Midterm Review

Chapter 1 Biology and You

7 Characteristics of Living Things Cellular organization Reproduction Metabolism Homeostasis Heredity Responsiveness Growth & development.

Levels of Organization in Living Things Organelles Cells Tissues Organs Organ system Organism

Science vs. Biology Science Biology Process of thinking & learning about the world Biology Study of life

Steps of the Scientific Method State the problem based on observations. Research the problem. Form a hypothesis. Test the hypothesis (experiment). Collect and analyze the data. Form a conclusion. Report the results.

Control vs. Variable Control Variable The standard of comparison for the experimental group Receives no experimental treatment Variable The one factor that differs among the test groups. Part of the experimental group

Independent vs. Dependent Variable Independent variable – factor changed by the experimenter (the factor tested) - a good experiment tests one variable. Dependent variable – factor that depends on the value of the independent variable (a result measured).

Independent vs. Dependent Variable

Observations Qualitative Quantitative Observations that deal with the characteristics of the object such as hardness, texture, beauty, etc. Quantitative Observations that deal with numbers such as the mass, how many, how long, etc.

Theory vs. Hypothesis vs. Prediction A set of related hypotheses that have been tested and confirmed many times by many scientists. Unites and explains a broad range of observations. Hypothesis An educated guess based on observations & research that can be tested. Prediction Expected outcome of a test assuming the hypothesis is correct.

Base Units of the Metric System Meter Measures length Liter Measures volume Gram Measures mass Celsius Measures temperature

Chapter 2 Chemistry of Life

Atom and Its Parts An atom is the smallest unit of an element that maintains the properties of that element. Nucleus contains: Proton (+) Neutron (Neutral) Electron cloud Electron (–)

Covalent vs. Ionic Bonds Covalent Bond Bond formed when atoms share pairs of electrons. Ionic Bond Bond formed by the attraction between oppositely charged ions.

Covalent vs. Ionic Bonds

Molecules and Polar Molecules A group of atoms held together by covalent bonds. Polar Molecule Shares its electrons unequally and therefore has partially positive and negative ends, or poles. Water is a polar molecule.

Molecules and Polar Molecules

Solvents Solvent Universal Solvent A substance, usually a liquid, capable of dissolving another substance. Universal Solvent Water.

pH Scale and Acids & Bases pH Scale ranges from 0 - 14 Acid A compound that forms hydrogen ions (H+) in water. Its pH is 0 to less than 7. (0 to < 7) Base A compound that forms hydroxide ions (OH-) in water. Its pH is greater than 7 to 14. (>7 to 14) Neutral Substances that have a pH of 7.

Organic Macromolecules Contain carbon atoms that are covalently bonded to other elements – typically hydrogen, oxygen and other carbon atoms. 4 principal classes of organic compounds found in living things are: Carbohydrates Lipids Proteins Nucleic acids

Organic Macromolecules Carbohydrates – organic compounds made of carbon, hydrogen and oxygen in a 1:2:1 ratio. Monomers are monosaccharides. Ex: Glucose and fructose Polymers are polysaccharides. Ex: Starches, potatoes, paper, crab shells Functions Stores energy. Makes up cell walls in plants and fungi. Makes up exoskeleton in some animals.

Organic Macromolecules Lipids are nonpolar molecules that are insoluble in water & include fats, phospholipids, steroids and waxes. Monomers are glycerol & fatty acids Polymer examples Butter & oil All membranes Cholesterol and Steroids Functions Stores energy Makes up cell membranes Acts as chemical messengers

Organic Macromolecules Proteins Monomers are amino acids Polymer examples Hemoglobin and antibodies Muscle, hair and nails Functions Hemoglobin carries oxygen and antibodies help defend against infection. Make up tissues that support body structures and provide movement Speed up chemical reactions (enzymes)

Organic Macromolecules Nucleic acids Monomers are nucleotides Polymer examples DNA RNA Functions Controls cellular activities Stores hereditary information Plays key role in the manufacture of proteins

Catalyst vs. Enzyme Catalyst Enzyme Speeds up chemical reactions by lowering the activation energy. Enzyme Specialized protein that acts as an organic catalyst.

Test Indicators & Positive Results Benedict’s solution Tests for simple sugars – blue color changes to red, orange, yellow, green. Lugol’s iodine Tests for starch – reddish–orange iodine turns blue-black or black. Biuret solution Tests for protein – blue turns purple. BTB (Bromthymol blue) Tests for CO2 – blue turns green, or yellow.

