Microbial Genetics Flashcards
(121 cards)
0
Q
What are the three components of a nucleotides?
A
- Phosphate
- 2, Deoxyribose
- Nitrogen Containing Base
1
Q
What is the basic subunit of DNA?
A
Nucleotides are the subunits of DNA.
2
Q
What kind of bonds hold the components of a nucleotides together?
A
Covalent bond
3
Q
What kind of bonds hold the two strands of a double helix together?
A
Hydrogen bond
4
Q
What component of a nucleotide specifies the genetic information?
A
Genome
5
Q
What are the four nitrogen-containing bases found in the DNA?
A
Adenine, Guanine, Thymine, Cytosine
6
Q
What is complimentarily what to what?
A
Adenine to Thymine
Cytosine to Guanine
7
Q
What is anti-parallelism?
A
Two strands of DNA are always oriented in opposite directions.
8
Q
What is semi-conservative replication?
A
Each cell receives one parental strand and one daughter strand.
9
Q
What enzymes are involved with DNA replication?
A
DNA Helicase, DNA Polymerase, DNA Exonuclease, and DNA ligase
10
Q
What are the three kinds of RNA?
A
tRNA, mRNA, rRNA
11
Q
What is the difference between DNA and RNA?
A
- RNA is similar to DNA, except RNA is single stranded helix, has ribose sugar, has URACIL, and it is shorter than DNA (1000 nucleotides in length).
- DNA has a double helix that is intertwined with 5 base pairs per turn. Always antiparallel. 2 strands of DNA are always oriented in opposite directions.
12
Q
What are the 3 kinds of RNA and what are their functions?
A
- rRNA (ribosome): part of ribosome (60% of a ribosome is made of RNA, the rest is made of protein).
- tRNA (transfers): carries amino acids to the ribosome during protein synthesis. tRNA is also known as anti-codon. It is bivalent with a so called clover leaf shape. Picks up and transfers 1 of 20 possible amino acids to the ribosome.
- mRNA (messenger): a complimentary strand of RNA equal in size to 1 gene (normally 1000 nucleotides). Codon - coded information from DNA. (bound for the ribosome.) The cells genetic plan contained in DNA is transcribed into a complimentary base sequence. mRNA is a blue print of DNA, a transcript, or a code.
13
Q
What is the central dogma of biology?
A
DNA (replication) –(transcription)–> mRNA –(translation)–> protein
14
Q
What enzyme performs transcription?
A
RNA polymerase.
15
Q
What is the product of transcription?
A
The product of transcription of DNA: RNA
16
Q
What are the three steps of translation? (Briefly summarize all steps)
A
Step 1) Initiation - mRNA bumps into the small subunit and triggers the two ribosomal subunits to bind together. The first tRNA anticodon (UAC) carries the the amino acid methionine hydrogen bonds with the codon AUG on mRNA.
Step 2) Elongation - The second tRNA hydrogen bonds to the second code word on mRNA. A peptide (covalent) bond forms between the two amino acids. The first tRNA leave. The enzyme translocase moved the ribosome down one code word of mRNA at a time. This repeats 333 times.
Step 3) Termination - 1 of 3 possible stop codons is reached. The last tRNA falls away and the two ribosomal subunits fall apart. Enzyme is complete with 333 amino acids and released into the cytoplasm.
17
Q
What is the production of translation?
A
Protein.
18
Q
What is the genetic code? How many nonsense codons? How many sense codons?
A
Genetic codes are the 64 codons. There are 61 sense codons for 20 amino acids, and 3 nonsense codons that are stop codons.
19
Q
How many bases are in one code word of the genetic code?
A
there are 3 bases in one code word of the genetic code.
20
Q
Where does the protein synthesis take place?
A
In the ribosome.
21
Q
What antibiotics block protein synthesis and by what mechanism?
A
Tetracycline and streptomycin. Their mechanism is a protein synthesis inhibitor (to block protein synthesis).
22
Q
Where does the lac repressor binds in the absence of lactose in the lac operon?
A
In the operator sites.
23
Q
What chemical process causes the epigenetic shut off of a gene?
A
Methyl Functional Group (CH3)
24
What are the 3 examples of point mutation?
Silent Mutation
Missense Mutation
Nonsense Mutation
25
What is the probable effect on the amino acid sequence after a silent mutation?
No change in amino acid or enzymes.
26
What is the probable effect on the amino acid sequence with the nonsense mutation?
Result incomplete defective enzymes.
27
What is the probable effect on amino acid sequence with missense mutation?
Changes amino acid. Usually no effect, however, if in the active site, it will cause defective enzyme.
28
What happens to the DNA sequence in a frame-shift mutation?
