(Summary) Brooks Biological Principles Exam 3 Latest 2024 Solved 100%.

(Summary) Brooks Biological Principles Exam 3 Latest 2024 Solved 100%. Mitosis • 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 1. Growth: to increase the number of cells 2. Tissue repair/replacement 3. Asexual Reproduction Cell Division A process by which a parent cell duplicates its genetic material and then divides into two similar cells = Cytokinesis Cytokinesis • 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 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 cells with more than one nucleus (plasmodium/slime mold) Ploidy number of the kinds of chromosomes found in a species denoted as "n" What is the ploidy for humans? diploid, 23 pairs of chromosomes, 46 chromosomes total What is the ploidy for bacteria? diploid, 46 chromosomes Haploid (n) 1 set of each kind of chromosome no homologous chromosomes only in gametes Diploid (2n) 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 the mitotic or meiotic stages have been completed, and new nuclear membranes separated into the sets of DNA Most cells in the body are diploid Mitosis takes any ploidy condition and makes exact copies of that condition Meiosis is not versatile (must have a diploid cell) to yield a haploid cell Germinal Cells Cells involved directly in the process of reproduction, like testes and ovaries Somatic Cells •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 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 Location of the genes in homologues How many different ways can homologous chromosomes line up? over 8 million ways Karyotyping 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? 21, less likely to separate due to nondisjunction Down Syndrome Problem with Chromosome 21 Does not separate like it should (Trisomy 21) Autosomal chromosomes Chromosomes 1 to 22 in humans Cell Cycle •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 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 G1 - Gap 1 S - DNA Synthesis G2 - Gap 2 G1 Phase • Active Growth and Metabolism • This is where you have the most cellular activity • The cell grows larger • Unduplicated DNA (chromatin); cellular content, excluding the chromosomes, are duplicated • Final destination for adult cells:neurons and muscles (don't divide, so they don't go thru S phase, just stay in G1, so called G0) A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in G1 S Phase • Synthesis of DNA & Duplication of Chromosomes • Twisted helix • DNA building blocks aren't detached • 46 chromosomes, 92 chromatids After S phase, almost all chromosomes look like an? X shape G2 Phase • synthesis of molecules in preparation for cellular division (mitosis) • final preparations for mitosis • Rapid production of tubulin for microtubules in formation of the spindle fibers • cell "double checks" for any duplicated chromosomes for errors, making any needed repairs G0 Phase when cells stay in G1, never entering S or G2 phase Ex: muscle, nerve, and liver cells (unless damaged due to excess alcohol consumption, causing the cells to go from G0→G1 resulting in liver damage & cancer) Eukaryotic Proteins histones and non-histones