Semester I Final ReviewSemester I Final Review

The SEMESTER IS OVA!!!!!!!The SEMESTER IS OVA!!!!!!!

Part I.Part I.

Meiosis and Punnett SquaresMeiosis and Punnett Squares

Standards: MeiosisStandards: Meiosis

BI2. Mutation and sexual reproduction lead BI2. Mutation and sexual reproduction lead to genetic variation in a population. As a to genetic variation in a population. As a basis for understanding this concept: basis for understanding this concept:

BI2. a. BI2. a. Students know Students know meiosis is an early step in meiosis is an early step in sexual reproduction in which the pairs of sexual reproduction in which the pairs of chromosomes separate and segregate randomly chromosomes separate and segregate randomly during cell division to produce gametes containing during cell division to produce gametes containing one chromosome of each type. one chromosome of each type.

BI2. b. BI2. b. Students know Students know only certain cells in a only certain cells in a multicellular organism undergo meiosis. multicellular organism undergo meiosis.

BI2. c. BI2. c. Students know Students know how random chromosome how random chromosome segregation explains the probability that a segregation explains the probability that a particular allele will be in a gamete. particular allele will be in a gamete.

Standard ExplanationsStandard Explanations

• BI2. a. BI2. a. Meiosis produces sex cells, Meiosis produces sex cells, chromosomes pairs are separated chromosomes pairs are separated randomly during this process, producing randomly during this process, producing gametes containing one chromosome of gametes containing one chromosome of each type (haploid).each type (haploid).

• BI2. b. BI2. b. Only sex cells (gametes) are Only sex cells (gametes) are produced meiosis.produced meiosis.

• BI 2.c.-Chromosomes segregate randomly BI 2.c.-Chromosomes segregate randomly during meiosis.during meiosis.

Standards:Meiosis and Punnett Standards:Meiosis and Punnett SquaresSquares

BI3. A multicellular organism develops from a single BI3. A multicellular organism develops from a single zygote, and its phenotype depends on its genotype, zygote, and its phenotype depends on its genotype, which is established at fertilization. As a basis for which is established at fertilization. As a basis for understanding this concept: understanding this concept:

BI2. d. BI2. d. Students know Students know new combinations of alleles may be new combinations of alleles may be generated in a zygote through the fusion of male and generated in a zygote through the fusion of male and female gametes (fertilization). female gametes (fertilization).

BI2. e. BI2. e. Students know Students know why approximately half of an why approximately half of an individual’s DNA sequence comes from each parent. individual’s DNA sequence comes from each parent.

BI2. f. BI2. f. Students know Students know the role of chromosomes in the role of chromosomes in determining an individual’s sex. determining an individual’s sex.

BI2. g. BI2. g. Students know Students know how to predict possible how to predict possible combinations of alleles in a zygote from the genetic combinations of alleles in a zygote from the genetic makeup of the parents. makeup of the parents.

BI3. a. BI3. a. Students know Students know how to predict the probable how to predict the probable outcome of phenotypes in a genetic cross from the outcome of phenotypes in a genetic cross from the genotypes of the parents and mode of inheritance genotypes of the parents and mode of inheritance (autosomal or X-linked, dominant or recessive).(autosomal or X-linked, dominant or recessive).

BI3. b. BI3. b. Students know Students know the genetic basis for Mendel’s laws of the genetic basis for Mendel’s laws of segregation and independent assortment.segregation and independent assortment.

Standards Explanation-Meiosis Standards Explanation-Meiosis and Punnett Squaresand Punnett Squares

• BI 2.d.-New combination of genes (alleles) BI 2.d.-New combination of genes (alleles) are produced from fertilization.are produced from fertilization.

• BI 2.e.-Half of an organisms chromosomes BI 2.e.-Half of an organisms chromosomes come from each parent because of come from each parent because of Meiosis.Meiosis.

• BI 2.f.-XX-female, XY-maleBI 2.f.-XX-female, XY-male• BI 2.g.,3.a.-Punnett SquaresBI 2.g.,3.a.-Punnett Squares• BI 3.b.-Mendel’s Laws-chromosome pairs BI 3.b.-Mendel’s Laws-chromosome pairs

separate, and genes for different traits are separate, and genes for different traits are inherited independently of each other.inherited independently of each other.

What we’ve learned so far…What we’ve learned so far…

• Chromosomes contain genetic infoChromosomes contain genetic info

• We get ½ our genetic info from our We get ½ our genetic info from our mom and ½ from our dadmom and ½ from our dad

• We don’t look exactly like our parents We don’t look exactly like our parents or siblings. Why?or siblings. Why?

