Microbio Unit 6 Genetics

copying

the code

• the copy
• ribonucleic acid

• result of the code
• the translation
• DNA is transcribed into RNA and translated as protein

interpretation; DNA transcribed into RNA and translated as protein

mode by which copies of DNA are made

• transcribing RNA into DNA
• done by viruses

Independently replicating peice of DNA that is passed on to all daughter cells and encodes some genes that are essential for the survival of the cell

• Complete set of genes in a cell
• Encodes all the genes necessary for a cell to survive

independently replicating piece of DNA passed on to all daughter cells but does not encode any genes essential for cell.

• -basic unit of of DNA/RNA
• -consists of a nitrogenous base, a phosphate, and a sugar

One strand points in a 5' direction and the other in a 3' direction

• -Helicase to unwind DNA
• -Two DNA polymerases that replicate DNA in a 5' to 3' fashion

synthesized continuously 5' to 3'

synthesized in short 5' to 3' fragments that are later ligated (glued together)

-All the genes in the cell

• -DNA code that results in the making of a functional unit of RNA
• -one specific unit of information

• -enzyme
• -responsible for copying DNA into RNA

-enzyme

• -Messenger RNA
• -contains message translated into a protein
• -in prokaryotes it is immediately translated into a protein
• -in eukaryotes it must first be processed

• Transfer RNA
• transfers a specific amino acid to the ribosome where the protein is made; it recognizes the message in the mRNA by using a code
• there is a tRNA for each amino acid and each tRNA recognized a spec code that represents that amino acid

• ribosomal DNA
• this DNA with ribosomal proteins froms the ribosome

Organelle that facilitates translation

code of DNA bases and amino acids

• 3 base code
• 64 codons which code for 20 amino acids
• 3 stop codons

• ejection site
• where tRNA no longer has an amino acid and is released back into cytoplasm

• peptide site
• where tRNA is located that has peptide chain attached

• active site
• where the next tRNA comes in a decodes the mRNA

• second step in protein synthesis
• the joining of one amino acid to another amino acid occurs via formation of a peptide bond
• occurs when P site and A site are full
• ribosome transfers the amino acid from the tRNA in the P site onto the amino acid that is on the tRNA in the A site

• movement of the ribosome three bases (once codon) along mRNA
• the tRNA that was in the Psite is now in the Esite
• the tRNA that has the peptide attached that was in the Asite is now in the Psite
• the A site is empty again

• change in the nucleotide sequence of the genome of an organsim/virus
• result in from the incorrect incorporation of a nucleotide into the genetic sequence
• some will allow an organism to become resistant to antibiotics

result from exposure to known mutagens which are primarily physical or chemical agents thta interact with DNA/RNA in a disruptive manner

random changes in DNA arising from mistakes in replication or the detrimental effects of a natural background radiation on DNA

• process involving several dozen proteins
• part of one sequence is inserted into another site with high sequence similarity

• site specific recombination with organisms genome
• results in a double stranded DNA being inserted into the genome

• 1) Integrase - enzyme which catalyzes double breaks
• 2) Recognition sequence - must be present in both organsims DNA and invading DNA
• 3) The invading DNA must encode the intergrase

Enzyme

• mobile genetic elements
• able to integrate into an organisms genome and then later move to a new location in that genome
• many are lysogenic phage
• most move from one organism to another by piggybacking during txfer of DNA from one cell to another

process by which cells can take up naked DNA from the environment

• cells that can be transformed
• naturally competent: streptococcus, heliobacter, haemophilus, neissira

take up DNA in their normal environment

self transmissable plasmids that direct the formation of a special pilus onthe surface of the bacterium

High frequency of recombination

transfer of genes from the donor cell to the recipient cell via a bacteriophage

• counteract the ease of gene transfer resulting in the rejection of most foreign DNA
• work by recognizing short sequences

each daughter cell receives a chromosome with one strand from the original parental chromosome, the opposite strand being a new copy of the original chromosome.

