Genetics and Molecular Biology Chapter 13
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Questions and Answers

What is the field of study that focuses on chromosome behavior and structure?

Cytogenetics

What are the two types of large molecules that make up chromosomes?

  • DNA and RNA
  • RNA and protein
  • DNA and protein (correct)

    • Which of the following is NOT a part of a nucleotide?

  • 5-carbon sugar
  • Amino acid (correct)
  • Phosphate group
  • Nitrogenous base

    • What is the name given to genes or small DNA fragments that can move to a new location within a chromosome?

    <p>Transposable elements</p> Signup and view all the answers

    Who discovered transposable elements in the 1950s?

    <p>Barbara McClintock</p> Signup and view all the answers

    The discovery of DNA structure in 1953 by James Watson and Francis Crick had little impact on the field of molecular genetics.

    <p>False</p> Signup and view all the answers

    Mutations are always harmful and lead to negative consequences for organisms.

    <p>False</p> Signup and view all the answers

    Which type of mutation occurs in body cells and is not passed on to offspring?

    <p>Somatic mutation</p> Signup and view all the answers

    Which of the following is NOT a type of change in chromosome structure?

    <p>Polyploidy</p> Signup and view all the answers

    Inversions and translocations are not important in the process of speciation.

    <p>False</p> Signup and view all the answers

    Which type of chromosome number change involves one or more extra chromosomes?

    <p>Aneuploidy</p> Signup and view all the answers

    What type of organism has at least one complete extra set of chromosomes?

    <p>Polyploid</p> Signup and view all the answers

    Gregor Mendel's work was widely recognized and accepted during his lifetime.

    <p>False</p> Signup and view all the answers

    What is the name given to the offspring of a cross between two true-breeding parents?

    <p>F1 generation</p> Signup and view all the answers

    Which of the following is NOT a fundamental Mendelian law?

    <p>Law of natural selection</p> Signup and view all the answers

    The law of dominance states that for any given pair of alleles, the dominant allele will always mask the expression of the recessive allele.

    <p>True</p> Signup and view all the answers

    What term refers to an organism's physical appearance?

    <p>Phenotype</p> Signup and view all the answers

    What term refers to an organism's genetic makeup?

    <p>Genotype</p> Signup and view all the answers

    What term describes an individual with two identical alleles for a trait?

    <p>Homozygous</p> Signup and view all the answers

    What is the genotypic ratio of a monohybrid cross in the F2 generation?

    <p>1:2:1</p> Signup and view all the answers

    What is the phenotypic ratio of a dihybrid cross?

    <p>9:3:3:1</p> Signup and view all the answers

    The law of independent assortment states that alleles for different traits are inherited together.

    <p>False</p> Signup and view all the answers

    What is the name given to a cross between a hybrid and one of its parents?

    <p>Backcross</p> Signup and view all the answers

    A testcross is used to determine whether a plant with a dominant phenotype is homozygous or heterozygous.

    <p>True</p> Signup and view all the answers

    What is the term for the phenomenon where a heterozygote exhibits an intermediate phenotype compared to the two homozygotes?

    <p>Incomplete dominance</p> Signup and view all the answers

    Which of the following is NOT a factor that contributes to the control of phenotype by genotype?

    <p>The presence of transposable elements</p> Signup and view all the answers

    Quantitative traits are typically studied using the same methods as discrete traits.

    <p>False</p> Signup and view all the answers

    What is the term for a chromosomal segment associated with a quantitative trait?

    <p>Quantitative Trait Loci (QTL)</p> Signup and view all the answers

    The endosymbiont hypothesis suggests that mitochondria and chloroplasts were once free-living bacteria that formed symbiotic relationships with early eukaryotic cells.

    <p>True</p> Signup and view all the answers

    The DNA found in mitochondria and chloroplasts is similar to bacterial DNA.

    <p>True</p> Signup and view all the answers

    How are extranuclear genes typically inherited?

