Microbiology Unit 7

Front 1

Genetics

Back 1

Study of science of heredity

Front 2

Chromosomes

Back 2

Structures containing DNA

Front 3

Genes

Back 3

Segments of DNA

Front 4

DNA

Back 4

macromolecule composed of repeating nucleotides

Front 5

Nucleotides base

Back 5

adenine, thymine, cytosine, guanine

Front 6

Nucleotide dexoxyrybose

Back 6

pentose sugar

Front 7

Base pairs

Back 7

Adenine w/thymine

Cytosine w/ guanine

Front 8

Gene expression

Back 8

DNA transcribed to produce RNA; mRNA then transferred to proteins

Front 9

Genotype

Back 9

Genetic composition of organism - entire DNA

Front 10

Phenotype

Back 10

Expression of the genes

Front 11

DNA

Back 11

One long double helix w/associated proteins

Front 12

Bacteria DNA

Back 12

Circular, 1000 times longer than cell

Front 13

DNA Replication

Back 13

1. Two strands of parental DNA unwind and separate in one small segment after another

2. Free nucleotides match up to exbosed bases

3. Newly added nucleotide is joined to growing DNA strand by DNA polymerase

4. Parental unwound a little more to allow addition of next nucleotides

Only occurs in ONE direction around chromosome

Front 14

Replication fork

Back 14

Point at which replication occurs

Front 15

Semiconservative replication process

Back 15

Each double-stranded DNA molecule contains one original and one new DNA strand

Front 16

DNA polymerase

Back 16

Makes a molecule of DNA from a DNA template

Front 17

Transcription

Back 17

Conversion of a DNA message (gene) to an RNA strand

Front 18

Pairs of DNA bases and mRNA

Back 18

G in DNA / C in mRNA
C in DNA / G in mRNA
T in DNA / A in mRNA
A in DNA / U in mRNA

Front 19

Steps of transcription

Back 19

1. RNA polymerase binds to DNA at promoter (site)

2. RNA polymerase assembles free nucleotides into new chain (base pairs)

3. As new RNA chain grows, RNA polymerase moves along DNA

4. RNA synthesis continues until terminator site

5. RNA polymerase and newly formed, single-stranded mRNA are released from DNA

Front 20

Promoter site

Back 20

Starting point for transcription where RNA polymerase binds to DNA

Front 21

Terminator site

Back 21

Region of DNA that is endpoint for transcription

Front 22

Translation

Back 22

Conversion of mRNA to a protein

Front 23

Genetic code

Back 23

Relationship among nucleo-base sequence of DNA, corresponding codons of mRNA, and amino acids for which codons code

Code is degenerate- most amino acids are coded for by more than 1 codon

Front 24

Sense codons

Back 24

61 codons code for amino acids

Front 25

Nonsense codons

Back 25

Stop codons signal the end of the protein molecule's synthesis

Front 26

Start codon

Back 26

AUG (methionine)

Front 27

Anticodon

Back 27

Found on the tRNA and matches the codon

Front 28

Steps of translation

Back 28

1. Two ribosomes subunits, tRNA wi/anticodon UAC, and mRNA molecule assemble.

2. First tRNA binds to start codon

3. First amino acid is transferred by the ribosome

4. After ribosome joins two amino acids w/peptide bond, first tRNA leaves the ribosom

5. Ribsome then moves along mRNA

6. Peptide bonds are formed between amino acids

7. Ends when one of three nonsense codons is reached

Front 29

Procaryote tranlsation

Back 29

Can begin before transcription is completed

Front 30

Codons

Back 30

Three-base sements of mRNA that specify amino acids. mRNA read in 5'--3' direction

Front 31

Mutation

Back 31

Change in nitrogenuous base sequence of DNA - causes a change in product coded for

Some are neutral, some disadvantageous, other beneficial

Front 32

Base-pair mutation

Back 32

One base pair in DNA is replaced w/a different base pair

Front 33

Missense mutations

Back 33

Base substitution results in amino acid substitution in the synthesized protein

Front 34

Nonsense mutation

Back 34

Base substitution results in nonsense codon

Front 35

Frameshift mutation

Back 35

A mutagen that causes insertions

Front 36

Mutagens

Back 36

Agents in the environment that cause permanent changes in DNA

Front 37

Spontaneous mutation

Back 37

Occur in absence of any mutation-causing agents.