• Meiosis-formation of sex cells (sperm Meiosis-formation of sex cells (sperm and egg)and egg)

• Human body cells=46 chromosomesHuman body cells=46 chromosomes

ChromosomesChromosomes

Meiosis VocabularyMeiosis Vocabulary

• Homologous chromosomes-Homologous chromosomes- chromosomes that each have a chromosomes that each have a corresponding chromosome from the corresponding chromosome from the opposite-sex parentopposite-sex parent

• Crossing OverCrossing Over – exchange of – exchange of portions of chromatids, genetic portions of chromatids, genetic recombinationrecombination

What are sex cells?What are sex cells?

• Scientific name–gametes (sperm and egg)Scientific name–gametes (sperm and egg)

• In humans, gametes have 23 chromosomes In humans, gametes have 23 chromosomes (haploid=1 set)(haploid=1 set)

• Half of 46Half of 46

• Fertilized egg contains 23 chromosomes from Fertilized egg contains 23 chromosomes from each parent (diploid= 2 sets)each parent (diploid= 2 sets)

What happens during What happens during meiosis?meiosis?• Two stages (Meiosis I & II)Two stages (Meiosis I & II)

• Meiosis 1-divides homologous chromosomes, Meiosis 1-divides homologous chromosomes, crossing overcrossing over

• Meiosis 2-divides sister chromatidsMeiosis 2-divides sister chromatids

• 1 diploid cell produces 4 genetically different 1 diploid cell produces 4 genetically different haploid cellshaploid cells

MeiosisMeiosis

Mendel’s Principle of Mendel’s Principle of DominanceDominance

• Some Some alleles alleles (diff. forms of gene) are (diff. forms of gene) are dominantdominant and some are and some are recessiverecessive

• Organisms with Organisms with dominantdominant alleles alleles will will always show that form of the trait (YY, Yalways show that form of the trait (YY, Yyy))

• Organisms with Organisms with recessive allelesrecessive alleles will only will only show that form of the show that form of the traittrait when there when there are no are no dominant allelesdominant alleles present ( present (yyyy))

Mendel’s LawsMendel’s Laws

• Law of Segregation: alleles that make up a Law of Segregation: alleles that make up a gene separate from each other, or segregate, gene separate from each other, or segregate, during the formation of gametes.during the formation of gametes.

• Law of Independent Assortment: the way in Law of Independent Assortment: the way in which alleles from different genes separate which alleles from different genes separate and then recombine is unconnected to other and then recombine is unconnected to other genes.genes.

Allele CombinationsAllele Combinations

• Homozygotes- two identical alleles Homozygotes- two identical alleles for a certain trait (YY,for a certain trait (YY,yyyy))

• Heterozygotes- two different alleles Heterozygotes- two different alleles for the same trait (Yfor the same trait (Yyy))

What are Punnett Squares?What are Punnett Squares?

• Punnett Squares are…Punnett Squares are…

• a grid system for predicting all possible a grid system for predicting all possible genotypes resulting from a cross.genotypes resulting from a cross.

• The sides of the square represent the The sides of the square represent the possible gamete genotypes of each possible gamete genotypes of each parent.parent.

• Shows all possible genotypes of Shows all possible genotypes of offspringoffspring

What’s actually happening?What’s actually happening?

Part II.Part II.

EvolutionEvolution

Big Idea: EvolutionBig Idea: Evolution

• is the theory that life has changed on is the theory that life has changed on Earth over long periods of time Earth over long periods of time through a process called natural through a process called natural selection, where individuals with selection, where individuals with beneficial inherited traits produce beneficial inherited traits produce more offspring than other individuals. more offspring than other individuals. This changes the frequency of the This changes the frequency of the alleles in the gene pool. There is a alleles in the gene pool. There is a broad range of evidence that broad range of evidence that supports evolutionary theory such as supports evolutionary theory such as fossils, anatomical evidence, and fossils, anatomical evidence, and genetic evidence.genetic evidence.

Standards:EvolutionStandards:Evolution

• BI7. BI7. The frequency of an allele in a gene pool of a The frequency of an allele in a gene pool of a population depends on many factors and may be population depends on many factors and may be stable or unstable over time. As a basis for stable or unstable over time. As a basis for understanding this concept: understanding this concept:

• BI7. a. BI7. a. Students know Students know why natural selection acts on the why natural selection acts on the phenotype rather than the genotype of an organism. phenotype rather than the genotype of an organism.

• BI7. b. BI7. b. Students know Students know why alleles that are lethal in a why alleles that are lethal in a homozygous individual may be carried in a heterozygote homozygous individual may be carried in a heterozygote and thus maintained in a gene pool. and thus maintained in a gene pool.

• BI7. d. BI7. d. Students know Students know variation within a species increases variation within a species increases the likelihood that at least some members of a species will the likelihood that at least some members of a species will survive under changed environmental conditions. survive under changed environmental conditions.

