Molecular Biology Test 1

Front 1

What are the 3 main shapes of bacteria?

Back 1

Cocci (spheres)

Bacilli (rods)

Spirilla (Spirals)

Front 2

Equation for Unrestricted Bacterial Growth

Back 2

dN/dt=kN

Front 3

Bacterial Size

Back 3

~1 micrometer (length or diameter)

Front 4

Other common bacterial shapes:

Back 4

Spirochete (corkscrew)

Vibrio (comma)

Front 5

Bacterial Growth: Lag Phase

Back 5

Time for bacterial to sense nutrient-rich environment. Repairs damage and begins growth. Length depends on recent life history.

Front 6

Bacterial Growth: Exponential Phase

Back 6

Unrestricted idealistic growth. Occurs for short periods.

Front 7

Bacterial Growth: Stationary Phase

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Caused by exhaustion of nutrients, toxic buildup. Altered prot. synth. "Dormant" -- Goal to survive w/out nutrients or growth until better conditions prevail.

Lose ability to respond to nutrition

Adapt: move or find new source of nut.

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Bacterial Growth: Death Phase

Back 8

Constant loss of viable cells. Mutations allow some cells to adapt and survive. A small number of cells use remains of dead cells as nutrients.

Front 9

Bacterial Habitats: Free-living

Back 9

live in soil, water, or on surfaces

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Bacterial Habitats: Symbiosis

Back 10

form mutually beneficial associations with a host.

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Commensalism

Back 11

neither benefit nor harm present from co-habitation

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Bacterial Habitats: Parasitic / Pathogenic

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presence of microbe harms or kills it's host

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Normal Flora

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co-habiting microorganisms normally occupying a habitat w/in an animal

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Probiotics

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live microorganisms confering a helath benefit on a host.

ex. Lactobacillus, Bifidobacteria

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Bacterial Habitats: Biofilms

Back 15

microbial communities w/ increased survival in conditions such as desiccation, starvation, and antibiotic treatment. can be + or -

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Chemiosmosis

Back 16

ATP prod. coupled to e- trans chain.

Respiration / Oxydative Phosphorylation

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Substrate level phosphorylation

Back 17

generation of phosphate bond as metabolic intermediate and subs. transfer to ADP --> ATP

Fermentation

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Phototrophs

Back 18

only need a simple carbon source (i.e. sugar)

Front 19

Auxotrophs

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complex nutritional req. (aa, vit, pyrimidines, purines)

Freq. symbiotic or pathogenic bacteria and get nutrients from host.

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Bacterial Nutritional Needs

Back 20

C
N
P
Sulfer
Mg+, Fe++, Zn++

some need only sugar as C source, others only CO2 (photosynth)

Front 21

How does cell have enough NAD+?

Back 21

e- trans chain cont. re-oxidizes NADH to make more NAD+ available, used to drive more gly.

w/out e- trans, use fermentation to regenerate NAD+ {etOH simply a biproduct, excreted}

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Gram +

Back 22

thick cell wall, no membrane

hold purple dye

susceptible to penicillin

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Gram -

Back 23

thin cell wall
retain pink counter-stain

susceptible streptomycin, tetracycline

Front 24

Cell Wall Construction

Back 24

polysaccharides cross-linked by aa

→ gives shape & rigidity

Front 25

Penicillin

Back 25

┤transpeptidation rxn

comp. inhib. / mimic of Enyzeme
--> no cross-links --> lysis

only kills growing bacteria

Front 26

Vanomycin

Back 26

binds & covers D-ala, D-ala

┤cell wall growth

Front 27

Spores

Back 27

Non-metabolizing/dormant
resistant to harsh environmental cond.
peptidoglycan coat protects bacterial DNA
S phase phenom.