Front 38

Chemical mutagens

Back 38

Base-pair mutagen (nitrous acid), Base analogs, frameshift mutagen

Front 39

Ionizing radiation

Back 39

A mutagen that causes the formation of highly reactive ions

Front 40

Nonionizing radiation

Back 40

UV radiation

A mutagen that causes the formation of pyrimidine dimers

Front 41

UV Damage

Back 41

Can be repaired by enzymes that cut out and replace damaged portion of DNA

Front 42

Mutation rate

Back 42

Probability that gene will mutate when cell divides, expressed as 10 to negative power

Front 43

Genetic recombination

Back 43

Rearrangement of genes to form new combinations

Front 44

Crossing over

Back 44

Genes from two different chromosomes are recombined into one chromosome

Front 45

Recombinant

Back 45

Some of donor's DNA integrated into recepient's DNA

Front 46

Transformation

Back 46

The transfer of DNA from a donor to a recipient as naked DNA in solution

Discovered first by Frederick Griffith w/Streptococcus pneumoniae

Front 47

Conjugation

Back 47

Contact between living cells

Transfer of a plasmid from a donor cell to a recipient cell

Front 48

Plasmid

Back 48

Circular piece of DNA that self-replicates outside of the chromosome

Front 49

Transduction

Back 49

The transfer of DNA from a donor to a recipient cell by a bacteriophage

Front 50

Steps of transduction

Back 50

2. Phage attaches to the donor bacterial cell wall and injects DNA into bacterium

2. Phage DNA acts as template for synthesis of new phage DNA. Bacterial chromosome is broken apart by phage enzymes.

3. Some pieces of bacterial DNA mistakenly packaged inside phage protein coats.

4. When released phage particles later infect new bacteria, bacterial genes are transferred to newly infected recipient cells

Front 51

F Factor plasmid

Back 51

Conjugative plasmid carries genes for sex pili and for the transfer of plasmid to another cell

Front 52

Dissimilation plasmid

Back 52

Code for ezymes that trigger the catabolism of certain unusual sugars and hydrocarbons

Front 53

Resistance factor

Back 53

Plasmids that have significant medical importance

Front 54

Transposons

Back 54

Small segments of DNA that can move from one region of a DNA molecule to another

Frequent movement can wreak havoc inside cell

Found in main chromosome of organism

Vary from simple to complex

Front 55

Complex transposons

Back 55

Carry other genes not connected with the transposition process.

Front 56

Genetic engineering

Back 56

Genes can be transferred between unrelated species via laboratory manipulations

Front 57

Recombinant DNA

Back 57

DNA that has been artificially manipulated to combine genes from two different sources

Front 58

Biotechnology

Back 58

All industrial applications of microorganisms as well as industrial uses of genetically engineered cells

Front 59

Vector

Back 59

Self-replicating DNA used to carry a gene from one organism to another

Front 60

Recombinant DNA Procedure

Back 60

1. Desired gene inserted into DNA vector such as plasmid or viral genome

2. Vector inserts the DNA into new cell, which is grown to form clone

3. Large quantities of gene can be harvested from the clone

Front 61

Sticky Ends

Back 61

Short stretches of single-stranded DNA at ends of DNA fragments

Fragments of DNA produced by same enzyme will spontaneously join by hydrogen bonding

Front 62

Shuttle vectors

Back 62

Plasmids that can exist in several different species

Front 63

Viral vector

Back 63

Can accept much larger pieces of foreign DNA

Can be inserted into cell by transduction

Front 64

PCR

Back 64

Technique by which small samples of DNA can be quicly amplified

Front 65

Electroporation

Back 65

An electrical current form microscopic pores in membranes of cells. DNA enters cells through pores.