Chapter 3 Cell Structure

Microscopes Review the different types of microscopes and their uses. Review the parts and functions of a microscope To determine the total magnification of a microscope multiply the eyepiece (ocular lens) times the objective lens.

Cell Theory All living things are made of one or more cells. Cells are the basic unit of structure and function in organisms. All cells arise from existing cells.

Prokaryote vs. Eukaryote No nucleus No membrane bound organelles Circular DNA Relatively small Reproduce quickly (20 min.) Examples: Bacteria

Prokaryote vs. Eukaryote Nucleus Many membrane bound organelles Linear DNA Relatively large Reproduce slowly (24+ hours) Examples: Plants, animals, fungi & protists

Cell Parts & Functions Cell membrane Nucleus Vacuole Controls what enters & leaves a cell; separates & protects the cell from the environment. Nucleus Contains the DNA in eukaryotic cells; controls cellular activities. Vacuole Membrane bound sac that stores water, may also contain ions, nutrients & waste.

Cell Parts & Functions Chloroplast Cytoplasm DNA Organelle that uses light energy to make carbohydrates from CO2 & H2O. Cytoplasm Region of the cell within the membrane that includes the fluid, the cytoskeleton and all of the organelles except the nucleus. DNA Material that contains the information that determines hereditary characteristics.

Cell Parts & Functions Ribosomes Mitochondrion Cell Wall Organelle composed of RNA & protein; site of protein synthesis. Mitochondrion Cell organelle surrounded by 2 membranes & is the site of cellular respiration, which produces ATP. Cell Wall Rigid structure that surrounds the cell membrane & provides support to the cell.

Cells and Their Environment Chapter 4 Cells and Their Environment

Diffusion vs. Osmosis Diffusion Osmosis The movement of particles from regions of higher concentration to regions of lower concentration. Ex: perfume spreading across a room. Osmosis The diffusion of water from an area of high concentration to an area of low concentration across a membrane. Ex: Getting thirstier when you drink salt water.

Passive vs. Active Transport Passive Transport Does not require energy. Movement down the concentration gradient. Examples: Diffusion Osmosis Facilitated diffusion

Passive vs. Active Transport Requires energy. Movement against the concentration gradient. Examples: Sodium-potassium pump Endocytosis Phagocytosis Pinocytosis Exocytosis

Photosynthesis and Cellular Respiration Chapter 5 Photosynthesis and Cellular Respiration

ATP The energy “currency” of the cell. An organic molecule that acts as the main energy source for cell processes Composed of a nitrogen base, a sugar & 3 phosphate groups. The energy is stored in the phosphate bonds. Powers metabolism.

Photosynthesis Process by which plants, algae & some bacteria use sunlight, CO2 & H2O to produce carbohydrates & O2. Takes place in the chloroplast Main pigment is chlorophyll. Reactants are CO2 and H2O End products are glucose & O2

Photosynthesis Stage 1 Consists of the absorption of light energy which excites the electrons in chlorophyll. The electrons enter the ETC (electron transport chain). Water is split to produce O2, H+, and the electrons to replace those lost by the chlorophyll molecules.

Photosynthesis Stage 2 The conversion of light energy into chemical energy that is temporarily stored in ATP and NADPH. The energy from ATP and NADPH will be used to power the third stage.

Photosynthesis Stage 3 CO2 fixation occurs Inorganic CO2 is fixed into organic compounds (sugars).

Cellular Respiration Process by which cells produce energy from carbohydrates; O2 combines w/ glucose to form H2O & CO2. Takes place in the mitochondrion. Reactants are glucose and oxygen. Products are carbon dioxide & water.

Aerobic Respiration vs. Anaerobic Respiration Requires oxygen. Produces much more ATP (38 net ATP) Anaerobic Respiration Does not require oxygen. Regenerates NAD+ so that gylcolysis can continue. (2 net ATP from glycolysis)

Aerobic Respiration Stage 1 – Glycolysis takes place in the cytoplasm. Does not require oxygen. Glucose is broken down to 2 pyruvate molecules Produces 2 net ATP and 2 NADH Stage 2 – Bridge reaction carries pyruvates into the mitochondrion. 2 CO2 and 2 NADH are produced

Aerobic Respiration Stage 3 – Krebs Cycle occurs in the matrix of the mitochondrion In the presence of oxygen. In two turns of the Krebs Cycle: 4 CO2 are produced 6 NADH are produced 2 ATP are produced 2 FADH2 are produced.