    <p>Through the egg</p> Signup and view all the answers

    Which of the following is NOT a characteristic of linked genes?

    <p>They always segregate independently during gamete formation</p> Signup and view all the answers

    Recombinant types of offspring are produced when crossing over occurs between linked genes.

    <p>True</p> Signup and view all the answers

    The frequency of crossing-over can be used to construct a genetic map of chromosomes.

    <p>True</p> Signup and view all the answers

    The Hardy-Weinberg Law describes the conditions under which allele frequencies remain constant in a population.

    <p>True</p> Signup and view all the answers

    The Hardy-Weinberg Law is often observed perfectly in natural populations.

    <p>False</p> Signup and view all the answers

    What is the most significant cause of deviation from the Hardy-Weinberg Law?

    <p>Natural selection</p> Signup and view all the answers

    What are transposable elements?

    <p>Transposable elements, also known as jumping genes, are genes or small DNA fragments that can move to a new location within the genome.</p> Signup and view all the answers

    What is the name of the process by which the DNA molecule is copied, or replicated?

    <p>Replication</p> Signup and view all the answers

    What are the three parts of a nucleotide?

    <p>Nitrogenous base, 5-carbon sugar (deoxyribose), and phosphate group.</p> Signup and view all the answers

    The two strands of DNA are held together by what type of bond?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What are the two main functions of DNA?

    <p>Storage of genetic information and replication/duplication of information.</p> Signup and view all the answers

    During transcription, DNA is copied into RNA.

    <p>True</p> Signup and view all the answers

    RNA contains the sugar deoxyribose.

    <p>False</p> Signup and view all the answers

    Translation occurs in the nucleus of the cell.

    <p>False</p> Signup and view all the answers

    Which type of RNA is translated to produce proteins?

    <p>Messenger RNA (mRNA)</p> Signup and view all the answers

    What is the name of the basic unit of heredity?

    <p>Gene</p> Signup and view all the answers

    What is the name of the process that involves copying the genetic message from a DNA template using RNA building blocks?

    <p>Transcription</p> Signup and view all the answers

    What is the name of the process of translating RNA to produce proteins?

    <p>Translation</p> Signup and view all the answers

    The flow of genetic information is bidirectional.

    <p>False</p> Signup and view all the answers

    Agents that alter DNA sequences are called what?

    <p>Mutagens</p> Signup and view all the answers

    What is the name of a mutation that occurs in body cells?

    <p>Somatic mutation</p> Signup and view all the answers

    What is the name of a mutation that occurs in tissues that will produce sex cells?

    <p>Germ-line mutation</p> Signup and view all the answers

    What is the name of the study of chromosome behavior and structure from a genetic point of view?

    <p>Cytogenetics</p> Signup and view all the answers

    In what type of environment is asexual reproduction more selectively advantageous?

    <p>Stable environments</p> Signup and view all the answers

    Which type of reproduction creates offspring that are genetically diverse?

    <p>Sexual reproduction</p> Signup and view all the answers

    The offspring created by asexual reproduction can quickly colonize a new site.

    <p>True</p> Signup and view all the answers

    What is the main advantage of sexual reproduction?

    <p>Genetically diverse offspring</p> Signup and view all the answers

    What are the two main types of reproduction?

    <p>Sexual and asexual reproduction</p> Signup and view all the answers

    What is the definition of reproduction?

    <p>The creation of new individuals within a species</p> Signup and view all the answers

    Where does meiosis occur in plants?

    <p>The anther and ovule</p> Signup and view all the answers

    What is the male gametophyte called?

    <p>Pollen</p> Signup and view all the answers

    Where is the female gametophyte located?

    <p>The ovule</p> Signup and view all the answers

    Mitosis is an important process that is only observed in haploid cells.

    <p>False</p> Signup and view all the answers

    Amitosis is the most common mode of cell division.

    <p>False</p> Signup and view all the answers

    Mitosis can be described as an equational division, involving the division of both nucleus and cytoplasm.