Front 66

Protoplast fusion

Back 66

"Hit and miss"

Does not add a specific gene to a cell

Front 67

Microinjection

Back 67

Use of a fine glass micropipette to inject DNA

Front 68

Gene libraries

Back 68

Can be made by cutting up an entire genome with restriction enzymes and inserting fragments into plasmids or phages

Front 69

Exon

Back 69

Stretches of DNA that code for protein

Front 70

Intron

Back 70

Stretches of DNA that do not code for protein

Front 71

cDNA

Back 71

cDNA made from mRNA by reverse transcription

Segment of eukaryotic DNA that lacks introns

Front 72

Synthetic DNA

Back 72

Can be made in vitro by a DNA synthesis machine

Front 73

E.coli

Back 73

Easily grown

Genetics are well understood

Produces endotoxins

Must be lysed or gene must be linked to gene that produces a naturally secreted protein

Front 74

Baker's yeast/Saccharomyces cervisiae

Back 74

Four times larger than E.coli

Best understood eukaryotic genome

May carry plasmids which can be transferred

More likely to continuously secrete product

Front 75

Mammalian cells

Back 75

Can be engineered to produce proteins such as hormones for medical use

Front 76

Plant cells

Back 76

Used to produce plants with new properties

Front 77

Clone

Back 77

Population of cells carrying a specific gene

Front 78

Human insulin

Back 78

Synthetic genes linked to beta-galactosidase inserted into E. coli, allowing E.coli to produce and secrete the two polypeptides

Front 79

Subunit vaccine

Back 79

Protein portion of a pathogen from genetically engineered yeasts

Front 80

Animal viruses

Back 80

Can be engineered to carry gene for pathogen's surface protein.

When used as vaccine, host develops immunity

Front 81

Southern Blotting

Back 81

DNA fragments are separated then exposed to radioactive probe

Locates gene in a cell

Front 82

Genetic Screening

Back 82

Uses Southern blotting to look for mutations responsible for inherited disease in humans

Screen available for more than 200 diseases

Front 83

DNA fingerprinting

Back 83

Restriction fragments

Front 84

PCR

Back 84

Can be used to increase amounts of DNA in samples to detectable levels

Front 85

DNA probes

Back 85

Used to identify bacteria carrying a specific gene

Front 86

Ti plasmid vector

Back 86

Plant cells can be engineered using this vector

Front 87

Rhizobium

Back 87

Enhances nitrogen fixation

Front 88

Restriction enzyme

Back 88

Protect a bacterial cell by hydrolyzing phage DNA

Front 89

Reverse transcriptase

Back 89

Enzyme that provides copy of mRNA to DNA

Front 90

Antibiotic resistance

Back 90

Can be acquired by bacteria by:

Mutation
Insertion of transposons
Acquiring plasmids

Use on plasmid makes direct selection possible

Front 91

Nucleoside Analog

Back 91

A mutagen that is incorporated into DNA in place of a normal base

Front 92

Ribosome

Back 92

Composed of rRNA and proteins

Performs translation

Front 93

tRNA

Back 93

Carries the specific amino acid to the ribosome

Front 94

mRNA

Back 94

Carries the message for a polypeptide, translated by the ribosome (translation)

Front 95

RNA Polymerase

Back 95

Makes of molecule of RNA from a DNA template

Front 96

DNA ligase

Back 96

Joins segments of DNA

Front 97

Transposase

Back 97

Insertion of DNA segments into DNA

Front 98

Spliceosome

Back 98

Removal of introns

Front 99

Gene Library

Back 99

Pieces of DNA stored in yeast cells

Front 100

Making cDNA

Back 100

1. Gene composed of introns and exons is transcribed to RNA

2. RNA processing to remove introns

3. Isolate mRNA from cell and add reverse transcriptase

4. First strand of DNA is synthesized

5. mRNA digested by reverse transcriptase

6. Add DNA polymerase to synthesize second strand of DNA