Presentation on theme: "Big Idea 16: Heredity and Reproduction Description A. Reproduction is characteristic of living things and is essential for the survival of species. B."— Presentation transcript:
Big Idea 16: Heredity and Reproduction Description A. Reproduction is characteristic of living things and is essential for the survival of species. B. Genetic information is passed from generation to generation by DNA; DNA controls the traits of an organism. C. Changes in the DNA of an organism can cause changes in traits, and manipulation of DNA in organisms has led to genetically modified organisms.
Benchmark Number & Descriptor SC.7.L.16.1 Understand and explain that every organism requires a set of instructions that specifies its traits, that this hereditary information (DNA) contains genes located in the chromosomes of each cell, and that heredity is the passage of these instructions from one generation to another. SC.7.L.16.2 Determine the probabilities for genotype and phenotype combinations using Punnett Squares and pedigrees. SC.7.L.16.3 Compare and contrast the general processes of sexual reproduction requiring meiosis and asexual reproduction requiring mitosis. SC.7.L.16.4 Recognize and explore the impact of biotechnology (cloning, genetic engineering, artificial selection) on the individual, society and the environment.
WHO ARE YOU?
DNA DNA = Deoxyribonucleic Acid Traits which are passed from parents to offspring are carried in DNA. DNA is a blueprint for the cells in an organism. Without DNA, an organisms traits would never form.
DIRECTIONS GENES Pieces of DNA Carry traits Characteristics Help pass traits from parent to offspring –You inherit your genes. Offspring receive only some genes from parents. Genes combine differently, so you look different. CHROMOSOMES Genes are located on chromosomes. –Thousands of genes can be found on a single chromosome. Chromosomes are found in the nucleus of the cells. Each type of organism contains a set number of chromosomes. –Humans = 23 Pairs
PUTTING IT ALL TOGETHER
KNOWLEDGE CHECK 1.What does DNA stand for? 2.Where is DNA located? 3.Why is DNA important?
KNOWLEDGE CHECK 1.What does DNA stand for? Deoxyribonucleic Acid 2.Where is DNA located? DNA is located on genes which are carried by chromosomes. 3.Why is DNA important? It’s the blueprint for how organisms are made.
WHY DON’T WE LOOK ALIKE?
What is Heredity? Heredity is the passing on of characteristics (traits) from parents to offspring. Genetics is the study of heredity.
Gregor Mendel WHO: –Austrian monk WHAT: –Worked with pea plants and discovered how traits get passed from generation to generation WHEN: –Around 1856
PASSING OF TRAITS Each gene contains 2 ALLELES –1 allele from mom –1 allele from dad Individual alleles are represented by an upper or lowercase letter. Some alleles are dominant, and others are recessive. BLUE = allele RED = allele together = gene
TRAITS TYPES OF TRAITS The trait that is observed in the offspring is the DOMINANT TRAIT (uppercase). –It only takes one dominant allele for that trait to be shown. The trait that disappears in the offspring is the RECESSIVE TRAIT (lowercase). –It takes 2 recessive alleles for that trait to be shown. LETTER COMBINATIONS Heterozygous - if the two alleles for a trait are different (Aa) –Also referred to as a hybrid combination Homozygous - if the two alleles for a trait are the same (AA or aa) –Also referred to as a purebred combination
TRAITS GENOTYPE Refers to the letter (allele) combination –TT, Tt. tt If a capital letter is present in the letter pair, the dominant trait will be expressed in that organism. If 2 lower case letters are paired, the recessive trait will be expressed in that organism. PHENOTYPE Refers to the physical characteristic being expressed Uses words/phrases to describe not letters Examples: –tall, short –white, black
PUNNETT SQUARES PUNNETT SQUARES Tool used to determine characteristics of offspring Each box represents the probability of an offspring receiving a trait. –Example: Top outside (Tt) is a gene passed on by the father Left outside (tt) is a gene passed on by the mother. 4 middle boxes are possible gene combinations an offspring may receive. T t T t Tt Tt Tt Tt T = Tall t = Short All offsprings will be tall (all boxes contain the dominant trait for tallness).
