Chapter 2

Question 1

Chemistry

Answer 1

the study of interactions between atoms and molecules

Question 2

Atom

Answer 2

• the smallest unit of matter that enters into chemical reactions
• atoms interact to form molecules

Question 3

Atoms are composed of:

Answer 3

• Electrons- negatively charged particles
• Protons- positively charged particles
• Neutrons- uncharged/ neutral particles
• Protons and Neutrons are in the nucleus
• Electrons move around the nucleus (electron shell)

Question 4

Chemical elements

Answer 4

• each element has a unique number of protons
• there are the same number of protons and electrons in a neutral atom
• Atomic number= number of protons
• Atomic weight = number of protons and neutrons

Question 5

Atomic symbols

Answer 5

Hydrogen-H
Carbon-C
Nitrogen- N
Oxygen- O
Sodium- Na
Magnesium- Mg
Phosphorus- P

Question 6

Electronic Configurations

Answer 6

• electrons are arranged in electron shells corresponding to different energy levels
• each shell has a maximum number of electrons
• electrons fill the inner-most shells first

Question 7

How atoms form molecules

Answer 7

• atoms combine to form molecules
• a molecule that contains 2 or more types of atoms is called a compound: H20
• The “2” indicates that there are 2 atoms of hydrogen combined with 1 atom of oxygen
• molecules hold together because of attractive forces. called chemical bonds, between the atomic nuclei

Question 8

Chemical Reactions

Answer 8

• involve the making or breaking of bonds between atoms
• a change in chemical energy occurs during a chemical reaction
• Endergonic- reactions absorb energy
• Exergonic- reactions release energy

Question 9

Synthesis reactions

Answer 9

• occur when atoms, ions or molecules combine to form new, larger molecules
  example: A + B –>(combines to form) AB (new molecule)

Anabolism: the synthesis of molecules in a cell

Question 10

Decomposition reactions

Answer 10

• occur when a molecule is split into smaller molecules, ions or atoms
  example: AB –> (breaks down into) A + B

Catabolism: the decomposition reactions in a cell

Question 11

Organic vs inorganic compounds

Answer 11

Organic- always contain carbon and hydrogen
-example: C6H12O6

Inorganic- typically lack carbon
-example: CO2, Water, Oxygen gas

Question 12

Polar Molecule (water)

Answer 12

• whole molecule is neutral

- but, one end has a negative charge and the other end has a positive charge

Question 13

water

Answer 13

• life on earth evolved based on the chemistry of water
• inorganic
• water makes up 65-75% of cells, on average
• water more easily maintains a constant temperature than many other solvents; protects cells from temperature fluctuations

Question 14

acids, bases and salts

Answer 14

• dissociate into positively charged H+ ions and negatively charged ions
• dissociate into one or more H+ ion

example: HCI–> H+ + CI-

Question 15

Bases

Answer 15

• dissociate into negatively charged hydroxyl ions OH- and positively charged ions
• one or more OH- ion

example: NaOH –> Na+ + OH-

Question 16

Salts

Answer 16

• dissolves into water; does not produce hydrogen ions or hydroxyl
• dissociate into cations and anions, neither of which is H+ or OH-

example: NaCI –> Na+ + CI-

Question 17

pH scale

Answer 17

• most organisms grow best between ph of 6.5 to 8.5
• neutral pH= 7
• acidic pH= 0-6
• basic pH= 8-14

Question 18

functional groups

Answer 18

are responsible for most of the chemical properties of a particular organic compound

Question 19

Organic Compounds

Answer 19

• small organic molecules can combine into large macromolecules (large)
• macromolecules are polymers consisting of many small repeating molecules (many)
• the smaller molecules are called monomers (one)

Question 20

Major Macromolecules in Living Organisms

Answer 20

• carbohydrates
• proteins
• lipids
• nucleic acids

Question 21

Carbohydrates

Answer 21

• cell structures and energy sources
• consist of C, H and O
• Monosaccharides- are simple sugars with 3 to 7 carbon atoms
• Disaccharides- are formed when 2 monosaccharides are joined together
• Oligosaccharides- consist of 2 to 20 monosaccharides
• Polysaccharides- consist of tens or hundreds of monosaccharides joined together
  
  • polymers of glucose that are covalently bonded differently
    
    • starch is a plant storage product
    • Glycogen is an animal storage product
    • Cellulose is a structural compound in plants
    • Chitin is a polymer of 2 sugars repeating many times
      
      • hard substance in insect, crustacean, fungal cell walls etc.

Question 22

Lipids

Answer 22

• primary components of cell membranes
  
  • examples: fats, oils, waxes
  • consist of C, H, and O
  • are nonpolar and insoluble in water

Question 23

Simple lipids

Answer 23

• fats or triglycerides
  
  • typically contain 1 glycerol molecule and 3 fatty acid molecules
  • glycerol is a 3-carbon compound
  • fatty acids contain long chains of carbons and are non-polar
• saturated fat- no double bonds
• unsaturated fat- one or more double bonds in the fatty acids

Question 24

Complex Lipids

Answer 24

• contain C, H, and O + P, N or S
• membranes are made of phospholipids
• phospholipids have 2 fatter aids and a phosphate group bonded to the glycerol molecule
• sterols (steroids)

Question 25

Protein

Answer 25

• are essential in cell structure and function
• function as
  
  • enzymes that speed chemical reactions
  • transporter proteins that move chemicals across membranes
  • flagella are made of proteins
  • some bacterial toxins are proteins

Question 26

Amino Acids

Answer 26

-proteins are polymers made of subunits

Question 27

Peptide bonds

Answer 27

• amino acids are joined by peptide bonds

Question 28

Levels of Protein Structure

Answer 28

-structure is important because the protein is not “active” or able to perform its function unless it is arranged in the correct structure

• primary structure- is a polypeptide cain (chain of amino acids)
• secondary structure- occurs when the amino acid chain folds and coils in a regular helix or pleats
• tertiary structure-occurs when the helix folds irregularly, forming disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain
• quaternary structure- consists of 2 or more polypeptides that are folded together

Question 29

Conjugated proteins

Answer 29

• consist of amino acids and other organic molecules bonded together
  
  • glycoproteins- protein + carbohydrate
  • nucleoproteins- protein + nucleic acid
  • lipoproteins- protein + lipid
• many important compounds in the cell are conjugated proteins

Question 30

Nucleic Acids

Answer 30

• consist of nucleotides
• nucleotides consist of a
  
  • pentose- 5 carbon sugar
  • phosphate group
  • Nitrogen-containing (purine or pyrimidine) base

Question 31

DNA

Answer 31

• deoxyribonucleic acid
  
  • codes for genetic information in the cell
  • has deoxyribose- type 5-carbon sugar
  • exists as a double helix
  • hydrogen bonds hold the two chains together
  • nitrogen bases- adenine, cytosine, thymine and guanosine
    
    • A bonds with T
    • C bonds with G

Question 32

RNA

Answer 32

• Ribonucleic acid
  
  • involved in protein synthesis in the cell
  • has ribose- a type of 5-carbon sugar
  • is single-stranded
  • nitrogen bases- adenine, uracil, cytosine and guanine
    
    • A bonds with U
    • C bonds with G

Question 33

ATP

Answer 33

• Adenosine triphosphate
  
  • has ribose, adenine, and 3 phosphate groups
  • energy carrying compound in the cell
  • Carries energy in the high energy bond of 3rd phosphate (2nd phosphate bond is also high energy)
  • when bond is broken useful energy is liberated for the cell