    <p>True</p> Signup and view all the answers

    Meiosis is a reduction division, which means the number of chromosomes is reduced.

    <p>True</p> Signup and view all the answers

    In a stable environment, sexual reproduction is more selectively advantageous.

    <p>False</p> Signup and view all the answers

    Asexual reproduction results in progeny that are genetically diverse.

    <p>False</p> Signup and view all the answers

    What is the process by which living plants produce one of their own kinds?

    <p>Reproduction</p> Signup and view all the answers

    Which of the following is NOT a type of cell division in plants?

    <p>Endomitosis</p> Signup and view all the answers

    The anther and ovule are the sites of meiosis.

    <p>True</p> Signup and view all the answers

    The pollen is the immature gametophyte.

    <p>True</p> Signup and view all the answers

    The female gametophyte is housed in the ovule.

    <p>True</p> Signup and view all the answers

    Amitosis is the usual mode of division.

    <p>False</p> Signup and view all the answers

    Mitosis is observed in all types of cells - haploid, diploid, or polyploid.

    <p>True</p> Signup and view all the answers

    Meiosis is a reductive division.

    <p>True</p> Signup and view all the answers

    Fragmentation is a method of sexual reproduction.

    <p>False</p> Signup and view all the answers

    Sexual reproduction gives rise to genetic variation.

    <p>True</p> Signup and view all the answers

    All flowers share the same basic floral plant.

    <p>True</p> Signup and view all the answers

    What are the outermost floral appendages?

    <p>Sepals</p> Signup and view all the answers

    Which of the following is a collective term for petals?

    <p>Corolla</p> Signup and view all the answers

    The ovule is housed within the ovary.

    <p>True</p> Signup and view all the answers

    The nucellus is a central mass of parenchyma that is housed within the ovule.

    <p>True</p> Signup and view all the answers

    An ovule develops into a fruit after it is fertilized.

    <p>False</p> Signup and view all the answers

    The microgametophyte in angiosperms consists of at most three cells.

    <p>True</p> Signup and view all the answers

    The megaspore nucleus divides into two nuclei.

    <p>False</p> Signup and view all the answers

    Which of the following are included in the megagametophyte?

    <p>All of the above</p> Signup and view all the answers

    Plasmogamy is the fusion of the protoplasts of the gametes.

    <p>True</p> Signup and view all the answers

    The pollen tube penetrates the nucellus, reaches the egg apparatus, and enters one synergid.

    <p>True</p> Signup and view all the answers

    In angiosperms, the second sperm nucleus migrates into the central cell, undergoes karyogamy with both polar nuclei, and establishes a large triploid endosperm nucleus.

    <p>True</p> Signup and view all the answers

    The endosperm nucleus undergoes very rapid mitosis, and the resulting endosperm nourishes the development of the zygote.

    <p>True</p> Signup and view all the answers

    The zygote grows and forms a short, stalk-like suspensor that pushes the embryo deep into the endosperm.

    <p>True</p> Signup and view all the answers

    The embryo elongates and the root/shoot junction (hypocotyl) is established.

    <p>True</p> Signup and view all the answers

    Cotyledons store nutrients that are used during and after germination.

    <p>True</p> Signup and view all the answers

    In monocots, the endosperm remains in the mature seed; the cotyledon is thin.

    <p>True</p> Signup and view all the answers

    Fruits are adaptations that result in the protection and distribution of seeds.

    <p>True</p> Signup and view all the answers

    Fleshy fruits are inedible to animals.

    <p>False</p> Signup and view all the answers

    Dehiscent fruits open, releasing the seeds.

    <p>True</p> Signup and view all the answers

    In grasses, the seed and fruit are fused together. There is little protection, and no attraction for animals.

    <p>True</p> Signup and view all the answers

    Beans and peas are called legumes.

    <p>True</p> Signup and view all the answers

    Wind-dispersed seeds are lightweight and often have wings or parachutes that carry them in the wind.

    <p>True</p> Signup and view all the answers

    Fruits that are transported by water must be buoyant and resist mildew and rot.

