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Bio Exam 2 Ch.7-10
| Question | Answer |
|---|---|
| Describe the basic structure of DNA | double helix composed of two strands of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base. Held together by hydrogen bonds between complementary bases: adenine pairs with thymine, and cytosine pairs with guanine. |
| Describe complementary base pairing | refers to the specific pairing of nitrogenous bases in DNA and RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine, ensuring accurate replication and transcription. |
| Define nucleotide | the basic building block of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar (deoxyribose in DNA and ribose in RNA), and a phosphate group. |
| List the nitrogenous bases found in DNA and mRNA | The nitrogenous bases found in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). In mRNA, the bases are adenine (A), uracil (U), cytosine (C), and guanine (G). |
| Describe the processes of transcription and translation and identify where in cells they occur | The process of synthesizing RNA from a DNA template, occurring in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. Translation is the process of synthesizing proteins from mRNA, occurring in the ribosomes in the cytoplasm. |
| Distinguish between genotype and phenotype | refers to the genetic makeup of an organism, including all alleles, while phenotype refers to the observable physical and biochemical characteristics of an organism, influenced by the genotype and environmental factors. |
| Explain the significance of the Lac operon in E. coli and identify the basic mechanisms involved | metabolism of lactose. Understanding gene regulation. it demonstrates how bacteria can control gene expression due to environmental changes. include the presence of lactose, which inactivates the repressor protein, allowing transcription of the operon. |
| Compare and contrast gene expression in bacteria and eukaryotes | bacteria, gene express. is regulated at the transcription level in the cyto. eukaryotes, gene express. involves multiple levels of regulation;chromatin remodel, transcript control, RNA process, translation. transcription in nucleus, translation in cyto. |
| What is DNA replication? | the process by which a cell makes an exact copy of its DNA before cell division, ensuring that each daughter cell receives a complete set of genetic information. |
| Why is DNA replication necessary prior to cell division? | necessary prior to cell division to ensure that each new cell has the same genetic material as the original cell, which is crucial for maintaining genetic continuity and proper cellular function. |
| What are the steps of the cell cycle? | several stages: G1 phase (cell growth), S phase (DNA synthesis), G2 phase (preparation for mitosis), and M phase (mitosis and cytokinesis). |
| What are the stages of mitosis? | prophase (chromatin condenses into chromosomes), metaphase (chromosomes align at the cell's equator), anaphase (sister chromatids are pulled apart), and telophase (nuclear membranes reform around each set of chromosomes). |
| What is binary fission? | a form of asexual reproduction in which a single organism divides into two identical daughter cells, commonly seen in prokaryotic organisms like bacteria. |
| Why does apoptosis occur? | eliminate cells that are damaged, infected, or no longer needed, thus preventing potential harm to the organism and maintaining overall health. |
| What cellular signals regulate cell division? | regulated by various signals, including growth factors, cyclins, and checkpoints that ensure the cell is ready to divide and that DNA is intact. |
| How are abnormalities in cell cycle control related to cancerous cells? | Abnormalities in cell cycle control can lead to uncontrolled cell division, resulting in the formation of tumors and cancer, as the regulatory mechanisms fail to prevent the proliferation of damaged or mutated cells. |
| Compare and contrast sexual and asexual reproduction | Sexual reproduction involves the fusion of gametes from two parents, resulting in offspring with genetic variation. Asexual reproduction involves a single parent producing genetically identical offspring without the fusion of gametes. |
| Define gamete | A gamete is a reproductive cell that carries half the genetic information of an organism, specifically sperm in males and eggs in females. |
| Explain the difference between haploid and diploid cells | Haploid cells contain one set of chromosomes (n), while diploid cells contain two sets of chromosomes (2n). Gametes are haploid, whereas somatic cells are diploid. |
| Explain how meiosis generates variability in gametes | Meiosis generates variability through processes such as independent assortment of chromosomes and crossing over, which shuffle genetic material and create diverse combinations of alleles in gametes. |
| Compare and contrast mitosis and meiosis | Mitosis results in two genetically identical diploid cells and is involved in growth and repair, while meiosis produces four genetically diverse haploid gametes and is essential for sexual reproduction. |
| List and describe the types of errors that can occur in meiosis | Errors in meiosis can include nondisjunction (failure of chromosomes to separate properly), leading to aneuploidy (abnormal number of chromosomes), and crossing over errors, which can result in genetic disorders. |
| Chromosomes | Structures within cells that contain DNA and carry genetic information. |
| DNA | Deoxyribonucleic acid, the molecule that carries the genetic instructions for life. |
| Genes | Segments of DNA that code for proteins and determine specific traits. |
| Alleles | Different versions of a gene that can exist at a specific locus on a chromosome. |
| Locus/Loci | The specific physical location of a gene or allele on a chromosome. |
| Dominant | An allele that expresses its trait even in the presence of a recessive allele. |
| Recessive | An allele that only expresses its trait when two copies are present (homozygous). |
| Heterozygous | Having two different alleles for a specific gene (e.g., Aa). |
| Homozygous | Having two identical alleles for a specific gene (e.g., AA or aa). |
| Phenotype | The observable characteristics or traits of an organism, influenced by genotype and environment. |
| Genotype | The genetic makeup of an organism, representing the alleles it carries. |
| Wild-type | The most common phenotype or genotype found in a natural population. |
| Mutant | An organism that has undergone a change in its DNA sequence, resulting in a new phenotype. |
| Monohybrid Cross | A genetic cross between parents that differ in a single trait, used to study inheritance patterns. |
| Dihybrid Cross | A genetic cross between parents that differ in two traits, allowing for the study of two genes simultaneously. |
| Incomplete Dominance | A genetic situation in which one allele does not completely dominate another, resulting in a blended phenotype. |
| Codominance | A genetic situation where both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits. |
| Multiple Alleles | A situation in which a gene has more than two alleles, leading to various possible phenotypes. |
| Pleiotropy | The phenomenon where a single gene influences multiple phenotypic traits. |
| Mendel's Law of Segregation | The principle stating that alleles for a trait separate during gamete formation, ensuring that offspring receive one allele from each parent. |
| Linked Genes | Genes that are located close to each other on the same chromosome and tend to be inherited together. |
| Pedigrees | Diagrams that show the occurrence and appearance of phenotypes of a particular gene or organism across generations. |
| Environmental Influence on Phenotype | The concept that environmental factors can affect the expression of genes, leading to variations in phenotype. Temperature, light, and toxins affect. "Act as signals to turn genes on or off". Incubation temperature of eggs determines sex of reptiles. |
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