Genetics and Inheritance

What makes you, you? DNA DNA is a system of codes that controls every aspect of your life (how you look, how you act, etc.) DNA is like the instruction manual to keep you working.

DNA  gene Gene: one section of DNA that controls one specific trait. (Examples: Hairline gene, earlobe gene, etc.)

DNA  gene  chromosome

How are these traits passed from one generation to the next? Every living things inherits traits, or characteristics, from its parents. How are these traits passed from one generation to the next? The answer lies in the study of genetics.

Essential Question: Mendelian Genetics "How can two brown fur rabbits have a white fur baby?"

Genetics Definition = The branch of biology that studies heredity. (Heredity = biological inheritance)

~Austrian monk ~Experimented with pea plants Gregor Mendel “Father of Genetics” Gregor Mendel 1822-1884   ~Austrian monk ~Experimented with pea plants

Mendel observed seven traits that are easily recognized and apparently only occur in one of two forms:

Mendel knew an important fact of his pea plants: the flowers have both male and female reproductive parts.

Pollination Pea plants contain both male and female parts, so they can produce seeds by SELF-POLLINATION Fertilization of a plant’s egg cells by the pollen of another plant: CROSS-POLLINATION

Terminology: 1. Gene: a section of DNA that controls a specific trait Allele: alternative form of a GENE (one version of the gene) Trait: a characteristic of a species determined by specific genes (observable)

Dominant gene: the presence of this type of gene will mask/hide the other gene Recessive gene: this gene is hidden by the other gene unless there are two copies of the recessive form.

Video from: http://ed. ted

By breeding many plants over and over, he found that "statistically" Results By breeding many plants over and over, he found that "statistically" certain traits appeared with a certain probability

Mendel’s Results and Conclusions: Biological characteristics are determined by genes. (Genes are passed from parents to their offspring.)

Mendel’s Results and Conclusions: Some forms (alleles) of a gene may be dominant, others may be recessive.

Mendel Devised 2 Laws 1. Law of Segregation: Two copies of each gene are segregated/separated from each other when gametes are formed. Remember: one copy from each parent

Mendel Devised 2 Laws 2. Law of Independent Assortment: The alleles for different genes segregate independently of one another. This is usually the case

When put together…

Terminology continued: 6. Hybrid: offspring of parents with different traits 7. Homozygous: both pairs of genes for a specific trait are the same 8. Heterozygous: both pairs of genes are different

Terminology continued 9. Genotype: the genetic makeup of an organism (ie. AA, Aa, aa) 10. Phenotype: the physical appearance of an organism (ie. Hair color, eye color, etc.)

Monohybrid Crosses A cross between individuals that involves ONE pair of contrasting traits

Punnett Squares!!! tool used to determine the probability of offspring of a cross between 2 parents

Punnett Squares B b MonoHybrid Cross = DOMINANT (capital letter) Can be used to predict & compare the genetic variations that will result from a cross = DOMINANT (capital letter) = DOMINANT B MonoHybrid Cross = recessive (lower case) = recessive b

Punnett Squares Squares Punnett Can be used to predict & compare the genetic variations that will result from a cross = DOMINANT = DOMINANT (capital letter) HOMOzygous = organisms that have 2 IDENTICAL alleles for the same trait B = recessive (lower case) = recessive HETEROzygous = organisms that have 2 DIFFERENT alleles for the same trait b

The likelihood that a particular event will occur 9/13/2018 3:06 AM Probability The likelihood that a particular event will occur Squares Punnett Segregation © 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Test Cross A mating between an individual with an unknown genotype and an individual that is HOMOZYGOS RECESSIVE. Look at offspring to determine parent genotype To determine the GENOTYPE of an organism expressing the dominant phenotype. Example: Labrador Retriever B- back fur b= chocolate brown fur Black lab X chocolate lab B___ X bb

Test Cross Example In humans, long eyelashes (E) is dominant to short eyelashes (e). A man with long eyelashes marries a woman with short eyelashes and they have three children, two of whom have long eyelashes and one of whom has short eyelashes. Draw the Punnett squares that illustrates this marriage. What is the man’s genotype? What are the genotypes of the children?

