1. what does the word ambition mean to you? 2. what are the 3 components of a nucleotide?

1. What does the word ambition mean to you?

2. What are the 3 components of a nucleotide?

I can understand simple Mendelian genetic principles. I can work punnett squares.

Recall

• What is the purpose of mitosis?

• What is the purpose of meiosis?


Organismal Development Remember…

• 1. A zygote is a _• 2. Cell Specialization is __• 3. As cells differentiate the body changes

shape called: _• 4. Apoptosis is critical in morphogenesis.


Cloning

• 1. Take haploid egg out of female.• 2. Remove haploid nucleus, implant diploid

nucleus of desired organism.• 3. Place egg in surrogate (recipient ).

• Dolly 1997

Cloning of DollyMammarycell donor

Egg celldonor

Egg cellfrom ovary Nucleus

removedCells fusedCultured

mammary cellsare semistarved,arresting the cellcycle and causingdedifferentiation

Nucleus frommammary cell

Early embryo

Grown in culture

Implanted in uterusof a third sheep

Surrogatemother

Embryonicdevelopment

Lamb (“Dolly”) genetically identicalto mammary cell donor


Stem Cells

• Embryonic Stem Cells- totipotent-can be anything– No genes are locked=can make any gene, protein,

enzyme,

• Adult Stem Cells-pluripotent-can be several things– Some genes locked, can be lots of different cells

LE 21-9

Embryonic stem cells Adult stem cells

Pluripotentcells

Totipotentcells

Culturedstem cells

Differentcultureconditions

Differenttypes ofdifferentiatedcells

Liver cells Nerve cells Blood cells

Genetics…We are leaving the cell!

• 1. When is DNA replicated in the cell cycle?

• 2. Mitosis = _ divisions of the cell.

• 3. Meiosis = _ divisions of the cell.

.

Propase

Duplicated chromosome(two sister chromatids)

Chromosomereplication

2n = 6

Parent cell(before chromosome replication)

Chromosomereplication

MITOSIS MEIOSIS

Chiasma (site ofcrossing over) MEIOSIS I

Prophase I

Tetrad formed bysynapsis of homologouschromosomes

Tetradspositioned at themetaphase plate

Metaphase IChromosomes positioned at themetaphase plate

Metaphase

AnaphaseTelophase

Homologuesseparateduringanaphase I;sisterchromatidsremain together

Sister chromatidsseparate duringanaphase

Daughtercells of

meiosis I

Haploidn = 3

Anaphase ITelophase I

MEIOSIS IIDaughter cells

of mitosis

2n2n

n

Sister chromatids separate during anaphase II

n n nDaughter cells of meiosis II

Figure 9.15 The Human Karyotype

DNA chromatin in Interphase in cell.Chromosomes have been stained in Metaphase to distinguish homologous chromsomes.

Heredity= Passing traits from parent to offspring

Chromosome Terminology

• As a human you have 46 chromosomes in your somatic cells.

• 23 from dad, 23 from mom.

• You only have 23 chromosomes in your sex cells (egg/sperm).

Homologous Chromosomes• Each of the 23

chromosomes inherited by your parents line up in pairs.

• These pairs are known as homologous chromosomes.

• These homologous chromosomes are identical in size, shape, and location of genes.

Locus(Gene locations on chromosomes)

Meiosis I

• During Prophase I, a process called synapsis/ chiasmata occurs. Homologous chromosomes pair by adhering at their lengths.

• Proteins aid in this adhesion by forming a scaffold called a synaptonemal complex.

• The four bound chromatids form a tetrad.• How many chromatids are in human cells during

Meiosis I?• 92

Meiosis I and Meiosis IIMeiosis I Meiosis II

• Homologues will meet and form a tetrad.

• Crossing over occurs: allele swapping.

• Telophase I- two new cells with one homologue per cell (still replicated chromatids)

• Prophase, Metaphase and Anaphase similar to Mitosis and Meiosis I.

• Telophase II results in four haploid daughter cells.

• One chromatid per cell

Meiosis I

• The chromatids that result are known as recombinant chromatids

• Not all organisms directly enter Meiosis II.• If an organism does not, it does form a nuclear

membrane at the end of Telophase I• Telophase I is followed by interkinesis, which is

similar to mitotic interphase

Meiosis II

• Homologues are not identical like in Meiosis I because of crossing over.

• The result is four haploid nuclei, with a single set of unreplicated chromosomes.

So what causes genetic diversity• Synapsis, crossing over, and segregation of homologues• Aneuploidy- when there are either missing or excessive

chromosomes.– Monosomy– Trisomy 10-30% human zygotes show trisomy– Aneuploidy, ~20% of miscarriages due to aneuploidy (extra

or missing chromosomes)– Polyploidy complete extra sets of chromosomes, can occur

naturally, can be result of genetic engineering– Aneuploidy Simulations- Utah Site

http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

Asexual reproduction (One parent)See the bud on the side… that is the “new” organism to be.

