Essay on Phage Dna Splices

Submitted By missvoc
Words: 1195
Pages: 5


­ Can be distinguished by the shape of their cells, and the colonies they form ∙ Spirochete (spiral) ∙ Bacillus (rod­shape)


­ a sticky layer that surrounds the cell walls of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces.
Cell wall
­ a protective layer external to the plasma membrane in plant cells, prokaryotes, fungi, and some protists.
Plasma membrane
­ the membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell’s chemical composition
­ a long, hair­like prokaryotic appendage that functions in adherence or in the transfer of DNA during conjugation; help bacteria adhere
­ a small ring of DNA that carries accessory genes separate from those of bacterial chromosome; also found in some eukaryotes, such as yeast
­ a cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits.
Bacterial flagellum
­ tail­like structure; enable bacteria to move; evolved independently of eukaryotic flagella.
Nucleoid (circular DNA)
­ a dense region of DNA in a prokaryotic cell. ­ Prokaryotic, unicellular, various nutritional modes
­ Cell walls made of peptidoglycan
­ Bacterial chromosome is a single circular piece of DNA
­ Have small extrachromosomal DNA segments called plasmids
­ Some bacteria have a capsule outside their cell wall making them more pathogenic.
­ Bacterial cell membrane is the major organelle used for bacterial metabolism
­ Bacteria have evolved all major forms of metabolism.
­ Bacterial ribosomes are smaller than eukaryotic ribosomes, which makes them a good target for antibiotics. ­ Binary fission: bacterial reproduction
∙ The cell copies the chromosomes and splits in half.
∙ Asexual, and can happen very fast
∙ 1 bacterium can reproduce every 20 minutes
Þ cell (chromosomal)à DNA replicationàsegregationà cytokinesis
­ what creates antibiotics resistance and why they are affected?
∙ Antibiotic penicillin­ mold, the thing that kills bacteria isolate that protein to kill it;
∙ Antibiotics kill bacteria by interrupting cell wall synthesis or interfering with vital processes like protein synthesis, all while leaving human cells unharmed.
∙ Ampicillin resistance­ can kill bacteria and the bacteria can’t fight.
∙ Individual bacteria can undergo random mutations, which can help bacteria from being killed by antibiotics; natural selection. Vocab
­ horizontal transfer­ exchange of genetic information between bacterial cell; increases and spreads genetic diversity.
∙ Examples of “recombination” of DNA from 2 sources
­ Transformation­ bacteria take in plasmids from the environment
­ Conjugation­ bacteria exchange DNA through a direct connection
­ Transduction­ bacteria acquire new DNA from a phage (bacterial virus) Viruses: DNA vs. RNA
­ Viruses consists of : gene information and a protein coat (capsid)
­ Are not traditionally considered to be alive because they can not carry out their life cycle independent of a host cell.
­ Prokaryotic viruses:
∙ Known as PHAGES: virulent phages and temperate phages
∙ Virulent phages: “classic” viral life cycle
­ Infection, synthesis, assembly release
­ Assembly is autocatalytic
∙ Temperate phages: “the lysogenic” cycle
­ Phage DNA splices in to bacterial chromosome.
­ When cell replicates, phage DNA is replicated, too.