy

Light reaches the specimen from the sides
Light reaching the lens has been scattered by specimen
Image appears light on a dark background
Excellent for observing motility

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Light reaches the specimen from the sides
Light reaching the lens has been scattered by specimen
Image appears light on a dark background
Excellent for observing motility

Dark Field Microscoy

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What type of Microscopy is this?

Dark field microscopy

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Floursecence Microscopy

Used to visualize specimens that fluoresce
Emit light of one color when illuminated with another color of light
Some cells fluoresce naturally (autofluorescence)
Fluorescent dyes are used
Example: DAPI
Widely used in microbial ecology for enumerating bacteria in natural samples

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Floursecence Microscopy

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Define Evolution

The process of change over time that results in new varieties and species of organisms

What is Phylogeny?

Evolutionary relationships between organisms Relationships can be deduced by comparing genetic information in the different specimens Ribosomal RNA (rRNA) is excellent for determining phylogeny Relationships visualized on a phylogenetic tree

What are the three domains of life?

Bacteria Archaea Eukarya

What is the endosymbiosis theory?

That the organelles are consumed other species.

What is used for comparative Sequencing?

rRNA

Eukaryotes general dexcription

DNA enclosed in a membrane-bound nucleus Cells are generally larger and more complex Contain organelles

What is this?

Eukaryote

General Description of Bacteria and Archea

No membrane-enclosed organelles, no nucleus Generally smaller than eukaryotic cells

What is this?

A Bacteria or Archaea

DNA enclosed in a membrane-bound nucleus Cells are generally larger and more complex Contain organelles

Eukaryotes general dexcription

No membrane-enclosed organelles, no nucleus Generally smaller than eukaryotic cells

General Description of Bacteria and Archea

How to make a phylogenetic comparison

1. Isolte DNA 2. PCR 3. DNA Sequencing 4. Sequence analysis 5. Aligned rRNA gene sequences 6. Genetic phylogenetic tree

Ribosomal Subunts

What phylogenetic branch do methanogens belong on?

Archaea

Horizontal gene transfer

The evolution of life is NOT as simple as the rRNA tree suggests Genetic information can be transferred horizontally across branches Transformation -Uptake introduction Transduction -Viral introduction Conjugation - “Cell mating” introduction Endosymbiosis

Horizontal gene transfer Tranformation

Uptake information

Horizontal gene transfer: Transduction

- Viral introduction

Conjugation

-Cell mating

What organelle are thought to have come from endosymbiosis?

Chloroplasts Evolved from phagocytosed photosynthetic Bacteria Mitochondria Evolved from phagocytosed oxygen utilizing Bacteria Nucleus Evolved from phagocytosed Archaea

Endosymbiosis

Endosymbiotic Origin of Eukaryotes (Tree Picture)

Origin of Eukaryotes Chimeric

Eukaryotes have similar lipids and energy metabolisms to Bacteria Archaeal lipids are unique Eukaryotes have genetic material and machinery most similar to Archaea Mitochondria and chloroplasts have genetic material and their own machinery most similar to Bacteria

All cells have the following in common

Cytoplasmic membrane Cytoplasm Ribosomes rRNA valuable comparison Genetic material

Not considered cells No metabolic abilities of their own No ribisomes Rely completely on biosynthetic machinery of infected cell Host cell transcribes and translates the viral genetic material Host’s ribisomes Infect all types of cells Smallest virus is 10 nm in diameter

Viruses

Infection by Viruses

Image "Prokaryote"

Nucleus

Membrane enclosed genetic material Eukaryote, only

Nucleoid

Non membrane enclosed, but condensed region of genetic material Bacteria, Archaea, and organelles

Plasmid

Extra chromosomal DNA All domains, mainly Bacteria and Archaea

Which are the bacterial chromosomes, and which are the plasmids?

Red - Bacterial Chromosomes Blue - Plasmids

Histones

Eukaryotes and Archaea Proteins associated with DNA to compact it DNA wraps around histones One human cell’s DNA is 6 feet long, wouldn’t fit without histone coiling

Linear Chomosomes are found in:

Eukaryotes

Circular chromosomes are found in:

Bacteria and arcaea

Mitosis

Eukaryotes Cell division by DNA replication, equally separating chromosomes physically, and dividing cell

Meiosis

Eukaryotes Cell division during sexual reproduction that leads to the halving of genetic material Ex: 46 -\> 23 chromosomes (human gametogenesis)

Binary Fission

Bacteria and Archaea Cell division by DNA replication and dividing cell

Chemoorganotrophs

Obtain their energy from the oxidation of organic molecules

Chemolithotrophs

Obtain their energy from the oxidation of inorganic molecules Process not found in Eukaryotes

Aerobes

use oxygen to obtain energy

Anaerobes

obtain energy in the absence of oxygen

Phototrophs

Contain pigments that allow them to use light as an energy source Oxygenic photosynthesis produces oxygen Anoxygenic photosynthesis does not produce oxygen

Anoxygenic photosynthesis

Does not produce oxygen

Oxygenic photosynthesis

produces oxygen

Autotrophs

Use carbon dioxide as their carbon source Sometimes referred to as primary producers or carbon fixers

Heterotrophs

Require one or more organic molecules for their carbon source Feed directly on autotrophs or live off products produced by autotrophs

Do extremophiles need or require extreme environments?

NEED

What was the environment of the LUCA

Without oxygen Without light Elevated temperatures Elevated pressure

Chapter 2 - PPT Flashcards

(72 cards)