Quiz 2 Biochemistry

Question 1

What are biochemicals

Answer 1

• organic compounds from a biological source–NO PLASTICS
• tend to be a bit larger and more complex than other organic compounds.
• 4 major types: proteins, carbohydrates, lipids, nucleic acids

Question 2

4 major types of biochemicals

Answer 2

1. proteins: made of amino acids
2. Carbohydrates: made of monosaccharides (simple sugars)
3. lipids: made of fatty acids
4. Nucleic acids: sugar phosphates and organic bases

*the building blocks or units of each biochemical are called polymers

Question 3

Polymers

Answer 3

• “mer” means “thing” in greek
• the building blocks of each biochemical i.e. amino acids, monosaccharides, fatty acids, sugar-phosphates+bases
• the building blocks combine to produce polymers
• the basic unit =monomer
• 2 together=dimer
• 3together=trimer
• 4-15 together=oligomers
• 15+ together =polymers

Question 4

3 types of biochemical reactions

Answer 4

1. decomposition rxn
   
   • ex. catabolic rxn. often happens in our stomach and intestines when we eat. break down molecules
2. synthesis rxn
   
   • happens at the cellular level. form more complex molecules
3. exchange rxn
   
   • happen at cellular level. require very little energy. like breaking down glucose. molecule just gets changed a little. AB+CD= AC and BD

Question 5

Monosaccharides

Answer 5

-carbohydrates
-they form lactone rings which contain carbon and one oxygen
-hexoses–6-carbon
sugars
-glucose–primary source of body’s energy
-fructose–fruits and veggies
-galactose–from dairy products
-pentoses–5-carbon sugars
-ribose and deoxyribose–these are found in our genetic material. not used for energy
-all taste sweet
-fuel our metabolism

Question 6

carbohydrates

Answer 6

• carbo=carbon
• hydrate= H2O aka hydrogen and oxygen
• normally composed of C, H, O in the ratio of C1H2O1.
• contain several -OH groups (hydroxyl groups are functional side groups) the molecules are generally polar and hydrophilic
• main role in body is fuel! through catabolic and redox rxns the energy stored in carbohydrates is released and used for cellular processes
• the monomer= monosaccharide

Question 7

disaccharides

Answer 7

• molecule with two monosaccharides joined by a polar covalent bond
• formed by dehydration synthesis–a hydrogen atom is removed from fructose and a hydroxyl group is removed from glucose and a molecule of water is formed and the two monosaccharides now share an oxygen left by the hydrogen atom.
• can be broken down by hydrolysis–the reverse process of dehydration synthesis.
• 2 most common disaccharides:
  1. sucrose–(glucose +fructose) table sugar
  2. lactose (glucose+galactose) milk and other dairy.

Question 8

polysaccharides

Answer 8

• largest and therefore, least soluble
• long branching chains of monosaccharides joined by covalent bonds formed by dehydration synthesis.
• plants and animals store their glucose for later use in the form of polysaccharides
  - plant glucose stored as starch, animal glucose as glycogen–found primarily in liver and skeletal muscles.
• glycogen is branched and this is an advantage as enzymatic reactions happen only on the ends of molecules but there are many ends so the blood glucose concentration can increase quickly when needed. but energy stores get used up quickly as well.
• sometimes attach to lipids and proteins==glycolipids and glycoproteins (responsible for cell recognition and structural integrity of cell)

Question 9

hydrocarbons

Answer 9

• all combos of hydrogen adn carbon
• as carbon increases by 1, hydrogen increases by 2 starting at CH4 (methane)
• their physical properties at room temperature (gas-solid-liquid-oil-etc) change as their size increases
• all are combustible
• but otherwise very stable so don’t undergo chemical rxns easily. need functional side groups for that.

Question 10

isomers

Answer 10

• molecules with the same molecular formula but different structures are called isomers
• “same parts”
• ex. fructose and galactose

Question 11

functional side groups

Answer 11

• structures that tack onto hydrocarbon back bone and change the fxn.
• these are more polar, give the hydrocarbons more polarity
• OH alcohol
• CHO aldehyde
• COOH carboxyl
• NH2 amine
• SH sulfhydryl
• R2CO ketone

Question 12

proteins

Answer 12

• monomer=amino acids
• 21 different amino acids
• only form bonds in single chains, no branches
• most proteins are 100-200 amino acids
• main fxns:
  1. fibrous proteins form scaffolding of body: skin, bone, tissues etc
  2. globular proteins help maintain homeostasis
  3. enzymes special proteins that acts as chemical catalysts and mediate chem rxns; decrease activation energy needed for rxn.

Question 13

protein structure

Answer 13

• 3 types
  primary: amino acid CHAIN
  secondary: chain COILS and FOLDS
  tertiary: coiled chain FOLDS in on itself and is stabilized by crosslinks and hydrogen bonds
• the sequence of amino acids in the chain determines both secondary and tertiary structure
• there can be a quarternary structure in which the proteins interact with each other

Question 14

“lock and key” mechanism for enzyme catalysis

Answer 14

• enzyme has active site where substrates (amino acids) can plug in.
• the enzyme changes shape to hold the amino acids in position
• energy is absorbed and a bond is formed
• water is released
• the bond has changed the shape of the substrates so they pop out as a new peptide bond.
• enzyme returns to original shape, ready to catalyze another rxn

Question 15

metabolism

Answer 15

• sum of all chem rxns in the body
• all rxns mediated directly or indirectly by enzymes
• if you control what enzymes are available, you control metabolism
• if you control metabolism, you control life.

