1 GENETICS

2 What is Genetics? The study of how traits are inherited through the interaction of alleles

3 Heredity The passing of traits from parent to offspring

4 endel The Father of Genetics: Gregor Mendel An Austrian monk who studied mathematics and science Studied how traits pass from generation to generation He thought it was possible to predict the kinds of flowers and fruit a plant would produce Most of his work was done studying peas An Austrian monk who studied mathematics and science Studied how traits pass from generation to generation He thought it was possible to predict the kinds of flowers and fruit a plant would produce Most of his work was done studying peas

5 Gregor Mendel Mendel was the first to trace one trait through several generations He also used mathematics and probability to explain heredity. He is famous for his work with pea plants. Why did he choose peas? The conclusions he came to was how traits pass from one generation to the next

6 1 Genetics of Pea Plants

7 Mendel’s Experiments Peas….. Purebred: parents always produced the same traits generation after generation –Example: tall pea plants Crossing two plants with different expressions of the trait he found the new plants all looked like one of the parents He called these HYBRIDS –Example: yellow and green purebreds produce all green peas Peas….. Purebred: parents always produced the same traits generation after generation –Example: tall pea plants Crossing two plants with different expressions of the trait he found the new plants all looked like one of the parents He called these HYBRIDS –Example: yellow and green purebreds produce all green peas

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9 Principles Of Heredity 1. Traits are controlled by alleles on chromosomes 2.An allele may be dominant or recessive 3.When a pair of chromosomes separates during meiosis, the different alleles for a trait move into separate sex cells

10 Genes located on chromosomes, -made up of DNA control an organisms form and function during meiosis, pairs of genes separate and each sex cell winds up with one form of a gene for each trait

11 Alleles Different forms of a trait that a gene may have Every sex cell has one allele for each trait Example…. Earlobes Attachedvs. Unattached

12 Alleles separate into separate sex cells during meiosis

13 Dominant / Recessive Traits Dominant factor- trait that dominates or covers up short form ( Use Upper case letter) seemsRecessive factor- trait that seems to disappear ( Use lower case letter )

14 Alleles Determine Traits Homozygous two alleles for a trait that are exactly the same TT or tt TT or tt Heterozygous two different alleles for a trait TtTt

15 Genotype We use letters to represent the trait or alleles. Example: Bb (heterozygous black) tt (homozygous short) The set of genes an organism has. Sometimes it refers to the entire Genome of an organism and sometimes it refers to the alleles.

16 Phenotype Physical trait that shows as a result of a particular genotype Example: curly ears straight ears

17 Punnett Square A tool used to predict results in genetics Dominant allele….Capital letter (T) Recessive allele….small letter (t) genotypeThe letters that represent the genetic make up are called: genotype Example: TtExample: Tt

18 Making a Punnett Square The letters indicating the alleles donated by each parent are written along the top and side. One letter per box.

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20 Probability A science that helps you predict the chance that something will occur Coin toss 50/50 probability Studying large numbers increased Mendel’s chances of seeing a pattern

21 Sex Determination Females produce eggs that have only an X chromosome (XX) Males produce both X-containing sperm and Y-containing sperm (XY) Sex of an offspring is determined by the male gamete since males have both the X and the Y chromosome

22 Boy or Girl?

23 “Blended” or intermediate expression Neither allele for a trait is dominant over another..both are expressed red and white flowers produced Pink flowers

24 CRCR CWCW CRCWCRCW

25 Codominance When 2 dominant alleles are expressed at the same time

26 Multiple Alleles Many traits are controlled by more than two alleles, or multiple alleles. Blood types: A, B, AB and O A and B are Dominant over O

27 Polygenic Inheritance Polygenic inheritancePolygenic inheritance - a group of gene pairs act together to produce a single trait Produces a wide variety of phenotypes –height –weight –body build –shape of eyes, lips and ear

28 Mutatio ns Changes or errors that occur when DNA is copied inside a cell. –Chemicals, radiation and radioactive substances can also cause mutations A mutation results in the change of genes Mistakes in meiosis can result in an organism with more or less chromosomes than normal. Incorrect chromosome number can cause chromosome disorders –Downs syndrome (an extra chromosome #21)

30 Environmen tal Impact Gene expression can be influence by the environment – people at risk for skin cancer should avoid sun exposure –Himalayan rabbits can only express the allele for dark fur in low temperatures

31 Recessive Genetic Disorders Occur when both parents pass on the recessive allele and both recessive allele must be inherited by the offspring –Cystic Fibrosis –Sickle Cell Anemia

32 Sex-linked Disorders Color-blindness inherited allele on the X chromosome that prevents from seeing certain colors An allele that is inherited on a sex chromosome

33 More Sex-linked Disorders Hemophilia blood does not clot properly Females are just carriers

34 A tool for following a trait through generations of a family

35 Importance of Pedigrees Pedigrees are important tools geneticists use to understand how a trait is inherited They can then predict the probability the offspring will be born with a trait Extremely important in breeding animals or plants because livestock and plant crops are used as sources of food

36 Genetic Engineering Scientists are experimenting with methods that allow them to go into cells to change or the arrangement of DNA Used to produce large quantities of medicine, such as insulin Also used to find new ways to provide people with more nutritious food

37 Genetic Engineering

38 Gene Therapy Placing a normal allele in a cell that has a mutation A virus is used as the vector to deliver the DNA

SELECTIVE BREEDING The selection of certain seeds or animals for reproduction in order to influence the traits inherited by the next generation.

SELECTIVE BREEDING The Liger is the result of breeding a female Tiger to a male Lion. The liger has both stripes and spots. The stripes are inherited from its tiger parent and the spots from the lion parent.

The Zebroid is the result of breeding a female Horse and a male Zebra. The Zedonk / Zonkey is the result of breeding a female Donkey and male Zebra.

OKAPI 42 Not selective breeding

43 The Human Genome Project identify all the approximately 20, ,000 genes in human DNA, determine the sequences of the 3 billion chemical base pairs that make up human DNA, store this information in databases, improve tools for data analysis, transfer related technologies to the private sector, and address the ethical, legal, and social issues (ELSI) that may arise from the project. Work is still on-going