• Benefits: Quick- good for takeover

• Pitfalls: Because of no variety one parasite/pathogen and all die.

Sexual Reproduction (Two parents)

• Benefits: VARIATION

• Pitfalls: Time, it takes 2, need opposite sexes, gametes are harder to make.

Life Cycles Review: Haploid, Diploid, Alternation of Generations

Key

HaploidDiploid

Gametesn

Diploidmulticellularorganism(sporophyte)

MitosisDiploidmulticellular

organism

FERTILIZATIONMEIOSIS

Zygote

n

n

2n 2n

Animals Plants and some algae Most fungi and some protists

n nn

n n

nn

n

n

nFERTILIZATION

FERTILIZATION

MEIOSIS

MEIOSIS

Gametes Gametes

Zygote

ZygoteMitosis

Mitosis Mitosis Mitosis Mitosis

2n 2n2n

Spores

Haploid multicellular organism (gametophyte)

Haploid multicellular organism


Autosomes vs. Sex Chromosomes

• Autosomes- chromosomes that codes for all traits except gender.– Homologous pairs #1-22

• Sex chromosomes- chromosomes that code for gender.– Homologous pair #23– Karyotyping Activity

http://www.biology.arizona.edu/human_bio/activities/karyotyping/Karyotyping.html

http://www.biology.arizona.edu/human_bio/activities/karyotyping/Karyotyping.html

Female (XX) Karyotype(Remember… “kary” means “nucleus”)

Male (XY) Karyotype

Figure 9.15 The Human Karyotype

Where do homologous chromosomes come from?What phase are these homologous chromosomes next to one another?

What are chromosome maps called?

All three of these conditions cause a form of mental retardation.


Mendel `1850s

• Known as the Father of Genetics

• Experimented with pea plants

• He used “true-breeding” plants which were self-pollinating.

• These would produce identical offspring.


Mendel and His Peas

• Mendel wanted to try cross-breeding pea plants.

• Cut off the male parts (pollen), and dusted pollen from another plant to cause fertilization.aka cross-pollination.


Mendel

• Mendel studied seven different traits.• Trait- specific characteristic, like flower color.• P generation- parent generation.• F1 generation- offspring of the P generation.• Traits are controlled by genes.• Genes- segment of DNA• Allele- different forms of a particular gene

– Ex. Hair color, eye color, plant flower color.


Mendelian Principles

• 1. Biological inheritance is determined by genes passed on from parents to offspring.

• 2. Principle of Dominance- some alleles are dominant and some are not (recessive).

• Mendel knew that dominant alleles would always be expressed, and

• Recessive alleles would only be expressed when the dominant allele was absent, and there are two recessive copies.


Dominant vs. Recessive• Dominant= capital letter• Recessive= lower case letter• If capital letter is present, then that trait is

expressed.• Must have two lower case letters for trait to

be expressed


Practice

• If (P) = purple, (p)= white what do the following flowers look like?

• PP = ?• Pp = ?• pp = ?• Study for your quiz tomorrow


Genotype vs. Phenotype

• Genotype- gene combinations an individual possesses

• Phenotype- what an individual looks like based on genotype


Homozygous vs. Heterozygous

• Heterozygous/ Hybrid: for a particular trait the individual has one dominant and one recessive allele. (Tt)

• Homozygous/ Purebreed: for a particular trait the individual has both dominant or both recessive alleles. (TT, tt)


Exploring Classroom Genetics

Trait Phenotype- what you look like Genotype- genetic make-up that makes up phenotype

Tongue-Rolling (R)

Free Earlobe (F)

Widow’s Peak (W)

Straight Thumb (N)

Straight Little Finger (S)

Left over Right Thumb Crossing (L)Chin Cleft (C)

Mid-digital Hair (H)

Six Fingers (F)


Law of Segregation

• Homologous chromosomes separate independent of one another…

• Don’t get all of mom’s DNA or dad’s DNA


Law of Independent Assortment

• Just because you have one dominant gene, does not mean all of your genes are dominant.

• They are inherited independent of one another


Probability

• The odds that a particular event is going to take place.

• If you flip a coin, there is a ½ chance that it will land on heads.

• Apply this concept to segregation of alleles.


Punnett Squares: Monohybrid(4), Dihybrid (16), Trihybrid (64)

• Used to predict possible offspring outcomes.• Cross one parent with another.

– Tall (TT) x short (tt)

– Genotypic Ratio:– Phenotypic Ratio:– # of Heterozygous Individuals:– # of Homozygous Individuals:


Trihybrid Probability


Pedigree

• A chart that shows the phenotypes for an organism and all of its ancestors.

• What is the difference between phenotype and genotype?


Pedigree Organization• Squares=males• Circles=Females• Each generation is denoted

by a roman numeral.• Each individual is

numbered in the generation

• Blood relations are linked by vertical lines.

