Biology 101 Exam 3 Study Guide
Biology 101 Exam 3 Study Guide BY 101
Jacksonville State University
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This 3 page Study Guide was uploaded by Kimberly Burke on Friday January 22, 2016. The Study Guide belongs to BY 101 at Jacksonville State University taught by Dr. Tolley-Jordan (TJ) in Fall 2014. Since its upload, it has received 57 views. For similar materials see Introductory Biology I in Biology at Jacksonville State University.
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Date Created: 01/22/16
Bio Exam 3 • Cells – basic unit of life, make new cells, ensure genetic material is transferred to new cell, new cell is clone • Asexual Reproduction – new growth, replace old cells, repair tissues, redundancy • Chromosome – DNA & attached proteins (histones) o Duplicated to form sister chromatids o Centromere – region where the duplicated chromosome will attach to the microtubules • Interphase – cell growth; 90% of the cell cycle – prep; DNA replication o Growth(G1), duplicate DNA(S), double # of cytoplasmic compone nts(G2), mitosis-very rapid(M) o G1: most activity, loss of control = cell death or cancer, bad DNA repaired • Mitosis – Cell Division; each new nucleus has the same chromosome # as the parent cell o New, identical cell formed = daughter cell ; cloning; 2 diploid o Prophase – DNA in chromosomes begins to coil to form balls of microfibers o Metaphase –chromosomes line up by the centromere to prepare to split o Anaphase – pulls half of each chromosome – chromatid; move to metaphase plate o Telophase – division begins & goes back to normal; decondense, nuclear envelope forms o Bad DNA: apoptosis (cell death), senescence, cancer (bad DNA copies in new cells) o Somatic cells – body cells • Cytoplasmic Division – between late anaphase & end te lophase; split phase o 2 mechanisms: cell plate formation (plants), cleavage (animals) • Cytokinesis – stage of cell cycle responsible for cell division ; cytoplasmic division • Sexual Reproduction – genetic diversity, gene combinations, survival of the fittest o Conjugation – genetic information exchanged from donor to receptor via tube o External fertilization – eggs fertilized by sperm outside of parent • Meiosis – reductive division – 1n + 1n = 2n/23+23=46 o Reduces the # chromosomes ; sorts a reproductive cell’s chromosomes into 4 haploid nuclei o Genes – linear stretch of DNA that codes for specific amino acid § Inherited on pairs of chromosomes, 1 maternal & 1 paternal o Alleles – different forms of the same gene – basis of traits o Haploid- having 1 of each type of chromosome character istics o 2 haploid gametes fuse & form a diploid zygote (1 cell of a new individual) o DNA is replicated once & divided twice forming 4 haploid nuclei o Meiosis 1 – each duplicated chromosome is separated from it’s partner – like mitosis; 2n to 4n to 2n o Meiosis 2 – sister chromatids are separated – 2n to 4n to 2n to 1n o Factors contributing to variation § Random sorting – random separation of chromosomes during metaphase 1 • Produces 10 (8,388,608) possible combinations à pick 23 § Crossover – exchange of gene segments in prophase 1 § Random combination of gametes in fertilization o Oogenesis – process of making eggs o Spermatogenesis – process of making sperm o Ploidy that represents human somatic cells = 2n(diploid) • Gene/point mutations – mistake in DNA copying o In a gamete – passed to offspring o In somatic cell – affect owner of that cell, not offspring o Gene flaw or abnormal separation of chromosomes during mitosis o Harmful, beneficial, lethal, benign • Tay-Sach’s Disease – 1 recessive allele – Holocaust • Huntington’s Disease – 1 dominant allele – after reproductive years • Sickle Cell – heterozygous advantage; gene for red blood shape ; autosomal recessive disease o SS = normal; ss = lethal; Ss = good or bad/ resistant to malaria /carrier • Color blind – sex linked, not mendelian o Carried on the X chromosome, recessive, rare • Non disjunction in somatic cells o Trisomy – lethal & down syndrome –mutations in mitosis, occurs in Anaphase o XXX – sterile female o XXY – sterile male; Klinefelter Syndrome (female in appeara nce) o XXY- sterile male; Jacob’s Syndrome (normal body appearance, mental instability) o