BSCI 170 Midterm 1

What are the five rules to simplify biology?

• Evolution is the key to understand everything in biology

• New properties emerge at successive levels of biological organization

• Structure and function are intimately related

• Biology is chemistry and physics in action

• Energy controls everything in biology

What is the criteria common to all living organisms?

• The cell is the fundamental structural unit

• Cells are complex and highly organized

• Cells have a genetic program to support and direct faithful reproduction

• Cells acquire and use energy

• Cells respond to their environment

• Cells self-regulate (homeostasis)

What are prokaryotes?

• Mostly unicellular forms that lack a defined nucleus and membrane-bound organelles

• Prokaryotes include bacteria and archaea, which are characterized by their simple cell structure.

What are eukaryotes?

Mostly multicellular forms of cells that have a defined nucleus and organelles, which allow for complex cellular processes and specialized functions.

How are prokaryotes different than eukaryotes?

• Prokaryotes vastly outnumber eukaryotes.

• Prokaryotes live in every conceivable environment or ecological niche.

• Prokaryotes have limited morphologies but more diverse metabolisms (the way they get energy)

How are eukaryotes different than prokaryotes?

• Eukaryotes are much more morphologically diverse than prokaryotes (but less metabolically diverse)

• Eukaryotes have a membrane-bound nucleus that stores and protects genetic material

• What is the plasma membrane?

• A cell membrane —> separates cell from outside environment

• What makes up the endomembrane system?

• Nuclear envelope (double membrane that surrounds nucleus of cell), endoplasmic reticulum, Golgi apparatus, lysosomes, and endosomes

• What is the cytoplasm?

• Everything between the plasma membrane and the nuclear envelope

• What is cytosol?

• Gel-like substance excluding the membrane-bound organelles

• Includes the cytoskeleton and non-membrane bound inclusions

• What are organelles?

• Discrete membrane-bound subcellular compartments specialized to carry out specific cellular functions

• What’s inside the nucleus?

• DNA

• Nucleolus - tightly packed RNA

• What’s the nucleus’s function?

• Separates/protects DNA from the rest of the cell

• What’s the nuclear envelope function?

• Helps regulate which molecules enter/exit the nucleus and interact with DNA

• What are the two types of endoplasmic reticulums?

• Rough ER and Smooth ER

• What does the Rough ER consist of?

• Layers of flattened membrane.

• Membrane surface studded with ribosomes for synthesis of protein for secretion. Rough ER is basically the place where proteins are made!

• What is in the lumen (tube) of the rough ER?

• Enzymes for adding sugars to proteins

• What are the functions of the smooth ER?

• Calcium Ions (Ca 2+) storage

• Cholesterol Synthesis

• Making of membrane

• Detoxification (breaking down of harmful chemicals)

• What does the Golgi Apparatus do?

• Processes and packages material for secretion either out of cell or to a different part of the cell

• Can modify proteins before sending them out

• Different regions contain distinct enzymes to modify it

• What are lysosomes?

• Uses enzymes to digest/break down large materials such as fats, proteins, carbohydrates, etc.

• What are vacuoles in animal cells?

• Membrane bound sacs. Help transport waste to lysosome to get broken down.

• What is the central vacuole in animal cells?

• Stores water mostly (also some ions, organic molecules, etc)

• What does the mitochondria do?

• In eukaryotic cells

• Oxidizes carbohydrates and fatty acids.

• Mostly, produces ATP

• What do chloroplasts do?

• Photosynthesis + starch production

• In plant cells only

• Reflects green light

• What is the cytoskeleton?

• Series of proteinaceous filaments and tubulus

• Helps keep cell structure, shape, and movement

• What makes each cell unique?

• The organization and composition of different cellular structures

  • REMEMBER: structure = function

• What does image resolution mean?

• Refers to how much detail can be gotten from an image (higher resolution = more detail)

• What is matter?

• Anything that takes up space and has mass

• What is matter composed of?

• Elements

• What is a compound?

• Contains 2 or more different elements in a defined ration

  • NaCl is a compound, but O2 isnt

• What are the main elements in the human body?

• • Oxygen, carbon, hydrogen, nitrogen

    • Other elements in the body are called trace elements

• What is one example of the importance of trace elements?

• Iron (trace element) located in our hemoglobin.

  • If we didn’t have enough, lots of health issues could occur

• What are atoms?

• smallest unit of structure, containing all of the chemical and physical properties of an element

• What happens when atoms interact?

• Only electrons interact, nuclei never interact

• Are all electrons the same?

• Electrons differ in energy levels, but all protons are the same

• What is energy?

• The capacity to do work (move something against an opposing force)

• What is potential energy?

• energy that matter possesses because of its location or structure

• What is kinetic energy?

• energy associated with the relative motion of objects

• What type of energy do electrons have?

• potential energy

• amount of potential energy they have is correlated with its distance from the nucleus

• the closer the electrons are to the nucleus, the lower their energy

• Where are electrons found?

• Orbitals (two electrons per orbital)

• What are shells?

• Where all electrons with approximately the same amount of energy are found

• Shells contain several orbitals and several electron pairs

• What is the chemical behavior of an atom determined by?

• The distribution of electrons in the shells

• What does shell 1 have room for?

• 2 electrons

• What does shell 2 + 3 have room for?

8 electrons

• When are most atoms stable?

• When their outer shells are full

• What are chemical bonds?

• Attractions that hold atoms together

• Strong/weak bonds

• What are covalent bonds?

