Control of Gene Expression and Mutations (8.3 - 8.5)

Question 1

What is horizontal gene transfer?

Answer 1

Any transfer of DNA that results in organisms acquiring new genes that did not come from parent organisms

Question 2

What is Conjugation? Is Conjugation direct or indirect? List an example of it.

Answer 2

Mode of genetic exchange in which a plasmid or other genetic material is transferred by a donor to a recipient cell via direct connection.

Direct ;

The F+ cell has a plasmid and builds a bridge connecting it to the F- cell. It then transfers its plasmid to the F- cell so that it become F+.

Question 3

What type of plasmids can be transferred through conjugation?

Answer 3

Resistance (R) Plasmids

Question 4

What is Transformation? Is it direct or indirect? List an example of it

Answer 4

Transformation is when chromosome fragments from a lysed cell are accepted by a COMPETENT cell. ; Indirect .

There is none, it requires no special appendages because its non-specific (meaning every bacterial cell does it differently)

Question 5

What is Transduction? Is it direct or indirect? List an example.

Answer 5

Transduction is using viruses to move DNA (bacteriophages- viruses that enter bacteria) ; indirect

when a bacteriophage enters Cell A and replicates with part of the bacterias DNA then the cell lyses, releasing those phages which then inject their DNA into Cell B. Cell B survives because the virus is now inactive and just uses the DNA.

Question 6

What are Transpoons and how do they move?

Answer 6

• Genes that can shift from one part of a genome to another or one cell to another.
• Can be transferred from a chromosome to a plasmid or vice versa
• some replicate themselves before jumping to the next location and some simply move

Question 7

What are Transpoons involved in?

Answer 7

• Changes in traits such as colony morphology and pigmentation
• Replacement of damaged DNA
• Intermicrobial transfer of drug resistance ( in bacteria)

Question 8

What is considered a mutation?

Answer 8

Any change in the nucleotide sequence in the genome.

Question 9

What is spontaneous mutation?

Answer 9

A random change in the DNA arising from errors in replication

Question 10

What is induced mutation?

Answer 10

Mutation due to physical or chemical agents that disrupt DNA (Radiation: UV light, x RAYS) and Chemicals like nitrous acid

Question 11

What are the five categories of mutations?

Answer 11

Point 
Missense 
Nonsense 
Silent 
Frameshift

Question 12

What is a point mutation?

Answer 12

An addition, deletion or substitution of a single base

Question 13

What is a missense mutation?

Answer 13

Any change in the code that leads to the placement of a different amino acid

Question 14

What is a nonsense mutation?

Answer 14

Changes a normal mutation into a stop codon.

Question 15

What is a silent mutation?

Answer 15

Doesnt usually change the wobble, alters a base but does not change the amino acid, has no effect.

Question 16

What is a back-mutation?

Answer 16

When a gene that has undergone mutation reverses back to its original base composition.

Question 17

What is a frameshift mutation?

Answer 17

changes the reading Frame of mRNA because codons are red in sets of 3. usually results in a nonfunctional protein.

Question 18

Explain UV/DNA photolyase reparation.

Answer 18

DNA photolyase repairs damage done by UV rays. because UV light damage is so common, bacteria created DNA photolyase

Question 19

What is excision repair?

Answer 19

Enzymes break the bonds between bases and sugar-phosphate strand at the site of error, a different enzyme removes the defective base and DNA poly. 1 and ligase fill it.

Question 20

What is the significance of Single nucleotide polymorphisms (SNPs) ?

Answer 20

Only a single nucleotide is altered and it is passed on genetically.

Identification is critical to medicine because its within a persons genetic makeup.

Ex: thrombophilla (a blood-clotting disorder)