OY – lethal o XO – sterile female; Turner Syndrome (mental instability) • DNA – series that makes up a gene is read in triplets (codons) that code for an amino acid (20 possible) o Eukaryotes – DNA found on chromosomes in nucleus o “Rosetta Stone” of biology o Nucleotide – nucleic acid monomer consisting of 5C sugar, 3 phosphate groups, & nitrogen base § 2 strands twisted together = double helix o Thymine, Cytosine, Adenine, & Guanine o Semiconservative – both the original & copy cell receive an original & replicated strand following mitosis o Enzymatic processes – get rid of bad DNA o Not able to repair = cell death • Rules of DNA replication o Must be a template strand to be copied o DNA polymerase cannot initiate DNA synthesis o Reaction mechanism requires the primer to have a free 3’OH end for synthesis to continue o 5 à 3 • Frame shift Mutations o Insertion – extra nucleotide added to the DNA copy o Deletion – nucleotide is deleted o Base pair substitution – base wrongly paired w/ another § Dimers – 2 of the same base pair next to each other & 1 is wrong § Sickle cell o Transposons – DNA segments that move spontaneously about the genome § Inactivate gene; sometimes beneficial, sometimes not o Mutations due to environmental factors & metabolic processes • Dominant Dogma of early 20 century – proteins were inherited traits • Griffith’s Experiment – bacteria are able to pick up material from dead bacteria o Live type R take on DNA elements from the heated S strand & became live type S o Live type S = lethal • Avery & McCarty – transformation process = nucleic acids o DNA has phosphorous, carbon, hydrogen, oxygen, nitrogen o Proteins have sulfur, carbon, hydrogen oxygen, nitrogen • Hershey & Martha Chase – confirmation of DNA o Bacteriophages – viruses made only of proteins & DNA 35 32 o Used S & P as tracers • Watson & Crick & Rosalind Franklin – double helix o Rosalind – died from radiation from x -ray • DNA à Proteins o Transcription – copying of DNA – nucleus § Only 1 region of DNA is used as template, uses RNA polymerase § Begins when RNA polymerase binds w/ promoter region § Transcript Modification • mRNA = unfinished product ; controls the rate • 1 end of RNA in capped & 1 end contains “poly A” signal • intron – cut out; exon – coding portion • Mature RNA – introns cut out § mRNA transcript – linear sequence of nucleotides carrying hereditary code § Activators - speed up transcription when bound to promoter or enhancer § Repressors –slow or stop § Homeotic genes – control transcription – master genes • Homeodomain – region of 60 amino acids that binds to promoter o Translation – RNA molecules shipped from nucleus to cytoplasm & used as templates for polypeptide assembly § 3 Stages • Initiation – tRNA attaches to ribosome • Elongation – mRNA passes through ribosome & tRNA delivers amino acids in order specified by mRNA, peptide bonds form between amino acids • Termination – stop codon in place, no tRNA w/ anticodon, release factors bind to ribosome, mRNA & polypeptide are released § New polypeptides – join pool of free proteins in cytoplasm, enter the endoplasmic reticulum & move through the cytomembrane system where they are modified • Cleaned up to be used o 3 classes of RNA § mRNA – carries “blueprint” for protein-building § rRNA – major component of rib osomes; makes up more than half of weight of ribosome • ribosomes are composed of 2 subunits that perform together only during translation § tRNA – delivers correct amino acid to ribosome & pairs w/ mRNA code for amino acid • Each has an anticodon (complementary to mRNA codon) • Carries 1 specific amino acid • Anticodon binds w/ codon on mRNA to bring correct amino acid in place • Genetic Code – complete set of triplets o AUG = start codon o 64 possible codons (61 codons, 3 stop codons) • Cell Differentiation – process by which cells become specialized; occurs in embryonic stage o Controlled by Homeotic Gene (master gene) ; Placement of tissues occurs early on o Embryo – ball of cells o X chromosome inactivation – mosaics – chimaerism § 4 parents cells – 2 eggs fused together o Product of genes that are switched on & off at specific stages of embryonic development affects transcription
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