Standards Standards Breakdown:EvolutionBreakdown:Evolution

• BI7. BI7. The frequency of an allele in a gene pool of a population depends The frequency of an allele in a gene pool of a population depends on many factors and may be stable or unstable over time. As a basis for on many factors and may be stable or unstable over time. As a basis for understanding this concept: understanding this concept:

• BI7. a. BI7. a. Students know Students know why natural selection acts on the phenotype rather than the why natural selection acts on the phenotype rather than the genotype of an organism.genotype of an organism.

Means: NS acts on the physical or physiological traits of an individual.Means: NS acts on the physical or physiological traits of an individual. • BI7. b. BI7. b. Students know Students know why alleles that are lethal in a homozygous individual may be why alleles that are lethal in a homozygous individual may be

carried in a heterozygote and thus maintained in a gene pool. carried in a heterozygote and thus maintained in a gene pool. Means: Lethal copies of genes (for homozygotes-have two copies of the gene) can be Means: Lethal copies of genes (for homozygotes-have two copies of the gene) can be

carried in the gene pool by heterozygotes.carried in the gene pool by heterozygotes.

• BI7. d. BI7. d. Students know Students know variation within a species increases the likelihood that at least variation within a species increases the likelihood that at least some members of a species will survive under changed environmental conditions. some members of a species will survive under changed environmental conditions.

Means: The more genetic variation a species has the better chance they will have of Means: The more genetic variation a species has the better chance they will have of surviving a changing environment because atleast some individuals will have the surviving a changing environment because atleast some individuals will have the characteristics needed to survive.characteristics needed to survive.

Standards:EvolutionStandards:Evolution

• BI8. Evolution is the result of genetic changes BI8. Evolution is the result of genetic changes that occur in constantly changing environments. that occur in constantly changing environments. As a basis for understanding this concept: As a basis for understanding this concept:

• BI8. a. BI8. a. Students know Students know how natural selection how natural selection determines the differential survival of groups of determines the differential survival of groups of organisms. organisms.

• BI8. b. BI8. b. Students know Students know a great diversity of species a great diversity of species increases the chance that at least some organisms increases the chance that at least some organisms survive major changes in the environment. survive major changes in the environment.

• BI8. e. BI8. e. Students know Students know how to analyze fossil evidence how to analyze fossil evidence with regard to biological diversity, episodic speciation, with regard to biological diversity, episodic speciation, and mass extinction. and mass extinction.

Standard Standard Summaries:EvolutionSummaries:Evolution

• BI8. Evolution is the result of genetic changes that occur in BI8. Evolution is the result of genetic changes that occur in constantly changing environments. As a basis for understanding this constantly changing environments. As a basis for understanding this concept: concept:

• BI8. a. BI8. a. Students know Students know how natural selection determines the differential how natural selection determines the differential survival of groups of organisms. survival of groups of organisms.

Means: Survival of the fittest and the struggle for existence.Means: Survival of the fittest and the struggle for existence.

• BI8. b. BI8. b. Students know Students know a great diversity of species increases the chance that a great diversity of species increases the chance that at least some organisms survive major changes in the environment. at least some organisms survive major changes in the environment.

Means: The more variety of organisms there are in an environment the better the Means: The more variety of organisms there are in an environment the better the chances are that some organisms will survive any major environmental chances are that some organisms will survive any major environmental changes. changes.

• BI8. e. BI8. e. Students know Students know how to analyze fossil evidence with regard to biological how to analyze fossil evidence with regard to biological diversity, episodic speciation, and mass extinction. diversity, episodic speciation, and mass extinction.

Means: Trend in fossil evidence show evolutionary patterns.Means: Trend in fossil evidence show evolutionary patterns.

What is natural selection’s role What is natural selection’s role in evolution?in evolution?

• Natural selection-Natural selection-mechanism by which mechanism by which individuals that have individuals that have inheritedinherited beneficial beneficial adaptationsadaptations produce more produce more offspring on average than do other offspring on average than do other individuals.individuals.

• These These adaptationsadaptations occur over many occur over many generations in a generations in a populationpopulation ( (descent descent with modificationwith modification))

How does natural selection How does natural selection drive evolution?drive evolution?

• Struggle for Existence-individuals within Struggle for Existence-individuals within a species compete for common a species compete for common resourcesresources

• Survival of the Fittest- Individuals better Survival of the Fittest- Individuals better suited for their environment reproduce suited for their environment reproduce more and have more offspringmore and have more offspring

What are adaptations?What are adaptations?

• The The inheritedinherited characteristics that characteristics that increase an organism chances of increase an organism chances of survival are called adaptationssurvival are called adaptations

• Natural selection results in changes of Natural selection results in changes of the inherited characteristics of a the inherited characteristics of a populationpopulation