ZOL 141: FINAL EXAM
149 Cards in this Set
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Trait
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An observable property of an organism, e.g. blue or brown eyes, yellow or green peas.
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Gene
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The fundamental unit of heredity; Basic structural and functional unit of genetics.
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DNA
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Deoxyribonucleic acid. A helical molecule cosisting of two strands of nucleotides ; Carrier of the genetic information.
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Genome
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The set of DNA sequences carried by an individual.
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Macromolecules
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Carbohydrates; Lipids; Proteins; Nucleic Acids
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Carbohydrates
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Monosacharrides (simple sugars; glucose. Used as an energy source.); Oligosaccharides (Short-chain; Sucrose. A common sugar.); Polysaccharides (Complex; Starch/glycogen. Stores Energy).
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Lipids
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Glycerides (Glycerol plus fatty acids; fats. Stores energy.); Phospholipids (Glycerol, fatty acids, phosphate group; Lecithin. Structure of cell membranes.); Sterols (Carbon-ring structures; Cholesterol. Membrane structure, precursor to steroid hormones).
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Proteins
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Mostly fibrous (sheets of polypeptide chains; mostly water insoluble. Keratin/Collagen. Structure of hair/bones.); Mostly globular (protein chains folded into globular shapes; mostly water soluble. Enzymes/Hemoglobin/Insulin/Antibodies. Catalysts/Oxygen transport/Hormone/Immune system.
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Nucleic Acids
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Adenosine Phosphates (ATP; Energy carrier.); Nucleic acids (Polymers of nucleotides; DNA/RNA; Storage, transmission of genetic information).
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Three key properties of DNA
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1. Needs to store genetic information. 2. Needs to be self-replicating. 3. Needs to be able to mutate.
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Nucleotide
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Basic building block of DNA and RNA; Consists of three components: 1.Phosphate. 2. Sugar. 3. Base.
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Polynucleotides
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Linking the nucleotides together to form chains; Polynucleotides have polarity: Phosphate (5') at one end and OH (3') at the other.
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Covalent bond
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Chemical bond in which electrons are shared; Within a molecule; Can only be formed or broken chemically (or enzymatically).
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Hydrogen bonds
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Weak, chemical bond between a hydrogen and an electronegative atom (e.g. Oxygen); Between molecules or within large molecules; Can easily be formed or broken by changing the temperature.
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DNA double Helix
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DNA is composed of two stands and forms a double helix; Strands run in opposite directions.
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DNA replication
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Each new DNA molecule contains one old and one newly synthesized strand. Depends on complementary base pairing; Works in only one direction (new nucleotides are always added to the 3' end (OH group)).
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Leading strand
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Synthesized continuously
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Lagging stand
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Synthesized discontinuously
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DNA polymerase
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Adds nucleotides to the 3' end of the newly formed DNA strand.
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DNA Helicase
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Unwinds DNA double helix ("unzips")
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Chromosome
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Threadlike structure in nucleus; Linear end-to-end arrangement of DNA, is wrapped around proteins; Carry genetic info; Define structure and function of each cell.
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Chromatin
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DNA and protein components, visible as clumps or threads.
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Homologous Chromosomes
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Pair of chromosomes carrying identical gen loci.
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Cell cycle
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Sequence from one cell division to the next cell division; Three stages: 1. Interphase (G1, S, and G2). 2. Mitosis. 3. Cytokinesis.
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Interphase: G2 (gap 1)
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Growth, i.e., organelles, membranes, ribosomes are made, cell increases in size; Takes several hours (9-10); Chromosome = 1 chromatid.
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Interphase: S (synthesis)
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DNA is synthesize, chromosomes are duplicated; Takes several hours (9-10); Chromosome = 2 sister chromatids.
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Interphase: G2 (gap 2)
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Preparation for cell division; Takes less time than G1 and S (4 hours); Chromosome = 2 sister chromatids.
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Mitosis
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Form of cell division that produces two genetically identical cells.
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Interphase (Mitosis)
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46 chromosomes
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Early Prophase (Mitosis)
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Chromosomes double to 92; Centrioles divide and move apart; Nuclear membrane disintegrates
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Late Prophase (Mitosis)
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Centrioles are at opposite poles; Nucleous and nulcear membrane have almost disappeared.