    <p>True</p> Signup and view all the answers

    Animals often disperse seeds by interacting with the fruit.

    <p>True</p> Signup and view all the answers

    Pomes (apples and pears) develop from superior ovaries and are accessory fruits.

    <p>False</p> Signup and view all the answers

    Drupes (peaches and cherries) provide a maximum attraction to animals with minimum danger to the seeds.

    <p>True</p> Signup and view all the answers

    There are benefits beyond dispersal for seeds that are distributed by animals. Seeds may find themselves in a mound of 'organic fertilizer'.

    <p>True</p> Signup and view all the answers

    Cross-pollination is by pollen from a different individual.

    <p>True</p> Signup and view all the answers

    Mechanisms have evolved to decrease the probability of self-pollination and increase the chances of cross-pollination.

    <p>True</p> Signup and view all the answers

    Self-pollination may be inhibited by compatibility barriers that include chemical reactions between pollen and carpels that prevent pollen tube growth.

    <p>True</p> Signup and view all the answers

    Flowers that lack either stamens or carpels are called perfect flowers.

    <p>False</p> Signup and view all the answers

    Dioecy ensures cross-pollination by having distinct individuals of a species that produce only staminate flowers and others that produce only carpellate flowers.

    <p>True</p> Signup and view all the answers

    Animal-pollinated flowers exhibit dramatic evolutionary changes that include a process called coevolution.

    <p>True</p> Signup and view all the answers

    Most flowers are bilaterally symmetrical and are called actinomorphic.

    <p>False</p> Signup and view all the answers

    Zygomorphic flowers are easier for animals to interact with successfully because both the flower and the insect receive their rewards.

    <p>True</p> Signup and view all the answers

    Wind-pollinated flowers usually have no petals and reduced or absent sepals.

    <p>True</p> Signup and view all the answers

    Long styles and stamens with buried ovaries help protect the ovary and ovules from pollinators. Ovaries that are partially buried are called half-inferior.

    <p>True</p> Signup and view all the answers

    Reproductive success may be increased by increasing the number of ovules per flower. Small flowers with fewer ovules may be grouped together in an inflorescence, being visible and less risky than a single large flower.

    <p>True</p> Signup and view all the answers

    Fruits can be described as 'true' fruits (which have only ovarian tissue) or accessory fruits.

    <p>True</p> Signup and view all the answers

    Fruits and seeds that are transported by water must be buoyant and resist mildew and rot.

