Micro Chapter 8
Why is base pairing in DNA important?
Because DNA replication the two strands of the double helix seperate at the replication fork, and each strand is used as a template by DNA polymerases to synthesize 2 new strands of DNA.
relaxes rupercoiling ahead of the replication fork
DNA gyrase
makes covalent bonds to join DNA strands
DNA ligase
synthesizes DNA proofreads and repairs DNA
DNA polymerase
Describe how DNA serves as genetic information.
DNA replications makes possible the flow of genetic info from one generation to the next.
Describe two ways mutations can be repaired.
Enzymes that cut out and replace the damaged portion of DNA, base repair by enzymes
Why can't the RNA transcript be used for translation?
Exons must be removed from the RNA transcript beofre translation
Compare the mechanisms of genetic recombination in bacteria.
Genetic recombination is an exchange, or rearrangement, of genes from seperate genes. It usually involves DNA from a different organism. The process of recombination contributes to genetic diversity. In crossing over, genes from 2 chromosomes are recombined into one chromsome containing some genes from each original chromosome.
How can a muation be beneficial?
If an altered enzyme encoded by the mutant gene has a new or enhanced activity that benefits the cell.
Does a base subsitution always result in a different amino acid?
No, because of the degernacy of the genetic code.
Describe the functions of plasmids and transpoons.
Plasmids- self-replication, gene-containing circular pieces of DNA.
Why can translation begin before transcription is complete in prokaryotes but not in eukaryotes?
Prokaryotes have ribosomes present inside the nucleus. In eukaryotes, the ribosomes are outside of the nucleus, nowhere near the DNA.
encode antibiotic resistance
R-factors
Describe the process of DNA replication: including function of DNA gyrase, DNA lligase, and DNA polymerase.
The double helix of DNA seperates as weak hydrogen bonds between nucleotides on opposite strands to break in response to action of replication enzymes, hydrogen bonds form new complimentary nucleotides and each strand of the parental template to form new base pairs, enzymes catalyze the formation of sugar-phosphate bonds between sequential nucleotides on each resulting daughter strand.
Why are transporons sometimes called jumping genes?
They are small segments of DNA that can move from one region to another, to another DNA molecule, or to a plasmid
What is the advantage of degeneracy of the genetic code?
b/c there are so many instances in which different codons specify the same amino acid
Classify mutations by type.
base subsitution, missense mutation, nonsense mutation. framshift mutation
Why is 1 strand of DNA synthesized discontinously?
because 2 strands of a DNA double helic are ant-parallel, but DNA polymerase can operate in only 1 direction
structures containing DNA that physically carry hereditary info
chromosomes
plasmid that carries genes for sex pili and transfer of the plasmid
conjugative plasmid
plasmid that encodes enzymes for catabolim for unusual compounds
dissimilation plasmid
segment of DNA, a sequence of nucleotides that encodes a functional product, usually a protein
gene
segments of DNA that code for functional products
genes
set of rules that determines how a nucleotide sequence is converted into the amino acid sequence of a protein
genetic code
science of heredity
genetics
genetic info in a cell
genome
sequencing and molecular characterization of genomes
genomics
genetic makeup, the info that codes for all the particular characteristics of an organism
genotype
When both glucose and lactose are present, why will cells use glucose first?
glucose is monosaccharide while lactose is disaccharide.
not only can pass genes vertically, but also laterall to other microbes of the same generation; involes a donor as well as a recipient
horizontal gene transfer
carries the coded info for making specific proteins from DNA to ribosomes where proteins are synthesized
mRNA
What is the advantage of semiconservative replication?
only use 1 strand from original DNA, which prevents autoimmune attacks
part of a reading frame that has the potential to code for a protein or peptide.
open-reading frame
operator and promoter sites and structural genes they control
operon
particular sequence in a genome at which replication is initiated
origin of replication
actual expressed properties
phenotype
transcription begins when RNA polymerase binds to the DNA at the site
promoter
When some of the donor's DNA has been integrated into the recipient's DNA, the resultant cell is called ____
recombinant
What causes transcription of an inducible enzyme?
repressible enzymes are transcribes unless the repressor is activated
Where does translation occur on the cell?
ribosomes
RNA synthesis continues until RNA polymerase reaches the site of DNA
terminator
Give a clinical application of genomics
tracking West Nile virus through nucleic acid sequencing
synthesis of a complementary strand of RNA from a DNA template
transcription
protein synthesis
translation
process used to build structural proteins (peptidoglycan) and regulatoru proteins (enzymes) needed by the cell
translation/protein synthesis
small segments of DNA that can move from one region to another
transposons
genes are passed from an organism to its offspring (plants and animals transfer this way)
vertical gene transfer
When does transcription stop?
when RNA polymerase encounters a termination sequenxes, usually signaled by sequence of AATAAA.