a protein that unwinds helical DNA

• binds to open DNA and makes a short RNA copy of the DNA that is called an RNA primer
• essential b/c DNA polymerase can not start a DNA strand, it can only EXTEND a DNA strand

enzyme which "glues" together fragments of information

enzyme which breaks open a circular chromosome to be re-linked

enzyme in eukaryotes which copies last bit of DNA such that the new chromosome are the same length as old chromosomes

• transcriptional unit
• may contain one or more different genes

• bind to DNA and help RNA polymerase to bind to DNA
• often allow RNA polymerase to bind at sites where they normally wouldnt

region containing the sequences that control gene expression

bind to DNA and prevent RNA polymerase from binding to the DNA or from copying the DNA into RNA

change that results in a different amino acid

mutation that results in the inserting of a stop codon

• results in the insertion of deletion of nucleotides that change the reading frame of the mRNA
• changes all amino acids from that point forward

• mutations that result in a correction of the original mutation
• may also result in a second mutation that compensates for the orig mutation without correcting it

• DNA --------> RNA -------------> protein
• transcripton translation

• 1) The strand itself
• 2) the strand wrapped around thousands of histones
• 3) The histones (ball like); form regions to make the DNA more compact
• 4) All regions can be linked together to make DNA tiny

The get DNA polymerase attached to the DNA thta is to be copied

• 1) Unwinding the DNA - must be opened by DNA helicase so that the initiation complex can bind to the DNA
• 2) Synthesis of an RNA primer - primase binds to DNA and makes a short copy of the DNA which is called an RNA primer
• 3) Binding of the DNA rep complex - DNA rep complex binds to RNA primer on DNA

• 1) Helicase to unwind DNA
• 2) Two DNA polymerases that replicate DNA in a 5 to 3 direction

• copying of the DNA
• involves leading strand and lagging strand

• they are linked like a chain
• there are enzymes that break one of the chromosomes and relink it so that they are separated

in eukaryotes telomerase copies the last bit of DNA such that the new chromosomes are the same length as the old chromosomes

• 1) 5' end is capped
• 2) Addtition of a poly-A tail
• 3) Removal of introns through splicing

• 1) docking site from mRNA and inititator tRNA
• 2) docking site for additional tRNA that recognizes the mRNA
• 3) Traspeptidation enzyme which allows two amino acids to be joined together to form a peptide chain or protein

• the ribosome binds to the mRNA molecule and rapidly scans until it finds an intitiator site
• the ribosome positions itself such that the P site is over the initiator site where the initiator or first tRNA can bind
• upon binding of initiator tRNA the ribosome now assumes an active state with the Asite open

• 1) filling of A site
• 2) Transpeptidation
• 3) translocation
• 4) Ejection of the rRNA*

• virus penetrates bacterial cell and enter the lytic cycle
• viral DNA begins to replicate immediately in the bacterial cytoplasm
• during replication enzymes accidentally use some bacterial DNA to make new viruses
• bacterial genes are randomly packaged into new viruses
• some new viruses have bacterial DNA and no viral DNA
• transducing viruses enter recipient bacterium
• donor bacterial genes are incorporated into the chromosome of recipient bacterium

• viruses penetrate and enter the lysogenic cycle
• replication begins at a later time
• during release from chromosome in replication, viral DNA accidentally excises bacterial DNA to make new viruses
• bacterial genes adjacent to previously incorporated virus are packaged into new virus

• 1) Enzyme causes a double stranded break
• 2) single stranded protruding 3 ends are created by degrading the 5 strand
• 3) strand invasion occurs - strand adheres to the other DNA homolog
• 4) (eukaryotes only) DNA synthesis copies the DNA - usually for 1000 more bases
• 5) A holliday junction forms and is resolved into to separate DNA molecules

• 1) external DNA is bound by proteins on the cell surface
• 2) DNA is taken up into the cell as either a single strand or a double strand
• 3) foreign DNA is incorporated into the cell's genetic material through recombination