(exam 1) chapter 8 microbial genetics

Question 1

what is genetics?

Answer 1

the study of genes, how they carry information, how information is expressed, and how genes are replicated

Question 2

what are chromosomes?

Answer 2

contain DNA that carries hereditary information; contain genes

Question 3

what do we know about bacterial chromosomes?

Answer 3

circular, has associated proteins, typically one

Question 4

what do we know about eukaryotic chromosomes?

Answer 4

linear, wrapped around histones, arranged in pairs (number varies with organism)

Question 5

what are Genes?

Answer 5

segments of DNA that encode functional products, usually proteins

Question 6

what is the Genome?

Answer 6

all the genetic information in a cell

Question 7

what is Genomics?

Answer 7

new field of sequencing and molecular characterization of genomes

Question 8

what does genetic code describe?

Answer 8

how the four nucleotide bases (A,T,G,C) are read and converted by cellular machinery into amino acids

Question 9

what central dogma of molecular biology?

Answer 9

DNA to RNA to Proteins

Question 10

what is genotype?

Answer 10

the genetic makeup of an organism

Question 11

what is phenotype?

Answer 11

expression of the genes

Question 12

what is vertical gene transfer?

Answer 12

occurs mainly in eukaryotes; flow of genetic information from one generation to the next
(Occurs during replication)

Question 13

what is Genetic recombination?

Answer 13

exchange of genes between two DNA molecules; creates genetic diversity

Question 14

what is crossing over?

Answer 14

Two chromosomes break and rejoin, resulting in the insertion of foreign DNA into the chromosome

Question 15

when does crossing over occur in eukaryotes?

Answer 15

occurs during production of reproductive cells

Vertical gene transfer

Question 16

how does recombination work in prokaryotes (vertical gene transfer?)

Answer 16

vertical gene transfer to offspring

Question 17

how does recombination work in prokaryotes (horizontal gene transfer)?

Answer 17

horizontal gene transfer is transfer of genes between cells of the same generation

Question 18

what are four methods of horizontal gene transfer?

Answer 18

1) mobile genetic elements
2) transformation
3) conjugation
4) transduction

Question 19

what are two types of mobile genetic elements?

Answer 19

1) plasmids

2) transposons

Question 20

what is mobile genetic elements?

Answer 20

move from one chromosome to another or from one cell to another

Question 21

what are plasmids?

Answer 21

Self-replicating circular pieces of DNA
(1 to 5% the size of a bacterial chromosome)
Often code for proteins that enhance the pathogenicity of a bacterium

Question 22

what are three types of plasmids?

Answer 22

1) conjugative plasmids
2) dissimilation plasmids
3) Resistance factors (R factors)

Question 23

what are conjugative plasmids?

Answer 23

carries genes for sex pili and transfer of the plasmid

Question 24

what are dissimilation plasmids?

Answer 24

encode enzymes for the catabolism of unusual compounds (when trying to eat something unusual)

Question 25

what are resistance factors (R factors) plasmids?

Answer 25

encode antibiotic resistance

Question 26

what are transposons?

Answer 26

’ jumping genes that move on their own’ segments of DNA that can move from one region of DNA to another; Contain insertion sequences (IS) that code for transposase that cuts and reseals DNA; Complex transposons carry other genes (e.g., in antibiotic resistance) - humans have them but they are inhibited in us

Question 27

what is transformation?

Answer 27

genes transferred from one bacterium to another as “naked” DNA; Cells must be “competent” meaning that the cell walls are altered for passage of large DNA molecules

Question 28

what is one pit fall of transformation?

Answer 28

because the cells are altered so the cell wall becomes semi permeable this makes the cells susceptible to damage because they are very fragile in this state

Question 29

what is conjugation?

Answer 29

genetic material transferred from one bacterium to another; Requires cell-to-cell contact via sex pili

Question 30

what is specific about gram negative cells that use conjugation?

Answer 30

gram negative cells can be a little farther away because they use a sex pilus

Question 31

what is specific about gram positive cells that use conjugation?

Answer 31

gram positive cells must be very close together because they use a mating bridge

Question 32

what is transduction?

Answer 32

DNA is transferred from a donor cell to a recipient via a bacteriophage; relies completely on the bacteriophage

Question 33

what do mutations and recombination create?

Answer 33

cell diversity

Question 34

what is diversity the raw material for?

Answer 34

Evolution!

Question 35

how does natural selection act on populations of organisms?

Answer 35

to ensure the survival of organisms fit for a particular environment (fit organisms survive and reproduce whereas nonfit organisms die off)