AAAS Science Assessment ^beta

Students are expected to know that:

1. Genetic (hereditary) information is the set of instructions that specifies the physical and behavioral characteristics of organisms.
2. Genetic information is found in all living organisms.
3. The instructions that specify the physical and behavioral characteristics of organisms are coded in DNA molecules (not in protein, carbohydrate, or fat molecules).
4. DNA molecules are made up of four different types of subunits called nucleotides that are linked together in long chains.
5. The sequence of subunits in a DNA molecule is what encodes the genetic information.
6. DNA is packaged as chromosomes in the cells of organisms.
7. Each chromosome is made of a single DNA molecule.
8. A gene is one or more segments of a DNA molecule that contributes to one or more particular physical and behavioral characteristics.
9. Each chromosome is made of many different genes.

Boundaries:

1. Students are not expected to know the names of the nucleotide subunits.
2. Students are not expected to know that DNA is bound to histones and other proteins in chromosomes.

Students are expected to know that:

1. DNA molecules are smaller than cells and, therefore, can fit inside cells.
2. DNA, and the chromosomes and genes that are made of DNA, are located inside almost all types of cells in the body.
3. Every body cell (not a sex cell) that contains DNA in a multi-cellular organism contains identical DNA molecules to every other body cell because every body cell is descended from a single fertilized egg cell, and the DNA in each cell is duplicated every time a cell divides.
4. In all organisms, whenever a single body cell forms two body cells, the resulting body cells each contain the same number of DNA molecules (and, therefore, the same number of chromosomes) as the original body cell.
5. Each DNA molecule in a body cell is a member of a pair of DNA molecules. With the exception of the sex-determining DNA molecules, the two DNA molecules that make up a pair contain instructions affecting the same traits. The two DNA molecules making up a pair contain similar sequences of subunits and are similar in length.
6. One member of each pair of DNA molecules contains genetic information from the mother and the other member of the pair contains genetic information from the father.

Boundaries:

1. Students are not expected to know that some cells in the body may not have an identical set of DNA molecules, because some cells may have DNA that has mutated.
2. Students are not expected to know that some cells in the body (e.g. red blood cells) do not have DNA..
3. Students are not expected to know specifically where in a cell the DNA is located (e.g., nucleus, mitochondria).
4. Students are not expected to know anything about DNA in viruses, bacteria, plasmids, or polyploidy.

Students are expected to know that:

1. In sexually reproducing organisms, only half of the genetic information of each parent is passed to each of its offspring.
2. During sexual reproduction, parents produce specialized cells called sex cells (e.g., eggs, sperm, pollen) that contain half as many DNA molecules (and, therefore, chromosomes) as are found in the other cells of the organism (body cells).
3. A sex cell from one parent merges with a sex cell from the other parent in a process called fertilization, and the fertilized egg cell has twice as many DNA molecules as the sex cell and the same number of DNA molecules (and, therefore, chromosomes) as the body cells of each parent.
4. The offspring that develop from the single cell that was formed from the combination of the two sex cells have traits of both parents because they have DNA from both parents.
5. In sexually reproducing organisms, traits that are acquired during the lifetime of an organism and affect its body cells (e.g. due to injuries, malnutrition, mutation, weight training) cannot be passed from parent to offspring. Only changes in the DNA of the sex cells of an organism can be inherited by offspring.
6. In asexually reproducing organisms (uni-cellular or multi-cellular), all of the inherited genetic information comes from one parent cell. The offspring’s DNA molecules (and therefore the offspring’s genes and chromosomes) contain the same information as the DNA molecules of the parent.
7. Following asexual reproduction, the genetic information contained in the DNA molecules in the resulting cells is the same as the genetic information in the DNA molecules of the original cell.
8. In both sexually and asexually reproducing organisms, there is no other mechanism by which genetic information is passed to offspring other than by the transfer of DNA.

Boundaries:

1. Students are not expected to know that sexual reproduction can involve self-fertilization by a single parent having both male and female sex cells.
2. Students are not expected to know that the amount of genetic material in a sex cell is not exactly half of that found in a body cell due to differences in the sizes of the different sex chromosomes and/or the transmission of the entire mitochondrial DNA molecule.
3. Students are not expected to know that environmental factors interact with DNA at the molecular level to affect the genetic information that is expressed.

Students are expected to know that:

1. Protein molecules are made up of amino acid subunits linked together in a specific sequence.
2. DNA molecules provide instructions for linking and ordering amino acids to form protein molecules.
3. Each sequence of three nucleotides in a molecule of DNA codes for an amino acid.
4. The set of nucleotides in a DNA molecule that provide instructions for assembling a particular protein molecule from amino acids is called a gene.
5. 20 different types of amino acids are used to make protein molecules.
6. A change to the sequence of nucleotides in a gene within a molecule of DNA can alter the protein that is produced.
7. Changes to the sequence of nucleotides in a molecule of DNA can come from insertions, deletions, or substitutions of one or more nucleotide subunits in a DNA molecule.
8. Changes to the sequence of nucleotides in a molecule of DNA are called mutations.
   

Boundaries:

1. Students are not expected to know the terms: transcription, translation, messenger RNA, transfer RNA, codons, or anticodons.

Students are expected to know that:

1. The presence, amount, type, or actions of protein molecules made in an organism’s cells are reflected in an organism’s traits.
2. Protein molecules are involved in chemical reactions that are responsible for an organism’s body functions.

Boundaries:

1. Students are not expected to know any of the specific reactions that link proteins to traits.