6 th Grade Science

1. 6th Grade Science This presentation consists of important information discussed in science class. While students should take advantage of using this resource at home, it will not be updated everyday. Students are expected to use the notes taken in class as a primary source of information.

2. Genetics • Traits- characteristics • Heredity- passing of traits from parents to offspring • Genetics- the scientific study of heredity

3. Gregor Mendel • “The Father of Genetics” • Studied pea plants and found that recessive traits can be masked by dominant traits, but they do not disappear. The recessive traits can be carried along in the genes and show up in future generations. • Dominant-stronger allele (always shows up if present) • Recessive-weaker allele (masked or hidden by dominant allele and only shows up when there is no dominant allele present) • Homozygous/Purebred- 2 of the same alleles (TT or tt) • Heterozygous/Hybrid- 2 different alleles (Tt)

4. The Cell • The basic unit of life. • The human body contains trillions of cells. • The cell contains a nucleus. • The nucleus contains chromosomes. • Chromosomes contain DNA. • Genes are segments of DNA that code for specific traits.

5. Parts of the Cell • Cell Membrane- controls what goes in and out of the cell • Nucleus- control center • Endoplasmic Reticulum- transports material throughout the cell • Ribosomes- make proteins • Golgi Bodies- receive, sort, and send out materials to other parts of the cell • Lysosomes- break down waste • Vacuole- stores food, water, and waste • Mitochondria- “powerhouse” (creates energy for the cell) • Cytoplasm- gel-like material that contains the different organelles. • Centrioles- pull apart cells for cell division • Chloroplast- uses sunlight to make food for plant cells • Cell Wall- the rigid wall on the outside of plant cells

6. DNAJames Watson and Francis Crick discovered the double helix structure of DNA • Deoxyribonucleic Acid • D= Deoxyribose Sugar • N= In the nucleus • A= Acid • Nitrogen Bases (Steps of the Ladder) • Adenine-Thymine • Cytosine-Guanine • Phosphates and Sugars (Sides of the Ladder) • Genes- factors that control traits (hair color) • Alleles- different forms of genes (brown)

7. Chromosomes • Human cells contain 23 pairs of chromosomes, a total of 46. • Each pair contains one from mom and one from dad. • The genes are located on the chromosomes and these genes code for specific traits. • Stronger Trait-Dominant • Weaker Trait-Recessive • 2 Dominant Traits=Homozygous Dominant • 2 Recessive Traits=Homozygous Recessive • 1 Dominant and 1 Recessive=Heterozygous (Dominant Trait will show up) • Genotype-genetic makeup/allele combination • Phenotype-physical appearance/visible trait

8. DNA Replication • In order for Mitosis (cell division) to occur, each chromatid must make a copy of its DNA so that each new cell has the same genetic information. • Steps: • DNA double helix unzips • Floating Nitrogen Bases in the nucleus match up with Nitrogen Bases on the DNA strands. • 2 identical DNA molecules are formed, which is 2 identical sister chromatids, or one chromosome.

9. Cell Division: Mitosis Interphase Cell grows to its mature size DNA and cell parts make copies of themselves Cell prepares to divide Mitosis Prophase, Metaphase, Anaphase, Telophase -The nuclear membrane break down -Chromatin condenses to form chromosomes -Chromosomes line up in the center of the cell -Chromatids separate and go to different sides -Two new nuclear membranes form around the chromatids as the cell stretches Cytokinesis The cell membrane pinches together in the center of the cell and the cell brakes into two identical cells.

10. Meiosis Cell division that results in cells with half the number of chromosomes (23). These cells are important for reproduction, since a new baby will need 23 chromosomes from each parent. Chromosome pairs line up in the center of the cell and separate to different cells. Those cells then go through a second division, much like Mitosis, resulting in cells with 23 chromosomes. The baby will then have 23 pairs of chromosomes, or 46 total. A karyotype is a picture of all the chromosomes in a cell. It reveals the gender of the baby (XX=Girl and Xy= Boy) and the number of chromosomes in the cell.

11. Probability and Punnett Squares • Probability- the chances of something happening • Punnett Square- a tool/chart used to predict the probability of all the possible allele combinations that could result from a genetic cross. • Ex. One parent is homozygous recessive with blue eyes and the other is heterozygous with brown eyes. What is the probability that the offspring would have blue eyes? Bb b b There is a 50% chance the offspring will have blue eyes since 2/4 boxes show bb.

