B2.1 Supplying the cell - Part 2 Flashcards
<p>Define Mitosis</p>
<p>A type of nuclear cell division that is used by cells for growth, repair, and healing and asexual reproduction.A stage within the cell cycle.</p>
<p>What is the cell cycle?</p>
<ul> <li>The process of cell growth and division for growth and repair of bodycells</li> <li>It has three main stages interphase, mitosis and cytokinesis,</li> <li>Resultsin two identical daughter cells.</li></ul>
<p>Why is interphase important?</p>
<ul> <li>It it the stage of growth (G1) and replication (S)</li> <li>Before a cell can divide it needs to grow and duplicate all of its cellular contents</li></ul>
<p>What are homologous chromosomes?</p>
<ul> <li>A pair of chromosomes, one from the mother, and one from the father,which arevery similar to one another and have the same size and shape.</li> <li>Most importantly, they carry the same type of genetic information: that is, they have the same genes in the same locations</li></ul>
<p>What do the terms 'diploid' and 'haploid' mean?</p>
<ul> <li>Diploid = full set of chromosomes, 23 pairs/46 strands in humans</li> <li>Haploid = half of the fullset of chromosomes, 23 strands in humans</li></ul>
<p>What is the name given to the two identical copies of each chromosome?</p>
<p>Sister chromatids</p>
<p>What is the name of the attatchment between sister chromatids?</p>
<p>Centromere.</p>
<p>What is the name given to the way in which DNA replicates?</p>
<p>Semi-conservative</p>
<p>What is meant by semi-conservative replication?</p>
<p>After replication each strand has one original strand, and one new'complementary' strand</p>
<p>List the key stages in DNA replication.</p>
<p>•Double helix untwists</p>
<p>•Hydrogen bonds between bases broken, DNA ‘unzips’</p>
<p>•Bases exposed on each of the two strands</p>
<p>•Free nucleotides form hydrogen bonds with the exposed base (A-T, C-T)</p>
<p>•Covalent bonds form between nucleotides to form ‘backbone’</p>
<p>What happens during the cell cycle after DNA replication but before mitosis?</p>
<p>The replicated DNA is checked for errors and corrections made to avoid mutations being pass on to new cells</p>
<p>Explain what happens in each of the key stages of mitosis</p>
<ul> <li>Prophase - Chromosomes align in the middle of the cell</li> <li>Metaphase - Spindle fibres pull the arms of each chromosome to opposite ends of the cell.</li> <li>Anaphase - Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells – the nucleus has divided.</li> <li>Telophase - Cytoplasm and cell membrane divide to produce two identical daughter cells, each containing the same chromosomes.</li></ul>
<p>What is cytokinesis?</p>
<p>The formation of the two new nuclear membrane, andpinching in of the cell membrane to separate and enclose the two new nuclei, to separate the two new cells.</p>
<p>Explain why the chromosome number must stay the same when cells divide by mitosis?</p>
<p>The chromosome number must stay the same when cells divide by mitosis to ensure the cells produced are normal body cells, identical to their parent cell.</p>
<p>When do the sister chromatids condense></p>
<p>During prophase the sister chromatids condense to form x-shaped chromosomes linked by a centromere.</p>
