Chapter 7- Microbial Genetics Flashcards
The genetic code is ______. This basically means that the structure of DNA is similar in all organisms.
The genetic code is universal. This basically means that the structure of DNA is similar in all organisms.
The chromosomes in each microbe are found in a ______ ____ in the cell. The chromosomes are not paired but instead are ______ and are usually circular in appearance. Frequently the microbe will have a _______ which is a small DNA molecule that _______ independently of the other chromosomes often carrying information required for replication.
The chromosomes in each microbe are found in a nucleoid region in the cell. The chromosomes are not paired but instead are HAPLOID and are usually circular in appearance. Frequently the microbe will have a PLASMID which is a small DNA molecule that replicates independently of the other chromosomes often carrying information required for replication.
Plasmid definition
a small DNA molecule that replicates independently of the other chromosomes often carrying information required for replication
4 different types of plasmids
Fertility
Resistance
Bacteriocen
Virulence
Fertility
instructions for conjugation
Resistance
antibiotic resistance
Bacteriocin
kills competitors
Virulence
enzymes/toxins that enable pathogenicity
Plasmids do not ________________
Plasmids do not control normal metabolism
Bacteria has a _____ _____ copy
single chromosome
Recall there are 3 steps involved in transcription:
- Initiation
- Elongation
- Termination
Difference between eukaryotes and prokaryotes
The ribosome in a eukaryote is 70S, in a prokaryote it’s 80S
Eukaryotes have 46 chromosomes and are diploids while prokaryotes have 23 chromosomes and are haploids. Bacteria has one chromosome.
The genes that are transcribed often are found as ________ in bacteria.
The genes that are transcribed often are found as OPERONS in bacteria.
Operons are composed of a
a Promoter, a series of genes, and an adjacent regulatory element called an operator.
The operator is important in determining when the operon is ______ ______ ______
The operator is important in determining when the operon is actively producing proteins
In essence, the bacteria are capable of turning genes off and on in response to changes in the environment. Some of the operons are turned on (_______) while others are turned off (_______). Two examples are the ____ _____ and_____ ______
In essence, the bacteria are capable of turning genes off and on in response to changes in the environment. Some of the operons are turned on (Inducable) while others are turned off (Repressible). Two examples are the lac operon and tryptophan operon
To start making any gene, you need a
promoter
The repressor gene/protein controls the _____ and needs a _____ to start
operator, promoter
The operator controls the _____
operon
Tryptophan Operon:
-_______: turns __ when conditions are favorable
-Operon is normally __, allowing bacteria to make its own tryptophan
-Repressor protein is made continuously but is normally _____
-When _______ is in the environment the repressor is ______
-Turns ___ the _____
-Repressible: turns off when conditions are favorable
-Operon is normally on, allowing bacteria to make its own tryptophan
-Repressor protein is made continuously but is normally inactive
-When tryptophan is in the environment the repressor is activated
-Turns off the operon
Lac Operon:
-______, turns __ when conditions are right
-Operon is normally ___ at all other times due to the production of a _______ ____
-Repressor protein blocks the _____
-When lactose is present, the bacteria can now ______ it
-Lactose is converted to ______
-________ _______ ___ ______ _____
-_______ of the lac operon can now occur
-Inducable, turns on when conditions are right
-Operon is normally off at all other times due to the production of a repressor protein
-Repressor protein blocks the operator
-When lactose is present, the bacteria can now catabolize it
-Lactose is converted to allolactose
-Allolactose inactivates the repressor protein
-Transcription of the lac operon can now occur
Gene Transfer
The genes will be passed to the next generation during binary fission
Vertical transmission
passes from one generation to the next as a result of binary fission
Horizontal transmission
transmission the bacteria acquire new genes from the same generation which it can then now pass on to the next generation vertically (gives to their ‘friends’)
3 methods of horizontal transmission:
Transformation
Transduction
Conjugation
Transformation is …
The bacteria capable of this are called _____
Absorption of DNA from the environment
The bacteria capable of this are called competent
Transduction
A replicating virus, (called a Bacteriophage), transmits DNA from one cell that is picked up to another
Conjugation
-Uses ___ ___
-_____ ___ can be associated with __ ____ OR gene can be _______ ___ ___ ______ (called ___)
-Uses sex pilus
-Fertility gene can be associated with F plasmid OR gene can be integrated into the chromosome (called Hfr)
