Genetics What is Genetics Branch of Biology that

Genetics

What is Genetics? • Branch of Biology that studies heredity • Gene: Part of DNA that holds genetic material • DNA- “genetic code” • Two factors that influence genetics – Heredity: passing of traits from parent to offspring – Environment: all of the outside influences that act upon an organism

Genetics Words to Know • Dominant: The trait that is expressed (what you see). – Is always an upper case letter – Ex: T=tall t=short • Tt= Tall organism • Recessive: The trait that is not expressed. – Is always a lower case letter – Ex: T=tall t=short • tt= Short organism

• Homozygous: Having a pair of identical genes for a trait (pure bred). – Homo= same – Example: TT or tt • Heterozygous: Having two different genes for a trait (hybrid) – Hetero= different – Example: Tt • Allele: Each copy of a gene • Phenotype: Physical appearance – Remember Ph= Physical! • Genotype: Genetic make up – Remember Gene= Genetic!

Mendelian Genetics

Gregor Mendel • • Father of genetics He was a monk Studied pea plants Interested in why some plants were different colors and why their seeds differed

Reasons for Mendel’s success: 1. He picked a organism that was easy to grow (peas) • short time for new generations • he was able to control pollination 2. He studied one trait at a time • 7 traits in all 3. Recorded data very carefully • He analyzed his data with mathematical reasoning

Mendel named offspring: – P generation: Parent generation – F 1 generation: First filial generation (off spring of the P generation) – F 2 generation: Second filial generation (off spring of the F 1 generation) P generation-parents F 1 generation F 2 generation

Mendel's Laws of Heredity • Developed two laws that all genetics is based upon. 1. Law of Segregation: When a gamete is formed, each pair of alleles separate – Each gamete gets a separate allele 2. Law of Independent Assortment: When a gamete is formed, pairs of alleles separate independent of one another – One gamete may get a recessive allele while the other gets a dominant allele

Predicting Heredity Outcomes • Probability: The likelihood a specific event will occur Number of one type of possible outcome Total number of all possible outcomes Example: You have 4 red marbles and 6 blue marbles in a bag. What is the probability of pulling a blue marble from the bag? 6/10

Punnett Squares • A diagram that helps predict the probable outcome of a genetic cross – Named for inventor Reginald Punnett – Uses Mendel’s laws and probability

Monohybrid Cross • A genetic cross that involves one pair of traits REMEMBER – – – T= Dominant t= Recessive TT= Homozygous Tt= Heterozygous Phenotype (physical) 4: 0 – Geneotype (genetic) 2: 2 or 1: 1 T TT TT t Tt Tt

Punnett Squares T TT TT • F 2 Generation: Cross the results of the f 1 generation t Ex: TT x Tt Tt Tt • Parental : TT x Tt • F 1 Generation: TT, Tt, Tt

Punnett Squares • Monohybrid Example In guinea pigs, black coat is dominant to white coat. Cross a heterozygous black coated pig with a homozygous white pig Step One: Identify what genotypes you are working with B=black b=white

Step Two Set up your cross Bb x bb Step Four Determine ratios -Phenotype: 2: 2 or 1: 1 -Geneotype: 2: 2 or 1: 1 b b Step Three Complete the Punnett Square using the genotypes from step two B b Bb bb

• Punnett Square example two: In pea plants, wrinkled peas are dominant to smooth peas. Cross a heterozygous wrinkled pea with a homozygous smooth pea 1. W=wrinkled 2. Ww x ww 3. P: 1: 1 G: 1: 1 w=smooth w w Ww ww

Step Two Set up your cross Bb x bb Step Four Determine ratios -Phenotype: 2: 2 or 1: 1 -Geneotype: 2: 2 or 1: 1 b b Step Three Complete the Punnett Square using the genotypes from step two B b Bb bb

Dihybrid Punnett Square • Dihybrid Cross: A genetic cross that involves two pairs of traits • Example: – Looking at the offspring of a white cat with a long coat and a black cat with a short coat

• Dihybrid Cross Example: – In snapdragons, red petal color is dominant over white petal color and tall plants are dominant over short plants. Cross a purebred tall plant with a white short plant. Step One: Identify what phenotypes you are working with: R=red r=white T=tall t=short

• Punnett Square example two: In pea plants, wrinkled peas are dominant to smooth peas. Cross a heterozygous wrinkled pea with a homozygous smooth pea 1. W=wrinkled 2. Ww x ww 3. P: 1: 1 G: 1: 1 w=smooth w w Ww ww

Step Two: • Set up your cross RRTT x rrtt Step Three: • Determine your F 1 generation RT rt Rr. Tt Only do this step when the P generation is homozygous dominant x homozygous recessive! RRRTT x rrtt

