Brooks Biological Principles Exam 3 Questions & Answers (RATED A)

Mitosis - ANSWER-• the duplication and division of the nucleus • results in clones with *no* variation or adaptation • takes place in somatic cells (non-sex cells) • starts with one cell and creates 2 identical daughter cells • replicated chromosomes are evenly divided so that each daughter cell receives a complete set (46 chromosomes) • *can occur by itself*, but usually involves cytokinesis • not synonymous with cellular division • single-celled prokaryotes and single celled eukaryotes reproduce asexually, but eukaryotes are followed by cytokinesis Purpose of Mitosis - ANSWER-1. Growth: to increase the number of cells 2. Tissue repair/replacement 3. Asexual Reproduction Cell Division - ANSWER-A process by which a parent cell duplicates its genetic material and then divides into two similar cells = Cytokinesis Cytokinesis - ANSWER-• the duplication and divison of the *rest* of the cell, *excluding* the nucleus • occurs during telophase • can happen during mitosis, but generally doesn't have to occur with mitosis • will either develop into new cell walls (plants) or plasma membranes (animals) for each daughter cell Mitosis is not equal to - ANSWER-Cell division/Cytokinesis Only duplicates the nucleus, not the entire cell In the cells of some organisms, mitosis occurs without cytokinesis. This will result in - ANSWER-cells with more than one nucleus (plasmodium/slime mold) Ploidy - ANSWER-number of the kinds of chromosomes found in a species denoted as "n" What is the ploidy for humans? - ANSWER-diploid, 23 pairs of chromosomes, 46 chromosomes total What is the ploidy for bacteria? - ANSWER-diploid, 46 chromosomes Haploid (n) - ANSWER-1 set of each kind of chromosome no homologous chromosomes *only in gametes* Diploid (2n) - ANSWER-2 sets of each kind of chromosome, one set inherited from each parent contains a pair of homologous chromosomes *in all other body cells* You should do a ploidy count when - ANSWER-the mitotic or meiotic stages have been completed, and new nuclear membranes separated into the sets of DNA Most cells in the body are - ANSWER-diploid Mitosis - ANSWER-takes any ploidy condition and makes exact copies of that condition Meiosis - ANSWER-is not versatile (must have a diploid cell) to yield a haploid cell Germinal Cells - ANSWER-Cells involved directly in the process of reproduction, like testes and ovaries Somatic Cells - ANSWER-•body cells that are not specialized for reproduction Ex: muscle and skin •can't undergo *meiosis* •human cells have *46 chromosomes* in their somatic cells (contain two sets of chromosomes known as *homologous pairs* they are not identical, but they have similar, specialized characteristics) Homologous Chromosome Pairs - ANSWER-Refers to *pairs* of the *same* kind of chromosome organized by having the same size that contain genes for the same traits They are diploid 23 pairs of homologous chromosomes in humans Locus - ANSWER-Location of the genes in homologues How many different ways can homologous chromosomes line up? - ANSWER-over 8 million ways Karyotyping - ANSWER-visual representation of chromosomes by length, size, & centromeres in the same position pairing up chromosome 23 determines sex chromosome 21 most likely to duplicate useful because you can count the number of chromosomes present Which chromosome has the tendency to have an extra? - ANSWER-21, less likely to separate due to nondisjunction Down Syndrome - ANSWER-Problem with Chromosome 21 Does not separate like it should (Trisomy 21) Autosomal chromosomes - ANSWER-Chromosomes 1 to 22 in humans Cell Cycle - ANSWER-•Before mitosis begins, the cell must first grow and duplicate chromosomes during *interphase;* cells go through four stages during cell reproduction •Once this cycle is complete the cell will either undergo mitosis or meiosis Interphase - ANSWER-known as "resting phase" •*majority* of the cell's life is spent in this phase •*occurs between mitotic events, not the first stage of mitosis* •it is a stage of the cell cycle where the cell grows and genetic material is copied •main metabolic events occur: photosynthesis & cellular respiration •*DNA is fully functional during interphase* 3 Stages of Interphase - ANSWER-G1 - Gap 1 S - DNA Synthesis