Micro Lecture Exam 3

Front 1

What is a frameshift mutation and what are the types of frameshift mutations?

Back 1

skipping a letter all together:

*addition of a base = insertion

*loss of a base = deletion

both of these lead to an entirely new AA sequence which leads to a non-functional protein => always LETHAL!

Front 2

What is a point mutation are the different types of point mutations?

Back 2

change of only one base (nucleotide)

*missense mutations

*neutral mutations

*nonsense mutations

Front 3

What are missense mutations?

Back 3

change the AA sequence and alter the protein -- could be good OR bad!

Front 4

What are neutral mutations?

Back 4

"silent" mutations -- new codon codes for the same AA, so there is no change in the protein

Front 5

What are nonsense mutations?

Back 5

new codon codes for STOP -- results in a short, non-functional protein => LETHAL!

Front 6

What are mutagenic agents?

Back 6

spontaneous mutations & induced mutations

Front 7

What are spontaneous mutations?

Back 7

due to mistakes in DNA replication, rare, effects of background cosmic radiation

Front 8

What are the types of induced mutations?

Back 8

chemical mutagens

base analogs

chemical induced frame shift

Front 9

What is a chemical mutagen?

Back 9

a base pair mutation (A-C instead of T caused by nitric acid [point])

Front 10

What is a base analog?

Back 10

CHM looks like a base (ie. 2-amino purine looks like A, but binds with C instead of T [point])

Front 11

What is a chemical induced frameshift?

Back 11

ie. Aflatoxin caused by fungus (mold) and is very LETHAL!

Front 12

What is the structure of DNA?

Back 12

double helix with complimentary base pairing (A-T, C-G)

Front 13

What are the components of DNA?

Back 13

it is a macromolecule made up of nucleotide subunits:

1. phosphate H3PO4

2. deoxyribose -- a 5-carbon sugar [pentose]

3. nitrogenous bases [A-T, C-G]

Front 14

What is the structure of RNA?

Back 14

single stranded (mRNA, tRNA, rRNA) with complimentary base pairing [A-U, C-G]

Front 15

What are the components of RNA?

Back 15

a macromolecule composed of:

1. a phosphate group

2. ribose sugar [also a 5-carbon sugar]

3. nitrogenous bases [A-U, C-G]

Front 16

What is a nucleotide?

Back 16

the building blocks of nucleic (DNA, RNA) acids -- nitrogenous base + phosphate group + pentose sugar [deoxyribose or ribose]

Front 17

What is complimentary base pairing?

Back 17

in DNA: A-T, C-G

in RNA: A-U, C-G

Front 18

Replication of DNA

Back 18

circular, double-stranded bacterial DNA

replication occurs before binary fission

proteins unwind, which separates DNA

DNA polymerase adds nucleotides to form new double strand

semiconservative replication (original strand splits in two --splitting up the pairs)

each daughter strand contains half of the original strand

Front 19

Transcription

Back 19

rewriting the code from the language of DNA to RNA

one gene = one mRNA = one tRNA

one gene has enough genetic info to make one protein, represents one inheritable trait

RNA polymerase adds RNA nucleotides to the new mRNA strand

mRNA can then be read by ribosomes to make proteins

Front 20

Translation

Back 20

3 nucleotides (3 bases) on a strand of mRNA code for 1 amino acid -- called a triplet or codon

copy of DNA template

codon on mRNA maters with anti-codon on tRNA -- complementary base pairing

ends of tRNA carry one specific amino acid

ribosomes "read" 2 codons at a time (join 2 AA via peptide bonds, continuation builds complete proteins)

4 bases arranged into triplets = 64 different possible combinations, but there are only 20 AA so several codons code for the same AA

AUG=start

UAG=stop

Front 21

What is the definition of transcription?

Back 21

DNA --> mRNA

Front 22

What is the definition of translation?

Back 22

mRNA --> protein

Front 23

What is the definition of transformation?

Back 23

DNA can be picked up from the environment [ie. from a dead bacterial cell]

Front 24

What is the definition of transduction?

Back 24

DNA is transferred by a virus

Front 25

What is the definition of transposon?

Back 25

"jumping gene"

Front 26

What is conjugation?

