Module 6 Flashcards
what are carbohydrates used for by micro-organisms?
energy
What is biochemistry?
The study of chemical reactions that occur in living systems
What are the 4 large complex biochemical molecules that compose all living things?
- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids
What are carbohydrates derivatives of?
Polyhydroxyalcohols
Which elements are all carbohydrates composed of?
- Carbon
- Hydrogen
- Oxygen
where are carbs found
cell wall/plasma membrane (glycocalyx)
What is one of the primary functions of carbohydrates in cells?
cell identification
What are three types of carbs
- monosaccharides
- disaccharides
- polysaccharides
what are monosaccharides
- simple sugars
- 5-6 carbons
Name 3 major examples of monosaccharides
- Glucose
- Galactose
- Fructose
what are disaccharides
2 monosaccharides linked through a glycosidic bond
Name 3 examples of disaccharides and their monosaccharide components
- Sucrose = glucose + fructose
- Lactose = glucose + galactose
- Maltose = 2 glucose monomers
what are polysaccharides
polymers of many linked monosaccharides
What are 3 examples of polysaccharides?
- Starch
- Glycogen
- Cellulose
How are lipids generally characterized in terms of solubility?
relatively insoluble in water BUT very soluble in nonpolar solvents like chloroform, ether and benzene
Name 3 examples of lipids
- Triacylglycerols (fats)
- Phospholipids
- Steroids
What are 3 functions of lipids?
- cell membrane component
- carbon and energy storage
- protective barrier against water
What common structural feature do most lipids comtain?
fatty acids with a carboxylic acid group on one end and a methyl group on the other (also features a long tail)
What are lipids soluble in?
nonpolar solvants (ether, benzene)
What are lipids insoluble in?
water
What are proteins composed of?
polymers of amino acids
What functional groups are present in each amino acid? (Structure)
- 1+ amino group
- 1 carboxyl group
- linked by peptide bonds
How are amino acids linked together in proteins?
by peptide bonds
How many standard amino acids are used to build proteins?
20 amino acids
How are the 20 amino acids identical and different?
they are identical except for the “R group” on the central carbon
What determines the properties of amino acids?
the R group attached to the central carbon
How do amino acids influence proteins?
they determine protein structure and function
What is the primary pr- structure
sequence of amino acids joined by peptide bonds
what is the secondary pr- structure
a helix or b pleated sheet formed by H-bonding
what is the tertiary pr- structure
folding and coiling due to interactions among R groups and between R groups and surrounding water
what is the quaternary pr- structure
association of 2 or more polypeptide chains with each other
What are enzymes
protein catalysts that control the rate of chemical reactions within cells
What role do enzymes play in cellular reactions?
They increase the rate of chemical reactions without being consumed in the process
Are enzymes specific to certain substrates and reactions?
YES. Enzymes are highly specific for their substrates and the reactions they catalyze.
What determines the specificity of an enzyme for its substrate?
The unique 3-D shape of the enzymes active sit matches the shape of its specific substrate
What is the active site of an enzyme?
the region on an enzyme where the substrate binds and the chemical reaction occurs
How do enzymes lower the activation energy of a reaction?
By stabilizing the transition state and bringing substrates into the optimal orientation for the reaction.
Can enzymes be used after a reaction?
YES. Enzymes are not consumed in the reaction, and can catalyze multiple reactions
What factors can affect enzyme activity?
- temperature
- pH
- substrate concentration
- presence of inhibitors or activators
What is an enzyme inhibitor?
A molecule that binds to an enzyme and decreases its activity
What is an example of an enzyme’s role in the cell?
DNA polymerase catalyzes the synthesis of DNA molecules during replication
What are nucleic acids and what do they do?
NA are polymers of nucleotides that store genetic information and direct protein synthesis
What are the 2 main types of nucleic acids?
- Deoxyribonucleic acid (DNA)
- Ribonucleic acid (RNA)
What is the primary function of DNA and RNA?
They store genetic information that directs protein synthesis
How do DNA and RNA differ in their sugar components?
DNA: contains deoxyribose sugar
RNA: contains ribose sugar
What are the 3 main differences between DNA and RNA?
