Unit%201%20and%202%20Review

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Unit 1 and 2 Review
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Atoms

• Chemistry will help you learn about biology
  because organisms are chemical machines!
• Atom smallest unit of matter that cannot be
  broken down by chemical means. Made of
• Protons positive, in nucleus
• Neutrons neutral, in nucleus
• Electrons negative, in electron cloud

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Elements and Chemical Bonding

• Atoms can join with other atoms to form sable
  substances. The force that joins atoms is a
  chemical bond.
• Element a pure substance made of only one type
  of atom
• Differ in the number of protons in the nucleus
• Compound a substance made of the joined atoms of
  two or more different elements in known
  proportions
• Represented by chemical formulas

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Atomic Bonds

• Covalent Bonds form when two or more atoms share
  electrons to form a molecule
• Molecule A group of atoms held together by
  covalent bonds
• Hydrogen Bonds Bonds based on polarity of
  molecules which causes chemical attraction.
• Bonds with an unequal distribution of electrical
  charge are called polar molecules.
• Water molecules are polar and often forms
  hydrogen bonds
• The different charges in each molecule makes the
  molecules attract each other.
• Sometimes atoms or molecules gain or lose
  electrons.
• Ion An atom/molecule that has gained or lost an
  electron
• Ionic Bonds a bond formed when ions of opposite
  charges are attracted
• Found in table salt (Sodium Chloride, NaCl)

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Dehydration Synthesis and Hydrolysis

• Dehydration Synthesis A chemical reaction that
  builds up molecules by losing water molecules.
• Hydrolysis The process of splitting a compound
  into fragments with the addition of water a kind
  of reaction that is used to break down polymers
  into simpler units, e.g. starch into glucose.
• So, Dehydration Synthesis LOSES water, while
  Hydrolysis ADDS water!

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Polarity

• The polarity of water enables many substances to
  dissolve in water.
• Ionic compounds and polar molecules dissolve best
  in water, because they are charged like the
  water.
• When ionic compounds are dissolved in water, the
  ions become surrounded by polar water molecules.

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Acids and Bases

• While the bonds in water molecules are strong,
  sometimes these bonds break, forming a hydrogen
  ion (H) and a hydroxide ion (OH-).
• H2O ? H OH-
• Acids compounds that form hydrogen ions when
  dissolved in water
• Bases compounds that reduce the concentration of
  hydrogen ions in a solution

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Carbohydrates

• Organic compounds made of carbon, hydrogen and
  oxygen atoms in the proportion of 121
• Carbohydrates are basically made of carbon and
  water!
• Carbohydrates are built from single sugars called
  monosaccharides
• Polysaccharides are chains or three or more
  monosaccharides.
• Polysaccharides are macromolecules

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Lipids

• Lipids are nonpolar molecules that are not
  soluble or are mostly insoluble in water
• Include fats, phospholipids, steroids, and waxes.
  
• Important in cell membranes
• Fats store energy

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Proteins

• A large molecule formed by linked smaller
  molecules called amino acids
• Amino acids are the building blocks or proteins.
• 20 different amino acids are found in proteins
• Some proteins are enzymes and promote chemical
  reactions

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Nucleic Acids

• All of your cells contain nucleic acids
• DNA and RNA are two common nucleic acids
• Nucleic acids are long chains of smaller
  molecules called nucleotides
• A nucleotide as three parts a sugar, a base, and
  a phosphate group

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ATP

• ATP Stands for Adenosine triphosphate
• A single nucleotide with two extra energy storing
  phosphate groups
• Cells need a steady supply of ATP to function

http//biochemisms.com/tag/atp/
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Activation Energy

• Activation energy the energy needed to start a
  chemical reaction
• Example a big rock rolling down the hillto make
  it roll, you must first push it. The activation
  energy is a push for chemical reactions!
• Enzymes are substances (mostly proteins) that
  increase the speed of chemical reactions
  (catalysts)
• Most biochemical reactions (reactions that occur
  in cells) require activation energy to begin.
• Chemical reactions can occur quickly and at the
  low temperature of our body because of enzymes.
• Enzymes substances that increase the speed of
  chemical reactions. Most enzymes are proteins.
• Enzymes help organisms maintain homeostasis.

