week 5 Flashcards
which groups have made the most important contribution to the science
Bacteria and viruses have made most important
contributions to the science of genetics.
why bacteria and viruses are so usefull
Evidence for the nature of genetic material
(DNA)
- First characteristics and definitions of a gene
- First evidence for gene interactions at the
molecular level
- Basic principles of inheritance
What makes bacteria valuable research objects:
- Small size
- Rapid reproduction
- Selective media (e.g., antibiotics) that can easily identify
the presence of an active allele - Simple structures and physiology
- Genetic variability
what is the Bacteriophages
- Bacteriophages reproduce by infecting bacterial cells.
- Several important genetic concepts have been
discovered through studies of bacteriophages.
what is the result of the interaction between the bacteriophages and the plates with dense bacterial culture
Bacteriophages produce clearances (plaques) on
plates with dense bacterial cultures within hours of
infection
phage T4 had a ……… head
- Protein head
how does the phage infect the other cells
The phage goes through a
lytic phase, meaning it lyses
the cell to infect other cells.
This feature provides for
quick and simple genetic
experiments
how many genomes anf base pairs does the phage t4 has
Genome contains 168,800
base pairs and 150
characterized genes
is the phage lambda lytic or lyses
May be lytic (lyses the cells like T4) or lysogenic (inserts
its DNA in the host cell genome and goes into latency)
how many genomes does the phage lambda contain
- Genome contains, 48,502 base pairs and about 50 genes
how the virus enter the host cell
lecture 8 page 11
what are the Bacterial genomes
Bacterial genomes are circular molecules of several million base
pairs, called bacterial chromosomes
what is the role of the plasmid in the bacteria
- Additional genetic material resides in plasmids (small circular DNA)
that can replicate independently of the bacterial chromosome
what are the Episomes
- Episomes are large circular DNA that can integrate into the bacterial chromosome for replication or remain separate
why the bacteria can not have chiasmata
- Bacteria do not have meiosis, hence they can not have chiasmata
how is the gene transfer in the bacteria
Gene transfer in bacteria is unidirectional—from donor cells to
recipient cells.
how we can recognize a gene mutation
Colony colour and morphology
* Nutritional mutants (can not metabolise
certain sugars, like lactose or galactose)
* Prototrophs and auxotrophs (can not make
certain amino acids, these need to be
added to the growth medium)
* Antibiotic resistance
explain the Transformation
Transformation – transfer of a free (out of the cell)
piece of DNA from one bacterium into another
explain the Conjugation
Conjugation – direct transfer of DNA from one cell
to another via the establishment of a cytoplasmic
bridge
explain the Transduction
. Transduction – transfer of genes from one cell to
another via bacteriophage (vector)
what is the process of the transformation
A process by which “competent” bacterial
cells take up DNA from the environment
what happens to the transferred DNA into the recipient bacteria
Transferred DNA can be incorporated into the recipient bacterial chromosome (stably inherited)
what we can determine from the transformantion
Transformation can be used to determine
the distance between bacterial genes
how much of the entire bacteria chromosome would go under the transformation
only about 0.2-0.5% of the entire bacterial
chromosome undergoes transformation