• Extremely strong and stable

• Atoms sharing valence electrons

• What is a single covalent bond?

• 2 elements shared between two atoms equals a single covalent bond

• What is a molecule?

• 2 or more atoms held together by covalent bonds

• What is a compound?

• requires two or more different elements in a defined ratio

• What is electronegativity?

• a measure of how strongly an atomic nucleus attracts and holds onto electrons

• more electronegativity = more pull towards nucleus

• How much electronegativity defines a covalent bond?

• Less than 1.7 (difference between two atoms)

• What are nonpolar covalent bonds?

• 2 atoms share electrons equally, no significant difference in electronegativity

• What are the two most electronegative atoms of biological importance?

• Oxygen and nitrogen

• What are polar covalent bonds?

• Electrons are shared unequally between two atoms (one has stronger pull)

• What are weak bonds?

• result from electrostatic attractions between two atoms

• hydrogen bonds, van der waals interactions

• What are hydrogen bonds?

• form when a H covalently bonded to one electronegative atom is attracted to another nearby electronegative atom

• each individual H bond is weak, but is collectively strong

• What are ionic bonds?

• electronegative difference may be so large as to literally pull electrons from the outer shell

• NaCl

• Is NaCl a compound or a molecule?

• compound (two different elements in a defined ratio)

• What are van der Waals interactions?

temporary fluctuations in electron distributions, leading to weak and transient bonds in nonpolar and polar molecules

• What are van der Waals interactions critical for determining?

• the 3D shapes of proteins

• the specific interactions between an enzyme and its substrate

• Why is water essential for life?

• Life began and evolved in water

• Our chemistry is an aqueous chemistry

• Living organisms are mostly composed of water

• Why is H20 so special?

• polar covalent bond

• simple structure

• partial + (near hydrogen) and - charge (near oxygen)

• each molecule can form hydrogen bonds with up to four water molecules (forms weak hydrogen bonds with other water molecules)

• What creates the four properties of water?

• polarity and hydrogen bonding

• What is the first property of water?

• sticky to other molecules because of hydrogen bonding

  • adhesion to other molecules

  • cohesion to other H2O

• What is the second property of water?

• moderation of temperature (due to hydrogen bonding)

  • high specific heat: the amount of energy required to raise the temp of water

  • heat of vaporization: the amount of energy needed to convert water from a liquid to a gas

• What is an example of water’s moderation of temp. property?

• when sweat evaporates from the skin, it absorbs a large amount of heat energy, thereby cooling the body down through a process called evaporative cooling

• What is the third property of water?

• solid H2O is less dense than liquid H2O (ice in water floats)

  • ice: hydrogen bonds are stable

  • liquid: hydrogen bonds constantly break and reform

• What is the fourth property of water?

• excellent solvent for polar and charged molecules and compounds

• What are hydrophilic molecules?

• molecules that break down and interact with the charges in water

• What does the pH scale range from?

• 0 (most acidic) to 14 (most basic)

• What does water being able to dissociate mean?

• It means that water can break apart into hydrogen ions (H+) and hydroxide ions (OH-), which is crucial for various biochemical reactions.

• What is an acid?

• increases the relative concentration of H+ in a solution (and decreases the relative concentration of OH-)

• What is a base?

• decreases the relative concentration of H+ in a solution (and increases the relative concentration of OH-)

• What does it mean by more acidic?

• More H+ ions

• What does it mean by more alkalinity?

• More basic/more OH-

• What is a neutral solution?

• roughly equal amounts of OH- and H+ ions (pH=7)

• What is an acidic solution?

• pH < 7.0 (more H+)

• What is a basic solution?

• pH > 7.0 (more OH-)

• Why are cells so sensitive to changes in pH?

• changes in H+ can change the ionization state of macromolecules

  • can change charge which can change structure which can change function!

• What is the backbone of every molecule, which makes up life?

• Carbon: able to form large, diverse, and complex molecules

• What type of bonds can carbon form?

• covalent bonds (single double and triple)

• What are hydrocarbons?

• molecules consisting of only hydrogens and carbons

• structurally diverse, may be complex

• nonpolar (equally share electrons)

• hydrophobic so not very useful

• What are isomers?

• molecules with the same molecular formula but with distinct arrangements of the atoms

• What are geometric isomers?

• differ in the spatial arrangement of their atoms, particularly around double bonds.

• What do functional groups do to hydrocarbons?

• make hydrocarbons more polar and soluble and reactive

• What are the four different types of molecules?

• carbohydrates, lipids, nucleic acids, proteins

• What are macromolecules?

• built from successive addition of smaller subunits called monomers

• formed from carbohydrates, proteins, and nucleic acids

• What are polymers?

• covalently attached monomers forms a polymer

• subunits are either identical or very similar

• How do you add a monomer to a short polymer?

• dehydration synthesis: we lose an H2O.

  • one molecule of H2O is released for every monomer added to the polymer

• How do we disassemble (take a monomer off a polymer)?

• hydrolysis: break up water into its component parts

  • one molecule of H2O is added for every monomer added to the polymer

• What is macromolecular diversity dependent on?

• the arrangement of monomers

• What are carbohydrates important for?

• energy storage, protection, recognition, and structural integrity of cells

• What makes up carbohydrates?

• simple sugars + polymers of sugars

• What is a monosaccharide?

• one sugar molecule (simple sugar)

• What is a disaccharide?

• two monosaccharides covalently bonded together