Addition and deletion of one or more bases on the DNA due to chemical or physical mutagens.
29
What are the three categories of chemical mutagens and provide one example of each?
* Nitrous Acid - examples: found in smog and form in the body when eating smoked meat. Alters adenine so it pairs with cytosine.
* Alkylating agents - examples: Formalin, Nitrogen mustard, and ethylene oxide. Reacts with guanine causes mispairing.
* Nucleoside analogs - ex: AZT - a modified sugar that substitutes for thymine. Another example is bromouracil.
* Intercalating agents - ex: aflatoxin - is a chemical produce by the peanut and grain modl. (aspergillus flavus [fungus]).
30
What are the 2 examples of physical mutagens?
* Non-ionizing raditation - causes formation of Thymine to Thymine dimers. Ex: UV light @ 260 nm.
* Ionizing radiation - breaks DNA forms "free radicals" leading to mutation. Ex: X-rays, Gamma Rays (from stars and nuclear blasts), Radon (natural in the enviroment), and Alpha rays (inhaling dust containing radioactive fullout).
31
What genus and species of bacteria is famous for transformation?
Streptococcus pneumoniae
32
In what two ways can this bacteria benefit from transformation?
1) Capsule Formation
| 2) Penicillin resistance
33
Briefly describe conjugation?
Conjugation is like a mating process between a donor F+ and an F- recipient cell. It occurs in Gram Negative (-) enteric bacteria (family Enterobacteriace) Conjugation was discovered by Lederberg and Tatum in 1946. F+ bacteria transmit a copy of the plasmid into F- bacteria, where F- becomes a F+. Plasmid carries genes that are nonessential life of bacteria. Unusual proteins are synthesized by plasmid genes, such as gene for pili, gene for plasmid replication enzymes, and genes for antibiotic resistance. (example would be Klebsiella Pnemoniae Carbapenemase [KPC])
34
What family of bacteria conjugate and where in the body they are located?
Enterobacteriace. Found in the human intestines.
35
Provide three functions of genes located on plasmids?
Gene Pili (Sex pilus)
Gene for plasmid replication enyzmes
Genes for antibiotics resistance (r-factors)
36
What does the acronym Hfr stands for?
High Frequency Recombination
37
Why is antibiotic resistance more of a problem with Hfr bacteria?
It is able to be passed down during binary fission every time the cell divides. Antibiotic resistance develops very quickly.
38
What occurs when an Hfr mates with a F- cell?
When the Hfr mates with F- bacteria, only the bacterial genes cross, not the plasmid genes. (Genetic diversity results in this case due to Hfr).
39
What microbe is found on the skin while performing transposition, and what is the acronym for its famous antibiotic resistant strain?
Staphylococcus Aureus is found on the skin while performing transposition. The acronym for the antibiotic resistant straing is MRSA (Methicillin resistant Staphylococcus Aureus).
40
Compare and contrast generalized and specialized transduction: name of the virus, mechanisms, and outcome for the recipient E. coli.
```
Generalized
•T2ø
•Lytic Cycle
•Random Packaging
•Recombination
•Genetic Diversity
```
```
Specialized
•Lambda Phage (λφ)
•Lysogenic/Stress = Lytic
•Specialized galactose gene
•recombination
•To metabolize lactose
```
41
What STEM cell research technique uses de-nucleated ovum inoculated with the somatic cell DNA for an individual needing transplant or replacement tissues?
Somatic Cell Nuclear Transfer (SCNT)
42
What is the function of phosphate group?
To be a structural part of DNA.
43
What is the 2 Deoxyribose?
It is a 5-carbon sugar that functions as a part of the DNA back bone. 2 Deoxy means "without oxygen" on the number 2 carbon atom.
44
What is the nitrogen base for?
To express the genetic information.
45
What are the two double ring of purines?
Adenine and Guanine
46
What are the two single ring of pyrimidines?
Thymine and Cytosine
47
What is a DNA?
DNA is deoxyribonucleic acid. It is made up of subunits called nucleotides, such as phosphate group, 2 deoxyribose, and Nitrogen base. Those three components are linked together with a covalent bond.
48
What is codon and anti-codon?
Codon is the three bases on a mRNA molecule that code for a specific amino acid. Anticodon is the three bases on a tRNA molecule that matches up with the codons on the mRNA (complementary to them).
49
What does PCR stands for and what is the function?
Polymerase Chain Reacion. Is a simple method for making unlimited copies of DNA fragments. It is used for research, medical diagnostic procedures, and forensics.
50
What is DNA Helicase?
It unwinds the DNA.
51
What does SSBP stands for and what is its function?
Single stranded binding proteins. It holds two strands apart.
52
What is DNA Polymerase?