Step Four Cross your f 1 generation to determine what phenotypes to use in the Punnett square Rr. Tt x Rr. Tt RT RT Rt Rt r. T rt rt F L I O t s Fir er t u O er n n I st La

Step Five Complete the Punnett square using the F 1 phenotypes from step four RT RT RRTT Rt RRTt r. T Rr. TT rt Rr. Tt Rt RRTt RRtt Rr. Tt Rrtt r. T Rr. Tt rr. TT rr. Tt rt Rr. Tt Rrtt rr. Tt rrtt

Step Six: – Determine pheonotypical and geonotypical ratios • P- 9: 3: 3: 1 • G-1: 2: 2: 4: 1: 2: 1 Example Two: These each add up to 16 total number of squares in box! In flies, double wings are dominant over single wings and green body color is dominant over black body color. Cross a purebred double winged green fly with a single winged black fly

1. D=double d=single G=green g=black 2. DDGG x ddgg DG 3. 4. Do this step since homozygous dominant x homozygous recessive! dg Dd. Gg x Dd. Gg DG DG Dg Dg d. G dg dg

DG Dg d. G dg DG Dg DDGG DDGg DDgg Dd. GG Dd. Gg d. G dg Dd. GG Dd. Gg Ddgg Dd. Gg dd. GG dd. Gg Ddgg dd. Gg ddgg

• Incomplete Dominance: A trait that is intermediate between two parents – Ex. A red snapdragon and a white snapdragon produce a pink snapdragon • Codominance: Two dominant alleles are expressed at the same time – Ex: Roan coat in horses

REPRODUCTION Sexual Reproduction • Gametes through meiosis • Genetic variability • Takes more time – growth and development • Good if changing environment Asexual Reproduction • • Does not require a partner Genetically identical to parent Short reproduction time Good if stable environment not needing change

Meiosis (review) • Increases genetic variability through genetic recombination (re-assortment of chromosomes) – Crossing over – 2 chromosomes overlap and exchange genetic material – Independent assortment (remember)

Genetics and Humans

DNA Technology • Biotechnology: Commercial application of biological principles • Recombinant DNA Technology: DNA of an organism is cut into pieces to create specific proteins. – Is used in agriculture to improve crops – Genetically altered crops can cause allergic reactions • GMO (genetically modified organism) • GEO (genetically engineered organism)

• Biotechnology in Medicine: – Used to make vaccines (Hepatitis B) – Interferon: Used to fight cancer – Gene Therapy: Bad gene is replaced with a good gene • Used to fight diseases such as cystic fibrosis and sickle cell anemia.

• Stem Cell Research: – Stem cells can be ANY type of cell, they are not specialized – Alzheimer's, Dementia, Parkinson’s – Is VERY controversial – Three sources of stem cells in humans: • Adult bone marrow • Umbilical cord blood • Embryos

• Cloning: – Making two genetically EXACT organisms – Dolly the sheep was cloned in 1997 Other organisms such as a cat, mule and pig have been cloned since – Very controversial due to possible human cloning – May help with disease (cloning healthy tissue)

• DNA Fingerprinting: – All DNA (except identical twins) is different – Scientists look at a small piece of DNA to determine a match – Process that pulls “markers” out is called gel electrophoresis – Used in paternity testing and forensic science

• Human Genome Project: – Genome: An organism’s complete set of DNA – Humans have aprox. 3 BILLION base pairs – 1990 scientists began mapping the genome to find out which base pairs make up specific chromosomes – Completed in 2003

Sex Linked Traits • Determined by a gene on the x chromosome • Colorblindness

Sex Influenced and Sex Limited Traits Sex Influenced • Traits that are dominant in one sex but recessive in the other • Baldness in males Sex Limited • Traits that only appear in the presence of estrogen or testosterone • Beards in men • Male or female body shape

Twins • Fraternal Twins: – Most common type – Two eggs are fertilized by two sperm – Genetically different • Identical Twins: – Are always the same sex – One fertilized egg splits into two – Genetically identical

Genetic Mutations • Mutation: A change in the genetic code • Point Mutation: One nitrogen base in the sequence is altered • Insertion Mutation: An extra nitrogen base is added to sequence • Deletion Mutation: One nitrogen base is deleted from the sequence • Substitution Mutation: Base pairings are incorrect (ex: T&G pair or A&C pair)

What Can Cause Mutations? • DNA Replication Errors: – DNA polymerase misses an error when proofreading new DNA strand • Mutagens: – Agents in the environment that can cause a mutation – Example: UV rays and chemicals