- sugars
- nitrogenous bases
- structure
What are the nitrogenous bases found in DNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
How does the nitrogenous base composition of RNA differ from DNA?
In RNA, Thymine (T) is replaced by Uracil (U)
What is the typical structure of DNA?
DNA is usually double stranded, forming a double helix
What is the typical structure of RNA?
RNA is usually single stranded
What are nucleotides composed of?
- phosphate group
- 5 carbon sugar (deoxyribose or ribose)
- nitrogenous base
How are nucleotides linked together in nucleic acids
phosphodiester bonds between the phosphate group of one nucleotide and the sugar of the next
What is the role of RNA in protein synthesis?
Messenger RNA (mRNA) carries genetic information from DNA to the ribosome, where it is translates into proteins
What are the three main types of RNA involved in protein synthesis?
mRNA (messenger), tRNA (transfer), rRNA (ribosomal)
What is the function of ribosomal RNA (rRNA)?
rRNA forms the core of the ribosome’s structure and catalyzes protein synthesis
What is the significance of the double-stranded structure of DNA?
it provides stability and enables the storage of genetic info through complementary base pairing
What is the primary role of carbon in an organism’s nutrition?
Carbon is often used as an energy source and is required to synthesize cell components
Why is oxygen essential for organisms?
Oxygen is required for aerobic respiration and the synthesis of cell components
What is the role of nitrogen in nutritional requirements?
Nitrogen is required to synthesize proteins, nucleic acids, and co-enzymes
How is sulfur utilized in cellular processes?
Sulphur is used to synthesize proteins and some co-enzymes
What is the role of phosphorus in nutrition?
Phosphorus is used to synthesize ATP, phospholipids, and nucleic acids
What are trace elements/micronutrients and macronutrients and why are they important?
- Trace elements/micronutrients are often required for enzyme function
- macronutrients are needed in larger amounts for various physiological functions
What are vitamins and what role do they play in nutrition?
Vitamins are organic substances required in small amounts and typically function as co-enzymes in various biochemical reactions
What are co-enzymes and why are they important?
Co-enzymes are organic molecules that bind to enzymes to help catalyze reactions. They are vital for the proper functioning of many metabolic pathways.
What are growth factors in microbial nutrition?
Growth factors are essential cell components/molecules that some microbes need to grow and survive, but they can’t produce these molecules on their own (must get from external environment)
Why do some microbes require external growth factors?
These microbes lack the metabolic pathways to synthesize certain essential components, making it necessary to obtain them from their environment
What determines the growth factor requirements of a microbe?
The specific cell type and its metabolic capabilities
What are 3 examples of growth factors required by some microbes
- Amino acids: for pr- synthesis
- Purines and pyrimidines: for nucleic acid synthesis
- Vitamins: function as enzyme cofactors
What characteristic does the plasma membrane of microbes possess regarding nutrient uptake?
The plasma membrane is selectively permeable, functioning as a barrier that regulates the entry and exit of nutrients
How do small molecules like O2, CO2, and H2O typically enter microbial cells?
passive diffusion, which relies on a large concentration gradient
What is passive diffusion in the context of nutrient uptake?
the movement of small, nonpolar molecules from an area of [high] to [low] without the use of energy
Can microbes use multiple transport systems for the same nutrient?
YES. Microorganisms can employ more than one transport system for a single nutrient
List the 4 different transport systems used by microorganisms for nutrient uptake.
- Facilitated diffusion
- Active transport
- Group translocation
- Endocytosis (EUKARYA ONLY)
What is endocytosis and which domain of life utilizes it?
endocytosis is a transport process that encloses solutes in vesicles pinched off from the plasma membrane. Utilized by Eukarya only.
How does facilitated diffusion differ from passive diffusion?
Facilitated diffusion used membrane-bound carrier molecules (permeases) to transport molecules, allowing significant uptake even with small concentration gradients
Is facilitated diffusion energy dependent?
NO
What types of molecules are effectively transported by facilitated diffusion?
Glycerol, sugars, and amino acids
In which group of organisms is facilitated diffusion more prominent?
