Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Genetics I > Horizontal Gene Transfer in Prokaryotes and Recombinant DNA Technology > Flashcards

Horizontal Gene Transfer in Prokaryotes and Recombinant DNA Technology Flashcards

(57 cards)

Start Studying
1
Q

What are the 3 types of gene transfer in bacteria?

A

Transformation. Conjugation. Transduction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is transformation?

A

Uptake of DNA from the environment and incorporation into the bacterial genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When was transformation discovered and in wat?

A
  1. In Streptococcus pneumoniae.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe transformation in Streptococcus pneumoniae

A
  1. Two strains S and R - S is lethal to mice and R is not
  2. Heat killed S strain did not kill mice
  3. Heat killed S mixed with R did kill the mice
  4. R had characteristics of S
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What were other experiments involving transformation in Streptococcus pneumoniae?

A

Destroyed different components of the S strain

Only when DNA destroyed was the generation of S strains prevented

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant when saying some bacteria are naturally competent? (transformation)

A

Can actively take up DNA from the environmen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does transformation work?

A

Have special pores and complexes located in their cell wall. During DNA entry one is degraded and the other is incorporated into the genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What bacteria needs to be made competent in order to allow for artificial transformation?

A

E.coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is conjugation?

A

Direct transfer of either plasmid or genomic DNA from one bacterium to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the experiment with E.coli to show conjugation.

A

Strain A = met-,bio-,thr+,leu+,thi+
Strain B=met+,bio+,thr-,leu-,thi-
Neither strain could grown on minimal medium but when mixed and incubated formed colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How was cross feeding ruled out during the E.col experiment to show conjugation?

A

Grew strains separated by a filter. Substances could pass but bacteria could not. Didn’t grow need cell to cell contact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does unidirectional mean?

A

One donor and on recipient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe unidirectional in relation to conjugation?

A

Some strains could only receive but not donate but would acquire the ability to donate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How was the ability to donate acquire?

A

Imposed by ‘fertility factor’ (F)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is F positive?

A

Carries F and can donate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is F negative?

A

Lacks F and can’t donate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the purpose of F in conjugation?

A

Directs the synthesis of pili that connects to another cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is transduction?

A

Transfer of genetic material between bacterial cells by viruses called bacteriophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe how transduction was discovered

A
  • Used salmonella typhimurium
  • U tube, direct contact between 2 autotrophic strains prevented by a membrane
  • gained prototrophic colonies on one side of the tube
  • genetic exchange was due to the infection of the bacteria by a phage called P22
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does transduction occur?

A

During lutic phases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the mechanism of transduction?

A
  • Phage infects bacteria
  • Genetic material of phage replicated
  • Phage proteins produced
  • Host DNA degraded
  • Phage carries some of the host DNA
  • Transferred to another bacteria when it is infected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is generalized transduction?

A

Any part of the genome can be transferred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is specialised transduction?

Study These Flashcards
A

Only transfer specific genes

24
Q

How is DNA cut?

Study These Flashcards
A

With restriction enzymes

25
Why are restriction enzymes produced?
By bacteria as a defense mechanism against bacteriophage
26
What sequences do restriction enzymes recognise?
Specific palindromic DNA sequences
27
What are cohesive ends?
Sticky ends. Single stranded overhangs (can get 5' or 3' overhangs)
28
What are blunt ends?
Cut DNA in the same place
29
Describe hybridization of DNA
- Cohesive ends - Cut with the same restriction enzymes = same single strand overhangs - Complemenatary base pairing
30
How are nicks joined?
- DNA ligase | - Catalyses the formation of a phosphodiester bond between nucleotides
31
What are cloning vectors?
DNA molecules that can hold pieces of DNA of interest for replication in an norganism
32
What are the most common cloning vectors?
Modified bacterial plasmids - not part of the bacterial chromosome
33
How can cloning vectors be amplified?
Using E.coli
34
Used pUC18 as an example of clonning vectors.
- Bacterial origin of replication - Selectable marker usually eg antibiotic resistance gene - Multiple cloning site → referred to as a polylinker → lots of restriction sites/recognition sites - Multiple cloning site is inside a lacZ gene
35
What does the multiple cloning site allow us to do?
Cut the plasmid and insert the gene of interest
36
How does the plasmid get into the E.coli?
Artificial transformation (only a few plasmid will be taken up)
37
What are the different possibilities that the cells could contain?
No plasmid. Plasmid that has re-litigated with itself. Plasmid with gene of interest.
38
How do you find out which cells contain a plasmid?
Plate on agar with antibiotic. Cells without the plasmid will be killed as they don't have the antibiotic resistance gene.
39
How does blue/white selection?
- Without inserted gene lacZ is functional - Codes for enzyme B galactosdiase - Add X gal - No inserted gene = ill produce a blue substance (oxidation_ - Inserted gene = the reaction won't take place
40
What is PCR?
Polymerase Chain Reaction - amplifies DNA
41
What are the 3 processes of PCR?
Denaturation, annealing, extension.
42
Describe denaturation.
Heated to 95 degrees - interferes with binding of complmentary pairs. Separated inot single strands
43
Describe Annealing
1. Primers bind to target sequence | 2. Binding of primares requires cooler temperatures (55 - 65 degrees)
44
What are primers?
Small pieces of DNA that are complementary to parts of the target sequence
45
Describe Extension
DNA polymerase uses the primers as a starting point to synthesise a new strand of DNA - occurs at 72 degrees
46
What happens when you repeat these steps?
Doubles each time
47
What DNA polymerase do we use?
Heat stable from the bacterium Thermus aquaticus - lives in hot springs.
48
What is added at the beginning of PCR?
DNA template. dNTPs. DNA primers. Taq polymerase. Buffer solution.
49
What is a thermocycler?
Can quickly heat up and cool down. Cycle between different temperatures.
50
How do we facilitate the insertion of PCR fragments into bacterial plasmid?
Use PCR primers which don't only bind but also contain restriction site in their 5' end. Produce PCR products with cohesive ends.
51
What is reverse transcription PCR?
- If you want eukaryotic protein need to remove introns - Produce cDNA - Use reverse transcriptase - Needs a primer
52
What is cDNA?
Complementary to mRNA and only contains the sequence of exons not introns
53
What is reverse transcriptase?
Viral enzyme. Uses RNA as a template to synthesise DNA
54
What is DNA sequencing?
Determination of the nucleotide sequence of a piece of DNA.
55
What is Sanger Sequencing?
- Single stranded DNA you want to sequence - Mixed with DNA primer which binds upstream, DNA polymerase and dNTPS - Complementary strand is synthesised - Small amounts of fluorescently labelled ddNTP are added → they don’t carry 3’ OH group and terminate DNA synthesis when they get incorporated
56
What is the result of Sanger sequencing?
Lots of DNA fragments of different lengths with fluorescent ends to tell you which was the last nucleotide incorporated
57
How can you separate the DNA fragments?
Gel electrophoresis

Genetics I (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions