Guiding / Driving Questions

• How are traits passed from parents to offspring?

• Why do the offspring of the same two parents all look different from each other?

• How does diversity in traits arise over generations?

• How can we determine the probability that an organism’s expressed version of a trait will be passed on to its offspring?

• How did scientists determine the structure of DNA?

• How does the information in DNA get transferred into observable traits?

• How is the flow of information from DNA regulated?

Prerequisite Knowledge

• A chromosome is a particular segment of DNA. It consists of numerous genes as well as regulatory information.

• A protein is an organic compound that is made of one or more chains of amino acids. Proteins carry out the essential functions of life through systems of specialized cells.

• There are different forms of RNA. Ribosomal RNA (rRNA) is a molecular component that allows protein synthesis to occur. Messenger RNA (mRNA) is formed in the cell’s nucleus. Transfer RNA (tRNA) is found in cytoplasm

Vocabulary: Inherited

Lesson 1: Meiosis

Pages 259-262, 268-271

Prior Knowledge:

• DNA is found in chromosomes.

• Each chromosome consists of a single molecule of DNA, which carries the instructions for genetic traits.

• Chromosomes occur in pairs called homologous chromosomes. One is inherited from the mother and the other from the father.

• DNA is replicated, or copied, before cell division begins.

• In mitosis, cells divide so that chromosomes are divided equally into two daughter cells.

Objective

Students observe patterns and use models to explain how meiosis produces genetically unique cells. They also use evidence to make a claim for how sexual reproduction, independent assortment, and crossing over increase genetic variation.

Exploration 1: Chromosomes and Meiosis

• Chromosome: Strand of condensed DNA

• Gene: Section of DNA that codes for a protein

• Homologous chromosomes: a pair of matching chromosomes (one from mom, one from dad)

• Chromatid: half of a duplicated chromosome

• Sister chromatids: A duplicated chromosome

• Centromere: what connects two chromatids together

• Karyotype: an image of chromosome pairs

• Autosome: body cells

• Sex chromosome: The two chromosomes that determine gender

• Somatic: body cell

• Diploid (2n): all 46 chromosomes

• Germ cells: the cells that divide during meiosis

• Gametes: sex cells

• Sperm: male sex cells

• Eggs: female sex cells

• Haploid (n): only one copy of each chromosome

• Sexual reproduction: the fusion of two parental gametes, resulting in a mixed offspring

• Fertilization: the joining of two gametes

Exploration 2: The Process of Meiosis

• Meiosis: The Process of dividing germ cells into gametes

• Meiosis I: separates homologous pairs forming two cells

• Meiosis II: splits two cells into four with undoubled chromosomes

• Homologous chromosomes: Chromosome pairs (one from each parent)

• Sister chromatids: a duplicated chromosome

• Centrosome: specialized structures that help DNA replicate during meiosis/mitosis

• Gametogenesis: The end process of meiosis where cells take their final forms (different between genders)

• Polar bodies: The other cells made during a female’s meiosis that are not typically fertilized.

• Flagellum: The whip-like tail on a sperm cell that allows it to manuver (like a propeller)

Exploration 3: Meiosis and Genetic Variation

• Genetic variation: The differences in genetic material in a population

• Independent assortment: how chromosomes independently and randomly line up during metaphase I

• Crossing over: during interphase, sections of homologous chromosomes switch with the other

• Genetic recombination: The processes that create genetic variation

• Fertilization: the fusion of two gametes

• Zygote: a fertilized gamete (a diploid cell created from two habloid cells during reproduction)

Lesson 2: Mendel and Heredity

Pages 275-293

Prior Knowledge:

• A chromosome is a long, continuous thread of DNA that consists of many genes. Human body cells have 46 chromosomes each.

• Homologous chromosomes are two chromosomes—one inherited from each parent—that have the same length, appearance, and gene copies (though the alleles may differ).

• Meiosis is the replication of germ cells in reproductive organs in which a cell’s nucleus divides into four nuclei, each with half the chromosome number.

Objective

Students construct explanations about how traits are passed from parents to offspring.

Exploration 1: Mendel’s Groundwork for Genetics

• Traits: distinguishing characteristics that are inherited

• Genetics: the study of biological interitance patterns and variations

• Geneticists: the scientists who study genetics

• Purebred: when an organism isn’t mixed (truebred)

• Genetic cross: the mating of two organisms

• P generation: the parental generation

• F 1 generation: the first generation of offspring

• F 2 generation: the generation of offspring from the F1 gen

• Mendel’s law of segregation: There are two alleles or copies of every gene

Exploration 2: Genes. Alleles, and Traits

• DNA: the genetic information that contains information on living organisms

• Gene: a piece of DNA that codes for a specific protein

• Chromosome: a condensed strand of DNA

• Locus: a specific location on a pair of homologous chromosomes

• Allele: any of the alternate forms of a gene that occur at a locus

• Homozygous: the two alleles are the same

• Heterozygous: the two alleles are different

• Genotype: the genetic makeup of an organism

• Traits: the phenotype

• Phenotype: the physical trait determined by the genotype

• Dominant: expressed when both are same or different (strong)

• Recessive: only expressed when it is homozygous (weak)

Exploration 3: Traits and Probability

• Punnett square: a tool used to determine likelyhood of phenotype based on genotype

• Segregation: homologous chromosomes are split or segregated during meisosis

• Fertilization: the combining of two gametes from different parents

• Haploid gametes: sex cells that contain one of each chromosome

• Diploid zygote: a fertilized gametes

• Probability: the likelyhood of a certain outcome

• Test cross: a experimental test designed by gregor mendel to figure out the genotype of an organism (breed unknown with known and study offspring)

• Homozygous-homozygous cross: crossing two homozygous alleles

• Heterozygous-heterozygous cross: crossing two heterozygous alleles

• Heterozygous-homozygous cross: crossing one of each type of allele

• Dihybrid cross: a cross that examines two traits

Lesson 3: DNA Structure and Function

Pages 297-298, 302-305

Prior Knowledge:

• DNA is found in chromosomes located in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells.

• Each chromosome consists of a single molecule of DNA, which is made up of billions of subunits.

• The part of the cell cycle in which DNA is replicated, or copied, is the synthesis (S) phase.

• Changes in DNA result in mutations.

Objective

Students use evidence to evaluate claims about DNA as the molecule of inheritance and about the structure of DNA.

Exploration 1: DNA Function

• DNA: the molecule that stores all genetic information on an organism

• heritable: is passed from parents to offspring

• RNA: the copy of DNA

• Central dogma: the flow of information from DNA to RNA to proteins

• Proteins: large complex molecules that play numerous roles in the body

• Enzymes: molecules that regulate chemical reactions in body

• Genetics: the study of biological inheritance patterns and variations

• Bacteriophages: viruses that infect bacteria made up of a DNA core surrounded by a protein coat (they inject material into bacteria cells to infect them)

Exploration 2: DNA Structure

• Subunit/monomer: a single molecule

• polymer: long chain of the same molecule (chain of monomers)

• Nucleotide: the monomers of DNA (sugar, phosphate, and nitrogenous base)

• Pyrimidines: nitrogen bases that have one carbon ring

• Purines: nitrogen bases that have two carbon rings

• Thymine: pairs with A and is a Pyrimidine

• Cytosine: Pairs with G and is a Pyrimidine

• Adenine: pairs with T and is a Purine

• Guanine: pairs with C and is a Purine

• X-ray diffraction: a technique used by Rosalind Franklin to examine the shape of DNA

• Photo 51: the famous image of DNA taken by RF using X-ray diffraction (x surrounded by circle); suggested that DNA is a two stranded, consistently spaced, and twisted into a helical shape

• Complimentary strands/bases: A + T and G + C

• Chargaff’s rules: adenine is equal to thymine and guanine is equal to cytosine

• Backbone: the phosphate-sugar sides of the ladder that are bondent with covalent bonds

• Hydrogen bond: weaker and in-between bases

• Covalent bond: stronger and used between sugar and phosphate

Lesson 4: Protein Synthesis

Pages 317-318, 320-324, 328-332

Prior Knowledge:

• DNA is a polymer composed of monomers called nucleotides. Each nucleotide is composed of a phosphate group, a ring-shaped sugar called deoxyribose, and a nitrogen-containing base.

• The four bases in DNA are cytosine (C), thymine (T), adenine (A), and guanine (G).

• The steps of DNA replication include (1) Proteins unzip the double helix by breaking hydrogen bonds between base pairs; (2) Free nucleotides pair with bases exposed in the unzipped strands; (3) Two identical DNA molecules result.

Objective

Students construct an explanation based on evidence for how the language of DNA is translated into the language of proteins.

