Presentation on theme: "Happy Friday! Please do the following: pick up the handouts"— Presentation transcript:
1 Happy Friday! Please do the following: pick up the handouts get a chrome-book and get out your Oreo Mitosis lab – you have 15 minutes to submit your video linkhttps://www.youtube.com/watch?v=gwcwSZIfKlM
2 REPRODUCTION All living things can reproduce themselves: Asexual reproductionSexual reproduction
3 REPRODUCTIONAsexual reproduction occurs when a single organism produces offspring on its own.The prefix a- means without.This produces offspring that are genetically identical to their parents.
4 REPRODUCTIONSexual reproduction begins with the sperm and egg…but where did the sperm and egg come from?
5 Where it all began… Zygote You started as a cell smaller than a period at the end of a sentence…Zygote
6 How did you get from a single zygote to 100 trillion cells? And now look at you…How did you get from a single zygote to 100 trillion cells?
7 Answer: Mitosis What is mitosis? Why is cell division important? amoebaWhat is mitosis?a parent cell creates two genetically identical daughter cellsWhy is cell division important?GrowthRepairUnicellular organismsCell division = reproductionReproduces entire organism& increase populationMulticellular organismsCell division provides for growth & development in a multicellular organism that begins as a fertilized eggAlso use cell division to repair & renew cells that die from normal wear & tear or accidents
8 Mitosis Which cells undergo mitosis? amoebaWhich cells undergo mitosis?Somatic cells aka regular body cellsSkin cellsFingernail cellsBone cellsSomatic cells contain 2 complete sets of chromosomes.That makes somatic cells DIPLOID (2n)Unicellular organismsCell division = reproductionReproduces entire organism& increase populationMulticellular organismsCell division provides for growth & development in a multicellular organism that begins as a fertilized eggAlso use cell division to repair & renew cells that die from normal wear & tear or accidents
9 You have 2 sets of chromosomes 1 set of chromosomes came from your mother (n)1 set of chromosomes came from your father (n)Chromosomes are found in homologous pairs (two of each chromosome – 2n)DIPLOID
10 REPRODUCTIONSexual reproduction occurs when two organisms share genetic material to create offspring.This creates offspring that are different from both parents & genetically unique.+
11 Typical Human Family Tree During sexual reproduction, organisms must share their chromosomes without adding or subtracting from the total number.This means that they must create special haploid cells with only one of each chromosome for sexual reproduction.
13 The zygote is a unique genetic mixture of both parents. What is Meiosis?Meiosis is:Cell division that halves the # of chromosomesThe process that germ cells go through to produce gametes (sperm & egg)Fundamental basis of sexual reproductionDiploid (2n) Haploid (n)The zygote is a unique genetic mixture of both parents.13
14 Meiosis Forms Haploid Gametes Meiosis must reduce the chromosome number by halfFertilization then restores the 2n numberfrom momfrom dadchildtoomuch!meiosis reducesgenetic contentThe right number!
16 Question: 10 chromosomes (haploid or 1n) A cell containing 20 chromosomes (diploid) at the beginning of meiosis would, at its completion, produce cells containing how many chromosomes?10 chromosomes (haploid or 1n)16
17 Facts About Meiosisdaughter cells contain half the number of chromosomes as the parent cellproduces gametes (sperm & egg)occurs in the testes in maleoccurs in the ovaries in females17
18 Gene Recombination This creates offspring that are similar to A pair of the same chromosomes, one from mom and one from dad, get blended together to form a single chromosome that is a mixture of both parents DNA.This creates offspring that are similar toboth parents, but genetically unique.
19 Increasing the genetic variations in a population is an important role of meiosis. Meiosis does not create new genes; however, it creates new combinations of genes.
20 Homologous chromosomes recombine to create new gene combinations. Genetic variations are increased even further through the process of crossing over.Homologous chromosomes recombine to create new gene combinations.
21 CROSSING OVER Homologous chromosomes in a tetrad cross over each other Pieces of chromosomes or genes are exchangedProduces Genetic recombination in the offspring
22 The Significance of Meiosis Meiosis helps create genetically unique offspring.Meiosis reduces the number ofchromosomes to create haploid gamete cells.Meiosis increases genetic variations andcreates new combinations of genes.
23 Is there anything that can go wrong during meiosis? Yes!It is called nondisjunction.Chromosomes don’t separate properly and some gametes end up with too many or not enough chromosomes.MonosomyTrisomy
24 MutationsspermeggOnly mutations that occur in gamete cells are passed on to the organisms offspring. Mutations to gamete cells usually occur during the process of meiosis.
25 Chromosomal mutations are typically the result of mistakes that occur when chromosomes cross-over.
26 Let’s review Mitosis Meiosis makes genetically unique cells makes genetically identical cellsallows asexual reproductionallows sexual reproductionoccurs in somatic cellsoccurs in germ cellsnew cells have full set of chromosomes (diploid)new cells have half set of chromosomes (haploid)number of divisions – 1number of divisions – 2makes 4 daughter cellsmakes 2 daughter cells26