DNA replication
the picture below shows a replicated, condensed chromosome consisting of two sister chromatids. How many total DNA molecules are present? - 4 - 8 - 2
2
DNA replication always moves from the 5' to 3', which means the final nucleotide will be added at _____
3'
there are _____ chromosomes in a human cell before mitosis & _____ chromosomes after mitosis & cytokinesis
46, 46
humans have 46 chromosomes in each of their cells in GI phase. how many chromosomes do we have in each of our cells during GII phase
46; the # of chromosomes does not change between GI & GII phases. the # of chromatids (DNA molecules) doubles, but the # of chromosomes does not
a cell has 6 chromosomes in GI phase. how many DNA molecules are in the cell during GI phase
6; the cellular contents duplicate, but the DNA does not. each cell therefore has 6 chromosomes in the form of 6 single chromatids, & each chromatid is one molecule of DNA
in S phase,
DNA is being replicated
_____ _____ requires a single-stranded template plus a primer to synthesize DNA
DNA polymerase
a chromosome consists of one DNA molecule. Which phase of the cell cycle is the cell in? - G1 - G2 - S
G1`
suppose that meselson and stahl first grew cells in light nitrogen (generation 0) and switched to heavy nitrogen (N15) for 2 rounds of replication. if the semiconservative model of DNA replication were true, what would have meselson and stahl observed in the tubes after 2 rounds of DNA replication?
H & I; half of the DNA would be heavy & half would be intermediate
in the meselson-stahl experiment, three potential models of DNA replication were tested. cells were grown in heavy nitrogen (N15), which incorporated into the bases (generation 0). the cells were then switched to medium that contained light nitrogen (N14) & allowed to replicate two times (generation 1 & 2). if the conservative model of DNA replication were true, what would have meselson and stahl observed in the tubes after 1 round of DNA replication?
L & H; if replication was conservative, then half of the DNA would be heavy and half would be light. if it was semi-conservative then half would be light & half would be intermediate.
suppose that meselson and stahl first grew cells in light nitrogen (generation 0) and switched to heavy nitrogen (N15) for one round of replication. if the conservative model of DNA replication were true, what would have meselson and stahl observed in the tubes after 1 round of DNA replication?
L & H; the result would be half light & half heavy, as shown below
scientists isolate cells from an individual in various phases of the cell cycle. they find a group of cells that have 1½ times more DNA than do G1 phase cells. the cells of this group are in the _____ phase of the cell cycle
S
sister chromatids are formed...
as the result of semiconservative DNA replicationt
when does cell division occur? - during cell division - before a cell divides - after cell division
before a cell divides
cell a has 5 picograms of DNA. cell b has 10 picograms of DNA. both cells are from the same organism. which of the following is the best description of the cell cycle stage of each cell
cell a is in GI phase; cell b is in GII phase; since the DNA replicates during S phase, a cell in GII phase would have twice as much DNA as a cell in GI phase
in GI phase,
cells are carrying out their normal cellular functions
in mitosis,
cells are dividing
in GII phase,
cells are preparing for cell division
during GI,
chromosomes consist of 1 long DNA molecule & associated proteins
a replicated chromosome,
consists of 2 identical DNA molecules/ 2 identical sister chromatids
in reference to the same chromosome as the previous question, how is "old" and "new" DNA distributed across the chromosome - each sister chromatid consists of 1 strand old and 1 strand new - 1 sister chromatid is old, 1 is new - each sister chromatid is a mix of old and new, but the ratio of old to new in each is difficult to predict
each sister chromatid consists of one strand old and one strand new
which DNA strands during DNA synthesis are synthesized in the 3' to 5' direction - leading strands - no strands - lagging strands - all strands
no strands
what is the difference between the leading strand and the lagging strand in DNA replication? - the leading strand is synthesized in the 3′ → 5′ direction in a discontinuous fashion, while the lagging strand is synthesized in the 5′ → 3′ direction in a continuous fashion - the leading strand requires an RNA primer, whereas the lagging strand does not - the leading strand is synthesized continuously in the 5′ → 3′ direction, while the lagging strand is synthesized discontinuously in the 5′ → 3′ direction
the leading strand is synthesized continuously in the 5′ → 3′ direction, while the lagging strand is synthesized discontinuously in the 5′ → 3′ direction
a single chromosome can contain either 1 DNA molecule or 2 identical DNA molecules held together
true
the DNA in your cells is, for the most part, the same - true - false
true
