MICRO > Genetics part 2 > Flashcards

Genetics part 2 Flashcards

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1
Q

What do structural genes code for?

A

Specific proteins

Structural genes are essential for various biological functions.

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2
Q

What is the first step in protein synthesis?

A

Transcription of a gene into mRNA

This process involves creating a sequence of nucleotide bases.

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3
Q

What is the role of mRNA in protein synthesis?

A

It is translated into an amino acid sequence of a protein

The sequence of amino acids determines the protein’s characteristics.

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4
Q

What initiates DNA replication?

A

Helicase unwinds a segment of DNA

This process opens up the hydrogen bonds between complementary strands.

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5
Q

What is the function of DNA polymerase during replication?

A

Adds new nucleotides to the free 3’ end of a nucleotide strand

It is crucial for synthesizing new DNA strands.

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6
Q

What is a short RNA primer’s role in DNA replication?

A

Provides a free 3’ starting point

It is essential for the initiation of DNA synthesis.

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7
Q

What are the two types of strands involved in DNA replication?

A

Leading and lagging strands

These strands are synthesized differently during replication.

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8
Q

What is the composition of the 70S ribosome?

A

Two sites for tRNA amino acids: the ‘P’ site and the ‘A’ site

The 80S ribosome has three sites.

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9
Q

Operons

A
  • Only found in bacteria and archaea
  • Consist of a coordinated set of genes regulated as a single unit
  • can be inducible or repressible

This regulation saves energy for the cell.

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10
Q

What is a catabolic operon?

A
  • Induced by the substrate of the enzyme(s) for which the structural genes code
  • Only produce the enzyme when the substrate (nutrient) is present

It produces enzymes only when the substrate is present.

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11
Q

What defines a repressible operon?

A

Anabolic enzymes turned off by the product synthesized by the enzyme

This mechanism helps regulate metabolic pathways.

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12
Q

What is conjugation in bacteria?

A

Direct transfer of DNA between living donor and recipient cells

It involves a bridge formed between cells.

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13
Q

what does the donor cell in conjugation contain?

A
  • pilus
  • fertility plasmid
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14
Q

Commonly transferred genes in conjugation

A
  • drug resistance
  • resistance to metals
  • toxin production
  • enzymes
  • adherence molecules
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15
Q

Transformation

A
  • Free donor DNA (fragments)
  • Live, competent recipient cell
  • indirect transfer

Requires no direct contact between donor and recipient cells.

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16
Q

Commonly transferred genes in transformation?

A

polysaccharide capsule

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17
Q

What is transduction?

A

Indirect transfer of bacterial DNA through a bacteriophage

It involves indirect transfer and a lysed donor cell.

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18
Q

Transduction facts

A
  • donor is lysed bacterial cell
  • Defective bacteriophage is carrier of donor DNA
  • Live recipient cell of same species as donor
  • Indirect transfer
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19
Q

Commonly transferred genes in transduction?

A
  • Toxins
  • Enzymes for sugar fermentation
  • Drug resistance
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20
Q

What are transposons?

A

‘Jumping genes’ that can shift within the genome

They can also transfer between chromosomes and plasmids.

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21
Q

Transposons fun fact

A
  • Can be transferred from a chromosome to a plasmid, or vice verse; or from once cell to another in bacteria and some eukaryotes
  • Some replicate themselves before jumping to the next location and some simply move
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22
Q

Transposons are involved in:

A
  • changes in traits such as colony morphology, pigmentation and antigenic characteristics
  • replacement of damaged DNA
  • intermicrobial transfer of drug resistance (in bacteria)
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23
Q