Question 16

lipids

Answer 16

• monomer=fatty acids
• consist of C, H, and O but normally the quantity of C and H are far greater than the O, unlike carbohydrates
• nonpolar and hydrophobic
• cannot form a ploymer, only monomer, dimer and trimer
• fatty acids attach to glycerol so they are called glycerides
  - mon-, di-, and triglycerides
  - consist of 1-3 fatty acids with a glycerol
• mono-, and di- phospholipids consist of 1-2 fatty acids and a glycerol phosphate
• steroids are multi-ring compounds and are all monomers.
  - ex. cholesterol

Question 17

fatty acids (3 types)

Answer 17

1. saturated fatty acids:
   
   • no double carbon bonds in the hydrocarbon chain=carbon is saturated with hydrogen atoms
   • predominantly found in animal fats
   • solid at room temp. b/c very dense
2. monounsaturated fatty acids:
   
   • has one double bond btwn two carbons in the hydrocarbon chain
   • this causes a bend in the chain, meaning the hydrocarbons can’t pack together as tightly, not as dense.
   • lower melting point than saturated fats
   • normally liquid at room temp. ex. plant oils like olive, grapeseed and peanut
3. polyunsaturated fatty acids:
   
   • has two or more double bonds btwn carbon atoms
   • lowest melting point
   • liquid at room temp. ex. linoleic acid

• fatty acids are stored by linking three of them together via dehydration synthesis to a modified 3-carbon sugar called glycerol
• these rxns produce a polymer called neutral fat/triglyceride

Question 18

triglyceride

Answer 18

• triglycerides that contains one or more unsaturated fatty acids is likely to be liquid–unsaturated have the double carbon bonds that cause kinks=less dense=liquid.
• triglycerides are stored in fat cells, help insulate the body and absorb shocks.
• also help regulate temp.
• they are also a great fuel supply.

Question 19

phospholipids

Answer 19

• like a triglyceride with a glycerol backbone and two fatty acid tails however in place of the third fatty acid tail there is a phosphate group (PO4) attached to a a nitrogen containing group
• phosphate and nitrogen groups are very polar while the tails are very non-polar
• now we have a two-sided molecule:
  
  • one side is the phosphate head which is polar/hydriophilic
  • other side is fatty acid tails which are non-polar/hydrophobic
  • this makes the molecule amphiphilic=”likes both”
• this gives it the properties to make cell membranes among other things (remember the phospholipid bi-layer of cells!!)

Question 20

steroids

Answer 20

• all share a 4-ring hydrocarbon structure called the steroid nucleus
• cholesterol, a steroid, also forms the basis for the body’s other steroids
• the hydrocarbon rings are non-polar and most molecues derived from it are non-polar as well

Question 21

nucleotides

Answer 21

• most found in the nucleus hence the name
• the monomers of our genetic material, the nucleic acids deoxyribonucleic acid and ribonucleic acid
• Adenosine triphosphate (ATP) is a nucleotide that is our main source of chemical energy
• composed of 3 parts
  
  1. nitrogenous base (purines double -ringed molecules A &G; pyrimidines single ringed C,U,T)
  2. a 5-carbon pentose sugar (ribose or deoxyribose)
  3. phosphate group

Question 22

ATP

Answer 22

• nucleotide called Adenosine Triphosphate
• the energy present in chemical bonds is main source of chemical energy
• nitrogenous base adenine attached to ribose =adenosine plus three phosphate groups (tri-phosphate); with two phosphate groups it’s ADP (di-phosphate) or AMP (mono-phosphate)
• each phosphate group is negatively charged so they repel eachother
• therefore, it is very difficult to add a third phosphate to ADP and this is where the energy comes from. when the bond is broken by hydrolysis leaving ADP and a phosphate group, the energy is released.
• cells must continually replenish ATP as it only lasts about 60 seconds in cell
• oxygen is required for ATP creation. when no breathing, no ATP=death

Question 23

DNA

Answer 23

• extremely large molecule located only in nucleus
• composed of two long strands of nucleotides in form of double helix
• contains deoxyribose as its 5-carbon sugar
  
  • one of the C atoms lacks an O containing OH group and just has the H atom instead. hence de-oxy
• bases are adenine, thymine, cytosine, and guanine
• two strands are held together by hydrogen bonds between the bases
• complementary base pairing; A and T, C and G. one purine (A and G) with one pyrimidine (T and C)
• DNA contains genes and “recipe” for protein

Question 24

RNA

Answer 24

• located in several parts of cell, nucleus, ribosomes
• one strand
• contains ribose as its 5-carbon sugar
• bases are adenine, uracil, cytosine, and guanine
• A and U, C and G
• RNA plays crucial role in protein synthesis
• RNA copies the “recipe” for protein from DNA (mDNA)and takes it to the ribosomes where DNA is created.

Question 25

protein sythesis

Answer 25

• how genes are expressed

- proteins can then either act structurally or act as enzymes and carry out chem rxns for metabolism

Question 26

carrier mediated transport

• what is it
• 3 types

Answer 26

• requires a transport molecule that can carry a specific molecule across the semi permeable membrane
• 3 mechanisms
  
  1. facilitated diffusion-moves down the concentration gradient and requires no energy
  2. primary active transport-moves up the concentration gradient and requires ATP
  3. secondary active transport- moves up a concentration gradient but does not require ATP because a molecule will bind to another molecule that is allowed to move through the pump and hitch a ride across.