    <p>True</p> Signup and view all the answers

    Study Notes

    Chapter 13: Genetics and Molecular Biology

    • This chapter covers genetics and molecular biology, specifically focusing on plant biology.
    • The book is titled Stern's Introductory Plant Biology, 15th Edition, by James E. Bidlack and Shelly H. Jansky.
    • The chapter outline includes: introduction to genetics and molecular biology, molecular genetics, cytogenetics, Mendelian genetics, the dihybrid cross, the backcross, the testcross, incomplete dominance, chromosomal interactions, phenotypic control, quantitative traits, extranuclear DNA, linkage and mapping, and the Hardy-Weinberg Law.
    • Introduction to plant biology discusses transposition.
    • Transposition involves the movement of a chromosome piece to another chromosome location.
    • Transposable elements, also known as jumping genes, are genes or small DNA fragments that can move.
    • These elements can disrupt the function of a gene or restore original function.
    • Barbara McClintock discovered transposable elements in the 1950s and received a Nobel Prize in 1983 for her work.
    • Molecular genetics involves the discovery of DNA structure in 1953 by James Watson and Francis Crick.
    • This discovery initiated the study of genes as sequences of nucleic acids that can be isolated and characterized.
    • Mutations were also better understood as a result.
    • Chromosomes are composed of DNA and protein.
    • DNA is a chain of nucleotides, each with a nitrogenous base, a 5-carbon sugar (deoxyribose), and a phosphate group..
    • Four types of DNA nucleotides exist: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
    • Purines (A and G) have two rings, while pyrimidines (C and T) have one ring in their structure.
    • Nucleotides bond to form a ladder-like structure that is twisted into a helix.
    • The sides of the helix are composed of alternating sugar and phosphate groups.
    • Hydrogen bonds hold the base pairs together (G-C and A-T).
    • Molecular genetics DNA functions include storing genetic information in DNA's nucleotide sequence.
    • Genes direct protein synthesis, which serve as structural or storage materials or enzymes for cell activity.
    • Genome refers to the total DNA in an organism's chromosomes.
    • Replication occurs during the S phase of the cell cycle.
    • Strands of the double helix unzip, creating single strands that act as templates for new strands.
    • Nucleotides are added in a precise sequence (G-C and A-T).
    • The new DNA molecule contains one strand from the original molecule and another built in a new strand, creating a semi-conservative replication process.
    • Expression of information occurs in different cell types, influenced by the cell's environment.
    • Expression requires transcription and translation.
    • Transcription involves copying a gene's message from DNA into RNA.
    • RNA contains ribose sugar instead of deoxyribose, is single-stranded, and replaces thymine with uracil.
    • Translation involves translating RNA into proteins in the cytoplasm.
    • Three types of RNA are produced during transcription: Messenger RNA (mRNA), which translates to produce proteins; Transfer RNA (tRNA), which functions as the machinery for translation; and Ribosomal RNA (rRNA), which serves as the machinery for translation as well.
    • During RNA synthesis, nucleotides are added to single-stranded DNA, using complementary base pairing.
    • Only portions of the genome are transcribed; the rest is noncoding DNA.
    • The process of transcription involves promoter regions at the beginning of each gene to signal transcription enzymes to begin copying the gene.
    • Terminator DNA sequences at the end of genes signal the enzymes to stop copying.
    • Nonprotein-coding DNA controls gene expression.
    • Chromosomes contain genes essential for tRNA.
    • tRNA acts as a translator during translation.
    • One end of tRNA binds to mRNA, and the other end binds to a specific amino acid.
    • Each tRNA has a specific anticodon to pair with a codon on the mRNA, and at least one tRNA form exists for every amino acid.
    • Genes for rRNA are also transcribed in the nucleus, and these are used to create ribosomes.
    • Ribosomes act as workbenches to assist in protein assembly during translation.
    • mRNA transcripts code for proteins using codons.
    • Codons are three nucleotides, and there are 64 possible combinations that code for 20 amino acids.
    • The order of nucleotides in mRNA determines the amino acid sequence during translation.
    • The genetic code remains the same in different organisms.
    • Anticodons of tRNA bind to mRNA codons, marking the start of translation.
    • Translation begins in the cytoplasm when a ribosome binds to mRNA.
    • Codons (AUG) set the reading frame for translation.
    • The central dogma of molecular genetics describes the unidirectional flow of information from DNA to RNA to protein.
    • Mutations are changes in DNA sequences.
    • Mutagens are agents that alter DNA sequences, such as ultraviolet light, ionizing radiation, and certain chemicals.
    • DNA repair enzymes correct most DNA damage.
    • Somatic mutations occur in body cells, while germ-line mutations occur in sex cells and can be passed to future generations.
    • All genetic variability comes from mutations.
    • Cytogenetics studies chromosomal behavior and structure for genetic view.
