Post on 30-Dec-2015
Hardy-Weinberg Principle
Van Roekel IB BIO II4/14/14
Used to calculate frequencies of alleles, genotypes, or phenotypes within a population
Useful in determining how fast a population is changing or in predicting the outcomes of matings or crossings.
Based off of Punnett squares and probabilities to model allele and genotype frequencies
Hardy-Weinberg Equation
When looked at individually, the frequencies of alleles on chromosomes must add up to 1
p + q = 1 p = frequency of dominant allele q = frequency of recessive allele
p = 0.5 q = 0.5
Allele Frequency
T
T
t
t
TT
Tt
Tt
tt
We are interested in diploid organisms that carry two copies of any trait, so…
(p+q)2 = 1 p2 + 2pq + q2 = 1
p2 = frequency of homozygous dominant q2 = frequency of homozygous recessive 2pq = frequency of heterozygote
Genotype frequencies
TT = p2 = ¼ tt = q2 = ¼ Tt = 2pq = ½
p2 + 2pq + q2 = 1 ¼ + ½ +1/4 = 1
Genotype Frequencies
T
T
t
t
TT
Tt
Tt
tt
What is the Hardy-Weinberg Equation and what does each variable represent? What does this equation tell us?
(p+q)2 = 1, or p2 + 2pq + q2 = 1 p2 = homozygous dominant frequency q2 = homozygous recessive frequency
2pq = heterozygous frequency p = dominant allele frequency q = recessive allele frequency
Used to calculate frequencies of alleles, genotypes, or phenotypes within a population
Useful in determining how fast a population is changing or in predicting the outcomes of matings or crossings
BILL - Hardy-Weinberg Equation
Populations being studies must be a large population, ideally infinite
Random mating between individuals with the particular alleles being examined, aka the trait is autosomal
There must be a constant allele frequency over time There is no allele specific mortality (sickle cell
anemia) There are no mutations that could introduce new
alleles There is no emigration or immigration which would
alter allele frequency
Hardy-Weinberg Assumptions
Consider a disease caused by a recessive allele t. The predicted allele frequency in a population in 10%, what is the frequency of the healthy allele in the population?
Answer: 90% p + q = 1 1-q = p 1-.10 = .90
Practice Problems
A study examined 989 members of the previous population, it was found that 11 people had the disease. Calculate the allele frequency of the recessive allele t.
Answer: 10.5% 11/989 = .011 = q2 = genotype frequency Square root of .011 = 0.105 = 10.5% = q
Practice Problems
Calculate the allele frequencies and genotype frequencies of the population in example 1. Calculate the number of carriers in 500 members of the population
Allele Frequencies: q = 0.10 or 10%p= 0.90 or 90%
Genotype Frequencies: q2 = .01 or 1% 2pq= 0.18 or 18% p2 = 0.81 or 81%
Carriers = 90 people (500 x 18%)
Practice Problem
Using information from example 3, calculate the number of people in 500 members that do not suffer from the disease.
Answer: 495 people p2 + 2pq = 81% + 18% = 99% 99% x 500 = 495
Practice Problem
Use binomial nomenclature to name and classify organisms
1st word refers to the genus, 2nd word to the species, i.e. Homo Sapiens.
Carolus (Carl) Linnaeus consolidated and popularized binomial nomenclature
Reasons:◦ Make sense of biosphere◦ Identify unknown organisms ◦ Show evolutionary links ◦ Predict characteristics shared by members of a group
Classification
Five Kingdoms◦Kingdom Plantae (plants) ◦Kingdom Animalia (animals)◦Kingdom Fungi (fungi and molds)◦Kingdom Protoctista (protozoa and algae)◦Kingdom Prokaryote (bacteria)
Hierarchy of classification
Within each kingdom, there are several subdivisions, called taxa
Seven-level hierarchy of taxa:◦Kingdom◦Phylum◦Class◦Order◦Family◦Genus◦Species
King Phillip Came Over For Good Soup
Hierarchy of Classification
Taxa Human Garden Pea
Kingdom Animalia Plantae
Phylum Chordata Angiospermae
Class Mammalia Dicotyledoneae
Order Primate Rosales
Family Hominidae Papilionaceae
Genus Homo Pisum
Species sapiens sativum
Examples
Feeding Habits (carnivore/herbivore) Habitat (land dwelling/aquatic) Daily activity (nocturnal/diurnal) Risk (harmless/venomous) Anatomy (vertebrates/invertebrates)
System of classification must be clear, consistent, easily implemented and a general consensus to apply it.