12. Human Inheritance • Phenotype-physical trait (Brown Eyes) • Genotype-allele combination (Bb) • Codominance-2 alleles are equally dominant (both show up) Ex. AB blood type • Male (Xy) Female (XX) • Sex-Linked Traits-traits whose genes are on the X or y chromosome • Pedigree-a family tree that traces the presence of a traits in past generations • Single Genes-trait is controlled by one gene (Widow’s Peak) • Many Genes- trait is controlled by more than one gene (Height) • Multiple Alleles- some genes have more than two alleles • (Blood Type and Hair Color)

13. Causes Consequences Treatments Recessive allele Mucus in the lungs and intestines No cure N. European Decent Difficulty breathing Medication and Physical Therapy to break up mucus Infections Lung damage Genetic Disorders Cystic Fibrosis

14. Causes Consequences Treatments Mutation-abnormal form of hemoglobin (protein which carries oxygen) Blood cells takes on sickle shape, so they cannot carry as much oxygen No cure Co-dominant allele(when a person has two alleles for sickle cell, the disease shows up, otherwise, there are also healthy cells in the body) Cells become blocked in blood vessels, blocking the vessels Drugs to relieve pain and to prevent blockages African Ancestry Pain and weakness Sickle Cell Disease

15. Causes Consequences Treatments Recessive allele on the “X” chromosome (Sex-Linked Disorder) Blood clots very slowly or not at all Missing clotting protein can be provided as treatment More frequently in males Internal bleeding from small bruises (can bleed to death) Avoid contact sports Hemophilia

16. Causes Consequences Treatments Extra Copy of Chromosome 21 Mental Retardation Treatment for heart defects Chromosomes fail to separate during meiosis Distinctive appearance Normal lives Heart defects Down Syndrome

17. Advances in Genetics Selective Breeding- the process of selecting a few organisms with desired traits to serve as parents for the next generation. -Inbreeding- crossing two individuals that have identical or similar sets of alleles. -Hybridization- breeding two genetically different individuals, in order to have the offspring receive the best traits from both parents. Cloning- making an organism who is identical to another. Genetic Engineering- genes from one organism are transferred into the DNA of another organism. “-gene splicing-” DNA molecule is cut open and a gene from another organism is spliced into it. Gene Therapy- inserting working copies of a gene directly into the cells of a person with a genetic disorder. DNA Fingerprinting- fingerprints found at a crime scene are used to help identify the person responsible for the crime. DNA samples come from Blood, Skin, or Hair. -Only identical twins have the same DNA, but their fingerprints are different.

18. Tools in Genetics • Amniocentisis- a technique by which a small amount of fluid that surrounds the baby is removed so that the chromosomes can be studied. This will then be used for a karyotype. • Karyotype- a picture of all of the chromosomes in a cell. (Determines if the baby will be a boy or girl and if the baby has the right number of chromosomes) • Punnett Square- a chart that shows all of the possible allele combinations that could result from a genetic cross and the probability of each combination. • Pedigree- a chart or “family tree” that tracks which members of a family had or have a particular trait. • Genetic Counselors- Professionals who use the tools above to help couples understand what traits can be expected when they have an offspring. Ex. genetic disorders

19. Nature of Science

20. The Goal of Science To understand the world around us A scientific law (fact) results from a theory (logical explanation) being tested over and over by scientists. The Branches of Science Life Earth Physical Geology Chemistry Biology

21. Problem Solving Steps • 1. Question: Use “affect” to separate the manipulated and responding variables • 2. Hypothesis: If, then, because… • 3. Materials: Be specific! • 4. Procedure: Step by step • 5. Observations: Graphs and Charts • Conclusions: Answer question/Did you prove your hypothesis?

22. Experimental Components Control Setup: setup without the variable Experimental Setup: setup with the variable Manipulated Variable: factor being tested Responding Variable: measurable factor being affected by the manipulated variable Constants: factors kept the same in both setups Unwanted or “Hidden” Variables-variables that we do not plan for that may affect our results (sometimes uncontrollable) Example Question: How does the amount of sunlight affect the lifespan of a plant? Example Hypothesis: If the plant gets more sunlight, then it will live longer, because sunlight gives off energy.

23. The Metric System The standard system of measurement used by scientists. The Metric Family

24. Steps to Converting • Underline the unit you know • Put your pencil on the unit on the chart • Loop from the unit you know to the unit you need to know • Put your pencil on the decimal point in your number • Move the decimal point the number of loops and in the direction you did on the chart. Remember: If the decimal point does not show up, it goes to the end of the number!

25. Metric Units

26. Graphing Temperature Line Graph Remember Y Title X and Y Axis Labels Equal Intervals Key Temperature (Degrees Celsius) Time (Minutes) X

27. Temperaturein Celsius • 100 Degrees…..Boiling Point • 80 Degrees……Hot Coffee • 50 Degrees……Hot Bath • 37 Degrees……Normal Body Temperature • 21 Degrees……Room Temperature • 0 Degrees……..Freezing Point • -15 Degrees…..Snowy Day

28. Floating and Sinking Volume: the amount of space an object takes up Capacity: the maximum amount a space can hold Weight: the amount of gravity pulling on an object Displacement: the space/water pushed aside when another object takes its place Buoyancy: the upward force keeping an object afloat Density: mass per unit volume Mass: the amount of matter in an object

29. Heat Transfer Heat transfer is The movement of thermal energy from Warm to cold Conductors allow heat to transfer through them. Ex. metal Insulators do not allow heat to transfer through them. Ex. wool Types of heat transfer Conduction Convection Radiation Direct contact Indirect contact the sun or electromagnetic waves

30. Motion, Forces, and Energy Motion- a change in position where an object’s distance from another object changes. Reference Point- a place or object used for comparison to see if an object is in motion. The most common reference point is the Earth. Force- a push or pull. Speed- the distance traveled in one unit of time. Velocity- speed in a given direction. Momentum-mass x velocity (determines how difficult it is to stop) Acceleration- the rate at which velocity changes (speeding up, slowing down, or changing direction.

