Chapter 13 Flashcards
Hereditary information in DNA directs the development of your?
biological, anatomical, physiological, and behavioral traits
Hereditary information is reproduced in cells during?
DNA replication
When T.H. Morgan’s group showed that genes are located on chromosomes and the two components ____ became _____.
DNA and protein, candidates for the genetic material
The discovery of the ______ began with ____.
genetic role of DNA, research by Fredrick Griffith
Transformation is defined as?
a change in genotype and phenotype due to assimilation of foreign DNA
bacteriophages
viruses widely used in molecular genetics research
Viruses must ____ and ____ in order to reproduce.
infect cells, takeover the cells metabolic machinery
Chargaff’s rules
-base compositions of DNA varies between species
-In any species, the percentages of A and T/ C and G bases are equal
____ X-Ray Crystallographic images of DNA enabled Watson to?
Franklin’s, deduce that DNA was helical
Watson built a model on which the backbones were?
antiparrallel
antiparrallel
subunits run in opposite directions
Since the two strands of DNA are ____, each strand ___.
complementary, stores info necessary to reconstruct the other.
In DNA replication, the ____ and two ___ are built based on ____.
parent molecule unwinds, new daughter strands, base-pairing rules
Watson and Crick’s Semiconservative model of replication predicts?
When a double helix replicates, each daughter molecule will have a new and old strand.
The copying of DNA is remarkable in its?
speed and accuracy
More than a dozen ____ participate in DNA replication.
enzymes and other proteins
Origins of replication
replication begins at these sights
What happens at origins of replication?
two DNA strands are separated
When the 2 DNA strands are separated what opens up?
replication bubble
At each end of a replication bubble there is?
replication fork
replication fork
y-shaped region where the parental strands of DNA are being unwound
For the long DNA molecules in eukaryotes, multiple ____ eventually, speeding up the ____.
replication bubbles fuse, copying of DNA
helicase
enzymes that untwist the double helix at replication forks
single-strand binding proteins
bind to and stabilize single-stranded DNA
Topoisomerase
relieves the strain caused by tight twisting ahead of replication fork by breaking, swiveling, and rejoining DNA strands
enzymes that synthesize DNA cannot ___, they can only add ____.
initiate synthesis of a polynucleotide, nucleotides to an already existing chain base paired with Template.
Short RNA primer
initial nucleotide strand
Primase
starts an RNA chain w/ single RNA nucleotide and adds RNA nucleotides one at a time using parental DNA as template
DNA polymerase
catalyze elongation of new DNA at a replication fork
DNA polymerase adds nucleotides to the?
3’ end of a preexisting chain
Most DNA polymerase require a ___ and ____.
primer, DNA template strand
dATP
used to make DNA
Difference between dATP and ATP?
dATP has deoxyribose, ATP has ribose
Newly replicated DNA strands must be formed?
antiparallel
Because DNA polymerases add nucleotides only to the free ___ the strand can elongate only in the ___.
3’ end of a growing strand, 5’ to 3’ direction
Along one template strand of DNA, the DNA polymerase synthesizes a ____ towards the ___.
leading strand continuously moving, replication fork
To elongate the lagging strand, DNA polymerase must?
work in the direction away from the replication fork
Okazaki fragments
lagging strand is synthesized as a series of segments
DNA ligase
joins the Okazaki fragments together
Errors in the completed DNA molecule amount to only?
one in 10 billion
Mismatch repair
enzymes correct errors in base pairings
One defect in DNA molecule allows cancer causing errors to?
accumulate in DNA faster than normal
DNA can be damaged by exposure to harmful?
chemical or physical agents
nuclease
cuts out and replaced damaged stretches of DNA
nucleotide excision repair
removes bulky lesions from DNA damage
Mutations are the source of____ upon which ____ operates.
genetic variation, natural selection
Telomeres
special nucleotide sequences at the ends of eukaryotic chromosomes
Telomeres do not?
contain genes
Telomeres do not prevent ____ but they do ___.
the shortening of DNA molecules, postpone it
Telomerase
catalyzes the lengthening of telomeres in germ cells
Telomerase is not active in most human ___ cells but can show inappropriate activity in some ____.
somatic, cancer cells
Nucleoid
Where the supercoilded DNA is found in bacterium
Chromatin
complex of DNA and protein found in nucleus of eukaryotes
Histones
responsible for the first level of DNA packing in chromatin
nucleosome
consists of DNA wound twice around a protein core of eight histones
In the nucleosome the eight histones have 2 of each?
main histone type
Centromeres and some other parts of chromosomes are?
highly condensed
heterochromatin
condensed chromatin
euchromatin
less compacted chromatin
Histones can undergo chemical modifications that result in?
changes in chromatin organization
Basis of nucleic acid hybridization
complementary base pairings of DNA
Nucleic acid hybridization
base pairing of one strand of a nucleic acid to another complementary sequence
Nucleic acid hybridization forms the foundation of?
virtually every technique used in genetic engineering
genetic engineering
direct manipulation of genes for practical purposes
plasmids
small circular DNA molecules that replicate separately from the bacterial chromosome
recombinant DNA
Plasmid is inserted with foreign DNA from another source
Gene cloning
production of multiple copies of a single gene
Cloning vector
plasmid that carries the cloned DNA
Gene cloning is used to make ___ and to produce ___.
many copies of a gene, protein product
Restriction sites
bacterial restriction enzymes cut DNA molecules at specific DNA sequences
Restriction enzymes usually yield?
restriction fragments
The most useful restriction enzymes cleave ___ to produce __.
the DNA in a staggered manner, sticky ends
Sticky ends can bond with?
complementary sticky ends of other fragments
Researchers use gel electrophoresis to?
see the fragments produced by cutting DNA molecules with restriction enzymes
Polymerase chain reaction
produce many copies of a specific target segment of DNA
The key to PCR is?
Taq polymerase
Taq polymerase
unusual, heat-stable DNA polymerase
DNA polymerase extends the primers in ____ direction.
5’ to 3’
PCR is used to provide the specific ___ to be ___.
DNA fragments, cloned
DNA Sequencing
laboratory technique for determining the exact sequence of nucleotides, or bases, in a DNA molecule
Several groups are working on “____” methods, which involve moving ____.
nanopore, a single DNA strand through a tiny pore in a membrane
CRISPR- Cas9 System
precisely modify a piece of DNA
Why do researchers use CRISPR?
to disable a given gene in order to determine its function
Researchers have also used CRISPR to repair?
a gene with a mutation
In 2018, CRISPR was used to correct?
a genetic defect causing sickle-cell disease
Altering genes in the insect may prevent?
it from transmitting the disease
Gene Drive
Bias of inheritance of an engineered allele which rapidly drives the allele through the population.
Who recognizes the dangers of CRISPR?
Jennifer Doudna
