Module 3
Module 3
This module includes details about how proteins are built and follows the role of DNA in cell division and inheritance. A human begins life as a diploid zygote. In our species, billions of cell divisions subsequently must occur in a controlled manner in order to produce a complex, multicellular human containing trillions of cells. Once a human is fully grown, cell reproduction is still necessary to repair and regenerate tissues. Cell division is closely regulated, and the occasional failure of regulation can have life-threatening consequences. This cover page provides all Module 3 Learning Objectives, a question answered by each chapter and respective chapter summaries.
Module 3 is aligned with the following course objectives
- Apply the basic principles of molecular and Mendelian genetics
- Relate mechanisms of genetic inheritance to evolution
- Test predictions from scientific hypotheses using basic biological laboratory techniques
- Relate cell structure to function
Learning Objectives Chapter 10
How do your abrasions heal after a wound?
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- Recognize the role of cellular division and associated vocabulary
- Identify four phases of mitotic division
- Examine the characteristics of cancer cells
Chapter 10 Summary
Eukaryotes have multiple, linear chromosomes composed of DNA wrapped around histones. The 46 chromosomes of human somatic cells are composed of 22 pairs of autosomes and a pair of sex chromosomes. This is the 2n or diploid state. Human gametes have 23 chromosomes, or one complete set of chromosomes, containing either X or Y. This is the n or haploid state. An organism’s traits are determined by the genes inherited from each parent. The cell cycle is an orderly sequence of events, including a long preparatory period, called interphase. Interphase is divided into G1, S, and G2 phases and chromosomes are replicated during S phase. The phases of mitosis (prophase, metaphase, anaphase and telophase) are followed by cytokinesis. Each step of the cell cycle is monitored by internal controls called checkpoints. Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms that regulate the cell cycle.
Learning Objectives Chapter 11
Why are you different than your siblings?
- Recognize the role of meiosis, particularly in humans
- Recognize the role of crossover, random alignment and random fertilization in variability
- Identify potential sources of error in meiosis
Chapter 11 Summary
Sexual reproduction requires that organisms produce cells that can fuse during fertilization to produce offspring. In most animals, meiosis is used to produce haploid gametes of egg and sperm. The fusion of an egg and sperm produces a diploid zygote. As with mitosis, DNA replication occurs prior to meiosis during the S-phase of the cell cycle. Meiosis has two rounds of nuclear division resulting in four different nuclei with half the number of chromosomes as the parent cell. The first division separates homologous chromosomes, and the second separates chromatids into individual chromosomes. Meiosis generates variation in the daughter nuclei during crossover in prophase I as well as during the random alignment of metaphase I. Cells produced by meiosis are genetically unique, and random fertilization is a result of gamete fusion. In a human karyotype, there are 22 autosomes and the XY sex chromosomes, which are not autosomes. Chromosome number disorders include duplicating or losing entire chromosomes. They are caused by nondisjunction, which occurs when homologous chromosome pairs or sister chromatids fail to separate during meiosis.
Sexual reproduction requires that organisms produce cells that can fuse during fertilization to produce offspring. In most animals, meiosis is used to produce haploid gametes of egg and sperm. The fusion of an egg and sperm produces a diploid zygote. As with mitosis, DNA replication occurs prior to meiosis during the S-phase of the cell cycle. Meiosis has two rounds of nuclear division resulting in four different nuclei with half the number of chromosomes as the parent cell. The first division separates homologous chromosomes, and the second separates chromatids into individual chromosomes. Meiosis generates variation in the daughter nuclei during crossover in prophase I as well as during the random alignment of metaphase I. Cells produced by meiosis are genetically unique, and random fertilization is a result of gamete fusion. In a human karyotype, there are 22 autosomes and the XY sex chromosomes, which are not autosomes. Chromosome number disorders include duplicating or losing entire chromosomes. They are caused by nondisjunction, which occurs when homologous chromosome pairs or sister chromatids fail to separate during meiosis.
Learning Objectives Chapter 12
Where did your chromosomes come from? Where are they going?
