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.