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Metaphase (Mitosis)
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Doubled chromosomes line up at the mid-cell
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Anaphase (Mitosis)
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Half of the chromosomes move to one pole, half to the other pole; the cell membrane pinches at the center.
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Telophase/Cytokinesis (Mitosis)
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Nuclear membranes form around the separated chromosomes; Mitosis is completed; there are two cells with the same structures and number of chomosomes (46)
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Hayflick limit
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Cells can divide about 50 times
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Meiosis
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Cell division which will reduce the number of chromosomes by half; Takes place in germ cells to produce gametes; Diploid cells will become haploid.
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Somatic Cell
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"Normal" human cell; 46 chromosomes (23 pairs/ 2n); two chromosome sets: one from dad and one from mom.
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Gamete
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Egg/Sperm cell; 23 chromosomes (no pairs/n); One chromosome set.
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Meiosis 1
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Reduces chromosome number to haploid
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Meiosis 2
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Separates sister chromatids
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Ineterphase (Meiosis 1)
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Chromosomes duplicate
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Prophase (Meiosis 1)
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Homologous chromosomes pair and exchange segments. Tetrads form (four-chromatid groups)
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Metaphase (Meiosis 1)
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Tetrads line-up at mid-cell
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Anaphase (Meiosis 1)
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Pairs of homologous chromosomes split up.
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Telophase (Meiosis 1)
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The cell membrane completes its constriction; there are now two cells.
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Prophase (Meiosis 2)
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Homologous chromatids do not duplicate, but merely separate.
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Metaphase (Meiosis 2)
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The chromatids line up at mid-cell.
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Anaphase (Meiosis 2)
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Chromatids separate and split.
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Telophase (Meiosis 2)
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There are now four, separate, cells. Each with half the number of chromosomes of the parent cell (23)
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Allele
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One variant of a gene; Sometimes, a different allele can result in a different phenotype; A gene can have many different alleles, but each individuals has only two alleles (one inherited from the father, and one from the mother).
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Spermatogenesis
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Spermatogonia in the testes divide by mitosis to produce spermatocytes; Spermatocytes undergo meiosis to form spermatids (haploid); Spermatids undergo structural changes to become functional sperm.
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Oogenesis
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Oogonia divide by mitosis to form primary oocytes; Primary oocytes undergo meiosis to form secondary oocytes (haploid); Secodary oocyte produced by the first meiotic division; Unequal division of the cytoplasm results in one larger, functional gamete (ovum), and two or three smaller polar…
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Spermatogenesis/Oogenesis Timing
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Spermatogenesis: 64 days Oogenesis: 12-50 years
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Homozygous
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Having identical alleles for one or more genes.
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Heterozygous
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Having two different alleles for one or more genes.
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Mendel's Law of Segregation (First law)
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During the production of gametes the two copies of each hereditary factor segregates so that offspring acquire one factor from each parent.
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Mendel's Law of Independent Assortment (Second law)
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Alleles of one gene sort into gametes independently of the alleles of another gamete.
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Chromosome theory of inheritance
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Proposed genes must be located on chromosomes.
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Incomplete Dominance
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A heterozygote displays a phenotype that is intermediate of the phenotype of the two homozygotes.
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Codominance
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Full phenotypic expression of both alleles of a gene pair in a heterozygote (Blood types)
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Complete Dominance
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Occurs when a dominant allele completely masks the expression of a recessive allele. A heterozygote will express one of the two homozygous phenotypes.
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Multiple alleles
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Genes that have more than two allelic forms within a population
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ABO blood group
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Controlled by a single gene (denoted as I) that has three different allels: IA = A antigen, IB = B anitigen, i = neither antigen.
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Immune system
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A network of cells, tissues, and organs that protect the body from infection.
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Antigen
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A substance to which the immune system can respond; Antigens that originate within the body are known as "self-antigens" and will not result in an immune response.
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Antibody
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A protein that is used by the immune system to identify and neutralize a foreign antigen.
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Rh (rhesus) blood group
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Called the D antigen; Rh+ individuals make D antigens, Rh- do not; Rh+ individuals will not make anti-D antibodies, Rh- individuals will not make anti-D antibodies, unless they encounter the D antigen.
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Pedigree
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A diagram that depicts the members and relationships of a family using standardized symbols.
