Genetics Unit Notes Pack

I. Meiosisa. Meiosis :

Gametes

Zygote

Haploid

Diploid

Why do gametes need to be haploid?

Meiosis MitosisDescription/purpose

Begins with n or 2n cells?# of divisions

Products

Divisions and Phases of MeiosisInterphase-Cell grows, metabolism-DNA replicates-Cell preps for division

*Prophase I-Homologous chromosomes form tetrads-crossing over occurs! Variety!

Metaphase I-Tetrads of homologous chromosomes line up along middle of cell

Anaphase I-Homologous chromosomes pulled apart*Sister chromatids stay together!

Telophase I-Sister chromatids remain in two new cells-Cells divide

Meiosis II proceeds just like mitosis, only with 2 cells at the same time!

Prophase II-Sister chromatids condense, connect in both cells

Metaphase II-Sister chromatids line up along middle of cell in both cells

Anaphase II-Sister chromatids are pulled apart in both cells

Telophase II-DNA unwinds, nucleus reforms in ALL 4 VARIED HAPLOID DAUGHTER CELLS!

Genetics Unit Notes Pack

Meiosis Diagram:

Meiosis provides Variety!!!!!Genetic Combinations

Crossing Over

Genetic Recomination

Gene Linkage:

_______________________________________________________________________________________________II. Genetics

a. Genetics :

i. Heredity :

ii. Traits :

iii. Fertilization :

iv. Pollination :

b. Gregor Mendel :

i. Describe how pea plants pollinate and why they are a great organism for studying genetics!

Genetics Unit Notes Packii. Mendel’s Pea Plant Experiment

Mendel cross-pollinated a tall pea plant with a short pea plant. (P1 generation)

_________ x _________ = 100% ___________ (F1)

*Is this the expected outcome? Explain your response.

Naming Generations in GeneticsParent Generation: _________________________ Ex. Your grandparentsFirst Generation of offspring: _________________________ Ex. Your parentsSecond Generation of offspring: _________________________ Ex. You/siblings

Understanding Mendel’s Experiment: Another Experiment!F1 ___________ x __________ (self-pollinating)

F2 ________% Tall, _________% Short

Explain:

Mendel’s ConclusionHow many “factors” determine trait inheritance? _______What do we call “unit factors?” ______________________

______________________________________________________________________________

iii. Allele :

1. Dominant :

2. Recessive :

-Example in pea plants: Tall Allele __________; Short Allele ___________

-Since T is tall, _______ = Tall, ________= Tall, and _______= Short-Why must you have two recessive alleles to show a recessive trait?

Genotype PhenotypeDefinition

Examples

*Understanding results of Punnett Squares!*

-Genotypic and Phenotypic Ratios show the chance of having that trait or genotype in offspring for each mating attempt.

Ex. If a family has 3 kids, each kid had a 25% chance of having the homozygous recessive trait, attached earlobes.

This DOES NOT mean that 25% of their kids have attached earlobes!

Genetics Unit Notes Pack

Homozygous HeterozygousDefinition

Examples Homozygous Dominant:

Homozygous Recessive:

Heterozygous:

iv. Mendel’s Laws of Heredity1. Law of Segregation of Alleles

a. Organisms have ____ alleles for each trait that separate into different gametes during meiosis. No gamete can have two alleles for a trait! (haploid)

2. Law of Independent Assortment of Alleles a. Alleles are inherited independently of each other. Individuals produce gametes

with GENETIC VARIETY! Many allele populations are possible!i. This is why YOU are so unique

v. Punnett Squares: Used to solve genetic problems.1. Write out the cross you are solving. _________ x ___________

-USE GENOTYPES!

2. Draw the Punnett square as shown.a. Divide genotypes by alleles.b. Place 1 of each allele from one parent over columns.c. Place 1 of each allele from other parent by rows.

