Biology Unit Two notes for Exam 2/Chapters 14.1-14.4; 15.1- 15.5Lecture 10 (Chapters: 13.1, 13.2)- Asexual reproduction results in genetically identical offspring.- Asexual reproduction is the genetic equivalent of cloning.- Sexual reproduction results in genetically similar but not identical offspring.- Asexual reproduction is the result of mitosis.- Chromosomes exist as homologous pairs in diploids (2N).- Meiosis produces haploid cells from diploid cells.- Sexual life cycles alternate meiosis and fertilization.- Sexual life cycles vary in the timing of meiosis and fertilization.Terms Haploid- cell containing only one set of chromosomesDiploid- a cell containing two sets of chromosomes, one set inherited from each parentHomolgous chromosome (homologous pair)-a pair of chromosomes the same length, centromere position, and staining pattern that posses genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism’s father, one from the mother.sister chromatid- either of two copies of a duplicated chromosome attached to each other by proteins atthe centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome; chromatids are eventually separated during mitosis or meiosis II gamete- a haploid reproductive cell, such as an egg or a sperm. Gametes unite during sexual reproduction to produce a diploid cellzygote-the diploid production of haploid gametes during fertilization; a fertilized eggmeiosis- modified type of cell division in sexually reproducing organisms consisting of two round of cell division but one round of DNA replication, it results in half the number of chromosomes setsfertilization- the union of haploid gametes to produce a diploid zygote gonad- the male or female sex organs; the gamete-producing organs in most animalssexual reproduction- a type of reproduction which two parents give rise to off spring that have unique combinations of genes inherited from the gametes of the parentsasexual reproduction- the generation of offspring from a single parent that occurs without the fusion of gametes, in most cases, the offspring are genetically identical to the parentclone-(1) lineage of genetically individuals or cells (2) in proper usage, a single individual organism that genetically identical to another individual (3)to make one or more genetic replicas of an individual or cellspore- in the life cycle of a plant or alga undergoing alternation of generations, a haploid cell produced in the sporophyte by meosis. A spore can divide by mitosis to develop into a multicellular haploid individual, the gametophyte, without fusing with another cell (2) in fungi, a haploid cell, produced eithersexually or asexually, that produces a mycelium after germinationgametophyte- in organisms that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophytessporophyte- in organisms that have alternation of generations, the multicellular diploid form that resultsfrom the union of gametes. The sporophyte produces haploid spores by meiosis that develop into gametophytes Each chromosome in our body has one homolog from our mom and one from our dad which means thatour chromosomes are genetically similar but not identicalA gamete is haploid. During fertilization a gamete becomes a zygote and is diploid.Lecture 11 (Chapters: 13.3, 13.4)- Understand that meiosis produces haploid daughter cells by separating homologous pairs of chromosomes so that one homolog goes to each cell- Know that meiosis consists of two stages: meiosis I and meiosis II - Know that the end product of meiosis is 4 haploid cells - Know that homologous chromosomes are separated in meiosis I Know that sister chromatids areseparated in meiosis II - Know the names of the stages of meiosis and what happens in each - Understand that the pairing of homologs and crossing over both occur in prophase I- Understand that both the random assortment of homologs into daughter cells and the process of crossing over result in genetically variable gametes - Know the differences between mitosis and meiosis Know that special molecules prevent the separation of sister chromatids in anaphase I TermsSynapsis-process during prophase I, replicated homologs pair up and become physically connected alongtheir lengths by a zipper-like protein structure, the synaptonemal complexcrossing over-genetic rearrangement between nonsister chromatidschiasma- X-shaped region that remain intact during late prophase, it’s a physical manifestation of crossing overmeiosis I- separates homologous chromosomes, 1) prophase 1- replicated homologous chromosomes pair and exchange segments 2) metaphase 1- chromosomes line up by homologous pairs 3)anaphase 1- each pair of homologous chromosomes separate 4) telophase and cytokinesis 1- two haploid cells form, each containing two sister chromatidsmeiosis II- separates sisters chromatids 1) Prophase II 2) Metaphase II 3) Anaphase II- sister chromosomes separate 4) Telophase II and cytokinesis- haploid daughter cells formingsegregation-two alleles for a heritable character segregate during gamete formation and end up in different gametesRatios:Mendel’s experiment mixing 1 trait 3:1Mendel’s experiment mixing 2 traits 9:3:3:1Lecture 13 (ch 14.1)- How did Mendel do his experiments? - How do Mendel’s results relate to blending - Inheritance? - Law of Segregation - Law of Independent Assortment Terms:Gene- a discrete unit of hereditary information consisting of specific nucleotide sequence in DNAAllele- any of the alternative versions of a gene that produce distinguishable phenotypic effectsLocus- a specific place along the length of a chromosome where a given gene is locatedHeterozygote- having two different alleles for a given geneHomozygote- having two identical alleles for a given geneRules for Probability:P(event1)xP(event2)“and” means MULTIPLY“or” means ADDGenotype- the genetic makeup, or set of alleles, in an organismPhenotype- physical and physiological traits of an organism, which are determined by its genetic make upDominant- an allele that is fully expressed in the phenotype of a heterozygoteRecessive- an allele that is only phenotypically expresses with two of the specific allelesF1- first generation of offspring, normally from two true breeding parentsF2- second generation of offspringMonohybrid- an organism that is
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