Dihybrid Crosses A cross between individuals that involves TWO distinct genes

Patterns of Inheritance and Non-Mendelian Genetics

One allele can completely hide the other (Mendellian trait) 1. Complete Dominance One allele can completely hide the other (Mendellian trait)

Flower Color in Snapdragon 2. Incomplete Dominance =both alleles influence the phenotype Flower Color in Snapdragon (blending)

Incomplete dominance in humans hypercholesterolemia Incomplete dominance in humans

Incomplete Dominance Snapdragons Red (RR) White (WW) Pink (RW)

Punnett Squares with Incomplete Dominance Cross a White Snapdragon with a Red Snapdragon a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes White WW W Red RR R b. Set up your punnett square . . .

Punnett Squares with Incomplete Dominance Results RR x WW R R Genotypes 100% RW Phenotypes 100% Pink W RW RW W RW RW

Punnett Squares with Incomplete Dominance Cross Two Pink Snapdragons a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes Pink RW R, W b. Set up your punnett square . . .

Punnett Squares with Incomplete Dominance Cross Two Pink Snapdragons Results Genotypes 25% RR 50% RW 25% WW RW x RW R W R RR RW Phenotypes 25% Red 50% Pink 25% white W RW WW

(both traits are seen—spotting) 3. Codominance Neither alleles totally masks the other (both traits are seen—spotting) RR = red hair rr = white hair Rr = roan (red AND white hairs present)

Codominance and multiple alleles Most common blood type Codominance and multiple alleles

Codominance Cattle coat color Red (RR) White (WW) Roan (RW)

Punnett Squares with Codominance Cross a white heifer with a red bull a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes white WW W red RR R b. Set up your punnett square . . .

Punnett Squares with Codominance Cross a white heifer with a red bull WW x RR Results W Genotype 100% WR Phenotype 100% Roan R WR

Punnett Squares with Codominance Cross two Roans a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring. Phenotypes Genotypes Gametes Roan RW R, W b. Set up your punnett square . . .

Punnett Squares with Codominance Results Cross two Roans Genotype 25% WW 50% WR 25% RR WR x WR W R W WW WR Phenotype 25% White 50% Roan 25% Red WR RR R

Punnett Squares with Multiple Alleles Human Blood Types Alleles: IA, IB, IO Type A: IAIA or IAIO Type B: IBIB or IBIO Type AB: IAIB Type O: IOIO

Punnett Squares with multiple alleles A woman who is homozygous for Type A has a child with a man who is heterozygous for type B. a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes Mom IAIA IA, IA Dad IBIO IB, IO b. Set up your punnett square . . .

Punnett Squares with multiple alleles Mom is homozygous Type A, Dad is heterozygous type B IAIA x IBIO Genotype 50% IAIB 50% IAIO Phenotype 50% Type AB 50% Type A IA IA IB IAIB IAIB IO IAIO IAIO

Punnett Squares with multiple alleles What would be the result of woman who is Type O with a man who is Type AB? a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring. Phenotypes Genotypes Gametes Mom IOIO IO, IO Dad IAIB IA, IB b. Set up your punnett square . . .

Punnett Squares with multiple alleles Mom is homozygous Type A, Dad is heterozygous type B IOIO x IAIB Genotype 50% IAIO 50% IBIO Phenotype 50% Type A 50% Type B IO IO IA IAIO IAIO IB IBIO IBIO

Punnett Squares with multiple alleles Jack and Jill have their first child. Jack is heterozygous type B while Jill is heterozygous Type A. Can they have a child with type O blood? a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring. Phenotypes Genotypes Gametes Mom IAIO IA, IO Dad IBIO IB, IO b. Set up your punnett square . . .