PUNNETT SQUARES Short hair (L) is dominant to long hair (l) in mice. What is the genotype and phenotype ratio of a heterozygous short- haired mouse crossed with a long- haired mouse? Punnett Square: L l l Genotype ratio: ½ Ll: ½ ll Phenotype ratio: ½ short hair: ½ long hair Llll Llll
PEDIGREE A chart used to trace traits throughout a family Parts of the chart –Circle = females –Squares = males –Half-filled in/Dotted = carrier Have the gene but do not show signs of it –Filled-in = affected Have both the gene and symptoms of that trait
KNOWLEDGE CHECK 1.What do we call the trait that is observed? 2.What case (upper or lower) is it written in? 3.What about the one that disappears? 4.What case is it written in? Trait Tall = Aa Trait short = aa Aa x aa 5. Complete the Punnett Square. ____
KNOWLEDGE CHECK 1.What do we call the trait that is observed? Dominant 2.What case (upper or lower) is it written in? Upper 3.What about the one that disappears? Recessive 4.What case is it written in? Lower Trait Tall = Aa Trait short = aa Aa x aa 5. Complete the Punnett Square. __A___a_ _a__Aaaa _a__Aaaa
HOW DO WE GET ALL THIS STUFF?
REPRODUCTION SEXUAL Primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants Characterized by two processes: –meiosis, halving of the number of chromosomes –fertilization, combination of two gametes and the restoration of the original number of chromosomes Results in increasing genetic diversity of the offspring. ASEXUAL A form of reproduction which does not involve meiosis or fertilization Asexual reproduction = one parent. The primary form of reproduction for single- celled organisms such as archaea, bacteria, and protists Mitosis is the main way of reproduction.
REPRODUCTION ASEXUAL MITOSIS –All forms of asexual reproduction utilize the process of mitosis. –Begins with one replication (copying of the chromosome material) and one division of the chromosome material –This results is 2 daughter cells being produced with the same number of and identical chromosomes as in the parent cell. Asexual reproduction in liverworts: a caducuous phylloid germinating
Mitosis Interphase –Normal functions –Upon trigger, chromosomes & centrioles duplicate. Prophase –Early: nuclear envelope degrades; chromosomes start to condense. –Late: chromosomes thicken; spindle forms between centrioles Metaphase –Spindle fibers attach to kinetochores. –Chromosomes line up at cell equator. sdst.org/shs/apbio/... /mitosis powerpoint.ppt
Mitosis Anaphase –Chromatids separate at centromeres –Chromosomes move to poles. Telophase –Nuclear envelope reforms in each of two daughter cells. –Cytokinesis separates two new cells. Interphase –Daughter cells are genetically identical to each other and the parent cell but smaller. sdst.org/shs/apbio/... /mitosis powerpoint.ppt
REPRODUCTION SEXUAL MEIOSIS –Process produces the sex cells Contain ½ the chromosomes as the parent –Since ½ male chromosomes and ½ female chromosomes combine = genetic variety Hoverflies mating in midair flight.
MEIOSIS Prophase I: the chromosomes condense and homologous chromosomes pair up to form tetrads. Metaphase I: the tetrads are all arranged at the metaphase plate. Anaphase I: the homologous chromosomes separate and are pulled toward opposite poles. Telophase I: movement of homologous chromosomes continues until there is a haploid set at each pole. Cytokinesis : by the same mechanisms as mitosis usually occurs simultaneously Prophase 2: spindle reforms and chromosomes move toward the metaphase plate. Metaphase 2: sister chromatids lined up on the metaphase plate. Anaphase 2: sister chromatids are separated and pulled toward opposite poles of the cell. Telophase 2 and Cytokinesis: nuclei form at either pole, and each cell is finally divided into two identical daughter cells.
Mitosis vs. Meiosis
REPRODUCTION SEXUAL EXAMPLES: –Sexual Reproduction DNA from 2 individuals merge to form one. Animals, plants –Fertilization Pollen is delivered to female part of plant. Flowering plants ASEXUAL EXAMPLES: –Fragmentation/Regeneration Body of parent breaks and produces offspring. Fungi, moss, sea stars, planarian –Budding Offspring grows out of parent. Yeast, hydras
KNOWLEDGE CHECK 1.Label each of the following as either Asexual or Sexual reproduction: Spores budding Nearly all organisms reproduce this way Mitosis Meiosis Starfish is cut in half; both halves grow into a whole starfish. One parent needed Not identical to parents Two parents needed Identical to parent Sperm and eggs
KNOWLEDGE CHECK ASEXUAL SEXUAL Spores budding Mitosis Starfish is cut in half; both halves grow into a whole starfish. Identical to parent One parent needed Not identical to parents Two parents needed Sperm and eggs Meiosis Nearly all organisms reproduce this way.