Vocabulary: Binary code

Exploration 1: Introduction to Protein Synthesis

• Central dogma: the flow of information from DNA to RNA to proteins

• Protein synthesis: the process of information flow from DNA to proteins

• Gene: a section of DNA that codes for a protein

• Protein: a complex molecules made of amino acids linked into a chain

• Melanin: the pigment that used in skin

• Amino acid: molecules made up of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur

  • Primary structure: amino acid chain called a polypeptide

  • Secondary structure: chain is folded into zig-zags and spirals

  • Tertiary structure: 3D shape of the protein

  • Quaternary structure: many tertiary structures come together to form final structure

• Enzyme: molecules that regulate chemical reactions in organisms

• Transcription: the process of creating RNA from DNA

• Translation: where mRNA is decoded to make proteins from amino acids

• Polypeptide chains: the chains of amino acids that are used to make proteins

• mRNA: messenger RNA which holds a copy of DNA

• RNA: there are three types, all used in protein synthesis

• Prokaryote: an organism with one cell that does not have a nucleus

• Cytoplasm: the space that fills cells

• Eukaryote: an organism with multiple cells that have nuclei

• Spliced: exons are joined together

• Codon: three bases that code for an amino acid

• Codon chart: a tool used to find what amino acid a codon codes for

• Mutation: a change in the DNA of an organism

• Point mutation: only one or a few bases are mutated (usually substitution)

• Frameshift mutation: mutation results in RNA being read differently

• Insertion mutation: A base is inserted

• Deletion mutation: A base is deleted

Exploration 3: Transcription

• Transcription: the process of transcribing DNA to RNA

• RNA polymerase: enzymes that bond nucleotides together to form RNA

• Uracil: a base that replaces thymine (pairs with Adenine)

• mRNA: messenger RNA which holds the copy of DNA

• rRNA: ribosomal RNA which reads the RNA and connects amino acids using peptide bonds

• tRNA: transfer RNA which brings the correct amino acid to the right codon

Exploration 4: Translation

• Translation: the process of making polypeptide chains from mRNA

• Ribosome: where translation is located and completed

• Small subunit: part of the rRNA that holds mRNA

• Large subunit: part of the rRNA that holds polypeptide chain

• tRNA: transfer RNA which matches up the right amino acids to the right codons

• Peptide bond: the bonds between amino acids

• Stop codon: the codon telling rRNA and tRNA to stop translating

• anticodon: codon attached to tRNA which allows it to find right codon for its amino acid

Lesson 5: Gene Expression and Regulation

Pages 337-348

Prior Knowledge:

• DNA nucleotides always pair in the same, complementary way.

• The DNA molecule has a double-helix structure, in which two strands of DNA wind around each other like a twisted ladder.

• DNA replicates itself during the process of cell division

Objective

Use evidence to explain that gene expression is a regulated process that results in differentiated and specialized cells, and recognize that genes are expressed differently in prokaryotic and eukaryotic cells.

Vocabulary: Homeobox genes

Exploration 1: Regulating Gene Expression

• Gene expression: the process by which nucleotide sequence of a gene is transcribed to make an mRNA molecule to a protein,

• Operon: section of DNA that contains a protein, an operator, and the genes

• Promoter: where RNA polymerase binds to start transcription

• Operator: what turns the gen on or off

• Lac operon: operon that controls the production of lactose (inducible)

• Repressor protein: protein that stops transcription

• Inducible operon: turns on by prescense of something

• Repressible operon: turned off by prescense of something

Exploration 2: Gene Regulation in Eukaryotes

• Pre-transcriptional regulation

  • Histones: proteins that DNA are tightly bound around

    • Epigenome: chemical compounds that determine how easily transcription enzymes can access genes to turn them on or off

    • Epigenetic changes: chemical changes caused by age, environmental inputs, and disease causing organisms (can cause transcription to start or stop)

• Transcriptional regulation

  • Transcription factors: proteins that bind to DNA sequence and control rate of transcription, also signals for RNA polymerase to start transcription

    • Enhancers: speed up transcription

    • Silencers: slow down transcription

• TATA box: a seven nucleotide sequence that is a promoter

• Post-transcriptional regulation

  • mRNA processing: one type of post-transcriptional regulation; introns are taken out and extrons are spliced together

    • Introns: parts that don’t code for amino acids, parts cut out

    • Exons: parts that do code for amino acids, parts spliced together

• 5’ cap: nucleotide added to front of mRNA to help it bind to ribosome and not break down

• Poly-A tail: nucleotide added to end of mRNA to improve stability and leave the nucleus

• Translational regulation

  • takes place in cytoplasm

  • caused by changes in proteins that manage translation

  • can prevent ribosomes from binding to mRNA (slows or stops translation) or can initiate process

Exploration 3: Factors That Influence Gene Expression

• polygenetic traits: traits affected by more than one gene

• Internal factors: factors inside an organism that can cause genes to be expressed differently

  • distribution of molecules

  • makeup of zygote

  • molecule signals

  • enzymes break down proteins

• Epistasis: genes that modify what other genes express

• External factors: factors outside an organism that

  • amount of oxegen

  • light and temperature

  • drugs and chemicals