3. Complete your Punnett square by matching alleles in each box.a. P1 __Bb__ x Bb____

b. You need to analyze your data in the boxes!i. Genotypic Ratio: Ratio of genotypes

1. List genotypes of offspring______, ______, ______

2. Use percentages to show ratios.______% BB, ______% Bb, ______% bb

Ratio: 1 : 2 : 1 BB Bb bb

ii. Phenotypic Ratio: Ratio of phenotypes1. Ex. If B is unattached earlobes and b is attached

a. _______% chance of unattached earlobesb. _______ % chance of attached earlobes

4. You try it: A homozygous dominant purple flowered plant is crossed with a heterozygous purple plant. Complete the Punnett square.

Genotypic Ratio:

Genetics Unit Notes Pack________ x __________ Phenotypic Ratio:

Summary of Mendel’s GeneticsGenes are passed from parents to their offspring. Some genes are dominant, some are recessiveEach adult has 2 copies of each gene, one from each parent, these genes are segregated from each other when gametes are formed. Alleles for different genes usually segregate independently of each other.

Stop. Please complete the Genetics Practice Problems #1-15 at back of packet before moving forward in your notes.__________________________________________________________________________________________________When genetics breaks the rules!

Incomplete DominanceDefinition Example Notation

Practice Problem: Cross a red snapdragon with a pink snapdragon. __________ x __________

CodominanceDefinition Example Notation

Practice Problem: Cross a black chicken with a b&w chicken. __________ x __________

Multiple Alleles – Blood TypeDefinition Example Notation Practice Problem

Blood type alleles: A, B, OType AB – ABType A – AO or AAType B – BO or BOType O – OO

ORType AB – IAIB

Type A - IAi or IAIA

Type B – IBi or IBIB

Type O - ii

Cross a person with type O with someone homozygous with type B.

________ x ________

Results:

Genetics Unit Notes PackHow do blood types not only show multiple alleles, but also include codominance? Explain.

Polygenic InheritanceDefinition Example Notation Practice Problem

Skin colorEye colorHair color

Why does it make sense that these traits are based on many alleles?

Normal dominant, recessive alleles, just lots of them!

Which individual would likely have a darker skin tone?

AabbccDdeeffGghhOrAABbCcDdeeFfggHh

Why?

Human GeneticsExamples of Human Autosomal Traits – Traits found on Chromosomes 1-22

Dominant Autosomal TraitsTrait Description/ExamplesTongue Curling

Earlobe Type

Huntington’s Disease

Polydactyly

Recessive Autosomal TraitsTrait Description/ExamplesCystic Fibrosis

Sickle Cell Anemia

Tay-Sachs Disease

Phenylketonuria

Pedigree Diagram that shows how one trait is passed on through a family Each horizontal row with a Roman numeral is a generation Has symbols to represent people in the generations

Genetics Unit Notes Pack

From the pedigree above, answer the following questions:1. How many females are in this family? How many males?

2. Assuming that the disease being shown is recessive, how many people are carriers?

3. If individual number 6 of the second generation mates with a female who is also a carrier, what are the chances that their offspring will have the trait? Show Work!

__________________________________________________________________________________________________Karyotypes Karyotype : picture of an individual’s chromosomes; show homologous pairs of chromosomes Humans have 23 pairs of chromosomes in their karyotypes typically

o Will show if the person has extra or missing chromosomeso Extra or missing chromosomes is caused by mistakes in meiosis leading to the wrong number of chromosomes in

an egg or sperm cell Typical human karyotype Individual with Down syndrome

Down Syndrome –

Trisomy 21 (3 of chromosome # 21)

Individuals can have the wrong number of sex chromosomeso XO, XXX: female (no Y chromosome)

Genetics Unit Notes Packo XXY, XYY: male (at least one Y chromosome)

Gender determination Humans have 46 chromosomes

o 44 of these chromosomes are autosomes; chromosome pairs #1-22o 2 of these chromosomes are sex chromosomes (determine the sex of an organism); chromosome pair #23

Sex chromosomes are X and Y Females are XX, Males are XY

Females can only make eggs with the X chromosome Males make sperm with the X or Y chromosome, so it is the male sperm that determines the sex of a babyExample: XX x XY

Sex-linked traits Traits controlled by genes on the sex chromosomes Example: Hemophilia (h) is a recessive disorder in which you cannot clot your blood. Normal blood clotting (H) is

dominant. These genes are located on the X chromosome.o For sex-linked traits, you must write genotypes like:

