The Unforgetables of Biology

The Unforgetables of Biology

Scientific Investigation

·  Biology is the study of living organisms and life processes.

·  All living things (organisms) share common characteristics. The characteristics of life are that all organisms: are made of cells, grow and develop, reproduce, respond and adapt to their environment and obtain and use energy.

·  Homeostasis is the regulation and maintenance of the organism’s internal conditions, keeping them steady.

·  A hypothesis is a scientific prediction relating variables in an experiment as cause and effect. Hypothesis can come from observations and background research.

·  Observations are made with the senses either in the field or in the lab.

·  Independent variables are the part of the experiment the scientists changes.

·  Dependent variables are the part of the experiment that responds to the change in the independent variable.

·  A control is a group in the experiment that didn’t have the independent variable applied and is used as reference.

·  Constants are all the parts of the experiment that aren’t changed during the experiment.

·  To get valid, reliable, data there must be a control, constants and enough trials. Error is a part of the data that isn’t valid because of mistakes in designing or carrying out the experiment.

Cells

·  Cells are the basic structural and functional units of life.

·  The Cell Theory states that cells: all living things are made of cells, cells are the basic units of structure and function, and all cells come from other cells. The main tool that allowed for the discovery of cells and cell theory was the compound light microscope.

·  There are two main types of cells: Prokaryotes do not have a nucleus or membrane-bound organelles. Eukaryotes do have a nucleus and membrane-wrapped organelles.

·  Organelles are membrane bound structures within a eukaryotic cell that have a specific function.

·  The nucleus contains the cell’s genetics information in DNA. The DNA condenses to form chromosomes during cell division.

·  The cell membrane (plasma membrane) encloses a cell and controls what goes in and out. It is also called a phospholipids bilayer because it is made of two layers of lipids. Because it isn’t solid and also has many proteins and other molecules in it, we also call the cell membrane a Fluid-Mosaic. The fact that it lets some molecules through and not others makes the membrane semipermeable (selectively permeable).

·  Some cells can have a cell wall, which is outside the cell membrane. It provides strength and protection for the cell.

·  Mitochondria are the powerhouses of the cell because they are the location of cellular respiration.

·  Vacuoles, which vary in size in different cells, store water and wastes for the cell.

·  Some cells have chloroplasts which have chlorophyll and are the sites of photosynthesis.

·  Ribosomes are where proteins are made because they are the site of protein synthesis (protein making).

·  Passive transport is a form of transport across a membrane from high concentration to low concentration, using no energy.

·  Active transport is a form of transport across a membrane from low concentration to high concentration, using energy.

·  A concentration gradient is when there is a higher concentration of solute on one side of the membrane than the other.

·  Diffusion is the movement of particles across a membrane from high concentration to low concentration.

·  Osmosis is the movement of water molecules through a membrane to help equalize a concentration gradient.

·  Bulk transport moves particles in or out of the cell that are too large to fit through protein channels. Endocytosis moves particles into the cell and exocytosis moves particles out of the cell. Phagocytosis moves solids and pinocytosis moves liquids.

Biochemistry

·  Biochemistry is the chemistry of living things.

·  Water is a very important molecule to life. It has many important characterstics: polar, good solvent, high boiling point, adhesion and cohesion (water molecules stick to each other and polar molecules).

·  PH is a measure of how acidic a solution is. The pH scale goes from 0 (most acidic) to 14 (most basic).

·  Acids release hydrogen ions (H+) in solution. Bases release hydroxide ions (OH-) in solution. When they are mixed a neutralization reaction takes place, creating water (pH 7).

·  Chemical reactions are when chemical bonds are broken or made. The starting materials, on the left side of the reaction, are called reactants. The results of the reaction, on the right side of the reaction, are called products.

·  Polymers are long string of monomers which have been put together. Monomers are put together with dehydration synthesis and taken apart by hydrolysis.

·  Organic compounds are molecules centered around carbon atoms. There are four main types or organic compounds: carbohydrates, lipids, proteins and nucleic acids.

·  Carbohydrates are made of simple sugars, containing carbon, oxygen and hydrogen. They are the main source of energy for living things. Glucose is the most common simple sugar.

