Test 3 Flashcards
isotope 14 C
useful to label amino acids and follow
isotope 32 P
label nucleotide
What are the two subunits of a ribosome?
small (30s)- 1rRNA + 21 proteins
large (50s)- 2rRNA + 31 proteins
Why are subunits labeled as 30s and 50s?
Ultracentrifugation used to separate the two units by measure of the sedimentation rate based on size, shape, & density of the molecule.
What is sedimentation unit?
suedberg units represented by S
How many units can be occupied at one time in the mRNA?
only 2 units
What helps transfer amino acid from A to P?
Peptidyl Transferase
What is the E site?
The exit
What is the A site?
entrance of amino acid
What is the P site?
Peptidyl transferase
How many codons can be moved at time and how many bases are in a codon?
one codon which has 3 bases
DNA helicase?
unwinds the DNA double Helix
ss DNA binding protein?
binds to and stabilizes the unwound single DNA strands
Primase?
synthesizes short (~10 bases) RNA primers
DNA polymerase I?
removes the RNA primers and replaces with DNA
DNA polymerase III?
extends the primers (the major DNA replication enzyme)
DNA ligase?
seals the newly synthesized pieces of DNA (okazaki fragments) together
What is genotype?
total genetic information that an organism posses.
What is phenotype?
the characteristics (appearance and behavior) that an organism displays.
What is a mutation?
a change in the base-pair sequence of DNA.
What is a gene?
a complete DNA base-pair sequence required to make a single final product that has a biological function.
What is a substitution mutation?
A single base is changed causing a possible change in the amino acid
What is a frameshift (deletion) mutation?
a single base is deleted causing the reading of the codon to be moved over.
What is a plasmid?
DNA molecules that can replicate independently of the bacterial chromosome
Plasmids ______ have genes for their own replication.
always
Plasmids _______ have genes that confer new phenotypic characteristics on the host cell such as antibiotic resistance, toxin production, new metabolic capabilities.
sometimes
Plasmids ________ have genes that mediate plasmid transfer to new cells (conjugation).
usually
What is homologous recombination?
the reassortment of similar nucleotide sequences.
What is RecBCD in E. coli?
unwinds double helix and cleaves single strands
What is RecA in E.coli?
facilitates strand exchange
Gene transfer is an ______ event and is ______ coupled to reproduction.
occasional; not
DNA transfer is ________ (from a ______ cell to ______ cell)
unidirectional; donor; recipient
Only _______ of a donor cell’s genetic material is transferred to a recipient cell.
part
Only _______ of a donor cell’s genetic material is transferred to a recipient cell.
part
What is conjugation?
DNA transfer when donor and recipient cells are in direct contact.
What is conjugation?
DNA transfer when donor and recipient cells are in direct contact.
What is transformation?
donor DNA in solution is taken up by recipient cells
What is transduction?
DNA transfer from donor to recipient cells mediated by bacteriophages (viruses)
What is transduction?
DNA transfer from donor to recipient cells mediated by bacteriophages (viruses)
Griffith Experiment?
any live virulent phenotype will result in death
Griffith Experiment?
any live virulent phenotype will result in death
Tobacco mosaic disease is caused by an infectious agent
Dmitri Ivanovsky
The infectious agent that cause tobacco mosaic disease is not a bacterium
Martinus Beijerinck
The infectious agent that cause tobacco mosaic disease is not a bacterium
Martinus Beijerinck