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Mitosis Definition: A cell division process in which a parent cell (original cell) divides into two identical daughter cells (new cells)Occurs in:Human and animal : somatic cellsPlants: tips of roots and shootsBuilt up ofcontainingdeterminingcontainingcontainingSimilarities And Differences Between Mitosis And Meiosis

Chromosomes, genes and DNACik Emy NUCLEUSCHROMOSOMES-threadlike structure-human beings have 46 (23 pairs-contain protein and DNADNADouble helix structure-Made up of series of genesGENESegment of DNA-Genetic codes which determine an organism characteristics

http://youtube.co/watch?v=nPG6480RQo0

Stages of mitosisChromosomes in the nucleus shorten, thicken and more visible.Replication of chromosomes occur.Each strand of chromosome is called chromatid.chromatidcentromerenucleus membrane

The nucleus membrane forms again.Two daughter cells are formed.Each daughter cell has the same number of the chromosomes as the parent cell.Spindle fibres emerge.Chromosomes align themselves in the centre of the cell.The nucleus membrane disappears.Chromatids divide and separate to the opposite ends of the cell.At the same time the cell starts to divide.spindle fibres

http://youtube.co/watch?v=AhgRhXl7w_g&feature=fvsthttp://youtube.co/watch?v=cvlpmmvB_m4orThe Importance of Mitosis

http://youtube.co/watch?v=D1_-mQS_FZ0Stages Of Meiosis : Meiosis 1 And Meiosis 2Chromosomes in the nucleus shorten, thicken and more visible.Crossing over and replication process occur on chromatids.

Meosis 1Chromosomes align themselves in the centre of the cell.The nucleus membrane disappears.Chromatids separate and move to the opposite ends of the cell.The cell begins to divide into two.Two daughter cells are produced.The nucleus membrane reforms.

The nucleus membrane is formed again.Four daughter cells are formed.Each daughter cell has half of the number of chromosomes in the parent cell.Spindle fibres emerge.Chromosomes align themselves in the centre of the cell.The nucleus membrane disappears.Chromatids divide and separate to the opposite ends of the cell.The cell starts to divide.Meosis 2

http://youtube.co/watch?v=eaf4j19_3ZgThe Importance of MeiosisCrossing over processIndependent assortment of chromosomes

(characteristics are separated during formation of gamete and randomly combined during fertilization)1. To produce gametes2. To allow variation through :Conclusion Of Mitosis And MeiosisMeiosis Fertilisation Mitosis Male (46 chromosomes)Female (46 chromosomes)Sperm (23 chromosomes)Ovum (23 chromosomes)Zygote(46 chromosomes)Baby(46 chromosomes)Comparing Meiosis And Mitosishttp://youtube.co/watch?v=Ba9LXKH2ztU

The Difference Between Mitosis And Meiosis DIFFERENCESMITOSISMEIOSISReplication processNumber of divisionNumber of daughter cells producedNumber of chromosomes in daughter cellCombination of geneOccur One onlyFour Same as in parent cellSame as parent cell Occur in the first divisionTwo timesTwo Half of parent cellDifferent from parent cell Crossing over processDoes not occurOccur 3.2 THE PRINCIPLES AND MECHANISM OF INHERITANCE

Chromosomes are in pair. One from the father while the other one from the mother.Same genes:Dominant gene and recessive gene are placedopposite to each otherHomologous chromosomestTExamples of dominant and recessive traitsTrait Dominant Recessive Earlobes Free earlobes

Attached earlobesTounge Ability to rollInability to roll

Dimples Presence

Absence HairCurly Straight Iris colourBrown Blue Height Tall Dwarf

The Mechanism Of Trait InheritanceGregory Mendel was the first person who discovered the principles of heredity.Genotype Phenotype The genetic information of an organismThe physical characteristics of an organismMonohybrid Inheritance By Gregory MendelTTttTall (pure breed)Dwarf (pure breed)TTttTttTTall Tall Tall Tall Tall Tall Tall Dwarf Phenotype :Genotype :Phenotype :Genotype :Phenotype :Genotype :F2 GenerationF1 GenerationGametes Gametes TtTtTtTtTtTtTTttKey: Homozygous: both genes are same Eg: TT, ttHeterozygous: genes are different Eg: TtExercise 1In the pea plant, the gene for round seed(R) is dominant to the gene for wrinkled seed(r). If a homozygous round-seeded pea plant is crossed with a homozygous wrinkled-seeded plant, what will be the phenotype of F1 plants?If the F1 plants are self-pollinated, what will be the genotype and phenotype ratios of the F2 plants?RRrrRound seedWrinkled seedRRrrRound Round Round Round Parental Phenotype :Parental Genotype :F1 GenerationGametes RrRrRrRrHence all the F1 plants have round seeds.a)Key: R: round seededr : wrinkled seededb)RrrRRound Round Round Wrinkled F2 Phenotype :F2 Genotype :F1 GenerationGametes RrRrRrRrRRrrGenotype ratio is 1 RR:2 Rr: 1rr

