Bacterial Genetics

Question 1

Genome

Answer 1

Genetic information of a cell

Question 2

Chromosome

Answer 2

Bacteria usually only have one, and maybe a plasmid (extrachromosomal genetic element)

Question 3

Nucleotide

Answer 3

Each on containsa pentose sugar, a phosphate, and one of five nitrogenous bases.

Question 4

DNA

Answer 4

present in a double-stranded form, wrapped around each other to form a double helix.

Each chromosome contains two strands.

Question 5

RNA

Answer 5

All (few exceptions) are single stranded. It can fold itself with complementary base pairing, called Secondary structure.

Three types:

1. Messenger RNA (mRNA)
   
   1. contians the genetic information that is transcribed from the DNA.
2. Transfer RNA (tRNA)
   
   1. translate genetic information from nucleotides to amino acids in protein synthesis
3. Ribosomal RNA (rRNA)
   
   1. Important components of ribosomes, the protein synthesizing system of the cell.

Question 6

Effect of Temperature on DNA structure

Answer 6

When temp is increased, hydrogen bonds break and the wwo strands will separate. (Denaturation)

If the temp is allowed to cool slowly, the strands will come together (Annealing)

Hybridization is the formation of a double stranded DNA by complementray base pairing of two single stranded nucleic acids

Question 7

Topoisomerases

Answer 7

These enzymes can cause DNA to super coil or relax.

Type 1 topoisomerases: Cleave only one strand of a double helix. Remove or unwind super coiling

Type 2 Topoisomerases: cleave both strands of the DNA, Induce supercoiling. DNA glycase

Question 8

Plasmids

Answer 8

Small molecules of DNA that replicate independent of hte chromosome.

Typically carries genes that are not essential for normal metabolism, growth, or cell division. Genes that are carried can confer advantages to the cells.

Question 9

Transposable Genetic Elements

Answer 9

Segments of DNA that can move from one site to another site on the same chromosome or to a different chromosome.

Transposition: gene moves from one place to another place

Transposable Elements: transposition is linked to the presence of specific genetic elements

Question 10

Bacteriophage (Bacterial Virus)

Answer 10

Viruses that specifically infect bacteria. Obligate intracellylar parasites.

Phages multiply by one of two alternative mechanisms:

Lytic Cycle

Lysogenic Cycle.

Question 11

Mutation

Answer 11

Change in the nucleotide base sequence ina genome that is inherited. Can lead to good or bad changes in the organism.

Can be natural or through genetic recombination.

Question 12

Auxotroph

Answer 12

mutant that lacks the ability to synthesize an essential nutriernt and therefore requires thea ddition of it or its precursor to the growth medium.

Question 13

Spontaneous Mutation

Answer 13

occurs as a result of exposure to natural factors (cosmic rays, oxygen radicals) that alter the structure of bases in the DNA.

Most common occurs during replication as a result of errors in the pairing of bases.

Question 14

Pointshift Mutation

Answer 14

change in a single base or nucleotide. Phenotypic change that results depend on where the mutation occurs

Question 15

Frameshift Mutation

Answer 15

Insertions or deletions of a single or multiple base pairds that later how the DNA is read.

They can result in loss of function.

Question 16

Transformation

Answer 16

DNA released from one cell is taken up by another cell.

Process by which free DNA is incorporated into a recipient cell and brings about genetic change.

Cells that are able to take up and utilize free DNA are called Competent.

Question 17

Transduction

Answer 17

Transfer of DNA from one to another cell is mediated by a bacteriophage.

Question 18

Conjugation

Answer 18

Tranfer takes place because of Cell to Cell contact, mediated by a plasmid passing through a Sex Pili.