It synthesizes the two daughter strands (nucleotide strands) from two parental strands (template).
53
What is DNA exonuclease?
It removes any mistaken pairs.
54
What is DNA ligase?
Seals any gaps and joins the two strands together.
55
What is a mRNA?
The cells genetic plan contained in DNA is transcribed into complimentary base sequence.
56
What is a gene? What is the average of a gene?
It is the region of a DNA that serves as a template for synthesis of mRNA. A gene averages about 1,000 base pairs.
57
What is an RNA polymerase?
The enzyme that synthesizes mRNA. It binds to a specific promoter sites on one of the strands of DNA to begin transcription.
58
DNA Sequence: ATG CCG GAC
| Find another DNA Sequence and find the mRNA sequence.
DNA Sequence: TAC GGC CTG
| mRNA Sequence: AUG CCG GAC
59
How many amino acids are produced by one gene?
1 gene produces about 1000 nuc's per 3 nuc's (333 amino acids).
60
How many proteins can E. Coli make?
4,000 protein/polypetides.
61
What happens after transcription?
The coded information in mRNA is translated into an enzymes (proteins).
62
Where does the translation takes place?
On the ribosome. (Ribosome is made of rRNA and proteins.)
63
What is the tRNA?
It is bivalent with a so-called "clover-leaf" shape. It picks up and transfers one of 20 amino acids to the ribosome. It corresponds to an anti-codon. The anticodon of tRNA hydrogen bonds to the codon of mRNA.
64
What is Streptomycin?
It blocks the assembly of the ribosome during initiation. 1st drug to be used for tuberculosis.
65
What is Chloramphenicol?
It is a broad spectrum antibiotic, toxic for the host, blocks peptide bond formation during elongation.
66
What is Tetracycline?
It is a broad spectrum antibiotic, blocks the 2nd site on the ribosome during elongation.
67
What is Erythromycin?
Used if allergic to penicillin. It blocks translocase during elongation.
68
What is Gentamycin?
It binds to small subunits (30S ribosome). Used to treat "large" Gram Negative (-) infections.
69
What are the methods of Gene Regulation?
Gene repression and gene induction.
70
What is a Gene Repression?
A response to overabundance of an end-product in the metabolic pathway. It acts as a regulatory protein being formed where there is an excess gene product. The repressor then blocks RNA polymerase (transcription) from binding to the DNA.
71
What does Gene Induction do?
In the presence of lactose (milk sugar), an inducer, called allolactose, binds to the repressor molecule on the operon there by activating a series of genes that catabolize lactose.
72
What happens during the absence of allolactose?
The inducer of the repressor molecule keeps the lac operon off. This is done by binding on the operator site and preventing transcription.
73
What happen when the allolactose is presented?
Qhen allolactose is presented, the repressor is inactivated and cannot bind to the operator. All lactose digesting enzymes in the metabolic path are transcribed. (Z, Y, and A)
74
What functions of epigenetic?
Epigenetic factors, such as methyl function group (CH3), helps determine expression of the human phenotype. Human gene expression is more complex than bacteria.
75
What are some of the gene expression?
individual microbiome, intra-uterine life, nutrition, toxins, stress, and emotions.
76
What are the 5 ways of creating Genetic Diversity in Bacteria?
Mutations, Transformation, Conjugation, Transposition, and Transduction.
77
What is mutation?
Mutation are changes in the nucleotide sequence usually due to an error in DNA replication. It occur naturally at low levels (spontaneous mutation). Mutation may be increased in rate with chemical agents called mutagens, or by physical agents like radiation.
78
If most mutation are neutral, what will the result be?
There will be no effect on the enzyme.
79
If some mutation result in less active enzyme, less often an inactive non-functional enzyme, what will happen?
The effects will not be passed on.
80
If there are very few mutation that improves enzymes function, what will happen?
Those mutation will be passed on.
81
What is point mutation?
It is a natural spontaneous mutation that involves change in one single base nucleotide of the DNA.
82
What is silent mutation?
It occurs in the 3rd base of the position. No change in amino acids (a.a.)/enzymes.
83
What is missense mutation?
Single base mutation in the 1st or 2nd base position. Changes amino acids.
84
What is nonsens mutation?
Single base substitution that results in a stop codon. Result is incomplete defective enzymes.
85
What happens during Transformation?
The passage of homologous DNA from a dead donor cell to a living recipient cell. It occurs in Streptococcus pneumoniae. When S. pneumo dies, the DNA can be absorbed by another living S. pneumo. It will recombined into the chromosome.
86
Transformation is discovered by who and what year?
Discovered by Frederick Griffith in 1929.
87
What is conjugation?
It is a mating process between a donor F+ and F- recipient.
88
What are transposons?
