Prokaryotes 1 Flashcards
Nutrients, Environment and Growth
Why are micro-organisms important?
4 reasons
Health - ‘good bacteria’ causes competition for pathogens and break down food
Producing 02 - cyanobacteria (photosynthesising bacteria)
Fixing N2 - important for amino acids
Biodegradation - recycling waste
Name the properties of cellular life.
7 properties
Cells/organisation Energy use/metabolism Response to stimuli Regulation & homeostasis Growth & development Reproduction/heredity Biological Evolution
What are the three domains all phylogeny trees can be split into?
Bacteria- prokaryotes
Archea - prok
Eucarya - eykaryotes
Definition of Eukaryote
A cell that has a nucleus and membrane bound organelles
Name some features of a eukaryotic cell
DNA contained in nucleus Transcription within nucleus Translation within cytoplasm Organelles in cytoplasm Divide my mitosis/meiosis
Definition of Prokaryote
Micro-organism that lack a cell nucleus and membrane bound organelles
Name some features of prokaryotic cells
Circular DNA contained in cytoplasm
No membrane bound organelles
Divide by binary fission
All bacteria are proks
Name three of the basic shapes of bacteria (prokaryote morphology)
Rods (bacilli)
Spirochetes
Cocci/coccus
What are the 2 factors bacterial growth is dependent on?
Nutrition
Environment
What is rate of binary fission affected by?
Species
Nutrition
Environment
Stages of binary fission
Parental cell Chromosome duplicated Growth Division Daughter cells
What are heterotrophs?
Cells that break down something to get energy
What are autotrophs?
Cells that produce what they need
What are the 2 types of metabolic reactions?
Catabolic - energy releasing, breaks molecular structures down
Anabolic - energy requiring, uses energy to build larger molecules
They are linked through ATP
What is the composition of bacteria?
70-80% water/10-20% dry weight
Carbon - 50% of dry weight
Nitrogen - 14% of dry weight
10-20% consisting of macro/micronutrients
What is the role of carbon, hydrogen and oxygen as major nutrients?
Source of new cell material/cell structures
What is the role of Phosphorus as a major nutrient?
Essential for DNA, phospholipid membrane and ATP
What is the role of Nitrogen?
Amino acids, protein synthesis, nucleic acids
What is the role of Sulphur?
Essential for amino acids and vitamins
What are the environmental conditions bacteria require to grow?
Temp - different species prefer different temps, enzyme function is optimized to this temp
pH - most prefer neutral 7, some prefer very acidic
Osmotic Pressure - cytoplasm contains 80% water, food is preserved by adding high levels of salt
Light - photoautotrophs
Atmosphere - oxygen, carbon dioxide & nitrogen levels
Name the two ways of measuring bacterial growth
Indirectly - spectrophotometry
Directly - viable counts
Describe spectrophotometry
Cells in liquid will scatter light which is measured (turbidity - units = optical density)
Increased bacteria causes an increase in measurement
Measurement is proportional to bacterial number
Different wavelengths are used
Good for manipulating growth phase
Limitations of spectrophotometry
No indication of the actual number of bacteria (gives an exponential phase)
Doesn’t tell you what organism or how many different organisms - poor diagnostic tool
Doesn’t tell you if bacteria are alive or dead
Name and describe the phases in the bacterial growth curve
Lag Phase - synthesis of enzymes/nutrients, no growth
Log/exponential Phase - Binary fission occurring
Stationary Phase - nutrients drop and waste products rise
Death Phase - exhausted nutrient supply and toxic waste levels