"last resort"
usually gram +

ex. anthrax, tetanus, botulism

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Streptococcus pneumoniae

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encapsulated: virulent

rough : not as pathogenic

Front 29

Capsules

Back 29

surround cells
polysaccharides / proteins / OR both

┤ phatgocytosis

Front 30

Vibrio Cholerae

Back 30

flagellated --> motile

in intestine, become non-motile / toxic

Front 31

Allele

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form of a gene

mult. copies can be derived from same gene and are alternative occupants of the same locus on the chromosome

Front 32

Anti-codon

Back 32

3 nt sequence on t-RNA which is complimentary to the mRNA codon

Front 33

Auxotroph mutant

Back 33

differs from wt by having additional nutritional requirements

Front 34

Capsule

Back 34

surface component of bacterial cell

loc. outside of cell wall

Front 35

Chromosome

Back 35

structure carrying genes in a linear order

bacteria have one large circular molecule of DNA

Front 36

Cis

Back 36

arrangement of mutations where 2 mutations are present on one copy of the chromosome and 2 corresponding wt sites are present on another chromosome in the same cell

Front 37

Cistron

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Complementation test: cis-trans test

If trans, 2 mutants are in different cistrons

Front 38

Clone

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Genetically identical cells from successive divisions of a single cell

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Codon

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Sequence of 3 nt in a nucleic acid coding for a specific aa

Front 40

Complementation

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Complementary action of different mutant genomes

gen. rule for mutations in different genes

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Conjugation

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Attachment to bacterial cells

Allows transfer of genetic material from one to another

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Cross

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encounter allowing formation of genetic recombinants

ex. bac: cong., transd., transf.

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Deletion

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Loss of a segment of chromosome

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Episomes

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Dispensible pieces of genetic material

Can independently replicate

Reversibly integratable

---> essentially "plasmid"

Front 45

Exchange

Back 45

exchange of homologous segments of DNA between chromosomes

Front 46

Flagellum

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long, thread-like structures

prot: flagellin

diameter: 12nm - 30nm

Front 47

Gene

Back 47

smallest genetic unit w/ independent fxn

Front 48

Genetic Code

Back 48

relationship between DNA/RNA nt seq. and aa seq.

triplet, degenterate

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Genome

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Complete single set of genetic material

Front 50

Genotype

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ensemble of genes in an organism

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Haploid

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Possessing a single genome

Front 52

Heterozygote

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a cell with 2 varying alleles of the same gene

Front 53

Homozygote

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a cell with 2 identical copies of a gene

Front 54

Linkage

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tendency of neighboring genes to be transmitted together through crosses and not separated by crosses

determined by physical proximity

Front 55

Lysogeny

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harboring by a lysogenic bacterial strain of a temperate bacteriophage

can multiply uncontrollably --> lysis
{response to induction or spont}

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Marker

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genetic mutation with distinctive, observable effect on organism

can trace transmission of locus through cell divisions and genetic crosses

Front 57

Merozygote

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zygote with one complete genome and fragment of a second

Front 58

mRNA

Back 58

specifies aa seq. for particular polypeptide chain

Front 59

Minimal medium

Back 59

contains minimal nutrient supply req. by wt of an organism

will not support growth of auxotrophs

Front 60

Mutagen

Back 60

substance capable of inducing mutation

Front 61

Mutant

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cell or clone carrying a particular mutation

Front 62

Mutation

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abrubt and usually stably inherited change in phenotype of an organism

-- usually stemming from change in DNA

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Operon

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number of adjacent genes subject to common control mechanism

Front 64

Phenotype

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observable characteristics of an organism

does not nec. reflect complete genotype (some genes may be masked)

Front 65

Pili

Back 65

surface appendage in some gram - bac.

shorter and thinner (7nm) than flagella

Front 66

Polynucleotide

Back 66

polymer consisting of nucleotides linked by 5' --> 3' phosphodiester bonds

Front 67

Polypeptide

Back 67

polymer of aa

Front 68

Peptide bond formation

Back 68

condensation of carboxyl group with successive amino group

Front 69

Polyribosome (polysome)

Back 69

several ribosomes assoc. with same strand of mRNA

Front 70

Prophage

Back 70

temperate bacteriophage in latent state

Front 71

Protein

Back 71

large macromolecule formed from one or more polypeptide chains

have 1, 2, 3, & sometimes 4 struc.
can have non-prot. prosthetic groups

Front 72

Prototroph

Back 72

bacterial strain having minimal nutritional req.