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Enzyme Specificity

• Substrate a substance on which an enzyme acts
  during a chemical reaction.
• Enzymes act ONLY on specific substrates.
• For example, amylase, an enzyme in your saliva,
  assists in the breakdown of starch to glucose in
  your food.
• An enzymes activity is determined by the shape
  of the enzyme.

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Protein Function

• The function of a protein depends on its
  confirmation which forms due to R groups and
  bonding.
• R groups have different properties, some are
  polar, some are non-polar. This causes
  particular bonds to form between R groups and
  makes the protein shape in a particular way. When
  a protein is heated, these bonds between R groups
  can break, causing the protein to denature.
• Enzymes are proteins and can also break down in
  this way. When enzymes denature, they do not
  speed up reactions properly!

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Breaking Down Food

• Before your body can use the nutrients in food
  you eat, the large food molecules must be broken
  down.
• Digestion the process of breaking down food into
  molecules the body can use.
• Digestion of food begins in your mouth.
• Teeth rip and chew food and mix food in with
  saliva.
• Saliva contains amylases.
• Amylases enzymes that begin the breakdown of
  carbohydrates such as starch, into
  monosaccharides (single sugars).
• Food then passes through the pharynx into the
  esophagus.

• Esophagus a long tube that connects the mouth to
  the stomach.
• No digestion takes place in the esophagus.
• Food is moved through the esophagus through
  peristalsis.
• Peristalsis successive rhythmic waves of smooth
  muscle contractions in the esophagus that moves
  the food toward the stomach.

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The Stomach

• The stomach is a saclike organ that stores food
  temporarily and mechanically breaking down food
  and chemically breaking down proteins.
• When food enters the stomach, it secretes gastric
  juice, a mixture of hydrochloric acid and pepsin.
• Pepsin a digestive enzyme that breaks protein
  strands into chains of amino acids.

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The Intestines

• Food passes into the small intestine is where
  carbohydrates are broken down into
  monosaccharides, proteins into amino acids, and
  lipids into fatty acids and glycerol.
• Fats are digested by pancreatic enzymes called
  lipases, but are first treated with bile which
  emulsifies the fats (turns them into little
  drops).
• Absorption of nutrients occurs in the small
  intestine through the lining of the small
  intestine on projections called villi.
• Components of food that are not for energy
  production are considered wastes.
• Wastes move into the large intestine, also called
  the Colon. No digestion takes place in the
  colon.
• Most of colons contents are dead cells, mucus,
  digestive secretions, bacteria, and yeast.
• Balancing water absorption is an important
  function of the colon.

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The Livers Role in Digestion and Metabolism

• The liver plays several roles in human digestion
  and metabolism.
• The Livers Role in Digestion
• Secretes bile, which aids in the emulsification
  of fat and promotes the absorption of fatty acids
  and fat soluble vitamins A, D, E, and K.
• The Livers Role in Metabolism
• The liver stabilizes blood sugar by converting
  extra sugar to glycogen for storage. The liver
  then breaks down the glycogen when needed.
• The liver also modifies amino acids.
• Fat-soluble vitamins and iron are stored in the
  liver.
• The liver monitors the production of cholesterol
  and detoxifies poisons. If the liver cannot make
  something non-toxic, it stores it.

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Cell Size

• Small cells function more efficiently than large
  cells.
• This is because they have a high surface area to
  volume ratio.
• We have lots of small cells so that all the
  substances that leave and enter cells have a
  large surface area to do it. If the surface
  area-to-volume ratio is too low, substances do
  not have enough space to move across.

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Common Cell Features

• Cell Membrane outer boundary of the cell,
  regulates what enters and leaves a cell
• Cytoplasm the cell interior, which contains many
  structures
• Cytoskeleton a system of microscopic fibers that
  suspend structures inside the cell
• Ribosomes cellular structures on which proteins
  are made
• Additionally, all cells contain DNA (unless they
  lose their DNA later).

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Characteristics of Prokaryotes

• Prokaryote the smallest and simplest cells,
  single-celled organisms that lack a nucleus and
  other internal compartments (organelles).
• Because they have no organelles, they cannot
  carry out many specialized functions.
• The familiar prokaryotes that cause infection
  belong to a type of prokaryotes called bacteria.
• Exist in a broad range of environmental
  conditions.
• A prokaryotes enzymes and ribosomes are free to
  move around in the cytoplasm because there are no
  internal compartments.
• Prokaryotes have a cell wall surrounding the
  membrane for structure and support.
• Prokaryotes lack a strong internal support
  system.
• Prokaryotes have a cell wall made of
  polysaccharides connected to amino acids.
• Some cell walls are surrounded by a capsule which
  allows prokaryotes to stick to things!
• Many prokaryotes also have flagellalong,
  threadlike structures for movement.

