into to amino acids and proteins

Question 1

what is the central dogma of molecular biology

Answer 1

The flow of genetic information from DNA to RNA to proteins can be represented by a scheme called the central dogma of molecular biology

Question 2

what is the information in DNA used for

Answer 2

• three nucleotides make a codon
• triplets code for amino acids

Question 3

what is the exceptions to the universal code

Answer 3

• some organisms have slight modifications eg. mitochondria
• triplets code for different amino acids

Question 4

greek name for protein

Answer 4

proteios meaning primary

Question 5

what are the components of proteins

Answer 5

C,H,O,N (approx 16%) and sometimes S

Question 6

what is the molecular weight of an amino acid

Answer 6

110 g mol-1

Question 7

what is protein mass weighed in and how much does a large bio molecular way

Answer 7

• Daltons (Da)
• large bio moleucules >10,000 Da

Question 8

what is the average protein length of amino acids

Answer 8

• 200
• most between 50 - 2000

Question 9

functions of proteins

Answer 9

• transport
• fluid balance
• source of energy and glucose
• acid- base balance
• cell membrane structure and function
• enzymes
• hormones
• immune factors - antibodies

Question 10

structure of amino acid

Answer 10

H2N—-CHR—–COOH
left- amine group
right - carboxyl group
central C - chiral carbon
R- residual group ( variable)

Question 11

what are the two isomers of amino acids and which are only found in proteins

Answer 11

L isomer - only found in proteins - amino group on left side
D isomer - amino group on right side

Question 12

what are the exceptions to the amino acid characteristics

Answer 12

• Glycine - has no enantiomers as it has two hydrogen groups
• Proline - a amino group is attached directly to side chain so makes an amide

Question 13

how many essential and non essential amino acids are there and what do they mean

Answer 13

Non essential - 11 - humans can synthesis them
essential - 9 - cannot be synthesised

Question 14

define peptide, polypeptide and proteins

Answer 14

peptide - <40-50 amino acids
polypeptide - >50 amino acids
protein - one or more polypeptides

Question 15

what is a peptide bond

Answer 15

link the alpha amino group to the carbonyl group of the next amino acid

Question 16

what is the primary structure of a protein

Answer 16

• sequence of amino acids in a single polypeptide chain
• most related to nutritional value
• makes the core amino acid backbone
• determines the chemical and physical characteristics

Question 17

where does hydrogen bonding occur in the primary structure

Answer 17

backbone due to carboxyl group and hydrogen atoms bonded to amine group

Question 18

cause, signs and treatment of sickle cell anaemia

Answer 18

cause - single error in amino acid sequence of haemoglobin

signs -anemia, chest, abdomen and join pain,
swollen hands and feet, frequent infections, stunted growth and vision problems

treatment - drug therapy, blood infusions, supplemental oxygen, bone marrow transplants, gene therapy

Question 19

what is the secondary structure of a protein

Answer 19

folding of a protein due to hydrogen boding between elements in the amino acid backbone forming alpha helix or beta folded sheets

Question 20

where do hydrogen bonds form in an alpha helix

Answer 20

every 4th amino acid forming a helical structure

Question 21

what are the two type of beta folded sheets and how are they formed

Answer 21

antiparallel - amino acid strands run opposite directions

parallel - amino acid strands run the same direction

• rows of amino acids are liked by hydrogen bonds

Question 22

where do loops form

Answer 22

outside of proteins when the protein folds into its tertiary structure

Question 23

what are loops used for and what are their properties

Answer 23

• often binding sites for other molecules
• rich in hydrophilic residues as they are exposed to water

Question 24

why are weak bonds important in polypeptides

Answer 24

• many weak bonds act in parallel to hold two regions tightly together
• stability determined by the number of non covalent bonds

Question 25

what is the tertiary structure of a protein

Answer 25

• 3D folding and coiling of the polypeptide forming a globular structure
• maintained by ionic bonds, disulphide bridges and hydrogen bonds aswell as hydrophobic interactions
• contains multiple secondary structures

Question 26

what are homomers

Answer 26

proteins made of all of the same sub unit

Question 27

what are oligomers

Answer 27

proteins made of multiple subunits

Question 28

what are heteromers

Answer 28

proteins made of different subunits

Question 29

what is a proteins quaternary structure

Answer 29

• interactive folding of several polypeptide chains forming a single functional protein
• subunits held together by non covalent forces

Question 30

what are protein domains

Answer 30

• a unit of organization distinct from the four structures
• usually contain 40 to 35- amino acids
• different domains are associated with different functions

Question 31

how are protein domains formed

Answer 31

a substructure is produced by any part of the polypeptide chain and is folded interdependently into a compact, stable structure

Question 32

what is sequence alignments used for

Answer 32

• identifys homologous protein domains
• uses short signature sequences

Question 33

what is paralogous

Answer 33

• homologous sequence separated via a gene duplication event
• a gene in an organism is duplicated to occupy two different positions in the same genome these two copies are paralogous

Question 34

what is orthologous

Answer 34

• homologous sequence separated via a speciation event
• species diverges into two separate species the copies of single gene in both species are said to be orthologous

Question 35

what is post translational modification and what does it involve

Answer 35

• allows the newly made polypeptide chain to become fully functional
• involves 3D shaping and/or adding methylation and phosphorylation

Question 36

how are proteins further modified

Answer 36

• attachment of carbohydrate, lipid or RNA groups
• attachment of small
  inorganic and organic molecules eg. metal ions, vitamins, methyl groups and phosphorylation

Question 37

what are cofactors

Answer 37

usually metal ions or small organic molecules necessary for protein activity