Plant Genetic

A vivid description of genetics in relationship to plants. it's a need to know.

1. B ota 103 Group 6 Plant Genetics Presented by: Emma Ford Watta Kamara Betty Lablah Sayenawuo Seekpee Marcus Jensen Tegeste Kollie Louisa Smith December 6, 2018

2. Lesson Outline Overview of plant genetics Mono and Dihybrid crosses Beyond Mendel’s Work Laws of Inheritance Gene interaction with the environment

3. Lesson Objectives By the end of this presentation, the students should be able to: Define genetics Distinguish between a mono and dihybrid cross D iscuss Mendel's laws of inheritance Discuss the cytoplasmic and polygenic inheritance

4. Overview of Genetics Genetics from the word “ genetikos ” meaning g enesis or origin It deals with the study of genes, genetic variation and heredity Gregor Mendel is known as the father of genetics Gregor Mendel

5. Gregor Johann Mendel Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants He found that the plants’ offspring retained traits of the parents Called the “ Father of Genetics ”

6. Mendel's Experiment on Inheritance Chromosomes are the particular carriers of genetic information These information are encode by genes These Genes consists of nucleotides on a strand of DNA’s double helix Genes consists information about an organisms feature .. Ex: plant height , seed color, leaf shape

7. Each character may appear in two or more forms called a trait The variant form of each trait, known as allel e, is a code for each trait Monohybrid cross involves individuals that have different alleles for a specific gene This type of hybrid cross is based on the law of segregation Mendel's Experiment on Inheritance Cont’d

8. Monohybrid Cross The monohybrid cross is between two parents, using a pair of contrasting characters. These characters that are being studied are governed by two multiple variations called locus. A locus is a fixed position on a chromosome, like the position of a gene

9. When two plants of the same trait are bred with each other, and all their offspring have the same trait, is called Pure breeding. In the cross, each parent is chosen to be homozygous for a given trait. Monohybrid Cross Cont’d

10. Usage of Monohybrid Cross It is used to determine the relationship between two alleles The offspring make up the first fillal generation (F 1 Gen) Members of F 1 are heterozygous. Phenotypes of the F 1 expresses dominant traits Crossing the F 1 , produces the F 2 generation with the phenotypic ratio of 3:1

11. Procedures of Mendel's Experiment

12. Results From Mendel's Experiment Mendel recorded the Data and conclusions from his experiment in a paper titled ‘experiment on plants hybridization in 1865

13. Results Cont’d He called the visible traits dominant and the masked traits recessive The dominant and recessive traits are controlled by two alleles of a specific gene A plant that has two copies of the same allele is homozygous A plant that has two different alleles is heterozygous Visible traits dominant Masked traits recessive

14. The combination of alleles of a plant is its genotype Example pp or PP The physical appearance of plant is its phenotype The results of Mendel's cross can be represented by a Punnett square Results Cont’d

15. The law of Segregation

16. Segregation of Alleles occurs during Anaphase 1 of Meiosis

17. Testcross Testcross is a genetic cross between a homozygous recessive individual and a corresponding suspected heterozygous. T o determine the phenotype of the latter This cross determines if an individual is homozygous dominant or heterozygous .

18. Testcross:

19. Dihybrid Cross A cross between two different genes that differ in two observed traits Mendel crossed a plant that produced smooth, yellow seeds ( two dominant phenotypes) with a plant that produce wrinkled, green seeds (two recessive traits)

20. Dihybrid Cross:

21. The Law of Independent Assortment

22. Law of Independent Assortment Cont’d Independent assortment of alleles occur because the segregation of alleles in one tetrad does not affect the segregation of alleles in another Another feature of independent assortment is recombination Recombination occurs during meiosis and it’s a process that breaks and recombines pieces of DNA to produce new combination of genes

23. Beyond Mendel's work Mendel didn’t report on trihybrid crosses which involves plants that differ in three characters A trihybrid cross can be analyzed by using his Method

24. Trihybrid Cross:

25. Incomplete Dominance If Mendel had used snapdragon instead of Peas during his experiments, he would have had a hard time formulating his laws of inheritance Crossing of pure breeding strain of white flower with red flower will produce an F 1 generation of pink Flowers The Flowers are pink because neither allele exhibits complete dominance over the other and this is referred to as incomplete dominance.

26. Incomplete Dominance:

27. Polygenic Inheritance and Pleiotropy Polygenic Inheritance occurs when some characters are controlled by genes with more than one allele It also occurs when characters are controlled by more than one gene Examples: in wheat when a plants with dark kernel is crossed with one that has a white kernel, the resulting F 1 generation will have medium red kernel Pleiotropy occurs when a gene has more than one effect on an organism’s phenotype

28. Location of Genes Affects Inheritance Pattern Linked genes are genes on a chromosomes that segregates as a unit during meiosis, causing the traits specified by those genes to be inherited together When linked gene are involved in a genetic cross the law of independent assortment does not apply Crossing over answers the question of the linked behavior of genes on the same chromosome

29. Location of Genes Affects Inheritance Pattern Cont’d Chiasma is an X-shaped structure formed when two chromatids of two homologous chromosomes lie across each other The chromatids in the Chiasma may break and exchange fragments and also alleles located on those fragments When two genes are very close together on a chromosome it is likely that they will be included in the same fragments Location is important for genes on sex chromosomes

30. Crossing Over:

31. Cytoplasmic inheritance Inheritance pattern are further complicated by genes not on chromosomes in the nucleus Chloroplasts and mitochondria have small cellular DNA molecules Characters coded for by genes in the DNA of these organelles are passed from parents to offspring through cytoplasmic inheritance It is the transmission of genes that occurs outside the nucleus.

32. Genes Interact With Each Other In The Environment Genes do act in isolation to affect an organism’s phenotype Epistasis occurs when one gene alters the effects of another In sweet peas two genes interact to determine flower color Each gene codes for an enzyme in the biochemical pathway of pigment synthesis

33. Genes Interaction

34. The actual interpretation of plant genes often depends on environmental factors. Ex: hydrangea

35. In other plants, temperature affects flower color ex: buttercup Buttercup leaves look different when they grow in air than when they grow in water Genes Interact With Each Other In The Environment Cont’d

36. Mendel’s Genes For Heights In Pea Plants DNA and RNA behaves as the molecule that carry genetic information In 1953, Watson and Cricks analysis revealed the structure of DNA The gene for height in Mendel's pea plants is known as the Le gene Tall pea plants contains 10 - 18 times as much growth-promoting hormone Gibberellin 1(GAI) as dwarf pea plants

37. Dwarf plants contain three to five time as much as Gibberellin 20 (GA20) as tall plants GA20 do not promote growth Mendel’s Genes For Heights In Pea Plants

38. Summary: Genetic is the study of genes, genetic variation and heredity in living things Genes carry information about an organism’s features Monohybrid cross involves individual with a pair of contrasting traits while dihybrid cross involves two pairs of contrasting traits Genes also interact with the environment to affect an organism’s phenotype

39. Reference: Nabor , Murray W., INTRODUCTION TO BOTANY , Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings, 1301 Sansome St., San Francisco, CA 94111 www.googleimage.com

40. THANK YOU FOR LISTENING Questions! Comments!! Contributions!!!