Punnett Squares with multiple alleles Mom is heterozygous Type B, Dad is heterozygous type A Genotype 25% IAIB 25% IAIO 25% IBIO 25% IOIO Phenotype 25% Type A 25% Type B 25% Type AB 25% Type O IBIO x IAIO IB IO IA IAIB IAIO IO IBIO IOIO

Blood Type Frequencies

One trait is controlled by multiple genes 4. Polygenetic One trait is controlled by multiple genes Examples: Height, skin color Manifests as a wide range (gradient) of phenotypes.

Punnett Squares with polygenic traits Even though eye color is controlled by at least three genes, we really understand how brown/blue/green colors work as controlled by two genes… Eyecolor: Gene 1: the green/blue eye color gene, located on chromosome 19. green is dominant (G) , blue is recessive (g) Gene 2: the central brown eye color gene, located on chromosome 15. brown in dominant (B) , blue is recessive (b)

Punnett Squares with polygenic traits Eyecolor: Gene 1: green is dominant (G) , blue is recessive (g) Gene 2: brown in dominant (B) , blue is recessive (b) Brown eyecolor: B??? Green eyecolor: bbG? Blue eyecolor: bbgg

Punnett Squares with polygenic traits What would be the result of a cross between a blue-eyed person (recessive for both genes) and a brown-eyed person (heterozygous for both genes) a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes Blue eyed bbgg bg Brown-eyed BbGg BG, Bg, bG, bg b. Set up your punnett square . . .

Punnett Squares with polygenic traits Results: 25% BbGg 25% Bbgg 25% bbGg 25% bbgg bbgg X BbGg bg BG BbGg Bg Bbgg Phenotypes: 50% brown 25% green 25% blue bG bbGg bg bbgg

Punnett Squares with polygenic traits What is the result when a brown-eyed man (heterozygous for both genes) is crossed with a heterozygous green eyed woman? a. Determine the genotypes of the parents and the gametes they will contribute to their offspring. Phenotypes Genotypes Gametes Green-eyed bbGg bG, bg Brown-eyed BbGg BG, Bg, bG, bg b. Set up your punnett square . . .

Punnett Squares with polygenic traits BbGg X bbGg Genotypes: Phenotypes: 1/8 BbGG 4/8 brown 2/8 BbGg 3/8 green 1/8 Bbgg 1/8 blue 1/8 bbGG 2/8 bbGg 1/8 bbgg bg BG Bg bG BbGG bbGG bbGg BbGg Bbgg bbgg

5. Pleiotropy One gene affects multiple traits In humans these usually present themselves with disease. Example: sickle cell disease

Human Genetic Disorders Images from: http://www.dnarss.com/Chromosome_9.html Ch. 9 (pg. 176)

Genetic Traits and Disorders Genes that control human traits can be altered (mutated) and then inherited by offspring Images from: http://www.aldanaanatomy.com/category/skin/page/2/, http://www.eyesurgeonspc.com/lasik-rock-island/cataract_surgery_rock_island/cataract-surgery-rock-island.html, http://en.wikipedia.org/wiki/Polydactyly

Mutation What is a mutation? Definition= a change in DNA sequence that affects genetic info The result of some mutations are genetic disorders. Image from: http://alsn.mda.org/news/c9orf72-mutation-most-common-cause-als-ftd-als-ftd

How are disorders passed or inherited? Four main ways Single gene Multifactorial Chromosomal abnormality X-linked

Single Gene Disorders Examples . . . The problem trait is controlled by a single gene and can be passed in a dominant or recessive manner (simple genetic trait) Examples . . .

Single Gene Disorders Examples Dominant Achondroplasia 2. Cataracts 3. Polydactyly Images from: http://www.tvchannelsfree.com/tvshows/232/Little-People--Big-World/3.html, http://www.avclinic.com/Cataract.htm http://www.beltina.org/health-dictionary/polydactyly-extra-fingers-toes.html

Single Gene Disorders Examples Recessive Albinism 2. Sickle Cell Anemia Images from: http://vitiligorelief.com/albinism-in-humans.html, http://www.albinism.org/, http://www.sciencephoto.com/images/download_lo_res.html?id=771080393, http://www.nhlbi.nih.gov/health/health-topics/topics/sca/

Multifactorial Disorders many factors Result from mutations in multiple genes Environmental factors can also affect the severity/onset of these disorders Difficult to study and treat

Multifactorial Disorders Examples Hypothyroidism Alzheimer’s disease Some cancers (colon, breast, etc.)

