Unit 1- Biological Molecules Flashcards
Compare the structure of DNA and RNA (4)
DNA has deoxyribose pentose sugar, whereas RNA has ribose
DNA is double stranded whereas RNA is single stranded
DNA contains the base thymine, RNA has uracil instead of thymine
DNA is longer than RNA
Describe the function und structure of
Starch (5)
Polysaccharides of alpha glucose
Osmotically inactive
Large - cannot cross cell membrane
Helical - compact store
1-4 glycosidic bonds - unbranched
Describe the function and structure of
Glycogen (5)
Polysaccharide of alpha glucose
1-4 and 1-6 glycosidic bonds - branched
Branched - compact store, easily releases glucose for respiration
Large and insoluble - can’t leave cell
Osmotically inactive
Describe function and structure of
Cellulose (3)
Polysaccharide of beta glucose
1-4 glycosidic bonds→ straight unbranched chains
Many hydrogen bonds link parallel strands to form microfibrils
Describe how the properties of phospholipids relate to their structure (3)
Phosphate heads are hydrophilic - orient to cytoplasm
Fatty acid tails are hydrophobic - orient to each other
Form a bi-layer in cell membrane
Allow diffusion of lipid soluble molecules
How do enzymes act as biological catalyst
Lowering activation energy to speed up rate of reaction
Describe the induced fit model (4)
Substrate binds to enzyme active site
Active site changes shape so its complementary to substrate
Enzyme substrate complex forms
Shape of enzyme unchanged
Describe the structure of mRNA (5)
Single helix
Polynucleotide
Phosphodiester bonds join adjacent nucleotides
Uracil instead of thymine
Pertose sugar is ribose
Describe process of semi conservative DNA replication (6)
1) DNA helicase breaks hydrogen bonds between bases, double helix unwinds
2) helix unwinds - both strands act as template
3) DNA nucleotides join to exposed bases by complementary base pairing
4) Hydrogen bonds form
Adenine - thymine
Cytosine - guanine
5)DNA polymerase joins adjacent nucleotides
6) phosphodiester bonds form in condensation reaction
How is ATP used in cells (2)
• Active transport - and other energy requiring reactions
• releasing inorganic phosphate to phosphorylate compounds
Describe and explain the 5 properties of water (5)
Metabolite - used in reactions e.g condensation, respiration, photosynthesis
Solvent - allows transport of substances e.g xylem
High specific heat capacity - temperature is stable so makes good habitat
Large latent heat of vapourisation - cooling effect provided by evaporation
Strong cohesive forces between molecules -
Supports column of water
Provides surface tension