Other Means of Classification
Four of the several types of plant phyla include:◦Bryophyta: short in stature such as moss◦Filicinophyta: ferns and horsetails◦Coniferophyta: coniferous, pine trees
cedar, juniper, fir◦Angiospermophyta: all plants that make
flowers and have seeds surrounded by fruit
Plant Phyla
Vegetative Characteristics such as leave types and stems◦Bryophytes: non-vascular, lack vascular
transport tissue such as xylem or phloem◦Filicinophyta: vascular plants, small
leaves◦Conifers: vascular, all produce woody
stems and leaves are needles or scales◦Angiosperms: vascular and have flowers
and fruit
Distinguish plant phylas
Reproductive characteristics◦Bryophytes: produce spores (microscopic
reproductive structures) transported by rain water
◦Filicinophytes: produce using spores in a similar manner
◦Conifer: use wind to help reproduce by pollination, produce seed cones with seed scales
◦Angiosperms: produce seeds, rely on birds, insects, and mammals to transport pollen. Sexual organ is flower, fruit is enlarged ovary
Distinguish plant phylas
Six of many animal phyla include: ◦Proifera: sponges◦Cnidaria: sea jellies (jellyfish), coral
polyps, and others◦Platyhelminthes: flatworms◦Annelida: segmented worms◦Mollusca: snails, clams, octopi, etc…◦Atrhtropoda: insects, spiders, crustaceans,
etc… All listed phyla are invertebrates
Animal Phyla
Porifera:◦ Simple marina animals that are sessile (stuck)◦ Feed by pumping water through tissues and
filtering out food◦ No muscle, nerve tissues, or internal organs
Cnidaria:◦ Very Diverse: Coaral, sea anamones, jellyfish,
hydra, Portuguese man-of-war ◦ All have stinging cells called nematocysts◦ Some sessile, some free swimming, some both◦ Gastric pouch for digestion
Details
Platyhelminthes:◦ Flatworms with one body cavity, gut with one
opening for food to enter and waste to leave◦ No heart, no lungs◦ Exchange gas by diffusion◦ Example: Tapeworms
Annelida:◦ Segmented worms such as earthworms, leeches,
and polychaetes◦ Bodies divided into sections separated by rings◦ Have gastric tracts, w/ mouth at one end and anus
at opposite
Details
Mollusca:◦ Aquatic animals, snails, clams, octopi◦ Shell produced with calcium◦ Non-segmented bodies
Arthropoda:◦ Hard exoskeleton made with chitin, segmented
bodies, and limbs (walking, swimming, eating)◦ Insects, spiders, scorpions, crustaceans such as
crab and shrimp◦ Live in most habitats throughout world◦ Vary in size
Details
Used to help identify which order, genus, and species an organism is by using observable characteristics
In General:◦ Look at first section of key which has a pair of sentences◦ Look at the organism to see if particular characteristics
are present◦ If answer is yes, to go end of line/next section that
contain a new pair of statements to examine◦ If answer is no, go to second statement just below it and
follow that one, should it be true◦ Continue this until the end of the line has a name, not a
number and if each question was answered correctly, should be your organism.
Example in book, pg. 149
Dichotomous Key
1. a. Organism is living........................................................go to 4. 1. b. Organism is nonliving..................................................go to 2. 2. a. Object is metallic........................................................go to 3. 2. b. Object is nonmetallic..................................................ROCK.
3. a. Object has wheels......................................................BICYCLE. 3. b. Object does not have wheels......................................TIN CAN. 4. a. Organism is microscopic...................................PARAMECIUM. 4. b. Organism is macroscopic............................................go to 5. 5. a. Organism is a plant.....................................................go to 6. 5. b. Organism is an animal.................................................go to 8. 6. a. Plant has a woody stem..............................................go to 7.
6. b. Plant has a herbaceous stem.................................DANDELION. 7. a. Tree has needle like leaves.....................................PINE TREE. 7. b. Tree has broad leaves............................................OAK TREE. 8. a. Organism lives on land................................................go to 9. 8. b. Organism lives in water...............................................CLAM.
9. a. Organism has 4 legs or fewer......................................go to 10. 9. b. Organism has more than 4 legs...................................ANT.
10 a. Organism has fur........................................................go to 11. 10 b. Organism has feathers................................................ROBIN. 11 a. Organism has hooves.................................................DEER.
11 b. Organism has no hooves............................................MOUSE.
Vocabulary can be challenging and technical
Make sure using the right key, no key can identify all the species
Making a Dichotomous Key◦ Start by putting things in groups by identical
characteristics◦ Invent statements that divide things into created
groups
Dichotomous Key