- Recognize the role of genes and genetics for inheritance patterns
- Apply principles of inheritance in a monohybrid cross with application of genotype and phenotype percentages
- Identify three patterns of inheritance in human disease
Chapter 12 Summary
Mendel selected a simple biological system and conducted methodical, quantitative analyses using large sample sizes. Because of Mendel’s work, the fundamental principles of heredity were revealed. Working with garden pea plants, Mendel found that crosses between parents that differed by one trait produced first generation (F1) offspring that all expressed the traits of one parent. Observable traits are referred to as dominant, and non-expressed traits are described as recessive. When homozygous individuals that differ for a certain trait are crossed, all of the offspring will be heterozygotes for that trait. If the traits are inherited as dominant and recessive, the F1 offspring will all exhibit the same phenotype as the parent homozygous for the dominant trait. Alleles do not always behave in dominant and recessive patterns. Genes are the basic functional units of heredity with the capability to be replicated, expressed, or mutated. Genetic disorders can follow autosomal dominant, autosomal recessive or sex-linked patterns of inheritance.
Mendel selected a simple biological system and conducted methodical, quantitative analyses using large sample sizes. Because of Mendel’s work, the fundamental principles of heredity were revealed. Working with garden pea plants, Mendel found that crosses between parents that differed by one trait produced first generation (F1) offspring that all expressed the traits of one parent. Observable traits are referred to as dominant, and non-expressed traits are described as recessive. When homozygous individuals that differ for a certain trait are crossed, all of the offspring will be heterozygotes for that trait. If the traits are inherited as dominant and recessive, the F1 offspring will all exhibit the same phenotype as the parent homozygous for the dominant trait. Alleles do not always behave in dominant and recessive patterns. Genes are the basic functional units of heredity with the capability to be replicated, expressed, or mutated. Genetic disorders can follow autosomal dominant, autosomal recessive or sex-linked patterns of inheritance.
Learning Objectives Chapter 14
What is your DNA doing right now?
- Recognize DNA structure and mechanisms
- Identify four major replication enzymes and their function
- Recognize the Central Dogma components, location and steps
- Describe the significance of DNA mutations
Chapter 14 Summary
The genetic code refers to the DNA alphabet (ATCG), the RNA alphabet (AUCG), and the polypeptide alphabet (20 amino acids). DNA replication occurs during S-phase of interphase and involves helicase, DNA polymerase, ligase and telomerase. The central dogma describes the flow of genetic information in the cell from genes to mRNA to proteins. Genes form the template for mRNA by the process of transcription. mRNA is used to synthesize proteins by the process of translation. Transcription occurs in the nucleus of eukaryotes, and translation occurs at the ribosome. Almost every species on the planet uses the same genetic code. The players in translation include the mRNA template, ribosomes, tRNAs, and various enzymatic factors. The formation of peptide bonds occurs between sequential amino acids matched to the mRNA template by their tRNAs according to the genetic code. DNA polymerase can make mistakes while adding nucleotides. It edits the DNA by proofreading every newly added base. Most mistakes are corrected during replication, but there are additional repair systems. If mistakes are not corrected, they may result in a mutation. This is a permanent change in the DNA sequence. Mutations can be of many types, such as substitution, deletion, insertion, and frameshift. Mutations in repair genes may lead to serious consequences such as cancer.
The genetic code refers to the DNA alphabet (ATCG), the RNA alphabet (AUCG), and the polypeptide alphabet (20 amino acids). DNA replication occurs during S-phase of interphase and involves helicase, DNA polymerase, ligase and telomerase. The central dogma describes the flow of genetic information in the cell from genes to mRNA to proteins. Genes form the template for mRNA by the process of transcription. mRNA is used to synthesize proteins by the process of translation. Transcription occurs in the nucleus of eukaryotes, and translation occurs at the ribosome. Almost every species on the planet uses the same genetic code. The players in translation include the mRNA template, ribosomes, tRNAs, and various enzymatic factors. The formation of peptide bonds occurs between sequential amino acids matched to the mRNA template by their tRNAs according to the genetic code. DNA polymerase can make mistakes while adding nucleotides. It edits the DNA by proofreading every newly added base. Most mistakes are corrected during replication, but there are additional repair systems. If mistakes are not corrected, they may result in a mutation. This is a permanent change in the DNA sequence. Mutations can be of many types, such as substitution, deletion, insertion, and frameshift. Mutations in repair genes may lead to serious consequences such as cancer.
When you are ready to prepare for Exam 3, this audio study guide might be helpful.
Biology-2e. (2018). Houston, RX: website: OpenStax Book title: Biology 2e .
Access for free at https://openstax.org/books/biology-2e/pages/1-introduction
