Unit Test Review Health No. 4

UNIT 4 REVIEW ● Asexual Reproduction: creation of genetically identical offspring by a single parent without the participation of sperm and egg ● Steps of Binary Fission: 1. Duplicate chromosomes 2. Opposite ends 3. Cell becomes bigger 4. Pinch in the middle to split 5. Divides the parent cell into 2 daughter cells ● 2 Main Stages of Cell Cycle: 6. Interphase (90%): cell performs normal activities cannot be seen on microscope ● G1 Phase: growth ● S Phase: chromosomes are doubled consisting of 2 sister chromatids ● G2 Phase: growth 7. Mitotic/M Phase (10%): cell physically divides and produces 2 daughter cells ● Mitosis: nucleus divides ● Cytokinesis: cytoplasm divides ● Mitosis: 8. Interphase (46 Chromosomes): ● Nucleolus and nuclear envelope are visible ● Chromosomes are in the form of chromatin 9. Prophase: ● Nuclear envelope is not apparent ● Chromosomes are condensed ● Begin to form microtubules and spindles 10. Prometaphase: ● Nuclear envelope breaks down and disappears ● Chromosome moves toward the center of the cell 4. Metaphase: ● Thick, coiled chromosomes ● Chromosomes contain 2 chromatids each ● Chromosomes lined up on the metaphase plate 5. Anaphase: ● Chromatids of each chromosome separate ● Chromatids are moving toward the poles () 6. Telophase: ● Chromosomes are at the poles ● Nuclear envelope is reforming ● Cytoplasm may be dividing 7. Cytokinesis: ● Division into two daughter cells is completed ● Similarities/Differences Plant and Animal Cells During Cytokinesis: 1. Similarities – Cytoplasm and cell membrane 2. Differences – Plant (divide by a cell plate that becomes a cell wall) Animal (divide by a cleavage furrow) ● Factors That Influence Cell Division: ● Anchorage Dependence (Physical)--distinguishes normal cells from cancerous cells ● Density Dependent Inhibition (Physical)-- crowded cells will stop dividing; fails in tumors because they continue to grow ● Growth Factor (Chemical)--signaling proteins; at least 50! ● Checkpoints: ● G1 Checkpoint: DNA? Resources? Proteins? Environment? (4/4 to advance to S – Stage) ● G0 Phase if any one of the 4 factors go wrong! ● Proto-Oncogenes: ● Proto-Oncogene: genomes that have the potential to become oncogenes ● Proto-Oncogene Oncogene: 1. Too much protein 2. Works too hard so there is a lot of protein activity 3. Protein in the wrong place @ the wrong time ● Proto-Oncogenes cause cancer because if the protein is messed up, then it also messes up the cell cycle ● Tumor Suppressor Genes: 1. Fix DNA! Tells cells when to stop dividing to prevent uncontrolled cell growth 2. Causes cancer when there is a mutation in a tumor suppressor gene 3. Cancer is caused by an active oncogene and a tumor suppressor gene mutation! 4. p53 Mutation = main cause of cancer; #1 tumor suppressor; excessive cell division ● Meiosis: 5. Interphase: ● Chromosomes duplicate 6. Prophase I: ● Sister chromatids cross over and create tetrads ● Chromosomes coil tightly and a spindle forms ● Nuclear envelope breaks down 7. Metaphase I: ● Chromosome tetrads (homologous chromosomes) are aligned on the metaphase plate 8. Anaphase I: ● Chromosomes are pulled apart to opposite poles() 9. Telophase I & Cytokinesis I: ● Chromosomes gather at the poles ● Cell pinches in the middle ● Cytoplasm divides 10. Prophase II: ● A new spindle forms around the chromosomes 11. Metaphase II: ● Chromosomes line up in the middle on the metaphase plate 12. Anaphase II: ● Centromeres divide ● Chromatids move to opposite poles( ) of the cell 13. Telophase II & Cytokinesis II: ● A nuclear envelope forms around each set of chromosomes ● The cytoplasm pinches in the middle and divides ● Similarities/Differences Mitosis and Meiosis: 14. Similarities – Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis 15. Differences – Mitosis (divides once, same # of chromosomes as parent, somatic) Meiosis (divides twice, half # of chromosomes as parent, gamete) ● Sources of Genetic Variability: 1. Arrangement of homologous chromosomes as a result of tetrad orientation 2. Crossing over during Prophase I of Meiosis 3. Random fertilization of the sperm and egg ● Nondisjunction: ● Occurs when the tetrads fail to separate either during Meiosis Phase I or Meiosis Phase II. Diseases as a result of nondisjunction’s… ● Down Syndrome (1/700 Children): 3 chromosomes on #21; have 47 chromosomes total; this is called “Trisomy 21” ● Klinefelter’s Syndrome (1/1,000 Male Births): abnormal number of sex chromosomes; an extra X chromosomes (1-8 extra X chromosomes are possible with this disease) ● Turner’s Syndrome: females who only have one X; symptoms of this disease include a short stature, web of skin from neck → shoulders, they are sterile, and have poor breast development3 ● 4 Types of Alterations in Chromosome Structure: ● Deletion: deletion of part of the chromosome (cause serious physical and mental problems) ● Insertion: insert an extra part to the chromosome (cause serious physical and mental problems) ● Inversion: switching parts of the chromosome around (less likely to produce harmful effects) ● Translocation (Reciprocal): switching non-homologous chromosomes (may or may not be harmful) ● Mendel’s Laws: ● Alleles (P vs. p) ● Homozygous vs. Heterozygous ● ● ● ● ● ● ● ● ● ● Dominant vs. Recessive ● 1 Allele from Mom & 1 Allele from Dad: law of segregation during Anaphase I of Meiosis Mono- Di- Tri- Hybrid Cross and % Ratio of Phenotypes & Genotypes: ● Genotype: PP:Pp:pp (1:2:1) ● Phenotype: 3 Purple Flowers: 1 White Flower Rule of Multiplication & Addition: ● Multiplication: independent event (probability of getting a boy and then getting another boy ½ X ½ = ¼) ● Addition: dependent event Incomplete vs. Complete Dominance: ● Incomplete Dominance: one dominant allele and one recessive allele make a mixed color/show both alleles (Red – RR x White – rr = Pink – Rr) ● Complete Dominance: one dominant allele and one recessive allele make a solid color/show dominant allele (Red – RR x White – rr = Red – Rr) Codominance: both alleles are expressed (IAIB = person has AB blood) Pleiotropy: one gene can influence multiple traits (sickle cell anemia can result in blindness, liver failure, and a possible heart attack) Polygenic Inheritance: ● The additive effects of two or more genes on a single phenotypic character ● Many genes (hundreds of them) on different chromosomes cause your height and skin color. ● Additive effect Sex Determining Region of Y: ● Ovaries will develop unless the SRY gene is there than testes will be produced and the gender of the baby is now male Sex Linked Disorders (affect mostly males): ● X chromosome contains more genes than the Y chromosome ● A gene located on either sex chromosome is called a sex linked gene ● Sex linked recessive alleles on X chromosome ● Male inherits 1 X allele from mom → disease expressed (more frequent) ● Female inherits 2 X alleles 1 from mom and 1 from dad → disease expressed X Linked Recessive Traits: ● Hemophiliacs: lack one or more proteins required to clot blood (high in royal families of Europe) ● Duchenne Muscular Dystrophy: progressive weakening of muscles and loss of coordination (individual becomes wheelchair bound and normal breathing becomes difficult; rarely live pass their early 20s