• Marriage relations are linked by horizontal lines.


Make a Pedigree with a Phenotype for Hair Color

• Use your Family starting with one set of your biological grandparents.

• Shade in all circles/squares of brunette people, and leave blank all other hair colors.


Mendelian Exception #1• Incomplete Dominance-

think of this as a blending of genes.

• Neither gene is dominant.• Heterozygous genotype is

a blend of the two alleles.• Red(RR) + White(WW) =

Pink flower(RW)• 1:2:1 ratio of offspring

phenotype


Incomplete Dominance Practice• 1. A cross between a blue blahblah bird & a white blahblah bird

produces offspring that are silver. The color of blahblah birds is determined by just two alleles. a) What are the genotypes of the parent blahblah birds in the original cross? b) What is/are the genotype(s) of the silver offspring? c) What would be the phenotypic ratios of offspring produced by two silver blahblah birds?

• 2. The color of fruit for plant "X" is determined by two alleles. When two plants with orange fruits are crossed the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit, 25% yellow fruit. What are the genotypes of the parent orange-fruited plants?


Mendelian Exception #2

• Codominance- both alleles contribute to the phenotype.

• Genes do not blend, but show up distinctly.

• Blood type, calicos, roan cattle

• Red bull (RR) x White Cow(WW) = Roan calf(RW)


Codominance Practice• 1. Predict the phenotypic ratios of offspring when a

homozygous white cow is crossed with a roan bull.

• 2. What should the genotypes & phenotypes for parent cattle be if a farmer wanted only cattle with red fur?

• 3. A cross between a black cat & a tan cat produces a tabby pattern (black & tan fur together). a) What pattern of inheritence does this illustrate? b) What percent of kittens would have tan fur if a tabby cat is crossed with a black cat?


Mendelian Exception # 3

• Multiple Alleles- a gene may have more than two alleles to code for a particular trait.


Mendelian Exception # 4

• Polygenic Traits- traits that are controlled by several different genes.

• Examples include hair color and skin color,


What happens when things go awry?


Nondisjunction

When chromosomes fail to separate during anaphase of meiosis.

Meiosis is the process that sex cells are formed.


Trisomy 13/Trisomy 18/Trisomy 21• Trisomy 13 (Patau’s)/18

(Edward’s)- typically die by 3 months of age

• Trisomy 21- Mental retardation, facial distortions.

• Down’s typically occurs in egg and sperm production.

• Likelihood of Down’s occurs with maternal age.


Down’s Syndrome Karyotype


Sexual Nondisjunction

• Turner’s Syndrome in females, results in a (XO).

• Klinefelter’s Syndrome in males, results in (XXY-XXXXY)


Sexual Disorders Karyotypes


Allelic Disorders # 1

• Albinism- animal/person lacks ability to produce pigment in hair, skin, and eyes if they have two recessive genes for pigmentation.


Allelic Disorders # 2 & 3

• Sickle Cell Anemia- when oxygen levels are low, blood cells will form a sickle shape.

• Mostly associated with African Americans

• Polydactyl- six digit. Henry VIII had a 6th finger. (dominant gene)


Sex Linked Disorders # 1 & 2• Hemophilia- blood is

unable to clot. Queen Victoria had this, also affected Czar Nicholas due to intermarriage. (inbreeding depression)

• Muscular dystrophy- chronic muscle wasting disease.

• Colorblindness- usually in males.


Amniocentesis

• Prenatal detection of chromosomal abnormalities.

• A thin needle is inserted into the amniotic fluid surrounding the fetus (a term applied to an unborn baby after the first trimester).

• Cells that are withdrawn have been sloughed off by the fetus, yet they are still fetal cells and can be used to determine the state of the fetal chromosomes, such as Down's Syndrome and the sex of the baby after a karyotype has been made.

Hardy Weinberg Equilibrium

• 1908 proposed that the frequency of alleles/genotypes will remain constant if…

• It explains why dominant alleles do not replace recessive alleles

• 1. A large breeding population • 2. Random mating- do not chose mates with certain

genotypes (selective mating)• 3. No mutation of genes (A/a no change, no new genes)• 4. No immigration or emigration (no gene flow)• 5. Natural selection does not affect the survival of a

particular genotype.


HW Equation• p = the frequency of the dominant allele q = the frequency of the recessive allele

• For a population in genetic equilibrium:p + q = 1.0 (The sum of the frequencies of both alleles is 100%.)

• p2 + 2pq + q2 = 1• p2 = (% in population homozygous dominant)

2pq = (% in population heterozygous)q2 = (% in population homozygous recessive)

• H-W Practice Problems

http://www.phschool.com/science/biology_place/labbench/lab8/intro.html

1. what does the word ambition mean to you? 2. what are the 3 components of a nucleotide?

Documents

homologous chromosomes

somatic cells

different cells

cell cycle

cell specialization

punnett squares

adult stem cellspluripotent

sex cells eggsperm