Bio Exam Question 1

distinguish between obligate anaerobic and facultative anaerobic

• obligate anaerobes can’t tolerate and die in the presence of oxygen, rely on fermentation and an example is clostridium botulinum

• facultative anaerobes can grow in the presence or absence of oxygen, rely on aerobic respiration and an example is E coli

distinguish between sterilization and disinfection

• sterilization is the complete elimination of all forms of microbial life including spores

• disinfection is the process of reducing most pathogenic microorganisms except spores

• sterilization is used on surgical instruments

• disinfection is used on countertops and floors

• sterilization methods are autoclaving, filtration and radiation

• disinfection methods include chemical disinfectants like bleach or UV

filtration as a form of sterilization

• used to remove bacteria and fungi from liquids and gases without using hear

• used for heat sensitive solutions such as vaccines

• its passed through a filter with pores small enough to trap microorganisms

• microbes are physically retained on the filter surface while the sterile fluid passes through

purpose of safranin during gram staining

• counter stain

  • stains gram negative cells after decolorization

purpose of crystal violet

• primary stain

  • penetrates cell wall and cytoplasm, bind to negative components of bacterial cells

purpose of iodine

• mordant

  • forms a crystal violet complex

  • gets trapped in gram positive bacteria

purpose of ethanol in gram staining

• decolourizer

• differentiates between negative and positive

functional groups of amino acid

• amino group - -NH2

• Carboxyl group - -COOH

• side group/variable group - R (could be 20 different amino acids)

Glycogen

• multistranded polysaccharide made of glucose units that serves as a form of energy storage in animals, fungi and bacteria

• function is to store glucose and release it when energy is needed, in the liver glycogen breakdown helps maintain blood sugar levels

  • found in the liver, skeletal muscle and kidneys

proteases and function

• enzymes that break down proteins by breaking peptide bonds between amino acids

• break down dietary proteins into amino acids for absorption, pepsin in the stomach

restriction enzymes and function

• enzymes that cut DNA at specific sequences known as recognition sites

• used in genetic engineering to cut and insert DNA fragments in molecular cloning

DNA polymerase and function

• enzyme responsible for transcribing DNA into RNA

• adds complementary ribonucleotides AUCG to build an RNA strand

tRNA and function

• small RNA molecule that plays a role in translation, the second step of protein synthesis

• transfer amino acids to the ribosome during protein synthesis

endospores - production, structure and characteristics

• highly resistant, dormant structure formed by gram positive bacteria as a means of survival under harsh conditions

• they allow bacteria to withstand extreme environments such as heat, desiccation, radiation and chemicals

• structure includes a inner membrane that surrounds the core with possess protein rich layers resistant to chemicals and enzymes. It has a cortex which is a thick layer of peptidoglycan which maintains dormancy

• characteristics include no metabolic activity until conditions improve, can remain viable for decades

• In DNA, the two strands are held together by hydrogen bonds

• A with T with 2 hydrogen bonds

• G with C with 3 hydrogen bonds

• DNA has two strands running in opposite directions

• Each base on one strand pairs with a complementary base on the opposite strand.

• base stacking interactions (hydrophobic and van der Waals forces) between adjacent base pairs help stabilize the double helix

oncovirus and example

• viruses that have the ability to cause cancer by inducing mutations in genetic material

• HPV - human papillomavirus

what categories of amino acid would you expect to find on the surface of a soluble protein and which would you expect to find in the interior

• on the surface = hydrophilic,

• on the inside = hydrophobic

codon and function

• sequence of three nucleotides in mRNA that encodes a specific amino acid of protein synthesis

• function is to signal start codons to begin translation and stop codons to stop protein synthesis

aseptic technique and example

• practises to prevent contamination by pathogens and microorganisms

• surgeons wear sterile gloves to prevent infection

• injections when skin is cleaned before needle insertion

• sterile environment when transferring bacterial samples between petri dishes, tubes and flasks

gram positive

purple

gram negative

pink/red

endospore stain colour

green

name of reagent that detects amino acids in TLC

ninhydrin

Phospholipids are amphipathic

• both hydrophilic and hydrophobic regions within the same molecule

• hydrophilic head

• hydrophobic tail

• semi permeable to help prevent the passage of water soluble molecules

what is the bacterial capsule and why is it considered to be a virulence factor

• A bacterial capsule is a layer of polysaccharides that surrounds the outer surface of some bacteria

• The capsule helps bacteria evade the immune system by preventing phagocytosis

distinguish between saturated fats, unsaturated fats and trans fats, which is in olive oil?

• Saturated fats have no double bonds between the carbon atoms in their fatty acid chains.

• Unsaturated fats contain one or more double bonds in the fatty acid chains,

• Trans fats are a type of unsaturated fat that has been artificially altered through a process called hydrogenation

• Olive oil is primarily composed of monounsaturated fats,

thermophilic, mesophilic and psychrophilic bacterial cells

• thermophilic bacteria thrive in high temperature environments between 50-80

• mesophilic bacteria survive in 37 degrees inside the human body soil and water

• psychrophilic bacteria thrive in cold environments between -5 - 15

define aerotolerant and microaerophilic

• Aerotolerant bacteria are organisms that do not require oxygen for growth but can tolerate its presence. They grow equally well in the presence or absence of oxygen.

• Microaerophilic bacteria are organisms that require low levels of oxygen to grow, typically around 2-10% oxygen concentration

gel electrophoresis in DNA analysis

the DNA sample is mixed with a loading buffer, which contains glycerol (to help the sample sink into the wells) and a dye (to visualize the loading process).

The electrical field is applied (positive electrode at the far end of the gel).

the gel is stained with a DNA-binding dye, commonly ethidium bromide

Under UV light, these dyes bind to the DNA and fluoresce, allowing the separation of DNA bands to be seen and compared.