    • Chromosome structure changes due to inversions (chromosomal piece breaks and reinserts in the opposite orientation) and translocations (chromosomal piece breaks off and attaches to another chromosome).
    • Inversions and translocations are important factors in speciation.
    • Changes in chromosome number can occur due to mistakes during chromosome pairing and separation.
    • Aneuploidy arises when a cell carries one or more extra or missing chromosomes.
    • Polyploidy involves having at least one complete extra set of chromosomes.
    • Meiosis may fail to halve chromosome number, leading to polyploidy, Often, polyploids are larger and yield more crops or higher amounts.
    • Examples of polyploids are cotton, potato, peanuts, wheat, oats, strawberries, and sugarcane.
    • Gregor Mendel's experiments in the 1860s, though not immediately understood, revealed the basis for modern genetics.
    • Mendel used pea plants with various traits.
    • He studied the parental (P) generation, first filial (F1) generation, and second filial (F2) generation.
    • This work forms the foundation of modern genetics.
    • Mendel's laws of unit characters include factors (alleles) that occur in pairs, controlling inheritance.
    • Genes are at specific positions (loci) on homologous chromosomes.
    • Mendel's law of dominance states that one allele (dominant) can mask the expression of another (recessive).
    • Phenotype refers to an organism's physical appearance, while genotype refers to the genetic information.
    • Homozygotes have identical alleles, while heterozygotes have contrasting alleles.
    • A monohybrid cross involves true-breeding plants differing for one trait, creating F1 and F2 generations and a 1:2:1 genotypic and 3:1 phenotypic ratio.
    • The dihybrid cross involves true-breeding organisms differing for two traits.
    • Factors controlling the traits segregate independently.
    • Linked genes are on the same chromosome, unlike unlinked genes found on different chromosomes.
    • The F1 generation of a dihybrid cross contains dihybrids.
    • The Punnett square determines the genotypes of zygotes, and the dihybrid cross produces a 9:3:3:1 phenotypic ratio.
    • The backcross is between a hybrid and one of its parents.
    • Mendel used this technique to test his predictions, expecting a 1:1 phenotypic ratio.
    • The testcross involves crossing a plant with a dominant phenotype with a homozygous recessive plant to determine if the dominant is heterozygous or homozygous.
    • Incomplete dominance occurs when the heterozygote is intermediate in phenotype compared to the two homozygotes.
    • Interactions among genes can involve more than one gene controlling a phenotype.
    • Genes that control a phenotype are responsible for producing proteins as parts of biochemical pathways.
    • Blue-eyed Mary plants have two genes that control flower color (W gene and M gene).
    • The dominant allele codes for a protein that catalyzes a reaction, while the recessive allele represents a mutant that cannot catalyze the reaction and does not produce a functional product.
    • Quantitative traits exhibit a range of phenotypes instead of discrete phenotypes.
    • These traits include things like fruit yield and flowering days and can differ within genetically identical groups due to environmental factors.
    • The genetically identical plants can have different traits under various growth conditions.
    • Molecular geneticists identify quantitative trait loci (QTLs), which are chromosomal fragments associated with quantitative trait traits.
    • QTLs contain genes influencing traits and behave like Mendelian genes.
    • Extranuclear DNA exists in mitochondria and chloroplasts.
    • The endosymbiont hypothesis suggests that mitochondria and chloroplasts are free-living bacteria.
    • They established a symbiotic relationship with cells.
    • Their DNA is similar to bacteria DNA.
    • Sperm rarely carry mitochondria or chloroplasts and therefore maternal inheritance transfers DNA
    • Linkage and mapping studies relate linked genes that are located close together on a chromosome.
    • These genes are more likely to be inherited together because there's less chance of crossing over.
    • Each gene has a specific locus on a chromosome.
    • Crossing over is more likely between genes located far apart.
    • Recombinant types are offspring with crossing-over.
    • Crossing frequency can be used to create a chromosome genetic map where 1 map unit equal to 1% crossing over between a pair of genes.
    • DNA sequence information reveals gene function in different species.
    • The Hardy-Weinberg law describes allelic proportions in a large, random mating population.
    • The proportions of dominant and recessive alleles remain the same from generation to generation.
    • Small population size and selection are forces that significantly impact allelic proportions within a generation.

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    Description

    Explore Chapter 13 of Stern's Introductory Plant Biology, focusing on genetics and molecular biology in plant systems. This chapter covers essential topics such as Mendelian genetics, transposable elements, and the Hardy-Weinberg Law. Test your knowledge on key concepts of plant genetics and its molecular mechanisms.

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