Eukaryotes (compared to bacteria or archaea)
What role do permeases play in facilitated diffusion?
Permeases are membrane-bound carrier proteins that facilitate the transport of specific molecules across the plasma membrane
What is active transport
- moving molecules against concentration gradient
How does active transport differ from passive diffusion?
Active transport is an energy-dependent process, unlike passive diffusion
What are the 2 types of active transporters?
- Primary active transporters: use ATP hydrolysis for energy
- Secondary active transporters: use energy from ion gradients (protein motive force)
What is the result of active transport in microbial cells?
It concentrates molecules inside the cell, allowing cells to accumulate nutrients even when external concentrations are low
How do permeases (carrier proteins) function in active transport?
They bind to specific solutes with high specificity and facilitate their movement across the plasma membrane using energy
What is carrier saturation in the context of active transport?
Carrier saturation occurs when all carrier proteins are engaged at high solute concentrations, limiting the rate of transport despite further increases in substrate concentration
What is group translocation in microbial nutrient uptake?
Group translocation is an energy-dependent transport process that chemically modifies a molecule as it is transported into the cell
What is the best known system for group translocation?
The phosphoenolpyruvate: sugar phosphotransferase system (PTS)
How do many anaerobic bacteria utilize the PTS system?
They transport sugars while phosphorylating them using phosphoenolpyruvate (PEP) as the phosphate donor
Do aerobes typically utilize the PTS system?
NO. Most aerobes lack the PTS system
Which sugars does E. coli uptake via the PTS system?
Glucose, fructose mannitol and sucrose
What is culture media?
Culture media are solid or liquid preparations used to grow, transport, and store microorganisms
What must culture media contain to support microbial growth?
Must contain all the nutrients required by the microorganism for growth
How is the composition of culture media determined?
The composition is highly dependent on the specific nutritional and environmental requirements of the organism(s) being cultured.
On what bases can culture media be classified?
Culture media can be classified based on chemical composition, physical nature, and function
Why is it important to select the appropriate culture media for growing microorganisms?
Different microorganisms have specific nutrient and environmental requirements; selecting the appropriate media ensures optimal growth and accurate results
What are the three functional types of media culture?
- Supportive or general purpose media
- Selective media
- Differential media
What are supportive or general purpose media used for?
They support the growth of a wide variety of organisms
Provide an example of a supportive or general purpose media:
Tryptic Soy Agar
What is the primary function of selective media?
Selective media favors the growth of certain microorganisms while inhibiting the growth of others
Provide an example of selective media and the type of bacteria it selects for:
MacConkey Agar is a selective media that selects for gram-negative bacteria
What is the primary function of differential media?
Differential media distinguishes between different groups of microorganisms based on their biological characteristics
Provide an example of differential media and what it differentiates:
MacConkey Agar is a differential medium that differentiates lactose fermenters from non-fermenters
What is a pure culture?
A population of cells arising from a single cell, containing only one type of microorganism
Why is it important to isolate pure cultures in microbiology?
Pure cultures are essential for accurately studying the characteristics, behaviors, and genetic of a specific microorganisms without contamination from others
What are the main techniques used to isolate pure cultures?
- Spread Plate
- Streak Plate
- Pour Plate
What is the spread plate technique?
The spread plate technique involves spreading a diluted mixture of cells evenly across the surface of an agar plate to isolate individual colonies
How does the spread plate technique help in obtaining pure cultures?
By diluting and evenly distributing cells, individual cells are well separated, allowing each to reproduce into distinct colonies
What is the streak plate technique?
The streak plate technique involves spreading a mixture of cells on an agar surface in a pattern that dilutes the cells and isolates individual colonies
How does the streak plate technique contribute to obtaining pure cultures?
By physically separating cells through streaking, individual cells are isolated and can form separate, pure colonies
What is the pour plate technique?
The pour plate technique involves mixing a diluted sample with molten agar and then pouring it into a Petri dish, allowing colonies to grow both on and within the agar
What is a unique feature of the pour plate technique?
It allows for the growth of microorganisms both on the surface and inside the agar, which can be useful for certain types of analyses.