Back 26

the transfer of genes between cells that are in contact with each other, involves a pilus, can transfer a plasmid (takes about 2 minutes) or part of the main chromosome (takes about 100 minutes & is unlikely)

examples: F-factor transfer, Hfr (high frequency recombination)

Front 27

What is the F-factor? How many genes is it composed of? How do we use it?

Back 27

The F-factor (or F-plasmid) means fertility -- it is composed of 15 genes, 9 of which code for the proteins used to make the pilus

Front 28

What is genetic engineering? How do we use it?

Back 28

genetic engineering uses endonucleases and ligases; cut out human genes & instert into plasmids -- induce bacteria to take up plasmid & reproduce!

can get expression of human proteins manufactured by bacteria (ie. insulin, interferon, growth hormone, clotting factor VIII, HBV, etc.)

Front 29

Define disinfection

Back 29

destroys vegetative cells, but not spores -- used on inanimate objects! reduces #s and inhibits growth

ie. bleaching, boiling, lysol

Front 30

Define sanitation

Back 30

reduces the level of microbes on eating utensils

helps to maintain public health

Front 31

Define sterilization

Back 31

destroys all microbial life -- use autoclave, etc.

it's all or nothing!

Front 32

Define degermination

Back 32

emulsifies skin oil, mechanically removes microbes on outer layers

ie. hand washing

Front 33

Define antisepsis

Back 33

chemical disinfection of skin and mucous membranes

ie. mouthwash, alcohol, betadine

Front 34

What are the conditions that affect antimicrobial activity?

Back 34

1. concentration of antimicrobial solution (full strength v. dilution)

2. # of organisms

3. type of organisms [Gram - are more resistant than Gram +, Mycobacterium are very resistant, spore formers are more resistant]

4. temperature [^ temp = ^ rxns, v temp = v rxns]

5. pH [strong acids/bases weaken bacterial structures and denature proteins]

6. organic materials -- substrates! many absorb chemical agents making them less effective; porous (harder to clean) v. nonporous

Front 35

What are the mechanisms of action for most antimicrobials? How do they work? What cellular components do they impact?

Back 35

1. damage of the cell wall -- disrupts the peptidoglycan layer, subject to osmotic pressure and lysis

2. alter cell membrane permeability -- causes membrane to leak

3. denature proteins and nucleic acids

4. inhibition of enzyme function [denature or change active site]

5. inhibition of protein synthesis

***ALMOST ALL OF THESE ALTER PROTEINS IN ONE WAY OR ANOTHER!!!***

Front 36

What are the parameters of the autoclave?

Back 36

physical means:

moist heat!! steam under pressure

15 psi above atmospheric (2 atmospheres), 121*C, 20 minute minimum exposure time

kills all microbes and spores

used to sterilize heat resistant materials [surgical instruments, dressings, agar, broth, syringes, etc.]

Front 37

Which techniques are sterilization techniques?

Back 37

most heat in autoclave

dry air in hot air and incineration, bunsen burner(can sterilize a piece or portion)

ionizing radiation (x-rays, gamma rays)

filtration sterilizes heat sensitive liquids like vaccines

chemical means:

ethylene oxide (gas sterilization!)

Front 38

What is thermal death time (TDT)?

Back 38

shortest TIME needed to kill all microbes in a liquid at a given TEMPERATURE

Front 39

What is thermal death point (TDP)?

Back 39

LOWEST TEMPERATURE able to kill all microbes in a liquid in 10 minutes

Front 40

What is decimal reduction time (DRT)?

Back 40

time required to kill 90% of a population of microbes at a given temperature

ie. 1000- kill 90%=100; kill 90% of 100=10

Front 41

What is lyophilization?

Back 41

a form of dessication (drying) where food/bacterial specimens are subject to rapid freezing and dehydration under a vacuum -- you just have to reconstitute it

Front 42

How does cold impact microbial organisms?

Back 42

the cold only slows metabolism (cells go into a dormant state), doesn't kill cells! it's static, not cidal! and is used to preserve cultures and food

Front 43

What is filtration? How does it work? What can it be used for?

Back 43

it doesn't kill, it just removes.

can be used for sterilizing heat-sensitive materials like culture media, enzymes, beer, milk, & vaccines -- .22-.45 nanometers for bacterial disinfection & .01 nanometers for viruses (sterilization!)

HEPA (high efficiency particulate air) filters: used in "clean air" work areas and under lab fume hoods