Microbio Chapter 1

what is a cell

a living compartment that interacts with environment and other cells

• smallest unit of life

what organelles do all cells have in common

cytoplasmic (cell) membrane, cytoplasm, ribosomes

what part of bacteria makes antibodies

plasmids

what type of chromosomes do prokaryotic cells have

circular chromosome

what type of chromosomes do eukaryotic cells have

linear chromosome

what are the subsections and characteristics of prokaryotes

Bacteria and Archaea

• no membrane bound organelles or nucleus

• small and compact

What are the subsections for eukaryotes

plants, algae, fungi, protozoa

• membrane closed organelles

• mitochondria & chloroplasts

  • large & complex

metabolism equals

catabolism + anabolism

properties of all Microbial cells

structure - organelles

metabolism - chemical reaction

growth - increase in cells

evolution - chance at mutations

what are properties of some cells

differentiation - form new cell structure

Communication - interact with other cells

mobility - movement (flagellum, cilia, etc.)

Horizontal gene transfer - transfer of DNA

length of most prokaryotes

.5 - 10 nanometers long

major structure/shapes of prokaryotic cells

coccus - circular

rod/bacillus - cylindrical

spirillum - spiral

what are the 3 domains

Bacteria (Prokaryotes), Archaea, Eukarya

Characteristics of Archaea

• can survive in extreme environments (extremophiles)

• do not cause disease or pathogens

Viruses

• are not cells

• obligate parasites

• take over infected cells to replicate

  • have small genomes of double-stranded or single-stranded DNA or RNA

history of life on earth

• anoxic - w/o oxygen

  • bacteria got ocygen via photosynthesis

microorganisms as disease agents are known as

bacterial and viral pathogens

beneficial microorganisms are known as

vaccinations and antibiotic therapy

What is rumen

degrades cellulose in animals like cows, and termites

Robert Hooke

first to describe microbes (All living things - Broader)

Antoni van Leeuwenhoek

first to see bacteria (More in depth “bacteria”)

resolution

the ability to distinguish 2 adjacent objects as distinct and separate

limitations of resolution

.2 nanometers

total magnification

objective magnification x ocular magnification

bright-field microscope

uses differences in light intensity (contrast) of specimen and surroundings to visualized specimens

what does staining do

increase contrast

Basic dyes and examples

Positively charged dyes that bind to negatively charged cell components
Ex. - methylene blue, crystal violet, and safranin
(blue purple red)

Differential stains

Renders different kinds of cells by different colors

Gram Stain

type of differential stain and divides bacteria into gram-positive (purple-violet) and gram-negative (pink) because of cell wall structure

Procedure of Gram Stain

1. flood the heat-fixed smear for 1 min

2. add iodine solution for 1 min (Iodine acts as mordant - enhances stain)

3. Decolorize with alcohol for 20 seconds (decolorizes by washing the thin peptoglycin cell wall) (thick cell wall remains purple)

4. counterstain with safranin for 1-2 min (safranin turns clear cells into pink enhancing contrast) Stain increases resolution and clarity

Phase-contrast microscope

improves image contrast of unstained live cells

Dark field microspy

light comes from sides instead of bottom

• great for observing motility (flagella)

fluorescence microscopy

visualize specimens that emit light

• good for counting amount of bacteria

CSLM - confocal scanning laser microscopy

generates 3-D image by taking images of every layer

Biofilm layers

top layer - aerobic

bottom layer - anaerobic

Electron microscopes

use electrons instead of visible light

what are the two types of electron microscopes

scanning electron microscope - only scans surface layer

transmission electron microscopes - slices specimen and able to scan inside of cell

• must be sliced (20-60nm) very thin to see inside of cell

Louis pasteur

used swan-necked pasteur flask to disprove spontaneous generation (life doesn’t need to come from other life)

• led to sterilization method and food preservation

Swan-neck flask experiment

• swan neck of flask prevents bacteria and dust from entering

• uses heat to sterilize liquid inside of flask

• recheck in few days seeing dust and microorganisms in neck

  • tilts liquid into neck to introduce bacteria to prove he is correct

Robert Koch

Father of Medical Microbiology linking microbes and infectious diseases identifying causing agent of tuberculosis

• developed solid media for obtaining pure cultures of microbes

Kock’s postulates

1. remove blood or tissue sample of suspected pathogen

2. streak agar plate with sample from dead rat

3. introduce cells from agar plate into another dead rat

   1. reisolate into agar plate to verify results

Sergei Winogradsky

proposed concept of chemolithotrophy - some organisms use inorganic compounds for energy

Martinus Beijerinck

developed enrichment culture technique - selectively encourages growth of specific organisms but supplying certain food

• first to observe a virus

phylogenetic map

history map of bacteria, archaea, and eukarya

Ribosomal RNA

present in all cells made it possible to build the first tree of life

is archaea closer to bacteria or eukarya

eukarya