Today• Taste• Experiments/projects

Bumps on your tongue are NOT taste buds

Most common typeNO taste buds

Taste buds

Taste buds

Few. At the back of tongueTaste buds

Papillae• Increase surface area of tongue•Makes tasting ‘easier’

Taste Buds•Chemo receptors ‘down inside’ papillae• Some also produce saliva

Taste Buds

Taste• Sweet, Salty, Sour, Bitter, Umami(amino

acids, proteins)•Receptor proteins on/in taste buds are coded

for via genes•Mutations (and gene duplications) happen• You get variation among and between

individuals and groups

Taste• Sweet – your body needs sugar•Umami – protein (proteins can also taste

sweet)• Salt – need salts (Na+, K+, etc.)• Sour – “bad” or ‘rotting’ food - acid•Bitter – poison, “bad” food• Fat usually tastes “sweet”

Taste•What you can taste has evolved within

groups/species•Cats – can’t taste sweet•No cat can – lion, tiger, house cat, etc.•Appears to have happened at least different

times

Taste• Pandas – NO umami• They eat bamboo•No/little protein – no need to taste it•Most birds can’t taste sweet•One group (hummingbirds) regained ability

Taste•Dolphins – No bitter OR umami receptors•But mostly meat diet…• Swallow meals whole – no need to ‘taste’

Taste•Humans – Some can taste bitter better than

others•Helps avoid alkaloids/poisons•Also helps avoid foods that interrupt thyroid

function• “We” can produce up to 25 different bitter

receptors (25 different genes)•Dogs – 16•Rats- 37!

Taste•Humans – Some can taste bitter better than

others• Variation within populations• PTC – Phenylthiocarbamide• You either taste it, or you don’t

Taste•Humans – Some can taste bitter better than

others• Variation within populations• PTC – Phenylthiocarbamide• You either taste it, or you don’t•Do YOU taste it?

Taste•How about ‘spicy’ foods?

Homework•Quiz on how taste and smell work tomorrow?