Chromosomal Abnormality In these disorders, entire chromosomes or large segments of chromosomes could be missing, duplicated, or otherwise altered. Image from: http://ghr.nlm.nih.gov/handbook/illustrations/chromosomaldeletion

Ways chromosomal abnormality can occur: Nondisjunction Failure of a chromosome to separate from its homologue during meiosis One gamete receives an extra copy of a chromosome and the other gamete lacks the chromosome entirely

Nondisjunction

Nondisjunction Utah Genetics simulation of how Monosomy/Trisomy develop (click on image) http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

Chromosomal Abnormality (cont.) Scientists can use karyotypes to identify disorders caused by chromosomal abnormalities. Example of a normal human male karyotype:

Ex. Down Syndrome is caused by three copies of chromosome # 21 Nondisjunction Ex. Down Syndrome is caused by three copies of chromosome # 21 Image from: http://learn.genetics.utah.edu/content/disorders/whataregd/down/

Ways chromosomal abnormality can occur: deletion Image from: http://members.cox.net/amgough/Fanconi-genetics-genetics-primer.htm

Ways chromosomal abnormality can occur: duplication Image from: http://members.cox.net/amgough/Fanconi-genetics-genetics-primer.htm

Ways chromosomal abnormality can occur: insertion Image from: http://members.cox.net/amgough/Fanconi-genetics-genetics-primer.htm

Ways chromosomal abnormality can occur: translocation Image from: http://members.cox.net/amgough/Fanconi-genetics-genetics-primer.htm

Checkpoint: Analyze Karyotypes Human? Male or Female? Genetic Disorder? Image from: http://www.biotechnologyonline.gov.au/popups/img_karyotype.html

Checkpoint: Analyze Karyotypes Human? Male or Female? Genetic Disorder? Image from: http://www.biology.arizona.edu/human_bio/problem_sets/human_genetics/11t.html

Checkpoint: Analyze Karyotypes Human? Male or Female? Genetic Disorder? Image from: http://www.humangenetik.uni-bremen.de/HundegenetikEng.html

X-Linked Disorders Disorders in which the mutation or errors are in genes found on the X chromosome Examples . . . 1. Hemophilia 2. Muscular Dystrophy 3. Red/Green colorblindness Images from: http://www.colour-blindness.com/colour-blindness-tests/ishihara-colour-test-plates/

Sex Determination In humans, what genetically makes you male or female???? Images from: http://www.careerwomaninc.com/blog/?p=1675

Gender is determined by our chromosomes females  XX males XY female male What can you notice about the difference between the X and Y chromosomes?

What do you notice about the difference between the X and Y chromosomes? Y chromosome is much smaller. The Y chromosome carries the “SRY” gene. This gene is called the “sex-determining gene” because it causes male sex organs to develop. SRY Images from: http://creationrevolution.com/2011/01/y-chromosome-adam-and-the-cambrian-explosion/

X X X XX XX XY XY Y The possible genotypes for gender are XX or XY. That amounts to 3 Xs and 1 Y. Why then aren’t there more females than males in the world?  Complete the Punnett square X X Results: Each mating there is a… 50% chance female and 50% chance male X XX XX XY XY Y

Phenotypes are used to infer Genotypes Pedigree Definition: A chart which shows the relationship within a family One of the best ways to study human patterns of inheritance & genetic disease Phenotypes are used to infer Genotypes

Pedigree Basics = normal female = normal male = affected female = affected male = affected female = carrier female = marriage line = children

Pedigrees can be used to predict if a trait is dominant, recessive, or sex-linked

Dominant At least one parent must show the trait if it is dominant

Recessive Recessive disorder can be passed from any combination of parents, as long as the dominant parent is heterozygous.

X-linked Females can be carriers More males may be affected