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Eukaryotic Cells

• Eukaryotes an organism with a cell nucleus
• Some eukaryote cells use flagella, others have
  hairlike cilia for movement.
• Nucleus an internal compartment that houses the
  cells DNA.
• Organelles an internal compartment that carries
  out specific activities in the cell.
• A complex system of internal membranes connects
  some organelles inside the cytoplasm.

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The Cell Membrane

• The inside of the cell (cytoplasm) is contained
  by the cell membrane.
• The cell membrane is fluid and selectively
  permeable, allowing only certain substances in
  the environment to pass through.
• The selective permeability of the membrane is
  caused by the way phospholipids interact with
  water.
• A phospholipid has a polar head and two
  nonpolar tails
• Lipid Bilayer the arrangement of phospholipids
  in the cell membrane. Nonpolar tails make up the
  interior of the bilayer because water in and out
  of the cell repels the nonpolar tails.
• Ions and most polar molecules are repelled.
  Lipids are allowed to pass through.

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Membrane Proteins

• Various proteins are located in the lipid
  bilayer.
• Proteins are made of amino acids. Some amino
  acids are polar, others are nonpolar.
• The nonpolar part of a membrane protein is
  attracted to the interior of the lipid bilayer
  but repelled by the water on either side. This
  holds the protein in place.
• Membranes contain different proteins.
• Marker Proteins attached to a carbohydrate
  advertise cell type.
• Receptor Proteins bind signal molecules outside
  the cell.
• Enzymes involved in biochemical reactions in the
  cell.
• Transport aid in the movement of substances into
  and out of the cell.

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The Nucleus, ribosomes, and the ER

• Controls most functions of the cell.
• Surrounded by a double membrane known as the
  nuclear envelope, made of two lipid bilayers.
• Nuclear pores, small channels, are scattered over
  the surface of the nuclear envelope so substances
  made in the nucleus can move into the cytoplasm.
• The hereditary information of a cell is coded in
  the DNA, which is stored in the nucleus.
• Eukaryotic cells have a system of internal
  membranes that play a role in the processing of
  proteins.
• Cells make proteins on ribosomes. Each ribosomes
  is made of proteins and RNA. Some ribosomes are
  found free in the cytoplasm (cytosol) while
  others are on the surface of the endoplasmic
  reticulum.

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Production of Proteins

• Proteins that are exported from the cell are made
  on ribosomes on the surface of the endoplasmic
  reticulum.
• Endoplasmic Reticulum a system of internal
  membranes that move proteins and other substances
  through the cell. Made of a lipid bilayer.
• The ER with ribosomes is called rough ER.
• The rough ER helps transport the proteins made by
  the ribosomes.
• Each protein crosses the membrane and enters the
  ER. The portion of the ER with the protein
  pinches off to form a vesicle.
• Vesicle a small, membrane-bound sac that
  transports substances in cells.
• The rest of the ER with no ribosomes is the
  smooth ER.
• Makes lipids and breaks down toxic substances.

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Mitochondria

• Mitochondria an organelle that harvests energy
  from organic compounds (biomolecules) such as
  such as to make ATP.
• Cells like muscle cells that use a lot of energy
  can have thousands of mitochondria.
• The outer membrane is smooth, the inner membrane
  is folded. These membranes are where the
  chemical reactions take place.
• Mitochondrial DNA independent of nuclear DNA,
  similar to bacterial DNA

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Plant Cells

• Plant cells have there additional structures not
  found in animal cells.
• Cell Wall a thick wall of proteins and
  carbohydrates including cellulose. Supports and
  maintains cell shape.
• Chloroplasts Organelles that use light energy to
  make sugar. Have DNA like mitochondria.
• Central Vacuole a large membrane-bound space
  that stores water and helps to make the cell
  rigid so plants can stand upright.

