Unit 3 AOS 1

Question 1

4 main elements that make up organisms

Answer 1

• carbon (black)
• hydrogen (white)
• nitrogen ( blue)
• oxygen (red)
• sulfur (yellow)
• phosphorus (orange)
  –> make up 99% of organisms

Question 2

monomers

Answer 2

smallest molecule of a substance
–> sugars, amino acids, nucleotides

Question 2

polymers

Answer 2

multiple units of monomers together
–> polysaccharides (from sugars)
–> proteins (from amino acids)
–> nucleic acids (from nucleotides)

Question 3

organic molecules

Answer 3

4 main types:
- carbohydrates –> monosaccharide chain, source of chemical energy (glucose), stored as glycogen
- lipids –> FFA & glycerol, non polar, hydrophobic, store energy as fats, oils and adipose tissue
- nucleic acids –> genetic material of all organisms, made out of nucleotides (monomer) joined by phosphodiester bonds
- proteins –> biomacromolecules made out of long chains of amino acids (polypeptides)

Question 4

inorganic molecules

Answer 4

• oxygen –> required to release ATP in cellular respiration, gained from the air
• carbon –> gained from the air
• nitrogen –> key component of proteins, in the air but unusable in gas form
• minerals –> occur naturally by weathering of rocks, mineral ions important within many parts of the cell

Question 5

proteins

Answer 5

• polypeptides –> chain of amino acids
• <50 polymers are called peptides
• polypeptide chain must carefully fold in the right shape to function properly

Question 6

proteome

Answer 6

• all the proteins that are expressed by a cell or organism
• expressed by genes (genome)

Question 7

amino acids

Answer 7

• building blocks of proteins
• chemical structure:
  –> central carbon
  –> carboxyl group
  –> amino group
  –> R-group
  –> hydrogen atom

Question 8

protein structure (folding)

Answer 8

four levels:
- primary
- secondary
- tertiary
- quaternary

Question 9

protein secretory pathway (PSP)

Answer 9

• ribosomes, RER, golgi apparatus
• proteins are synthesised from mRNA at ribosomes on the RER, then inserted into the RER to be folded and modified. they are moved to the golgi apparatus via transport vesicles where they are further modified and packaged into secretory vesicles. these secretory vesicles then move to the PM to release their contents from the cell via exocytosis

DNA –> mRNA –> RER ribosomes –> vesicle –> golgi (folded/modified) –> exocytosis

Question 10

exocytosis

Answer 10

• requires ATP
• secretory vesicles form within the cell cytosol to fuse with PM
• once vesicles form around the material being secreted, its contents are released from the cell and secretory vesicle becomes part of the PM

Question 11

protein classification

Answer 11

2 types:
- fibrous proteins: elongated & insoluble, used for structural proteins and have little folding
–> eg. collagen, keratin
- globular proteins: folded & coiled into tertiary & quaternary structures, soluble, inside hydrophobic, outside hydrophilic
–> eg. enzymes and hormones

Question 12

factors affecting protein functioning

Answer 12

due to environmental factors which lead to denaturing
- temp
- pH range
- concentration of ions or molecules that are cofactors

Question 13

cofactors

Answer 13

any organic or inorganic molecule, such as a coenzyme or metal ion, that assists enzyme or protein functioning.

Question 14

nucleotide structure

Answer 14

• small segment (monomer) of nucleic acid (polymer)
  sugar-phosphate backbone –> phosphate group, five carbon (pentose) sugar, nitrogenous base

Question 15

DNA

Answer 15

2 strands of nucleotides bonded together through complementary base pairing
sugar-phosphate backbone runs antiparallel
nucleotides can only be added to the 3’ end.

Question 16

RNA

Answer 16

ribonucleic acid, single strand of nucleotides
- tRNA
- mRNA
- rRNA

Question 17

types of RNA

Answer 17

• ribosomal RNA (rRNA): makes up ~half of the ribosome, forming the site of protein synthesis
• transfer RNA (tRNA): carries amino acids to the ribosome during translation
• messenger RNA (mRNA): created during transcription and RNA processing (transcription) in the nucleus by RNA polymerase, carries a copy of the nucleotide sequence (code) that codes for a protein