<p>Review sheet – Chapter 8</p><p> Understand that asexual reproduction involves the creation of a genetically-identical offspring from a single parent; no eggs or sperm (fertilization) are involved</p><p> Understand that genetic diversity is sacrificed during asexual reproduction (all offspring are exact replicates of ‘parent’)</p><p> Know that gametes are sex cells: eggs and sperm, which can combine to form a new, unique, genetically-distinctive offspring</p><p> Know that prokaryotes reproduce via binary fission, where chromosomes are replicated and the cell splits in half into 2</p><p> Know that prokaryotes have 1 chromosome, while human cells contain multiple chromosomes</p><p> Know that chromosomes contain not only DNA, but also proteins which provide structure and control over the activity of genes</p><p> Know that human cells contain 46 chromosomes, consisting of 22 pairs of autosomes and 1 pair of sex chromosomes</p><p> Understand that before a cell can divide, its DNA (chromosomes) must first be replicated</p><p> Know that a replicated chromosome consists of 2 “sister chromatids”</p><p> Know that the cell cycle consists of interphase and the mitotic phase</p><p> Understand that most of the cell spends its life in interphase – a period of growth and preparation for cell division</p><p> Understand that DNA (chromosome) replication occurs during interphase</p><p> Understand that interphase is made up of 3 stages: G1, S, and G2, with DNA replication occurring in the “S” phase</p><p> Understand that the mitotic stage is made up of mitosis (nuclear division and distribution) and cytokinesis (the physical act of splitting 1 cell into 2)</p><p> Understand that mitosis is made up of 5 stages:</p><p> o Prophase – mitotic spindle forms, chromatin condenses</p><p> o Prometaphase – nuclear envelope dissolves, chromosomes attach to spindle</p><p> o Metaphase – chromosomes align perpendicularly at center</p><p> o Anaphase – each sister chromatid of replicatec chromosome separates o Telophase – nuclear envelope reforms, chromatin uncoils, mitotic spindle disappears</p><p> Understand that proteins regulate each step of the cell cycle</p><p> Understand that cancer is a disease of the cell cycle, where the control over cell division becomes unchecked and unregulated</p><p> Understand that meiosis is a type of cell division resulting in cells containing half the number of chromosomes as the ‘parent’ cell</p><p> Know that meiosis occurs only in reproductive organs and produces gametes (sex cells) such as eggs, sperm, and pollen</p><p> Understand that cells containing 2 sets of chromosomes are called diploid; cells containing only 1 set are called haploid</p><p> Understand that sex cells (gametes) are haploid, but all other cells are diploid</p><p> Understand that a homologous pair of chromosomes can bear 2 different kinds of genetic information for the same characteristics (different version of a gene)</p><p> Understand that crossing over occurs only in meiosis (not mitosis) and results in genetically-new chromatids (chromosomes)</p><p> Understand that most changes in chromosome number are harmful and some are fatal</p><p> Know that Down’s syndrome (trisomy 21) results from having 3 copies of chromosome 21 (instead of 2)</p><p> Understand that alterations in the number of chromosomes in sex chromosomes are not fatal</p><p> Understand that females inactivate their extra (second) X chromosome to prevent a lethal overdose of genetic information; this inactivation is random and can result in different chromosomes (the X from the mother, or the X from the father) being inactivated in different cells (calico cats are an example)</p>