Phenotype ratio is 3 plants with round seeds : 1 plant with wrinkled seedExercise 2B represents the dominant gene for black cat, and b represents the recessive gene for a white cat. What is the phenotype ratio of the number of black cats to the number of white cats if black fur cat (Bb) is crossed with another black fur cat (Bb)?BbbBBlack Black Black White F1 Phenotype :F1 Genotype :Parents Gametes BbRbBbBbBBbbPhenotype ratio is 3 black fur cats: 1 white fur catKey: R: black catr: white catAnswer:Exersice 3In the pea plant, the gene for purple flowers (P) is dominant to the gene for white flowers (p). A cross between a heterozygous pea plant with purple flowers and a homozygous pea plant with white flowers is done. What are the genotypes of the offsprings?PpppPurple White Purple White F1 Phenotype :F1 Genotype :Parents Gametes PpppppPpPpppGenotype ratio is 2 Pp : 2 ppKey: Pp: heterozygous , purple flowerpp: homozygous , white flowerAnswer:3.3 SEX DETERMINATION AND THE OCCURRENCE OF TWINS IN HUMAN BEINGSSex chromosomes: the last pair in human chromosomesMale: 22 pairs of autosomes and a pair of sex chromosomes XY.

Female: 22 pairs of autosomes and a pair of sex chromosomes XX.Sex determination : the sex of baby is determined by the fathers sperm (XY)

44 + XY44 + XX

Y

XGamete cells:or

XFertilisation Baby girl 44+XXBaby boy44+ XY3644+XX44+XY22+X22+X44+XX44+XY22+Y22+X44+XX44+XYMother Father Gametes :Parents :Offsprings:Ratio of daughter : son is 1:1

Therefore , the chance to get daughter or son is 50:50.Daughter Daughter Son Son The Formation Of Identical And Non-identical TwinsAn ovum is fertilised by a sperm to form a zygote.

Zygote undergoes mitosis and separates into two to develop into two embryos.

Genetically identical.

Share the same placenta.

Same sex.IDENTICAL TWINSTwo different ova fertilised by two different sperms at the same time.

Two different zygotes are formed and develop into two embryos.

Genetically different.

Each has own placenta.

Same sex or different sex.

Known as fraternal twins.NON-IDENTICAL TWINS

IDENTICAL TWINSNON-IDENTICAL TWINSZygote undergoes mitosisTwo embryosFoetus share the same placentaTwo ova are fertilised

Two different zygotes are formedTwo separate embryosEach foetus has his own placentaSiamese twinsIdentical twins that are joined at some parts of the bodies.Formed when zygote fails to divide completely in the course of formation.

Similarities And Differences Between Identical And Non-identical TwinsIDENTICAL TWINSNON-IDENTICAL TWINSSimilarities:The twins are formed in the uterus.Two babies are formed.OneOne Same sexYes Same / identical Yes / sharing placenta Two Two Same or different sexNo Different No / separate placentaNumber of spermsFertilised ovum splits into twoGenetic make upSharing of placentaSex Number of ovaDifferences Why do these happen to them?

3.4 MUTATIONMutation: the spontaneous change to the structure of genes or chromosomesExamples Of Chromosome MutationDowns syndrome: an extra chromosome in autosome 21 (47 chromosomes)

Klinefelters syndrome: a male with extra X chromosome (XXY)

Turners syndrome: a female with one less X chromosome (XO)

Polyploidy: having one or more chromosomes in a set of chromosomeExamples Of Gene MutationColour blindness: a mutated gene in the X chromosome

Sickle cell anemia: mutation in gene that produces haemoglobin; inefficient in transporting oxygen in the blood

Albinism: the gene for skin colour is mutated; unable to produce black pigment (melanin)

Haemophilia: mutation in gene that is important for blood-clotting

Examples Of Chromosome MutationDowns syndrome

Additional chromosome at autosome 21.

Physical retardationThick neckSlanted eyesProtuding toungeReduced resistance to diseases

Klinefelters syndrome

A male with extra X chromosomes (having XXY)

InfertileUnderdeveloped testesNarrow shoulder Enlarged breastsTurners syndrome

A female having one less X chromosome (XO)

InfertileShortMentally retardedHas no ovariesSmall breastsFolded skin on neckNo menstrual cycle

PolyploidyThe number of chromosomes is increased by one or more sets.More common in plants.

Examples Of Gene MutationColour blindness

Mutant gene (recessive gene) on the X chromosome.