·  Lipids, also made of carbon, oxygen and hydrogen, are used for long term energy storage, cell membranes and hormones. Fats, oils and waxes are the common examples.

·  Proteins are made of amino acids. They have many uses: structure building, muscles, enzymes and much more.

·  Nucleic acids are made of nucleotides. Nucleic acids (DNA and RNA) are used to store genetic information.

·  Enzymes are special protein catalysts. A catalyst is something that speeds up a chemical reaction. The enzyme has an active site that holds the molecule the enzyme will use in the reaction. Heat or extreme pH can denature an enzyme so it no longer works.

Energy

·  ATP is the energy transfer molecule for cells, meaning it carries energy where it is needed.

·  Photosynthesis is a process that converts light energy from the sun into chemical energy stored in food. Photosynthesis uses carbon dioxide and water to make glucose and oxygen. This happens in the chloroplast.

·  Cellular respiration breaks down food and releases the energy as ATP. It requires food (glucose) and oxygen and makes carbon dioxide, water and ATP. This happens in the mitochondria.

·  Aerobic respiration uses oxygen to break down the food in three steps: glycolysis, Kreb’s cycle and electron transport chain.

·  Anaerobic respiration doesn’t use oxygen. After glycolysis, either ethyl alcohol fermentation (yeast) or lactic acid fermentation (people and bacteria) happen.

·  Some bacteria on the ocean floor can make food by chemosynthesis using heat and sulfur from ocean vents.

·  Metabolism is the sum of all the chemical reactions in a cell.

Cell Division

·  The cell cycle can be separated into two main parts – interphase and cell division (mitosis or meiosis). During interphase the cell grows and prepares to divide.

·  Mitosis is the process by which the nuclear material (chromosomes) of a cell divides to make two identical daughter cells, with a complete set of chromosomes in each.

·  Mitosis has 4 distinct phases (PMAT): prophase, metaphase, anaphase and telophase.

·  Cells with a full set of chromosomes (two copies of each) are called diploid. Usually somatic cells (body cells) are diploid.

·  Cell with one copy of each chromosome are called haploid. Gametes (sex cells) are usually haploid. The male gamete is called sperm and the female gamete is called an egg.

·  In talking about chromosome number, n = the number of chromosome pairs. If a cell has 2n chromosomes then it has two of each chromosome and is diploid. If a cell has n chromosomes then it has one copy of each chromosome and is haploid.

·  Meiosis is the type of cell division that has two divisions to make four haploid gametes.

·  The actual process of a cell’s cytoplasm and contents dividing is called cytokinesis.

DNA and Protein Synthesis

·  DNA is a double stranded helix built by matching pairs of nucleotides. According to the base-pairing rules, adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C).

·  DNA has deoxyribose as its sugar and RNA has ribose. The other differences are that DNA is double stranded, RNA is single stranded; DNA has thymine while RNA has uracil; and DNA strands last the cell’s life, RNA is short-lived.

·  DNA replication occurs in the nucleus of the cell and results in an exact copy of the original strand.

·  On the long chromosomes are individual genes. A gene is a section of DNA that codes for a protein.

·  DNA is the template for all protein synthesis (protein making) in cells. The first step of protein synthesis is called transcription. This occurs in the nucleus and makes a messenger RNA (mRNA) copy of the gene.

·  The second step of protein synthesis is translation, which happens at the ribosome. The mRNA is decoded three bases at a time (codons) by transfer RNA (tRNA). Each tRNA brings a specific amino acid, which are linked to make the protein.

Genetics

·  Gregor Mendel carried out the first important studies of heredity, using pea plants. He discovered that genes are the units of inherited information.

·  Alleles are the possible variations of a particular gene. A genotype gives the allele combination of an individual. A phenotype is the appearance, or observable trait, of an organism.

·  If an individual has matching alleles for a gene, it is homozygous (or True-breeding) for that gene. If an individual has two different alleles for a gene, it is heterozygous (or hybrid) for that gene.

·  Punnett squares are used to determine the proportions and probabilities (in percentages) of the possible genotypes in the offspring of a cross.

Evolution

·  Geologic evidence indicates the earth formed 4.6 billion years ago and that no free oxygen was present at the time.