mutation

A

any change to the nucleotide sequence in the genome

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24
Q

Mutations can involve …

A

the loss, addition, or rearrangement of base pairs

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25
When are mutations most noticeable?
when a genotypic change leads to a change in phenotype
26
Wild type
a microorganism that exhibits a natural non-mutated characteristic
27
Mutant strain shows variance in:
* morphology * nutritional characteristics * genetic control mechanisms * resistance to chemicals * temperature preference
28
Spontaneous mutation
a random change in the DNA arising from errors in replication
29
Induced mutation
results from exposures to known mutagens
30
What are mutagens?
physical or chemical agents that disrupt DNA such as: - Radiation (UV light, xrays) - Chemicals (Nitrous acid)
31
What is a point mutation?
Addition, deletion, or substitution of single bases ## Footnote This type of mutation can lead to significant changes in protein function.
32
What is a missense mutation?
Change in the code that leads to a different amino acid ## Footnote It can create faulty proteins or alter their function.
33
Missense mutation can ...
* create a faulty, nonfunctional protein * produce a protein that functions differently * cause no significant alteration
34
What is a nonsense mutation?
Changes a normal codon into a stop codon ## Footnote This usually results in a truncated, nonfunctional protein.
35
What is a silent mutation?
Alters a base but does not change the amino acid (has no effect)
36
What is a back-mutation
When a gene reverse back to its original base composition
37
What is a frameshift mutation?
* one or more bases are inserted or deleted * changes the reading frame of the mRNA * nearly always results in a nonfunctional protein ## Footnote It nearly always results in a nonfunctional protein.
38
Single nucleotide polymorphism
* Only a single nucleotide is altered * passed on genetically * identification is critical to personalized medicine (customized to a person's genetic makeup)
39
Thrombophilia
a point mutation in the gene for a clotting factor cause an arginine to become a glutamine
40
What is the role of DNA photolyase?
Repairs UV damage in DNA using visible light and light sensitive enzyme ## Footnote This repair mechanism works for a limited number of UV mutations.
41
UV damage repair
* successful only for a small number of UV mutations * cells cannot repair severe widespread damage and will die
42
What is excision repair?
Involves enzymes breaking bonds to remove defective bases and filling the gap with DNA polymerase I and ligase ## Footnote It fills gaps with DNA polymerase I and ligase.
43
What is the difference between spontaneous and induced mutations?
Spontaneous mutations arise from replication errors; induced mutations result from mutagens ## Footnote Mutagens can include radiation and chemicals.
44
What are restriction endonucleases?
recognize foreign DNA and break phospodiester bonds between adjacent nucleotides on both strands of DNA ## Footnote They are crucial for recombinant DNA technology.
45
What do restriction endonucleases protect?
Protects bacteria against incompatible DNA of bacteriophages or plasmids
46
What is the relationship between restriction endonucleases and recombinant DNA technology?
* Restriction endonucleases is necessary for recombinant DNA technology * Allow biotechnologists to cleave DNA at desired sites * Recognize and clip at palindromes
47
Palindromes
Sequences of DNA that are identical when read from the 5' to 3' direction on one strand and the 3' to 5' direction on the other strand like "RACE CAR"
48
Ligase
* seals sticky ends together * used in final splicing of genes into plasmids and chromosomes
49
Reverse transcriptase (RT)
* converts RNA into DNA to make cDNA * used in replication of the AIDS virus
50
Complementary DNA (cDNA)
* Made from messenger, transfer, ribosomal and other forms of RNA * used to synthesize eukaryotic genes from mRNA transcripts, free from introns
51
What is PCR?
A technique to rapidly increase DNA amounts in a sample ## Footnote It can amplify DNA from a few copies to billions within hours.
52
How sensitive is PCR?
sensitive enough to detect cancer from a single cell or diagnose an infection from a single gene copy
53
Primers in PCR
DNA strands 15 to 30 bases long, serve as landmarks for DNA amplification start
54
DNA polymerases from Thermophilic Bacteria in PCR
Taq polymerase remains active at elevated temperatures used in PCR
55
Thermal cycler in PCR
automatically performs cyclic temperature changed required for PCR
56
gel electrophoresis
* Produces DNA fragments of different lengths * Samples placed in agar gel and subjected to electrical current * Phosphate groups have a negative charge, causing DNA to move toward positive pole * Larger fragments migrate more slowly and vice versa * Position determined by staining the gel ## Footnote DNA moves toward the positive pole due to its negative charge.
57
Sequence maps
exact order for bases in a plasmid, chromosome or entire genome
58
Shotgun sequencing
Genome broken into fragments, separated through gel electrophoresis, inserted into plasmids and cloned, purified, sequenced, overlaps identified by computer, contigs put in order, editing for irregularities
59
High throughput sequencing
DNA fragmented and fitted with adaptors, sequences added to PCR machine, immobilized and copied, sequenced, aligned using software
60
Genomics
systematic study of an organism's genes and their functions
61
Proteomics
study of an organism's complement of proteins and functions mediated by the proteins
62
Metagenomics
study of all the genomes in a particular ecological niche
63
metabolomics
* study of the complete complement of small chemicals present in a cell at any given time * provides a snapshot of the physiological state of the cell and the end products of its metabolism
64
What is recombinant DNA technology?
* Deliberately removing and combining genetic material from different organisms * bacteria genetically engineered to mass-produce hormones, enzymes vaccines ## Footnote It allows for the mass production of hormones and vaccines.
65
Synthetic biology
creating new biological molecules and organisms from scratch
66
Craig Venter
created a self-replicating bacterial cell from DNA nucleotides in 2010
67
Synthetic biology has the potential to revolutionize medical science through:
creation of precise chemicals, customizes immune components, biological molecules targeting cancerous cells or pathogens
68
Gene therapy
replacing faulty gene responsible for disease with healthy gene
69
What is CRISPR?
A technology that allows scientists to cut DNA at specific locations ## Footnote It is used for gene editing and therapeutic applications.
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