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Autosomal Dominant traits
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Trait is expressed in makes and females in roughly equal proportions; All affected individuals have at least one affected parent (all generations); Offspring of affected parents can be unaffected.
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Autosomal Recessive traits
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The trait is expressed in males and females in roughly equal proportions; Trait appears in offspring of unaffected parents (skips generation); Offspring of affected parents must be affected.
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X-Linked Dominant traits
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Often more females are affected than males; Affected males must transmit the trait to all daughters; Affected males must have affected mothers; Affected females must have one affected parent.
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X-Linked Recessive traits
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More males are affected than females; Affected females must have affected sons; Affected females must have affected fathers.
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Y-Linked traits
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No females will be affected; Sons must have the same status as their father.
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Mitochondrial traits
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Offspring have the same status as their mother; Non-Mendelian inheritance.
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Penetrance
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The probability that a phenotype will be expressed when a particular genotype is present.
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Expressivity
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The range of phenotypes resulting from a given genotype.
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Complex traits
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Phenotype is determined by: Multiple genes; Interaction of those genes with each other; Effects of environment.
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Polygenic traits
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Traits controlled by two or more genes.
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Multifactorial traits
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Traits that result from the interaction of one or more environmental factors and two or more genes.
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Threshold traits
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Affected or not, sometimes different severity; Many diseases: diabetes, cancer, cholesterol.
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Varience
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Measurement of how far a set of measurements is spread out; Average of squared differences from the mean
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Heritability Index
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Gives measurement of "how much of the phenotypic variation is due to genes"; H^2 = Vgenetic/Vtotal
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Genome-Wide Association Studies (GWAS)
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Uses SNP (single-nucleotide polymorphism): = single nucleotide differences between and among individuals in a population or species; Associates certain SNPs with a specific phenotype; Progress has been made: more and more genes causing obesity, diabetes, certain cancers or controlling hei…
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Intelligence
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The ability to learn or understand things or to deal with new or difficult situations.
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Intelligence Quotient (IQ)
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Good predictor of academic success, earning potential, health, longevity.
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Karyotype
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Complete set of chromosomes of a cell that has been photographed during cell division and arranged in a standard sequence.
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Ploidy
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Number of sets of chromosomes in the nucleus of a biological cell.
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Euploid
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Organisms having an exact multiple of the haploid number of chromosomes.
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Polyploidy
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More than two haploid sets of chromosomes.
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Aneuploidy
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Abnormal chromosome number; Monosomy: Missing a chromosome (2n-1); Trisomy: One chromosome is present in three copies (2n+1)
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Monoploidy
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Only one set of chromosomes; For most species, including humans, lethal.
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Errors in Meiosis
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-Non-disjunction; Meiosis 1: no separation of homologous chromosomes; Meiosis 2: production of diploid gametes.
-Dispermy: fertilization of one egg by two sperm.
-Errors in mitosis after fertilization.
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Mosaicism
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Presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.
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Lyon Hypothesis
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Dosage compensation in mammalian females is accomplished by partially and randomly inactivating one of the two X chromosomes.
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X chromosome inactivation
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Equalizes transcript levels of X-linked genes between female and male cells; Results in one transcriptionally active and once silenced X chromosome; Takes place in early development; Is permanent (with exception of germ cells); Females are mosaic for expression of X-linked genes.
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Relocation of genetic material
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Translocation; Inversion.
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Loss of genetic material
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Deletion; Missing chromosomes.
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Gain of genetic material
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Duplication; Extra chromosomes.
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Balanced rearrangements
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No genetic information is lost; Translocation or inversion.
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Unbalanced rearrangements
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Genetic information is lost or duplicated; Deletion or duplication.
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Inversions
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Mitosis proceeds normally; Problems might arise in meiosis; Break point might be within gene; Inversion might put gene after a new promoter.
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Duplication
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Might alter gene dosage; Mitosis proceeds normally; Problems might arise in meiosis; Break point might be within gene; Can be beneficial in evolution.
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Reciprocal Translocations
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Interchange of parts between non-homologous chromosomes.
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Robertsonian Translocations
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Non-reciprocal; Chromosomal aberration in which the long arms of two acrocentric chromosomes become joined to a common centromere.
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Survivable Aneuploidies
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Trisomy 21; Trisomy 13; All others are lethal.