31. Friction-the rubbing together of two objects-causes an object to slow down or stop

32. Forces • Force – A push or a pull • Balanced force – equal and opposite (wrestling face-off) • Unbalanced force – unequal and opposite (one person wins) In this case the winner is the gift!

33. Newton’s Laws • #1: Inertia- An object at rest will stay at rest and an object in motion will stay in motion unless acted upon by an unbalanced force. • #2: Force = Mass X Acceleration • (the larger the mass, the more force needed to make it move faster) • #3: Every action has an equal and opposite reaction.

34. Simple MachinesMake work easier by multiplying your effort or changing the direction of your force.Mechanical Advantage- the number of times a machine multiplies your effort force (how helpful the machine is) • Inclined Plane • Wedge • Screw • Wheel and Axle • Pulley • Lever

36. Inclined Planea flat, slanted surface Advantage: Allows you to use less force over a longer distance Example: wheelchair ramps

37. WedgeThick at one end and then tapers to a thin edge at the other end. Two inclined planes back to back. • Examples: knife, teeth, ax, zipper • Advantages: The longer and thinner, the easier it is to use.

38. Screwan inclined plane wrapped around a cylinder • Examples: bolts, faucets, jar lids, light bulb • Advantages: When the threads are close together, it is easier, but takes longer. Effort is multiplied over a longer distance.

39. Wheel and Axletwo circular objects that are fastened together and rotate about a common axis. The larger object is the wheel and the smaller object is the axle • Examples: screwdriver, doorknob, windmill, steering wheel • Advantages: multiplies your force over a longer distance

40. Pulleya grooved wheel with a rope wrapped around it • Fixed-attached to a structure • Changes the direction of your force • Moveable-attached to the object • Multiplies your force • Pulley System-a combination of a fixed and moveable pulley • Examples: flagpole, blinds

41. Levera rigid bar free to rotate about a fixed point • First Class Lever-fulcrum in between the effort and load scissors, seesaw, crowbar • Advantage: changes direction of force • Second Class Lever- load is between the effort and fulcrum • -Wheelbarrow, door, nutcracker • Advantage: multiplies effort force • Third Class Lever- effort is in between the load and the fulcrum • -baseball bat, tweezers, fishing pole • Advantage: multiplies effort force

42. Potential and Kinetic Energy • Potential energy is stored and ready to use. • Kinetic energy is energy in motion. • A pendulum stores potential energy before it is released and uses kinetic energy as it swings.

43. Pendulum Notes Pendulum- a weight hanging freely from a fixed point. Cycle- a system of events that occurs over and over. System- a related set of objects working together in one arrangement. Controlled Experiment- a study designed with a control group and experimental group, where all factors are kept constant except one (manipulated variable). Variable- a factor that changes.

44. Pendulums in our Lives • Galileo’s Influence • Grandfather Clock • Foucault Pendulum • Metronome

45. Galileo • Who? A scientist • What? He studied pendulums and how they move. • When? 1602 • Where? University of Pisa, Italy • Why? These studies lead to further inventions. • What did he discover about pendulums? • A Pendulum never returns to its release height. • All pendulums come to rest. • The cycle rate is independent (not dependent upon) of the weight or release height. • The cycle rate depends on the length of the pendulum. • Shorter pendulums complete cycles faster

46. Grandfather Clock • Who? Christian Huygen • What? A clock composed of a pendulum that keeps precise time. • When? 1656-1657 • Where? England • Why? It revolutionized time-keeping by including minutes. • Many of these antique clocks have been passed down from generation to generation.

47. Foucault Pendulum Who? JBL Foucault What? An instrument used to show the rotation of the Earth. When? 1848-1851 Where? Paris, France. Now found in many areas around the world. Why? It proves that the Earth rotates. How? A cannon ball attached to a wire made a circular pattern in the sand, demonstrating the circular rotation of our planet.

48. Metronome • Who? Winkel and Maelzel • What? A device that regulates sound for musical beats. • When? 1814 • Where? Holland (The Netherlands) • Why? Musicians needed a way to keep a regular tempo. • How? The transfer of momentum allows the weights on opposite sides to make the pendulum back and forth.

49. Atom- the basic unit of matter • 3 particles • Protons +charge • Neutrons no charge • Electrons –charge • If an atom has more protons than electrons, the atom is positively charged. If an atom has more electrons than protons, the atom is negatively charged.

50. Static and Current Electricity Electricity is a form of energy used around the world. Static electricity is the build-up of electrons. (Lightning) Current electricity is the flowing of electrons. (Wall Outlets)