Intro to Micro Exam 2

genetics

the transmission of traits from parent to offspring

central dogma of biology

1. DNA is replicated

2. RNA is made through transcription

3. Proteins are made through translation

DNA

deoxyribonucleic acid

makes up DNA

Nitrogenous bases: Adenine, Guanine, Cytosine, and Thymine

phosphate backbone

pair up with one another to make a double strand, A with T, C with G, strand are antiparallel to each other, create a double helix

bacterial replication

process of making two strands of DNA out of one, chromosome is replicated, two different cells are created, circular DNA speeds up process

bacterial replication process

start at both ends of the circle and go both directions around the circle (bireplication), new DNA is made from the old (replication fork), enzymes meet up at the other end of the circle (termination of replication), enzymes come back and tie up the ends to create two pieces of DNA

helicase

enzyme that unwinds the DNA strands so that the polymerase can do its work

DNA polymerase

enzyme that adds new enzymes to the growing DNA strand

DNA ligase

enzyme that is responsible for gluing pieces of DNA back together

okazaki fragments

one strand containing short fragments of DNA

leading strand

5’ to 3’ , the only strand that can be synthesized as a continuous, complete strand

lagging strand

3’ to 5’ , the polymerase adds nucleotides a few at a time in the direction away from the fork

transcription

DNA to RNA

RNA

ribonucleic acid, Adenine, Guanine, Cytosine, Uracil, typically single-stranded

genes in RNA

have the potential to be transcribed, have a promoter and termination site

RNA polymerase

complex enzyme site, unwinds DNA, adds nucleotides, and reaches termination site in transcription

3 stages of transcription

initiation, elongation, and termination

initiation

RNA polymerase binds to the promoter

elongation

polymerase rides along DNA adding new nucleotides

termination

polymerase hits the termination site and realizes it’s done and falls off

3 types of RNA

rRNA, mRNA, tRNA

rRNA

ribosomal RNA, come together to produce the structures that do protein synthesis (ribosomes)

tRNA

transfer RNA, bring in the amino acids to build the protein chains

mRNA

messenger, translated in a protein, has all of the codons that will be translated

translation

RNA to protein

codon

group of 3 nucleotides that dictate which amino acid is going to be brought in, for every 3 nucleotides there is 1 amino acid (patterns are developed)

redundancy

the repetitive nature of the codons, protects against mutations

anticodon

triplicate nucleotide that binds to codons present in every tRNA

nucleus, cytoplasm

replication and transcription happen in the _______ in Eukaryotes; translation happens in the __________

all in cytoplasm

where translation, transcription, and replication happen in prokaryotes

recombination

DNA is changed and new pieces are added to old pieces of DNA, horizontal gene transfer, plasmids

horizontal gene transfer

DNA is donated to another cell in the same generation

plasmids

function in conjugation through the pili

modes of recombination

transformation, transduction, horizontal gene transfer, conjugation

transformation

what happens when a bacterial cell picks up bacterial chromosomes in the environment (competent cells)

competent cells

cells that are able to pick up DNA in their environment

transduction

viruses infect bacterial cells with their DNA, process performed by bacteriophages

bacteriophages

virus that can infect a bacterial cell

two types of mutations

point mutation and frameshift mutation

point mutation

incorrect nucleotide is added to the strand

frameshift mutation

bases are either added or deleted → effects the whole chain and changes the amino acids

results of mutations

missense mutation, nonsense mutation, silent mutation

missense mutation

the incorrect amino acid is placed

nonsense mutation

a normal codon is changed to stop a codon, protein is shortened, almost always results in a nonfunctional protein

silent mutation

what happens when redundancy solves the problem and the amino acid is added anyways

nutrition

a process by which chemical substances are acquired from the environment then used in cellular activities

bacteria eat

macronutrients and macronutrients

macronutrients

things like carbon, hydrogen, and oxygen that are required by the microbe in order to survive

micronutrients

things required for cell growth that are needed in very small quantities such as nickel, zinc, and iron

bacteria food is used for

enzyme functions and protein structure and function

why do bacteria eat?

need large amounts of carbon to survive, need energy in the form of ATP to survive

how do bacteria eat?

transport mechanisms

diffusion

movement of molecules from an area of high concentration to an area of low concentration, goal: equilibrium

osmosis

different from diffusion because there is a membrane involved that the nutrients move through selectively

isotonic conditions

normal, no difference in the concentration on the outside or inside

hypotonic conditions

concentration of molecules is high inside the cell, takes water into the cell, cell swells up really big, osmotic pressure low

hypertonic conditions

concentration of molecules high outside the cell, cell pushes water out, cell shrivels, osmotic pressure very high

active transport

movement of molecules across the semipermeable membrane that requires energy, pushing molecules out instead of water, requires specific proteins/pumps on the cell membrane specific to the molecules moving in and out

growth requirements

temperature, oxygen concentration, osmotic pressure, pH

correct temperature

optimum, shortest generation time, 37 C

psychrophiles

like extremely cold conditions, important for freezing food

mesophiles

prefer middle temperatures, important for pathogens

thermophiles

prefer hot temperatures, important for hot environmental conditions

danger zone for food

5 C to 60 C

oxygen free radicals

try and steal electrons from bacteria to balance themselves, O, O2-, H2O2, OH-

oxygen classifications

those that use oxygen and detoxify it, those that neither use nor detoxify it, and those that do not use oxygen but can detoxify it

superoxide dismutase

enzyme that breaks down oxygen

catalase

present if SOD is, breaks down hydrogen peroxide into water and oxygen

obligate aerobes

oxygen required for growth

facultative anaerobes

can grow with or without oxygen, grow better with oxygen

obligate anaerobes

dies in the presence of oxygen

aerotolerant anaerobes

don’t need oxygen to grow but can tolerate it

microaerophiles

can only grow with low concentration of oxygen

right osmotic pressure

hypotonic conditions, hypertonic conditions, halophiles

halophiles

bacteria that love salt

proper pH

most bacteria need a neutral pH (6-8)

strong acids are not friends with proteins

can destroy protein structures

generation time

the time it takes for a bacteria to replicate or the time it takes for a population to double

binary fission

how bacteria reproduces

lag phase

when a bacteria is inoculated into a new place, making sure the environment has the nutrients they need to survive before they expend energy possibly needed to survive

log phase

the population is doubling as quickly as it possibly can after discovering the environment is good

stationary phase

the log phase levels off, the rate of cell growth is equal to the rate of cell death

death phase

the rate of cell death is higher than the rate of cell growth

how do we measure bacterial growth?

directly and indirectly

directly

plate count, filtration, direct microscope count

plate count

plate the bacteria on agar and count the number of colonies

filtration

filter out bacteria from water then count the colonies on the plate

direct microscope count

count the number of cells on the slide of the microscope

indirectly

turbidity, metabolic activity, and dry weight

turbidity

measurement of the amount of cloudiness in broth, shoots light through the test tube

metabolic activity

looking overtime at how quickly the metabolic action occurs

dry weight

spin bacteria out of a sample and weigh it to see how much was there

sterilization

process that destroys or removes all forms of viable microorganisms (including viruses)

aseptic

no microbial growth

commercial sterilization

physical technique of preserving food that is packaged airtight in a container

disinfection

physical process of a chemical agent to destroy vegetative pathogens but not bacterial endospores, removes harmful products of microorganisms from material

decontamination/sanitization

cleansing technique that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels

antisepsis/degermation

reduces the number of microbes on the human skin, a form of decontamination but on living tissues

bactericidal

kills bacteria