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MIB10306 - Microbiologie deel samenvatting
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Alles wat je voor het microbiologie deel van het microbiologie & biochemie tentamen moet weten, samengevat. Zelfde samenvatting, lagere prijs:
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BROCK BIOLOGY OF MICROORGANISM 16TH EDITION
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Samenvatting MicrobiologieHoofdstuk 1
1.1
Microorganisms are essential for the well-being and correctly functioning of other life forms and the
planet.
1.2
Different types of cells are made up of different types of structures that interact to make up the
living organism. Prokaryotic and eukaryotic cells are composed differently, which is defined by the
cells genome, its collection of genes that determine certain characteristics. Universal cellular
activities are metabolism, growth and evolution.
Eukaryotes
• Larger than prokaryotes
• Contain organelles such as
mitochondria, the ER, chloroplasts and
a nucleus
• Transcription and translation are
separated physically by the nuclear
membrane
• DNA is present as linear molecules
Prokaryotes
• Include Bacteria and Archaea
• The chromosome(s) of archaea
resemble those of bacteria, but are
packed together and replicated like
eukaryotic chromosomes
• Small cells that have structural similarities
• DNA is present as a circular molecule that clumps together to form the nucleoid
• DNA/mRNA are in direct contact with ribosomes
• Many also have one or more plasmids, which contain genes that give the cell a special
property such as antibiotic resistance instead of genes essential to life
Microbial activities:
Universal
- Metabolism: taking up nutrients, transforming and expelling them for genetic processes and
catalytic processes
- Growth: nutrients are used to make new cell materials to make new cells
- Evolution: the changing of the genome of a cell’s lineage over time to display new properties
,Some
- Differentiation: microbial cells change into modified cells, which have specialised characteristics
- Communication: cells exchange signals in order to communicate and start/stop certain chemical
processes
- Genetic exchange: transferring to or accepting genes from neighbouring cells
- Motility: moving around with a flagellum for example
1.3
Microorganisms were the first living things to populate the Earth for billions of years, after
cyanobacteria oxygenated the atmosphere higher organisms were able to develop. The phylogenetic
lineages of cells are Bacteria, Archaea and Eukarya (domains).
1.4
Microbial communities consist of populations of microorganisms that interact with each other. Their
activities can alter the physical and chemical properties of their habitat. Microorganisms have the
biggest total biomass on Earth, most live deep under the Earth’s surface underground or underwater.
1.5
Microorganisms can be useful to humans, but also harmful. Pathogens make humans sick, but
microorganisms are also used to produce certain foods, such as yoghurt, butter, beer, bread etc.
1.9
Martinus Beijerink and Sergei Winogradsky explored soil and water for microorganisms that carry out
important natural processes, such as nutrient cycling and the biodegradation of particular
substances. Beijerink formulated the enrichment culture technique, where microorganisms are
isolated from natural samples by making use of highly selective nutrient and incubation conditions to
favour a particular metabolic group, this led to the discovery of nitrogen fixation by Winogradsky and
the first isolation of pure cultures.
Chemolitho(auto)trophy:
Chemo: energy is yielded from chemical reactions
Litho: inorganic electron donor is used for metabolism
Autotrophy: koolstofbron is CO2
Habitat: leefomgeving van een microbiële populatie
Ecosysteem: alle levende organismen plus de fysieke en chemische componenten van die habitat
Microbial ecology: the study of microbes in the environment and their interactions with each other
Aërobe organismen: halen adem met zuurstof als elektronenacceptor. Zuurstof wordt dan
opgenomen om een verbinding te “verbranden”, waardoor er elektronen vrijkomen, die via de
ademhalingsketen naar de elektronenacceptor gaan. Via de ademhalingsketen wordt energie
gegenereerd. O2 wordt gesplitst door oxidase. Elk atoom neemt vervolgens 2 electronen en 2 H+
op.
,Anaërobe organismen: halen adem met een andere electronenacceptor van buitenaf (bijv N) de
oxidatietoestand van een stikstofverbinding geeft aan hoe geoxideerd (elektronarm) of hoe
gereduceerd (elektronrijk) die stof is
Fermentatief: het organisme maakt gebruik van een zelfgemaakte organische verbinding als
elektronenacceptor.