SHOULD WE MESS WITH MOTHER NATURE?
MAKING IT JUST RIGHT SELECTIVE BREEDING The process of using specific plants or animals with specific traits to reproduce offspring with those traits These breeded plants/animals can be: –Larger in size –Provide more food –Resistant to disease HYBRIDIZATION The process of crossing to plants/animals with different variations of the same trait The resulting offspring is created to have the best traits of the parents. Examples: –Corn: farmers each year try to grow corn that are disease free and higher quality. –Animals: if 2 different species are bred, a stronger but sterile species may be produced
MAKING IT JUST RIGHT Involves using two plants/animals that have the same or similar genes. The offspring produced will be purebred. If purebreds are created, specific genes can be passed along. Inbreeding, though, can cause a population to die. –Since they are genetically similar, if one animal/plant comes down with a disease, the entire population may have it. INBREEDING
BREEDING EXAMPLES Due to inbreeding, all cheetahs are closely related. Miniature Horse was specifically bred small to work in mines. Disease resistance, greater nutritional value Mule combines the best traits of a horse and a donkey.
GENETIC ENGINEERING Processes in which genes with specific DNA strands are removed and transferred into another organism. –This process is much faster then altering organisms through breeding techniques. Genetic engineering is used in biotechnology, medicine, and cloning.
GENETIC ENGINEERING BIOTECHNOLOGY Involves growing cells for industrial purposes Agriculture: –Many plants and crops are susceptible to disease. –Scientists have been able to isolate fighting genes and insert them into plants/crops for better survival rates. GENETIC MODIFICATION Genetic engineering produces a lot of strong feelings among people. PROS: –Crops and farm animals may be produced to better tolerate drought, disease, and infestations, therefore increasing the food production around the world. CONS: –Many people are concerned about mixing genetic material with different species. –Once in the wild, the effects of changes are out of the scientists hands.
GENETIC ENGINEERING MEDICINES Insulin has been able to be created through Genetic engineering. –Insulin was once made from animals, but people were allergic to it. Now it is created from bacteria with no allergies and is less expensive. Vaccines have been able to be produced through Genetic engineering. –Vaccines such as Hepatitis B are now less expensive to produce and can be made in mass production. CLONING Clones are living things that have exactly the same genes. Agriculture has done this forever: –Taking clippings of plants and replanting them –The cuttings grow into new and identical plants. Humans and animals, however, become more controversial: –Is it ok to clone spare body parts?
GENETIC ENGINEERING GENE THERAPY Faulty genes inside a human bodies can be replaced with normal, healthy ones Unfortunately, most cells in our body only live for a short period of time. –The new cells with the new genes can function for a short period of time. WHAT WOULD YOU DO? The more we know about DNA and genes, the more we may be able to predict our future. People today can be screened for certain genetic conditions. For example –If a person is found to be a carrier of a specific gene defect, he/she will need to make a choice if he/she are to have kids. –Perhaps you carry a gene for cancer which may or may not turn on. What would you do?
KNOWLEDGE CHECK 1.Name three types of breeding and a reason why they are used. 2.What is Genetic engineering? 3.Why is Genetic engineering supported by some yet forbidden by others?
KNOWLEDGE CHECK 1.Name three types of breeding and a reason why they are used. Selective breeding, hybridization, inbreeding. All 3 can be used to make specific higher yielding crops. Crops less vulnerable to disease and animals for specified jobs 2.What is Genetic engineering? Processes in which genes with specific DNA strands are removed and transferred into another organism. 3.Why is Genetic engineering supported by some yet forbidden by others? Supported = create medicines and cells for people to survive Forbidden = Messing with mother nature. Do not have control if changes were to get into the wild