Asexual Prokaryotes

Question 1

Mutations

Answer 1

Permanent change in the DNA sequence of an organism.

Question 2

Mutant

Answer 2

Resulting organism of a mutation may have a recognizable change in phenotype compared to wild type

Question 3

Wild type

Answer 3

Phenotype most commonly observed in nature.

Question 4

Point mutation

Answer 4

Affects a single base and most commonly occurs when one base is substituted or replaced by another.

Question 5

Insertion

Answer 5

Addition of one or more bases in mutation

Question 6

Deletion

Answer 6

Removal of one or more bases in mutations

Question 7

Silent mutation

Answer 7

Sequence change having no effect on the proteins structure.

Question 8

Missense mutations

Answer 8

Results in a different amino acid being incorporated into the resulting polypeptide. The effect depends on how chemically different the new amino acid is from the wild type amino acid. Location of the changed amino acid in the protein is also important.

Question 9

Conditional mutations

Answer 9

Effects of missense mutations may be only apparent under certain environmental conditions.

Question 10

Nonsense mutations

Answer 10

Point mutation that converts to a codon encoding an amino acid (sense codon) into a stop codon (nonsense codon). Result in synthesis of proteins that are shorter than the wild type and typically not functional.

Question 11

Frameshift mutations

Answer 11

Causes by insertions or deletions of a number of nucleotides that aren’t a multiple of 3 are problematic because a shift in the reading frame results. Can change every amino acid after the point of mutation. Always nonfunctional

Question 12

Spontaneous mutations

Answer 12

Caused by mistakes in the process of DNA replication

Question 13

Induced mutations

Answer 13

Caused by exposure to mutagens which are various types of chemical agents or radiation

Question 14

Carcinogens

Answer 14

Mutagen agents that cause cancer

Question 15

Nucleoside analogs

Answer 15

Chemicals structurally similar to normal nucleotide bases and can be incorporated into DMA during replications.

Question 16

Intercalating agents

Answer 16

These molecules slide between stacked nitrogenous bases of the DNA double helix, distorting the molecules and creating atypical spacing between nucleotide base pairs. As a result, In DNA replication, DNA polymerase may have insertion or deletion.

Question 17

Strong ionizing radiation

Answer 17

Like x rays and gamma rays can cause single and double stranded breaks in the DNA backbone through formation of hydroxyl radicals or radiation exposure. Can also modify bases
Used to kill microbes to sterilize medical devices and food.

Question 18

Nonionizing radiation

Answer 18

Like UV light can induce dimer formation between 2 adjacent pyramidine bases, commonly 2 thymines with a nucleotide strand.

Question 19

Thymine dimer

Answer 19

During formation the 2 adjacent thymine become covalently linked and if left I repaired both DNA replication and transcription are stalled at this point. DNA polymerase may proceed and replicate the dimer incorrectly, potentially leading to frameshift or point mutations.

Question 20

Proofreading

Answer 20

Dna polymerase reads the newly added base ensuring that it’s complimentary to the corresponding base in the template strand before adding the next one. if an incorrect base has been added, the enzyme makes a cut to relax the wrong nucleotide and a new base is added.

Question 21

Mismatch repair

Answer 21

A mechanism where enzymes recognize the incorrectly added nucleotide, excise it and replace it with the correct base.

Question 22

Nucleotide excision repair

Answer 22

Enzymes remove the pyramidine dimer and replace it with the correct nucleotide

Question 23

Direct repair

Answer 23

Of thymine dimers occurs through the
Process of photoreactivation in the presence of visible light.

Question 24

Replica plating

Answer 24

Technique used to identify bacterial mutants used to identify nutritional mutants called auxotrophs

Question 25

Ames test

Answer 25

An inexpensive method that uses auxotrophic bacteria to measure mutagenicity of a chemical compound. Mutagenicity is an indicator of carcinogenic potential.

Question 26

Vertical gene transfer

Answer 26

The transmission of genetic info. From generation to generation. Main mode of transmission of genetic info in all cells.

Question 27

Horizontal gene transfer in prokaryote occur by what 3 primary mechanisms

Answer 27

1) transformation- naked DNA is taken up from the environment
2) transduction- genes are transferred between cells in a virus
3)conjugation- use of a hollow tube called a conjugation polis to transfer genes between cells.

Question 28

Transformation

Answer 28

Prokaryote takes up a naked DNA found in its environment and that is derived from other cells that have lysed on death and released their contents including their genome into the environment

Question 29

Recombinant DNA

Answer 29

Molecule of DNA that contains fragments of DNA from different organism

Question 30

Transduction

Answer 30

Viruses that infect bacteria may also move short pieces of chromosomal DNA from one bacterium to another

Question 31

Conjugation

Answer 31

DNA is directly transferred from one prokaryote to another by means of a conjugation pilus, which brings organisms into contact with one another.

Question 32

R plasmids

Answer 32

Genes encoding proteins that make a bacterial cell resistant to a particular antibiotic are encoded on this plasmid

Question 33

Transposons

Answer 33

“Jumping genes” are molecules of DNA that include special inverted repeat sequences at their ends and a gene encoding the enzyme transposase

Question 34

Transposition

Answer 34

Transposons allow the entire sequence to independently excise from one location in a DNA molecule and integrate into the DNA elsewhere through the process. “Copy and paste” or “cut and paste”. They have the ability to introduce genetic diversity.