Elektronenacceptoren zijn dus elementen/verbindingen die 1 of meer elektronen op kunnen nemen
en daarbij gereduceerd worden.
• Elke verbinding waarin C, N en S in gereduceerde vorm voorkomt, kan als energiebron dienen
voor bepaalde micro-organismen.
Hoofdstuk 2
Lichtmicroscopie: kleuring is vaak noodzakelijk om details in cellen te waarnemen
fasecontrast: kleine verschillen in brekingsindex zorgen voor contrast
fluorescentie: fluorescerende verbindingen maken het mogelijk details te zien
Elektronenmicroscopie: kan je veel details mee zien, SEM en TEM voor doorsnede of oppervlak
In het cytoplasma:
- DNA, er is geen membraan, vormt nucleoïde
- 1 chromosoom en eventueel plasmide(n)
- Dubbelstrengs DNA
- Transcriptie en translatie gebeuren tegelijkertijd
- Essentiele genen op het chromosoom
- Speciale genen op de plasmide
▪ Een deel van de genen op de plasmide is betrokken bij de start van de replicatie, maar de
replicatie van plasmiden is afhankelijk van chromosomaal gecodeerde enzymen
▪ Hebben dubbelstrengs DNA
▪ Meestal circulair, maar ook lineair
▪ Voorbeeldeigenschappen: productie van antibiotica, afbraak van herbicides, resistentie
tegen antibiotica, nodulation and symbiotic nitrogen fixation
▪ Aantal van een bepaalde plasmide kan verschillen
▪ Sommige plasmiden raken geïntegreerd in het chromosoom
▪ Bevatten soms onnodige genen
▪ Overdracht vindt plaats tussen zowel prokaryoten en prokaryoten als prokaryoten en
eukaryoten via conjugatie
3 mechanismen voor de overdracht van genetisch materiaal
Conjugatie: de pilus (haarachtige structuur van eiwitten) van een
cel zit vast aan een andere cel en wordt korter. Hierdoor worden
de twee cellen samengetrokken en verbonden met speciale
eiwitten in het membraan. De plasmide wordt dan overgedragen.
, Transformatie: De donor bacterie breekt het chromosoom in stukken die
opgenomen worden door de ontvanger. (zie rechts boven)
Transductie:
Lytische
cyclus:
Lysogene
cyclus:
Prokaryoten hebben ook een soort afweersysteem:
CRISPR systeem: bezit een geheugen van dat genetische informatie van
virussen opslaat. RNA moleculen en eiwitcomplex zijn op zoek naar DNA
van bekende virussen en als ze het vinden knippen ze het kapot
Unicellular organisms are small because their ability to transport nutrients
decreases with increasing cell size. The metabolic rate of a cell varies inversely with
the square of its size. Thus, large cells are uncommon among prokaryotes in
contrast to eukaryotes. Cells do, however, need to be big enough to have the
essential cell components that support life.
Morphology: cell shape
Coccus: spherical or ovoid cell shape
Rod/BacillusI: cylindrically shaped cell
Spirilla: spiral-shaped cells
The morphology doesn’t predict any other cellular properties
Why does a cell have a certain morphology?
It is a genetic characteristic that maximises the fitness of the organism in its particular habitat
Ex: Optimisation of nutrient uptake with large surface-to-volume ratio
Advantages of being small:
• Small cells have a higher surface-to-volume ratio
• The growth speed of a cell depends on the rate of nutrient exchange, which increases with a
higher surface-to-volume ratio, so, small cells grow faster.
• In an environment with a given amount of resources the small cells have a larger population, so
more cell-divisions have occurred and the amount of mutations within the population is higher.
Thus, populations of small cells are able to evolve quicker.
• So, small cells can adapt to changing environmental conditions faster and exploit new habitats
quicker
The cytoplasmic membrane serves to separate the cytoplasm of a cell from its environment and
allows transport with its selective permeability. It is constructed of lipids and proteins that form a
bilayer that is hydrophobic on the inside and hydrophilic on the outside. This blocks charged polar
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