XhXh : female with hemophilia XHXh : female carrier XhY : male with hemophilia XHY : normal male without hemophilia Example: XHXh x XhY

Example: Red-green color blindness: an individual cannot tell the difference between red and green XaXa : female with color blindness XAXa : female carrier XAXA : female without color blindness, not a carrier XaY : male with color blindness XAY : male with color vision Example: XaXa x XaY

Sex-linked recessive traits occur more frequently in males than females becauseo Males only need one recessive allele on the X chromosome to show the affected phenotypeo Females need two recessive alleles on both X chromosomes to show the affected phenotype

Mistakes in Meiosis1. Nondisjunction :

Genetics Unit Notes Pack

a. Aneuploidy

i. Monosomy

ii. Trisomy

iii. Polyploidy __________________________________________________________________________________________________Genetic TechnologyEthics: moral principles, what is determined to be right and wrong based on one’s values and experiences

Biotechnology: advancements in knowledge and application of genetics as a way to benefit or advance living things

Why is it important to consider ethics when discussing genetic technology?Who is responsible for how genetic technology is used?

__________________________________________________________________________________________________Types of Genetic biotechnology

A. DNA Fingerprinting : using gel electrophoresis to determine the identity of an unknown individual

a. Used in crimes, forensic, etc.b. DNA samples are multiplied by a process called PCR (polymerase chain reaction)c. DNA is cut into smaller pieces by restriction enzymes; longer fragments move

slower and not as far as shorter, small piecesd. DNA samples are placed in the gel at the negative end of the apparatuse. Once electricity is on, DNA (-) will move to the positive end of the gel/apparatusf. Banding patterns can be used to determine individual

B. Genetic Engineering : altering or manipulating genes to produce desired traits and outcomes

Genetics Unit Notes Packi. Designer babies”: altering traits of organisms based on human preferences

b. Gene Therapy : a technique for correcting defective genes that cause diseases (currently not used except in clinical trials)

i. Often genes function improperly leading to improper protein function, therefore, disease results

ii. Once faulty gene is identified, appropriate gene can be introduced into organism’s genome

iii. “Normal” gene is carried via a vector into organism: viruses often usediv. Once gene is replaced, if successful, new function should beginv. *Ethical Concerns: can be performed in adult cells or in egg or sperm; value

of life/demeaning consequences; financial concerns; various uses1. Transgenic Organisms : organisms with DNA/genes from another

sourcea. Bacteria (1982) often used:

pharmaceuticals; produce insulin and human growth hormone

b. Glofish (2003)c. Recombinant DNA :

DNA/genes from different organisms combined

d. GMO’s : genetically modified organisms; contain recombinant DNA

i. Why? To improve quality of crops/livestock, protection from environmental threats, resist parasites/pathogens, produce drugs or other pharmaceutical

ii. Issues: safety concerns – toxins or allergies? Impact on biodiversity? Ethical concerns, control concerns

C. Cloning : producing new individuals from cells of other individuals, no varietya. Benefits: top traits get produced again and again; production of agriculture; un-

extinction of species?b. Risks: inviable clones, control/sustainability of clones?

D. Stem Cells : undifferentiated cells of the human body that have the potential to develop into many different cell types with different functions; can be used to replace cells and/or organs, fix organs that function improperly, for research purposes

Genetics Unit Notes Packa. Embryonic stem cells: from embryos (early in development, just after the zygote starts

to divide); can give rise to any cell in the human bodyi. Requires the destruction of the artificially-fertilized embryo after stem cells are

harvestedb. Stem cells of adults or umbilical cords: capable of producing some types of cells, but

much more limited than embryonic; generally less controversial than embryonic stem cells

E. Human Genome Project : Sequenced the entire human genome; completed between 1990 – 2000a. Directors: Dr. Francis Collins and Dr. Craig Venterb. 35,000 to 40,000 genes are found on human chromosomesc. Knowing the genome opens up a wide variety of genetic knowledge and technological

advancements for society