·  In 1952, scientists Stanley Miller and Harold Urey demonstrated that organic molecules could be created if a simulated primitive atmosphere was exposed to an energy source.

·  The heterotroph hypothesis states that heterotrophs that fed on naturally occurring organic compounds were most likely the first organisms to evolve.

·  Charles Darwin originated the theory of evolution by natural selection. Evolution is a change in the genetic make-up of a population over time.

·  Natural selection is the process by which characteristics that permit survival and reproduction are passed on to future generations.

·  The main points to natural selection are: variation in the species, over reproduction, competition for resources and survival of the fittest.

·  Adaptations are specific characteristics that enable individuals in a population to survive and reproduce better than other members of the same population.

Classification

·  Scientific classification is based on homologies (similarities that indicate related ancestry).

·  Scientific names, based on classification, are two-word names in which the first word is the genus name and the second name is the species. They are written as follows: Genus species (upper case and italics do matter).

·  From least specific to most specific, the classification system is arranged: Kingdom, Phylum, Class, Order, Family, Genus, and Species. There are also three Domains, which are larger divisions than kingdoms.

·  Prokaryotes are single-celled organisms that lack a true nucleus and cellular organelles. There are two domains of prokaryotes: Archaea (which holds the Kingdom Archaebacteria) and Bacteria (which holds the Kingdom Eubacteria).

·  Archeabacteria are the ancestors to more advanced life on Earth and they can survive in extreme and hostile environments, such as high salt, pH or heat.

·  Eubacteria are diverse and can be found almost anywhere on earth. They are what we typically think of as bacteria.

·  Antibiotics are chemicals that are able to kill bacteria cells.

·  Eukaryotes are organisms that have a nucleus, and most advanced organisms fall in this category. The domain containing all eukaryotic kingdoms is called Eukarya.

·  The kingdoms in Domain Eukarya are: Protista, Fungi, Plantae and Animalia.

·  Protists are unicellular, eukaryotic organisms. They are very diverse and can be plant-like, animal-like or fungi-like. Protists are thought to have been the first eukaryotic organisms and therefore the ancestors of fungi, plants and animals.

·  Fungi can be unicellular (yeasts) or multicellular. They are all decomposers, meaning they are heterotrophs that break down dead organisms. They reproduce with spores and are made of hyphae, thin tubes that move food and water. Fungi cells are protected by a cell wall made of chitin.

·  Viruses are not living things. Viruses cannot reproduce on their own; they have no metabolism; they do not take in and use energy; they do not have cell parts. Viruses take over and use a host to carry out functions they need to make more viruses.

Plants

·  Members of the plant kingdom share the following characteristics: photosynthetic, have cell walls, multicellular and eukaryotic.

·  Turgor pressure is the pressure place on a plant cell’s wall by the water concentration inside the cell. High turgor pressure = rigid cells; low turgor pressure = wilting cells.

·  The plant kingdom is divided into two major categories: bryophytes (mosses) and vascular plants (everything else).

·  Structures such as leaves, roots, stems, seeds and flowers are only found in vascular plants. Bryophytes have rhizoids instead of roots.

·  Vascular plants are divided again into seedless plants (ferms) and seed plants. Gymnosperms (pines) and Angiosperms (flowering plants) are the two types of seed plants.

·  Plant movements in response to a stimulus are called tropisms. Common forms of plant tropisms include phototropism and gravitropism.

Animals

·  Members of the animal kingdom share the following characteristics: eukaryotic, multicellular and no cell wall.

·  The animal kingdom is divided up into several major groups (phyla) based on the animals’ characteristics. The first eight groups are invertebrates (they have no backbone). Porifera are sponges that filter feed. Cnidaria are animals with stinging cells like jellyfish and anemones. Platyhelminthes are flatworms, Nematoda are roundworms and Annelida are segmented worms like earthworms. Mollusca are soft-bodied mollusks like snails, clams and octopi. Arthropods have jointed legs, like insects, arachnids and crustaceans. Echinodermata are spiny skinned water animal like starfish and sea urchins. The final group, Chordata contains all the vertebrates (animals with backbones).