Disorders Caused By Genetic Mutations • Sickle Cell Anemia: – Mainly occurs in the African American race – Recessive gene – Attacks red blood cells – Crescent shaped cells rupture easily and get lodged in circulatory system – People with malaria are naturally resistant

• Hemophilia – Blood does not clot – Is called the “Royal Disease” – Recessive gene – Sex-linked trait

• Tay-Sachs Disease – Attacks Nervous System – Recessive trait – Occurs mainly in Orthodox Jewish population – Appears around 6 months of age, death usually occurs by 4 years old

• Phenylketonuria (PKU) – Causes mental retardation if left untreated – Recessive gene – Caused by a defective enzyme (can not change phenylalanine into tyrosine) – Tested for at birth

• Cystic Fibrosis – Thick mucus covers lungs, liver and pancreas – Recessive gene – May cause secondary infections – Occurs mostly in white race

• Huntington’s Disease – Causes insanity – Is usually fatal – Dominant gene – Deterioration of brain tissue in middle age (begins 35 -40 years old)

Nondisjunction • Chromosomes do not separate during meiosis • Down’s Syndrome – Extra 21 st Chromosome – Autosomal nondisjunction – Called Trisomy 21 • Trisomy: Diploid individual has an extra chromosome

Turner’s Syndrome • • • In sex chromosomes XO (no second sex chromosome) Abnormally short female No sex organs-sterile Webbed neck

Trisomy X Syndrome • Also called Triplo-X syndrome • In sex chromosomes • XXX • Fertile • Normal intelligence

Klinefelter’s Syndrome • In sex chromosomes • XXY • Sterile male • Does not mature • Very tall with slight breast development

XYY • In sex chromosomes • Fertile male • Associated with criminal behavior • Associated with aggression

Prenatal Testing • Amniocentesis: Needle is used to remove amniotic fluid from the placenta. – A karyotype is then developed – Tests for Huntington’s Disease, Down’s Syndrome, Cystic Fibrosis, Tay-Sachs, Sickle Cell Anemia

Prenatal Testing • Fetoscopy: Tiny camera inserted into the uterus – Allows Dr. to see the baby – Collection of umbilical cord blood (test for genetic diseases) • Ultrasound: High frequency sound waves – Allows Dr. to see the development of the baby

Prenatal Testing • Chorion Villi Sampling – Collection of cells from the placenta – Tests for genetic disorders – Similar to an Amniocentesis, completed earlier in the pregnancy

Blood Typing • Type A: – IA I A – IA I o • Type B: – IB I B – IB I o • Type AB: IA I B • Type O: i i. O O

• Endosymbosis: – Mutalistic relationship between 1 organism and another that lives within it. – A small aerobic prokaryote entered and began to live and reproduce in a larger anaerobic prokaryote. – The aerobic prokaryote evolved into the mitochondria – Ancestor to the modern eukaryotic cell – The chloroplast followed a similar evolutionary route.

• Mitochondrial DNA: – Evidence that supports endosymbosis – Replicates independently from the cell cycle – DNA is circular in shape (prokaryotes) – Contains some of its own genes which are different than the rest of the cell’s.

Blood around the world Where did these different blood groups come from? In the same way that people, cultures and languages change from country to country, so do blood groups. This means that some types are more common in certain ethnic and national groups and, despite the fact these groups become more mixed as people move around the globe, it's still possible to see how blood groups differ from population to population. The O group is the oldest of the blood groups. Back in the Stone Age, everyone would have been O - and today it's still the most common group in the UK, especially in the North of England. Over in Central and South America and the USA most people are O too. The fact that anyone can receive O blood reflects the fact that all other blood groups are derived from it. Group A is the second oldest blood group, appearing around 25, 000 - 15, 000 BC, when larger human settlements first appeared as farming developed. You'll find a lot of A in Central and Eastern Europe. It's the commonest group in Norway, Denmark, Austria, Armenia and Japan. If you're looking for group B, then try the Chinese or Asian communities, where around a quarter of all people share this blood group. It emerged between 15, 000 and 10, 000 BC as tribes migrated from Africa to Europe, Asia and the Americas and mingled with other populations. The newest and rarest group, AB, only appeared between 1000 and 500 years ago, and is believed to have occurred as a response to the mixing of existing blood groups on a major scale. In Japan, China and Pakistan around 10% of the population boast this rarest of blood groups. Amazing! http: //www. blood. co. uk/pages/world_blood. html

Body Type: Large: BB or Bb Small: bb Legs: Long and colored: FF or Ff Short and not colored: ff Eyes: Large: EE or Ee Small: ee Antennae: Shiny: AA or Aa White: aa Wings: Waxy: WW or Ww Shiny: ww