Untitled Quiz

Chromatin consists of DNA tightly coiled around proteins called histones. DNA is wrapped around histones to form nucleosomes. The nucleosomes are wrapped up to form chromatin - a thick, ropy fiber.

Before cell division, so that each daughter cell gets a complete copy of the genome.

Chromosomes condense only for DNA replication; the rest of the time DNA is in chromatin form.

<p>A parent strand is used as a model while new nucleotides attach. This means that each new piece of DNA has one original strand and one new strand.</p> Signup and view all the answers

<p>In prokaryotic cells, DNA is located in the cytoplasm. Most prokaryotes have a single, circular DNA molecule containing nearly all of the cell's genetic information. Replication begins at a single point and proceeds in two directions simultaneously until the DNA is copied. It is faster than DNA replication in eukaryotes.</p> Signup and view all the answers

<p>DNA replication begins at origins of replication. Two strands open forming replication forks (Y-shaped region). New strands grow at the forks.</p> Signup and view all the answers

<p>In eukaryotic chromosomes, DNA replication occurs at hundreds of places.</p> Signup and view all the answers

<p>Many in eukaryotes</p> Signup and view all the answers

<p>Enzyme helicase unwinds and separates the 2 DNA strands by breaking the weak hydrogen bonds.</p> Signup and view all the answers

<p>Single-Stranded Binding Proteins attach and keep the 2 DNA strands separated and untwisted (like thumb tacks).</p> Signup and view all the answers

<p>Primase is the enzyme that synthesizes the RNA primer needed to start the addition of new nucleotides.</p> Signup and view all the answers

<p>The primer will be removed by DNA polymerase and replaced with DNA nucleotides.</p> Signup and view all the answers

<p>It adds new DNA nucleotides, removes primers, and proofreads the DNA for errors.</p> Signup and view all the answers

<p>3' end.</p> Signup and view all the answers

<p>5' —&gt; 3'.</p> Signup and view all the answers

<p>Leading strands are synthesized continuously toward the opening replication fork, while lagging strands are synthesized discontinuously in fragments called Okazaki fragments.</p> Signup and view all the answers

<p>Okazaki fragments.</p> Signup and view all the answers

<p>All segments of the sugar-phosphate backbone are sealed by ligase.</p> Signup and view all the answers

<p>DNA polymerase.</p> Signup and view all the answers

<p>Nuclease (exonuclease).</p> Signup and view all the answers

<p>Prokaryotes.</p> Signup and view all the answers

<p>Chromosomes are supercoiled chromatin; chromatin is DNA wound around proteins.</p> Signup and view all the answers

<p>Telomeres are repeating segments of DNA located at both ends of a chromosome. They ensure that all genes are replicated and not lost, preventing the ends of chromosomes from fraying or sticking together.</p> Signup and view all the answers

<p>23 pairs; 46 total.</p> Signup and view all the answers

<p>Pairs of chromosomes (maternal and paternal) that are similar in shape and size.</p> Signup and view all the answers

<p>22 of the homologous pairs match more or less exactly (the autosomes); the 23rd pair (sex chromosomes) will match if it's XX (female) but be different if it's XY (male).</p> Signup and view all the answers

<p>In humans, the autosomes are sets of 1-22, and the 23rd set of chromosomes are sex chromosomes.</p> Signup and view all the answers

<p>XX = female; XY = male.</p> Signup and view all the answers

<p>New cells are produced for growth and to replace damaged or old cells (or in unicellular organisms, for reproduction).</p> Signup and view all the answers

<p>Eukaryotes: Mitosis. Prokaryotes: Binary fission.</p> Signup and view all the answers

<p>Nucleus/genetic material.</p> Signup and view all the answers

<ol> <li>Large cells experience DNA overload; as a cell grows, it has the same amount of DNA for increased responsibilities. 2. They can't efficiently exchange materials; the surface area to volume ratio decreases as the cell enlarges. 3. Aging cells are less efficient.</li> </ol> Signup and view all the answers

<p>G1 Phase = Primary Growth: cells grow and synthesize proteins and organelles. S Phase = Synthesis: cells replicate DNA. G2 Phase = Secondary Growth: the cell grows slightly more and prepares for mitosis.</p> Signup and view all the answers

<p>Centrioles and spindle fibers are part of the cytoskeleton. Spindle fibers connect to chromosomes to separate them during cell division.</p> Signup and view all the answers

<p>Mitosis: PMAT; Cell Cycle: IPMATC.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>During prophase, the centrioles lineup on opposite sides of the nucleus, spindle fibers form, chromatin condenses into visible chromosomes, and the nucleolus disappears.</p> Signup and view all the answers

<p>During metaphase, chromosomes line up across the center of the cell and microtubules connect the centromere of each chromosome to the spindle fibers.</p> Signup and view all the answers

<p>During anaphase, centromeres separate and chromatids become individual chromosomes that move apart until they reach the centrioles.</p> Signup and view all the answers

<p>During telophase, chromosomes tangle back into chromatin, a nuclear envelope re-forms around each chromosome set, spindle breaks apart, and nucleoli become visible.</p> Signup and view all the answers

<p>In animals, cytokinesis occurs by a cleavage furrow where the cell membrane is drawn in. In plants, a cell plate forms between the new nuclei.</p> Signup and view all the answers

<p>Daughter cells have the same number of chromosomes and genes as the parent cell, identical to each other but smaller than the parent cell.</p> Signup and view all the answers

<p>Density-dependent regulation occurs when cells stop growing upon contact with other cells; they will divide to fill gaps and stop when touching neighbor cells.</p> Signup and view all the answers

<p>Anchorage dependence is when most animal cells require attachment to a substratum to divide.</p> Signup and view all the answers

<p>Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells, present in high amounts during division.</p> Signup and view all the answers

<p>Internal regulators are proteins that respond to internal cell events and stop the cycle at checkpoints.</p> Signup and view all the answers

<p>A checkpoint is a critical control point in the cell cycle where stop and go signals regulate progression.</p> Signup and view all the answers

<p>If the cell receives a go-ahead signal, it continues to divide; if not, it exits to a non-dividing state (G0 phase).</p> Signup and view all the answers

<p>The M phase checkpoint ensures all chromosomes are attached to the spindle before moving to anaphase.</p> Signup and view all the answers

<p>External regulators are proteins that respond to external events and direct the cell cycle to speed up or slow down.</p> Signup and view all the answers

<p>Growth factors are important external regulators that stimulate growth and division, particularly during development and healing.</p> Signup and view all the answers

<p>Cancer is a disorder in which some of the body's cells lose the ability to control growth.</p> Signup and view all the answers

<p>Cancer cells do not respond to the signals that regulate growth in normal cells.</p> Signup and view all the answers

<p>A tumor is a mass of cancer cells.</p> Signup and view all the answers