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Three stages if DNA to pre-mRNA
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1. Initiation 2. Elongation 3. Termination
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Promoter
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Regulator region that is a short distance from the 5' end of a gene and acts as a binding site for RNA polymerase ("on-off switch").
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Template Strand
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Used for mRNA synthesis, complementary in sequence.
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Coding Strand
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Non-template DNA strand, identical in sequence to mRNA (with the exception of U which is replaced by T in DNA).
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Exon
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DNA sequences that are transcribed and translated into proteins.
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Intron
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DNA sequences that are transcribed, but not translated into proteins.
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Splicing
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Removal of introns and joining of the exons.
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Alternative splicing
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Production of different RNAs from the same gene by slicing the transcript (mRNA) in different ways.
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Codon
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A linear series of three nucleotides (triplet); Specifies an amino acid.
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Start Codon
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AUG = Methionine
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Stop Codons
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UAA, UAG, UGA
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Enzymes
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Carry out chemical reactions in cells.
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Messenger proteins
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Transmit signals between different cells, tissues, and organs.
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Structural components
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Proteins provide structure and support allow us to move.
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Transport/Storage proteins
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Bind and carry atoms and small molecules.
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Functions of Ribosomes
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Bind messenger RNA and start codon; Facilitate complementary base pairing of mRNA and rRNA anticodons; Catalyze peptide bond formation between amino acids.
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Primary Structure
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Amino acid sequence
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Secondary structure
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Hydrogen bonds between amino acids; Helix; Pleated sheet.
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Tertiary Structure
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Three dimensional structure of a protein generated by folding on itself.
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Quaternary structure
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Structure formed by the interaction of two or more polypeptide chains.
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Gene switched on
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Active chromatin; Unmethylated cytosines; Acetylated histones.
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Genes "switched off"
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Silent (condensed chromatin); Methylated cytonsines; Deacetylated histones.
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Mutation
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Process that produces a gene (or chromosome) different from wild type; A heritable change in a DNA sequence; Can occur in any cell of the body-Somatic or gamete (and precursors).
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Metabolism
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Sum of all biochemical reactions by which cells convert and utilize energy.
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Metabolic Pathways
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Series of chemical reactions occurring within a cell; Chemical reactions are catalyzed by enzymes.
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Pleiotropic Effect
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One gene influences multiple, seemingly unrelated phenotypic traits.
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Haplosufficient Gene
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One functional copy of a gene is sufficient to promote wild-type phenotype; mutations are recessive.
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Galactosemia
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Inability to use galactose as an energy source; Inability to break down galactose; Autosomal recessive.
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Germline mutation
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Mutations that occurs in gametes or in cells that eventually become gametes; Mutation might be transmitted to offspring; All cells in offspring will carry the mutation.
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Somatic Mutation
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Mutation that occurs in non-reproductive cells; Mutation cannot be transmitted to offspring; Mutation can be transmitted to daughter cells through mitosis.
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Point Mutation
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A mutation that involves alteration of a single nucleotide in DNA.
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Nucleotide Substitution
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A point mutation that results from replacement of one nucleotide in DNA with another nucleotide.
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Missense Mutation
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A nucleotide substitution that causes replacement of one amino acid with another amino acid in a protein.
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Silent Mutation
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A nucleotide substitution that does not cause a change in an amino acid in a protein.
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Nonsense Mutation
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A nucleotide substitution that causes replacement of a codon for an amino acid with a stop codon in a protein.
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Sense Mutation
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A nucleotide substitution that causes replacement of a stop codon with one that codes for an amino acid in a protein.
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Frameshift Mutation
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An insertion or deletion that causes a shift in the codon reading frame.
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Trinucleotide Repeat Expansion
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Mutation that results in expansion of the number of trinucleotide repeats.
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Chromosomal Alteration
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Mutation that involves >1000 bp
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Trinucleotide Repeat
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Sequence of three nucleotides repeated several times in tandem.
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Anticipation
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The signs and symptoms of genetic conditions tend to become more severe and appear at an earlier age as the disorder is passed from one generation to the next.
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Spontaneous Mutations
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A mutation that arises in the absence of a mutagenic agent.
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Induced Mutation
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A mutation that arises after exposure to a mutagenic agent.
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Hydrolysis
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The process of breaking covalent bond in a molecule using water.
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ZOL 141: Exam One (Chap. 1 - 4)