Aerobic Respiration Stage 4 – Electron Transport Chain occurs in the inner membrane of the mitochondrion In the presence of oxygen. 34 net ATP produced 2NADH from glycolysis = 6ATP 2 NADH from bridge reaction = 6 ATP 6 NADH from Krebs cycle = 18 ATP 2 FADH2 from Krebs cycle = 4ATP

Anaerobic Respiration or Fermentation Alcoholic Fermentation Occurs in the absence of oxygen Occurs in yeast and some bacteria Produces: Ethyl alcohol Carbon dioxide Regenerates NAD+ so glycolysis can continue

Anaerobic Respiration or Fermentation Lactic Acid Fermentation Occurs in the absence of oxygen Occurs in the muscle tissue of animals & in lactic acid bacteria Produces: Lactic acid Regenerates NAD+ so glycolysis can continue

Chromosomes and Cell Reproduction Chapter 6 Chromosomes and Cell Reproduction

Chromosomes Chromosomes are DNA & its associated proteins. We have 46 chromosomes or 23 pairs of chromosomes. In a prokaryotic cell, it is the main ring of DNA.

Autosomes vs. Sex Chromosomes Autosomes are any chromosomes that are not directly involved in determining the sex of an individual. We have 22 pairs. Sex chromosomes contain genes that will determine the sex of the individual. We have one pair. Females are XX. Males are XY.

Gametes Gametes are an organism’s reproductive cells. Female’s gametes are eggs or ova. Male’s gametes are sperm.

Haploid vs. Diploid Haploid refers to a cell (gamete) that contains only 1 set of chromosomes. It is represented by “n.” Diploid refers to a somatic or body cell that contains 2 sets of chromosomes. It is represented by “2n.”

Karyotype A karyotype is a photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size. A trisomy at 21 indicates the individual has Down syndrome.

5 Stages of the Cell Cycle

5 Stages of the Cell Cycle The first 3 stages are collectively called interphase. (90% of a cell’s life is spent here.) First growth (G1) phase Cell grows rapidly & carries out routine functions. (Major portion of a cell’s life is spent here.)

5 Stages of the Cell Cycle Synthesis (S) phase Cell’s DNA is copied. Each chromosome consists of 2 chromatids attached at the centromere. Second growth (G2) phase Preparations are made for the nucleus to divide. Microtubules are rearranged. Organelles are manufactured or reproduced.

5 Stages of the Cell Cycle Mitosis The nucleus of a cell divides into 2 nuclei each with the same # and kinds of chromosomes as the original cell. Cytokinesis The cytoplasm divides and 2 new cells are formed.

3 Checkpoints A checkpoint is an inspection point at which feedback signals from the cell can trigger the next phase of the cell cycle or delay it. Cell Growth (G1) checkpoint at the end of the G1 phase Makes the decision of whether or not a cell will divide.

3 Checkpoints DNA synthesis (G2) checkpoint at the end of the G2 phase DNA replication is checked by DNA repair enzymes. Mitosis checkpoint at the end of mitosis Triggers the exit from mitosis

4 Phases of Mitosis Prophase Chromosomes become visible. Nuclear envelope dissolves. The spindle forms. In animal cells, the centrioles move to opposite poles and the spindle forms between them.

4 Phases of Mitosis Metaphase Chromosomes move to the center of the cell & line up along the equator. Spindle fibers link the chromatids of each chromosome to opposite poles.

4 Phases of Mitosis Anaphase Centromeres divide. The 2 chromatids (now called chromosomes) move toward opposite poles as the spindle fibers attached to them shorten.

4 Phases of Mitosis Telophase A nuclear envelope forms around the chromosomes at each pole. The chromosomes uncoil and return to chromatin form. The spindle dissolves. Cytokinesis begins.

Cytokinesis Division of the cytoplasm of a cell Follows the division of the cell’s nucleus by mitosis or meiosis Cytokinesis in animal cells occurs when a belt of protein threads pinches the cell membrane in half. Cytokinesis in plant cells occurs when vesicles from the Golgi apparatus fuse to form a cell plate.

Cytokinesis Cytokinesis in Cytokinesis in animal cells plant cells

Energy pathway from sun to fox

Enzymes Organic catalyst Speeds up chemical reactions by lowering the activation energy

Photosynthesis vs. Cellular Respiration

Review the following labs: Compound Light Microscope Lab Cell Structure Lab (Lab 9) Diffusion Demo Lab Osmosis worksheet Fermentation Lab (Inv. 17)