Chapter 16: Molecular Basis of Inheritance Flashcards
Antiparallel elongation
the process by which DNA polymerases can only travel along the DNA strand from the 5 prime end to the 3 prime end
Telemorase
enzyme that creates/attaches the telomere base sequences to the ends of DNA strands to fill in the gaps left during replication (each replication causes the strand to get shorter and shorter)
(nucleotide) excision repair
nuclease enzyme cuts out and removed damaged stretch of DNA, then DNA polymerase replaces the removed nucleotide with the correct one
Origins of DNA replication
Particular sites on DNA where replication begins
Two strands open up in a replication ‘bubble’
(Bacterio)phage
Viruses that infect bacteria
Mismatch REpair
when enzymes other than DNA polymerase can correct nucleotides
DNA Polymerase
enzyme that catalyzes the elongation of new DNA at a replication fork
also proofreads newly made DNA & replaces incorrect nucleotides
heterochromatin
highly condensed chromatin that exists during interphase
exps. telomeres and centromeres
Chargaff’s rule (from before we knew about the double helix)
- base composition of DNA varies between species
2. In any species, the number of adenines and thymines are equal, and the number of cytosines and guanines are equal.
Helicases
enzymes that untwist the double helix at the replication forks
(Debunked) Conservative model of DNA replication
original double-stranded helix somehow codes for a completely new double helix while still maintaining the original double helix.
Transformation
Changes in genotype and phenotype d/t assimilation (like when Griffith put dead toxic virus DNA in live harmless virus and the harmless virus became toxic)
pyramidines
The 2 nitrogenous bases whose molecule consists of 1 ring (cytosine and thymine)
Purines pair up with pyramidines
DNA ligase
holds together the Okazaki fragments by joining their sugar-phosphate backbone
DNA pol III
synthesizes the leading strand of DNA during replication
Nuclease
enzyme that cuts out nucleotide mistakes in DNA strands during replication
Single strand binding proteins
bind to a strand of the unzipped DNA (during replication) to stabilize it/keep it from snapping back to the other parent strand
DNA Replication (3 steps)
- Orgins form to initiate replication
- Synthesize the leading strand
- Synthesize the lagging strand
Telomere
the ends of DNA molecules (made of special nucleotide sequences)
reduces/slows the rate of erosion/shortening of genes at the end of the DNA molecules
euchromatin
loosely condensed chromatin
Antiparallel strands (of DNA)
describes that fact that DNA lines up is 5 to 3 prime ends in an antiparallel fashion with its 3 to 5 prime end
Virus
DNA or RNA enclosed in a protective coat
Coat usually made of protein
Alfred Hershey and Martha Chase experiment
Used T2 viruses to infect e. coli to prove DNA was the genetic material
Made T2 protein and DNA radioactive, then infected bacteria cells with them, one at a time. Protein did not go into the host cell, but DNA did
nucleiod
the place in bacteria where DNA is coiled together (instead of in a nucleus like with eukaryotes)
Maurice Wilkins and Rosalind Franklin
used x-ray crystallography to create the photo of DNA’s double helix that Watson and Crick used
Waston and Crick
Used Rosalind Franklin’s DNA photo to deduce that:
- DNA made of 2 outer sugar-phosphate backbones
- DNA has paired nitrogenous bases in its interior
- Purines only match with pyrimidines
(DNA) replication fork
Y shopped region where DNA strands are elongating
Lagging strand
The DNA strand that DNA polymerase synthesizes, working away from the replication fork
Leading strand
The DNA strand that DNA polymerase continuously synthesizes, moving TOWARDS the replication fork
Frederick Griffith experiment
Proved DNA was the genetic material
Killed mice:
put dead toxic virus DNA in live harmless virus and the harmless virus became toxic
Purines
The 2 nitrogenous bases whose molecule consists of 2 rings (adenine and guanine)
Purines pair up with pyramidines
Primase
enzyme that creates primer strand (about 10 nucleotides long)
can start an RNA strand from scratch and adds RNA nucleotides at one time using parental DNA as a template,
Semi-conservative model (of DNA replication)
When DNA unzips and duplicates to make 2 dgt strands, each strand will have one old/original (“conserved”) and one newly made strand
(Debunked) Dispersive model of DNA replication
original double-stranded helix is broken apart into individual nucleotides; original nucleotides recombine with new nucleotides to make new double helices that are a combo of old and new nucleotides
Topoisomerase
corrects “overwinding” ahead of replication forks by breaking, swiveling, and rejoining DNA strands
Replication “bubble”
The place where a strand of DNA opens up for replication
Mathew Meselson and Franklin Stahl experiments
Proved the semi-conservative model of DNA replication by inserting ‘heavy’ nitrogen into DNA, chopping it up, centrifuging it, and comparing the relative locations of the nitrogen in test tubes
https://www.khanacademy.org/test-prep/mcat/biomolecules/chromosomal-inheritance/v/evidence-that-dna-is-genetic-material-1
