Unit 8
Chapter Overview
In this unit, students recognize the significance of meiosis and make predictions using Mendelian and non-Mendelian genetics. Students also recognize that disruptions of the cell cycle lead to diseases in the context of meiosis and the mechanics of genetics. Students also learn about the use of biotechnology to study genomes. Students analyze, evaluate, infer, and predict trends using data from various genetic combinations. Finally, students learn about the contributions of scientists, such as Gregor Mendel, to the field of genetics and recognize the advancements that have been made in this field in recent time.
Main Ideas
Genes are expressed or not expressed, based on allele dominance and chromatin structure regulated by the cell’s DNA, RNA, and response to environmental factors
What factors influence inheritance patterns and expression of genes?
In what ways does gene expression influence cell differentiation?
Many genes are expressed in predictable patterns based on allele dominance behavior, and the probability of offspring inheritance of these genes and traits can be calculated.
In what ways can the probability of offspring inheritance be calculated?
What are the limitations of calculating the probability of offspring inheritance?
What role does meiosis play in the probability of offspring inheritance?
The genome of each species can be analyzed using scientific technology and techniques that provide details on the function and heredity of genes.
How do genes and chromosomes relate to heredity?
In what ways are scientific technology and techniques used to study genomics?
What information does the study of genomics provide about genetics and heredity?
Misconceptions
Students may think that Punnett squares give the exact genotypic and phenotypic ratios of a genetic cross, when in fact the ratios only indicate the probability of a particular outcome.
Students may think that dominant traits are more common in the population than recessive traits, rather than dominance only indicating which allele will be expressed, but not the rarity of the alleles.
Students may think that all or most traits follow the well-studied Mendelian Laws of Inheritance rather than understanding that the expression of most traits (especially in humans) are controlled by many factors and mechanisms not directly explained by Mendelian Laws.
Vocabulary
Centrioles – Organelles in the cell that help to move chromosomes during cell division
Chromatid – One of the “arms” of a chromosome ‘X’. Each chromatid is identical to the other because it is created by replication. A chromosome is made of two Sister Chromatids.
Chromatin – What you call the DNA during Interphase, Very easy to access the genes for transcription and translation to create proteins
Chromosome – What you call the DNA during the actual cell division stages (Pro-, Meta-, Ana-, and Telophase). Condensed/packed DNA for easy movement during cell division
Crossing Over – A kind of chromosomal mutation that happens in Prophase 1 of meiosis. Homologous chromosomes overlap and exchange pieces of the chromosome which caused genetic variability.
Diploid – A cell that has twice the amount of chromosome. A cell that is “2N” for chromosome amount
Fertilization – The process of making a zygote. When egg and sperm cells fuse and combine their genetic information (DNA)
Gamete – the haploid “sex” cells (in animals they are sperm and egg cells)
Haploid – A cell that has half the amount of chromosomes. A cell that is “N” for chromosome amount
Homologous Chromosomes – the same numbered chromosome that pair up from mother and father (ex: mom’s chromosome 1 and dad’s chromosome 1)
Nondisjuction – Happens in either Anaphase 1 or Anaphase 2 of meiosis when one centriole does not connect to the chromosome with a spindle fiber. Causes the gametes to have extra or missing chromosomes.
Reduction division – When the number of chromosomes per cell is cut in half
Somatic Cell – all diploid cells (body cells) that are not gametes
Spindle Fiber – fibers created and used by the centrioles to move the chromosomes around during the division stages.
Zygote – fertilized egg cell formed form the joining of the gametes (sperm and egg)
Notes
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