Unit Overview

In the previous unit, students were introduced to the parts of the cell. In this unit, students will focus on DNA, found in the nucleus, and its role in reproduction of cells and full organisms (meiosis and meitosis).

Standards

Next Generation Science Standards – Middle School (NGSS-MS):

LS1-1: Conduct an investigation to provide evidence that living things are made of cells, either one cell or many different numbers and types of cells.

Emphasize: living things are made of cells, living things can be made of one or more than one cell or type of cell; distinguish between living and non-living cells

LS1-2: Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.

Emphasize: cell functioning and the primary role of identified parts of the cell – such as the nucleus

LS3-1. Develop and use a model to describe why structural changes to genes (mutations) located on chromosomes may affect proteins and may result in harmful, beneficial, or neutral effects to the structure and function of the organism.

Core Ideas: Genes are located in the chromosomes of cells, with each chromosome pair containing two variants of each of many distinct genes. Each distinct gene chiefly controls the production of specific proteins, which in turn affects the traits of the individual. Mutations to genes can result in changes to proteins, which can affect the structures and functions of the organism and thereby change traits. In addition to variations that arise from sexual reproduction, genetic information can be altered because of mutations. Though rare, mutations may result in changes to the structure and function of proteins. Some changes are beneficial, others harmful, and some are neutral to the organism.

Emphasize: changes in genetic material may result in making different proteins; do not include specific changes at the molecular level, mechanisms for protein synthesis, or specific types of mutations.

LS3-2. Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.

Core Ideas: Organisms reproduce, either sexually or asexually, and transfer their genetic information to their offspring. Variations of inherited traits between parent and offspring arise from genetic differences that result from the subset of chromosomes inherited. In sexually reproducing organisms, each parent contributes half of the genes acquired (at random) by the offspring.

Emphasize: using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parent(s) to offspring and resulting genetic variation.

LS4-5. Gather and synthesize information about the technologies that have changed the way humans influence the inheritance of desired traits in organisms.

Core idea: In artificial selection, humans have the capacity to influence certain characteristics of organisms by selective breeding. One can choose desired parental traits determined by genes, which aare then passed on to offspring.

Emphasize: synthesizing information from reliable sources about the influence of humans on genetic outcomes in artificial selection (such as genetic modification, animal husbandry, gene therapy)

Science and Engineering:

• Oral and written argument supported by evidence to support or refute an explanation or model
• Develop and use a model to describe phenomena.
• Gather, read, synthesize information from multiple sources

Crosscutting concepts:

• Phenomena that can be observed at one scale may not be observable at another scale.
• Cause and effect relationships may be used to predict phenomena in natural systems.
• Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.
• Engineering advances have led to important discoveries in virtually every field of science; these have led to development of industries and engineered systems.
• Science knowledge can describe consequences of actions but does not make the decisions that society takes.
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California Science Standards:

Life Science Standards:

2a. Students know the differences between the life cycles and reproduction methods of sexual and asexual organisms.

2b Students know how sexual reproduction produces offsprings that inherit half their genes from each parent.

2c Students know an inherited trait can be determined by one or more genes.

2d Students know plant and animal cells contain many thousands of genes and typically have two copies of each gene. The two copies (alleles) may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive.

2e. Students know DNA (deoxyribonucleic acid) is the genetic material of living organisms and is located in the chromosomes of each cell.

Investigation and Experimentation Standards:

7a. Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data.

7b. Use a variety of print and electronic resources (including the World Wide Web) to collect information and evidence as part of a research project.

7c. Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.

7e. Communicate the steps and results from an investigation in written reports and oral presentations.