Front 73

Recombinant

Back 73

cell or clone resulting from recombination

Front 74

Recombination

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formation of a new genotype by reassortment of genes during a genetic cross

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Replica plating

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replication of a pattern of colonies from one plate to another

sterile disk pressed on surface of first plate, adhering bacteria printed on second

Front 76

Segregation

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separation of 2 distinct alleles originally present in same cells

Front 77

Suppressor mutation

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mutation which masks the effect of another mutation elsewhere in the genome

Front 78

Temperate Bacteriophage

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bacteriophage capable of replication in step with host bacterium, thus is transmitted through cell divisions w/out nec. --> lysis

Front 79

Trans

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Arrangement of 2 mutations in same cell on different chromosomes or fragments with each one linked to the non-mutant homologue of the other

Front 80

Transcription

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DNA --> RNA

complementary bases

Front 81

Transduction

Back 81

transfer of fragment of genome from donor to recipient strain of bacteria

infecting recipient with bacteriophage particles grown on donor strain

Front 82

Transformation

Back 82

transfer of fragment of genome from donor to recipient strain

treating recipient cells with DNA isolated from donor

Front 83

Translation

Back 83

RNA --> Protein

aa seq. determined by triplet genetic code in mRNA

Front 84

Transversion

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mutation consisting of a change in one base pair of the DNA

a purine subs. for a pyrimidine and a pyrimidine for the purine

Front 85

Transition

Back 85

mutation consisting of a change in one base pair of the DNA

a different purine subs. for the purine and a different pyrimidine for the pyrimidine

Front 86

Zygote

Back 86

cell which is the immediate product of a cross

diploid

Front 87

Periplasmic space

Back 87

between cytoplamic membrane and outer membranes

incl. cell wall.

found only gram -

hydrolytic enzymes, transp. prot., buffer

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Outer Membrane

Back 88

phospholipid & LPS (lipopolysacch.)

Front 89

LPS

Back 89

lipopolysaccharide

endotoxin -- > cause of septic shock when released in dying cells

barrier to influx of hydrophobic compounds

Front 90

Membrane pores

Back 90

created by porins

"barrel"

OUT: hydrophobic -- membrane
IN: "hydrophillic -- allow H2O to flow

Front 91

G - > resistant > G +

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b/c outer membrane adds another external barrier against hydrophobic substances

Front 92

Bacterial Secretion

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I: straight out

II: transport to periplasm, transport out

III: injection into another cell

Front 93

Pili

Back 93

straight, hair-like appendages

short, project outwards

aka "fimbriae"

sex pilus, other simply attach to cells

Front 94

Adhesions

Back 94

cause bac. to stick to surfaces

loc. on surface or on pili

bind specific cell receptor mol. on surface of cells, usually sugars

Front 95

Flagella

Back 95

used for locomotion (find food, avoid danger, etc..)

i) Filament - hair like, flagelin, antigenic
ii) Hook -- joint
iii) Basal Body -- anchor, rotation
iv) Axial Filaments -- insertion

Front 96

Heat Shock Response

Back 96

i) elicited by ↑↑T
ii) synth. of > 30 heat shock prot.
iii) designed to renature damaged proteins or destroy them so new, active prot. can be synth.

σ32 replaces σ70 to modify mRNA expression

Front 97

Unit of transcription

Back 97

seq. of DNA bases transc. into single discrete complementary RNA

Front 98

Promoter site

Back 98

"Start region"

where RNA poly binds for initiation

usually -10 → -100 bp

Front 99

Termination Site

Back 99

STOP, synthesis ceases

Front 100

β subunit

Back 100

catalytic activity

binds substrates, holds σ in place on RNA poly, held over site 1

Front 101

β' subunit

Back 101

allows RNA poly to bind and stay bound to DNA

non-specific

Front 102

α subunit

Back 102

interacts w/ regulatory prot.

struc. of RNA poly, sits @ tail

2 copies

Front 103

σ subunit

Back 103

recognizes promoter region (@-10, -35)

ejected to make room for transc.

↑ affinity for correct sites
↓affinity for incorrect sites

can vary; different copies attach to same core E

Front 104

Holoenzyme (RNA poly)

Back 104

req. for initiation

ααββ'σ

Front 105

Core enzyme (RNA poly)

Back 105

sufficient for elongation of transc., has no idea where to start

ααββ'

Front 106

NusA

Back 106

joins RNA poly after σ released

recognizes termination sites

Front 107

Transc. Termination

Back 107

Factor independent: stem-loop structure

Factor dependent: req. rho

Front 108

Actinomycin D

Back 108

binds G-C pairs, renders DNA unusable as a template for RNA poly

Front 109

Rifamycins

Back 109

(inc. rifampicin)

bind β subunit and prevent ejection of σ

thus ┤transc. at initiation