BIO 110 1nd EditionExam # 3 Study Guide Lectures: 9,10,13,14Lecture 91. What do capital letters represent in alleles? Lowercase?- Capital letters represent a dominant allele- Lowercase letters represent a recessive allele2. What is the difference between homozygous and heterozygous?- Homozygous: organism with two identical alleles- Heterozygous: organism with two different alleles3. What is a phenotype and genotype?- A phenotype is a physical appearance- A genotype is the genetic makeup4. What is the law of segregation?- States that two alleles for a heritable character separate during gamete formation and end up in different gametes5. What are the monohybrids? Monohybrid crosses?- Monohybrids are individuals that are heterozygous for one character- A monohybrid cross is a cross between such heterozygotes is called a monohybrid cross6. What are dihybrids?- Results from crossing two true-breeding parents differing in two characters (heterozygous for both characters)7. What is the law of independent assortment?- States that each pair of alleles separates independently of each other pair of alleles during gamete formation8. What is incomplete dominance? Complete?- Incomplete: when alleles are not completely dominant or recessive- Complete: occurs when phenotypes of the heterozygote and dominant homozygote are identical9. What are the sex chromosomes in males and females?- Males: XY- Females: XXLecture 101. What is a gene?- Unit of inheritance2. What are polynucleotides and what are they made out of?- Nucleic acids are polymers called polynucleotides- They are made out of monomers called nucleotides3. What do nucleotides consist of?- Nitrogenous base, pentose sugar, and a phosphate group4. What are the two families of nitrogenous bases?- Pyrimidine’s (cytosine, thymine, uracil) single six membered ring- Purines (adenine, guanine) six membered ring fused to a five membered ring5. What is a phosphodiester linkage?- Consists of a phosphate group that links the sugar of two nucleotides6. What are the hydrogen bonds in the nitrogenous bases in DNA?- Adenine always with thymine (A and T)- Guanine always with cytosine (G and C)7. What is gene expression and what are the two stages?- The process by which DNA directs protein synthesis- The two stages are transcription and translation8. What is transcription?- Synthesis of RNA under the direction of DNA it produces messenger RNA (mRNA)9. What is translation? What are the sites?- Synthesis of a polypeptide, which occurs under the direction of mRNA10. What is a triplet code?- Series of nonoverlapping, three-nucleotide words known as a CODON11. What is the reading frame?- Correct groupings that codons must be read in order for the specified polypeptide to be produced12. What is the difference between RNA synthesis and DNA synthesis?- RNA synthesis follows the same base pairing rules as DNA except uracil substitutes for thymine13. What are the three stages of transcription?- Initiation, elongation, termination14. What do tRNA molecules consist of and what is its function?- Consists of a single RNA strand that is only about eighty nucleotides long- Each carries a specific amino acid on one end, each has an anticodon on the other endChapter 131. What were the two main ideas developed by Darwin?- Descent with modification explains life’s unity and diversity- Natural selection is a cause of adaptive evolution2. What is natural selection and artificial selection?- Natural: process in nature by which, only the organisms best adapted to their environment tend to survive and reproduce while those that are less adapted are eliminated- Artificial: natural selection by analogy to how farmers select crops or livestock for breeding3. What were Darwin’s four observations?- Members of a population often vary greatly in their traits- Traits are inherited from parents to offspring- All species are capable of producing more offspring than the environment can support- Owing to lack of food or other resources, many of these offspring do not survive4. What is homology and what are homologous structures?- Homology: similarity resulting from common ancestry- Homologous structures: anatomical resemblances that represent variations on a structural theme present in a common ancestor5. What is comparative embryology?- Reveals anatomical homologies not visible in adult organismsChapter 141. What is speciation?- Process by which one species split into two more species2. What is a species?- A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; do not breed successfully with other populations3. What is reproductive isolation?- Existence of biological factors that impede two species from producing viable, fertile offspring4. What are hybrids?- Offspring of crosses between different species5. How do pre-zygote barriers block fertilization from occurring?- Impeding different species from attempting to mate- Preventing the successful completion of mating- Hindering fertilization if mating is successful6. What are the five types of isolation?- Habitat: two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers- Temporal: species that breed at different times of the day, different seasons, or different years cannot mix their gametes- Behavioral: courtship rituals and other behaviors unique to a species are effective barriers- Mechanical: morphological differences can prevent successful mating- Gametic: sperm of one species may not be able to fertilize eggs of another species7. How do post-zygote barriers prevent the hybrid zygote from developing into a viable, fertile adult?- Reduced hybrid viability- Reduced hybrid fertility- Hybrid breakdown8. What is reduced hybrid viability and reduced hybrid fertility?- Reduced hybrid viability: genes of different parent species may interact and impair hybrids development- Reduced hybrid fertility: even if hybrids are vigorous, they may be sterile9. In what two ways can speciation occur?- Allopatric: gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations- Sympatric: speciation takes place in geographically overlapping populations10. What is punctuated equilibrium?- Describes periods of apparent stasis punctuated by sudden