Not able to differentiate colours especially green and redMore common in males because male has only one X chromosome

Albinism

The gene for skin colour is mutated (recessive gene)

Unable to produce melanin (black pigment)White hairPink eyes and pinkish skinSkin is sensitive to sunlight

Sickle-cell anemiaMutation in gene that produce haemoglobin

Sickle-cell shaped of red blood cellsNot efficient in transporting oxygenFacing painful crises such as chest pain, fatigue, bone pain,Yellowing of eyes Inherited from both parents

Haemophilia

Mutation in chromosome X (for blood clotting)

Have problem in blood clotting May bleed continuously or for a longer period A woman carrier may inherit the disease to a son

Causes Of MutationAdvantages And Disadvantages Of Mutation3.5 THE EFFECTS OF GENETIC RESEARCH ON HUMAN LIFEGene therapy: to replace damaged/faulty genes during the foetal stageGenetic screening: to predict diseases likely to developGene test: to screen unborn children for diseasesGenetic engineering: to transfer DNA from one organism to anotherHuman genome project: maps all human genes to determine genes which causes diseasesField of Medicine

To produce plants which are resistant to diseases and infectionsTo produce engineered plants which are able to live in unfavourable conditionsTo produce plants which grow and mature fastTo produce higher yieldsTo produce high quality of crops and livestockField of Agriculture

Selective BreedingA process which involves cross breeding and cloning of plants or animals Advantages New varieties with desired characteristics can be producedTo produce new and high quality cropsMore resistant to diseases Disadvantages May produce new varieties with undesirable characteristics59Example 1: Cow

is cross bred withFriesian CowSahiwal CowMafriwal Cow-Grow faster-Bigger in size-More milk-High resistant to disease Example 2: Palm oil

is cross bred withDuraPisiferaTenera-Thick mesocarp and large kennel :much oil-Thin shell: easier to extractThinmesocarpLarge kennelThickmesocarpSmallkennelTissue CultureA process of cloning a plant by using a plant part or single cell in a test tube under a controlled condition AdvantagesTo produce many copies of the same plants in a short timeTo produce plants anytime we wantShorter maturation timeNo variationDisadvantages Complete wipe-out of crops if there is spread of diseases62Steps of Tissue Culture

a) Explant: b) Multiplication: c) Transplanting: Cloning The process of producing an organism that is an exact genetic copy of another

Process:64Animation For CloningNatural and artificial twinninghttp://learn.genetics.utah.edu/content/tech/cloning/whatiscloning/twinning.html

Somatic cell nuclear transfer (as in Dolly)http://learn.genetics.utah.edu/content/tech/cloning/whatiscloning/scnt.html

Genetically Modified FoodFoods from plants and animals which have had their genetic information changed by adding genes from another organismsAdvantages: For crops: enhanced taste and quality, increased yields, matures faster, better resistance to diseases, remain fresh longerFor livestock: increased resistance to infections and diseases, higher yield of milk, meat and eggsCause allergies and side effects to human beingsDisadvantages of Genetically Modified Food and Organisms: Milk of genetically modified animals may be unsafeAntibiotic-resistant genes in GM organisms may be pass on to bacteria; difficult to kill themGenetic research is expensive, poor farmers cannot afford3.6 VARIATION AMONG LIVING THINGSVariation: The differences among individuals of the same speciesContinuous variationDiscontinuous variation-Characteristics among individuals which do not show distinct differences

-Quantitative and can be measured

-Determined by genes and can be influenced by environmental factors

-Characteristics among individuals which show distinct differences

-Qualitative and cannot be measured

-Determined by a single gene and is not influenced by environmental factors

Continuous variationDiscontinuous variationHeight Skin colourLength of footIntelligence Weight Earlobes Iris colourColour blindnessTongue rollingBlood group

Factors That Cause VariationImportance Of VariationDiscuss the similarities and differences between continuous variation and discontinuous variation.CONTINUOUS VARIATION DISCONTINUOUS VARIATIONSimilarity:Show differences in characteristics among individuals of the same speciesYesNot distinct If it is influenced by environmental factors cannot be inherited Two or more genes for the same character Quantitative/ can be measuredNo Distinct Can be inherited Single gene Qualitative/ cannot be measuredInfluenced by environmental factors?Inheritance No of gene Type of dataCharacteristic Differences Similarities And Differences Between Continuous And Discontinuous Variation3.7 THE NEED TO ADHERE TO A CODE OF ETHICS IN GENETIC RESEARCHDiscuss the effects of misusing the knowledge of genetics research.We need code of ethics!! The produce of biological weapon: anthrax bacteriaGMF may have side effects and endanger human health, should be labelledHuman cloning: against religionManipulation of human genes when carrying out research on human being