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Bacteria A Prokaryote

• Bacteria Differ from Eukaryotes in at least seven
  ways
• Internal Compartmentalization
• Cell Size
• Multicellularity
• Chromosomes
• Reproduction
• Flagella
• Metabolic Diversity

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Bacterial Cell Shapes

• Cell Walls Eubacteria have two types of cell
  walls, distinguished by a dye called Gram stain
  (Gram negative, Gram positive). This is
  important because it helps determine the type of
  antibiotics needed to fight the bacteria.
• Endospores Some bacteria form thick-walled
  endospores around their chromosomes with a bit of
  cytoplasm when the bacteria are exposed to harsh
  conditions. This allows the bacteria to remain
  dormant and survive the environmental stress.
• Pili Allow bacteria to adhere to the surface of
  sources of nutrition. Also allow bacteria to
  connect and exchange genetic material.
• Conjugation a process in which two organisms
  exchange genetic material. In prokaryotes, pili
  from on bacterium connects to a second and
  genetic material is exchanged.

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Diffusion and Random Motion and Concentration

• Your body responds constantly to external
  conditions to maintain a stable internal
  environment.
• Homeostasis the maintenance of constant internal
  conditions in spite of changing external
  conditions.
• Homeostasis can be conducted in many ways
  including moving substances across the cell
  membrane with or without energy from the cell.
• Passive Transport Movement across the cell
  membrane that does not require energy.
• Concentration Gradient a difference in the
  concentration of a substance across a space
• Equilibrium a condition in which the
  concentration of a substance is equal through

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Movement of Substances

• Particles of substances of a solution move around
  randomly.
• Concentration gradients cause substances to move
  from an area of high concentration to an area of
  low concentration.
• Diffusion the movement of a substances from an
  area of high concentration to an area of lower
  concentration caused by the random motion of
  particles
• The cell membrane is selectively permeable to
  substances the nonpolar interior of the lipid
  bilayer repels ions and most polar molecules.
• Many substances such as molecules and ions enter
  or leave the cells by diffusing across the
  membrane.
• Concentrations are different inside the cell than
  they are outside, so substances move down the
  concentration gradient (high to low!).
• Diffusion Video

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Osmosis

• Osmosis the diffusion of water through a
  selectively permeable membrane
• Because water molecules are so small, they can
  diffuse through the membrane even though they are
  polar.
• Osmosis is caused because some water molecules
  are attracted to ions on one side or the other of
  the membrane. If the different sides of the cell
  has different concentrations of dissolved
  particles, they will have different
  concentrations of free water. Osmosis occurs
  as free water moves into the solution with the
  lower concentration of free water.

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Hypertonic, Hypotonic, Isotonic

• Three directions water can move in a cell
• Water moves out hypertonic solutions cause a
  cell to shrink the solution outside has a higher
  concentration of dissolved particles than
  cytosol.
• Water moves in hypotonic solutions cause a cell
  to swell the solution outside has a lower
  concentration of dissolved particles than
  cytosol. Could cause a cell to burst.
• No net water movement isotonic solutions cause
  no change in cell volumes the cytosol and
  outside solution have the same concentration of
  free water molecules.

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Movement Against a Concentration Gradient

• Facilitated diffusion can only transport
  substances down their concentration gradient.
• Active Transport the transport of a substance
  across the cell membrane against its
  concentration gradient
• Active transport requires the cell to use energy
  because the substance is being moved against its
  concentration gradient.
• Usually this energy comes from ATP.
• Some active-transport processes involve carrier
  proteins which require energy and act as pumps to
  move substances against their concentration
  gradient.

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Sodium-Potassium Pump and Vesicles

• Extremely important in animal cells.
• In a complete cycle, it transports three sodium
  ions (Na) and two potassium ions (K) into the
  cell because sodium cells are usually more
  concentrated outside the cell than inside, while
  potassium are usually more concentrated inside
  the cell.
• The energy for this pump is provided by ATP.
• This prevents sodium from accumulating in the
  cell (what would happen if there were too many).
• Helps maintain the concentration gradient
  because this is used to transport other
  substances.
• Some substances (proteins, polysaccharides) are
  too large to be transported by carrier proteins
  and instead use vesicles.
• Vesicle a small cavity or sac in a eukaryotic
  cell made of cell membrane part of the membrane
  surrounds the materials to be taken into the
  cell.
• Endocytosis the movement of a substance into a
  cell by a vesicle.
• Exocytosis the movement of a substance by a
  vesicle to the outside of the cell.