Chunk of DNA that randomly excise and relocate in certain areas of the nucleus or nucleoid.
89
Transposon is discovered by who?
It where discovered in 1950 by Barbara McClintock in corns.
90
What is the function of transposon?
To control elements in genomic orgranization/biological evolution.
91
What is Transduction?
It transfers genetic material from one donor bacteria to many recipient bacteria via a transducing agent (virus).
92
What are bacterial viruses are called and what is the symbol for it?
Bacterial viruses are called bacteriophage. The symbol for it is ø.
93
Transduction is founded by who?
It would founded by Zinder and Lederberg in 1952.
94
What is the Lytic Cycle?
T2ø infects E. coli by killing the host cell, and synthesizing 2,000 copies of itself in the cell.
95
What is the Lysogenic Cycle?
Lambda Phage integrates into a specific point in the nucleoid of the bacteria and remains dormant.
96
What does the T2ø do?
It randomly packages bacterial DNA in a few defective phage. Then the T2ø def. infects another E. coli.
97
What happens to the genetic information in generalized transduction?
Genetic information may recombine into the host cell without lysis. New genetic information tansduced from one bacteria to another.
98
What happens to the Lambda Phage?
They replicate and passed to all daughter cells until the bacteria is under environmental stress from lack of nutrients.
99
What happens during under stress of Lambda Phage?
Lambda Phage excise from the E. coli nucleoid and enters he lytic cycle taking one adjacent gene for galactose metabolism.
100
What happens to Lambda Phage Galactose?
It makes 2000 copies of itself including the gal gene and infects the E. coli. Then it integrates into the nucleoid of newly infected E. coli, then confer galactose metabolism.
101
What is STEM Cell Research's other name?
Regenerative tissue research.
102
What do 99% of biotechnologist want to do research on STEM cells for?
For therapeutic cloning, not for reproductive clonging.
103
Stem cells have how much capacity to developed cell types that can make up human bodies?
About 220 different types of cells.
104
What is the goal of STEM cell research?
To create specific tissues or organs in people who needs transplant, or for tissue regeneration, such as alzheimer's, parkinson's, NIDDM, cancer, osteoporosis, heart failure, MS, and spinal cord injuries.
105
What are the Parthenogenesis derived steam cells?
Unfertilized eggs tricked into cell division without sperm.
106
What are Adult Stem cells?
It is from bone marrow that are currently used to treat leukemia and other blood cell cancers, but it is offer a limited range of tissue differentiation. Adult stem cell to embryonic cells back to specialized cells and tissues.
107
What is the umbilical cord cells?
it is coaxed into specialized cells and tissues.
108
What is amniotic cells?
Coaxed into specialized cells and tissues.
109
What is Animal Stem cells?
Coaxed into specialized cells and tissues. Genetically modified to eliminate molecules that would cause transplant rejection.
110
What happens to frozen embryos from in vitro fertilization if not used?
It will be destroyed if not used. 64 cells lines are approved for federal funding.
111
What happens to fresh embryos from IVF?
It will be frozen if it is not in used.
112
What happens to fresh embryos from aborted fetus?
It will be destroyed if it is not in used.
113
What is used to depress the immunity and why?
Cyclosporin. Because any organ could be rejected by the immune system if using the first 3 sources of the ten stem cell.
114
What is the importance of the first three of the Ten Stem Cell Sources?
The first three can be developed into virtually any organ that is needed, but it could be rejected by the immune system. These three are the subject of moral controversy because of fertilization. Theorictically, the embryos can be planted into the uterus for cloning.
115
Why are the last 7 stem cell sources are less controversial? Will the last 7 stem cell source will have transplantation rejection?
It can never be used to implant into a human uterus for human cloing. No, the last 7 stem cell source will not have transplantation rejection.
116
Steps of T2ø.
1) Attachment
2) Penetration
3) Biosynthesize
a) DNA replication
b) Transcription
c) Translation
4) Assembly
5) Packaging
6) Bursting
117
Steps of Lambda Phage
1) Express one gene
2) Insertion sequence
3) Always integrates a particular gene
4) Cuts only next to a gene that has galactose
5) Excise zygotic induction
118
What is translation?
Translation occurs in the cytoplasm where the ribosome is located. It has intiation, elongation, and termination. It is a step in protein biosynthesis where the genetic code is carried by mRNA which is decoded to produced the specific of amino acids in a polypeptide chain. Translation follows transcripton in which the DNA sequence is copied or transcribed into an mRNA.
119
What is transcription?
A process that involves transcribing genetic information from the DNA to RNA. The transcribed DNA message, or RNA transcript, is used to produce proteins.
120
What is translocase?
An enzyme that assists in moving another molecule, usually across a membrane.
