Biology: Digestive System etc Flashcards
mouth
teeth mechanically break down food
larger surface area for enzyme action
oesophagus
connects mouth and stomach
peristalsis
how food bolus moves through gut
stomach
churns food to break down further and mix
releases proteases and hydrochloric acid- helps to sterilise food
has epithelial cells in stomach lining to stop acid (why bile is needed in s.i.
what makes a effective diffusion surface (in body)
large surface area
good blood supply
short diffusion distance
small intestine, what helps this
nutrients absorbed into bloodstream (only soluble food molecules)
villi greatly increases surface area along with folded shape
large intestine/colon
absorbs water
forms faeces
gut flora- what
bacteria in our gut
gut flora purpose
break down substances we can’t digest
supply essential nutrients
synthesise (put together) vitamin K
compete with harmful bacteria (restricts their growth)
rectum
stores faeces- mainly indigestible food
anus
muscle controlled opening out of the body
salivary glands
produce amylase
lubricates food bolus for easy swallowing
bile- purpose
to emulsify fats
neutralises stomach acid
bile- where produced and stored
produced in liver
stored in gall bladder
emulsify fats?
break them down into smaller globules so they have more surface area for enzyme action
pancreas
produce amylase, protease, lipase
enzyme
biological catalyst
made from proteins/amino acids
other things about digestive enzymes
work outside body cells
produced by glands
secreted into the digestive tract
pH of oral cavity
6.8-7.5
pH of stomach cavity
1.5-2.0
duodenum
first part of small intestine
pH of duodenum
5.6-8
pH of small intestine
7.2-7.5
pH of colon
7.9-8.5
difference between simple and complex carbohydrates
complex: longer chains eg starch
take longer to digest
shorter: opposite eg sugar
carbohydrates -> ?? used for what?
glucose- fuel for respiration- to release energy
proteins -> ?? used for what?
amino acids- building new proteins for growth and repair, also enzymes and antibodies
lipids-> ?? used for what?
fatty acids and glycerol- used to rebuild lipids for use as an energy store
insulation
protect vital organs and build cell membranes and hormones
carbohydrase- where produced, action
saliva -> mouth
pancreas -> small intestine
small intestine
protease- where produced, action
stomach
pancreas -> small intestine
small intestine
lipase- where produced, action
pancreas -> small intestine
eg of carbohydrase
amylase
eg of protease
pepsin: stomach
trypsin: pancreas -> small intestine
starch food test
iodine
orange/brown
blue/black
sugar food test
benedict’s
light blue
green to brick red
85 celsius water bath for 5 mins (this is so solution can get to the same temperature of the water bath)
lipid food test
ethanol
clear and colourless
cloudy emulsion
protein food test
biuret
blue
lilac/purple
specificity of enzymes
a substrate can only be binded if it has a complementary shape (enzymes are folded to produce a unique shape)
substrate
reactant
how is enzyme held together
by forces between amino acids (enzymes are large protein molecules / chains of amino acids)
lock and key theory
- substrate temporarily binds to enzymes active site- forms an ENZYME-SUBSTRATE COMPLEX
- bonds broken
- enzyme converts substrate into product(s)- forms an ENZYME-PRODUCT COMPLEX
products released from enzymes active site- enzyme remains unchanged
induced fit theory
shape of enzymes active site and substrate are not complementary
when substrate enters active site, a conformational change occurs
denatured
when the shape of an enzymes active site is distorted and its substrate can no longer fit (reaction is not catalysed)
largely irresversbile
enzymes and temperature
low temp:
little kinetic energy
few successful random collisions
more kinetic energy as temp increases, more collisions
optimum temp:
most successful collisions (37 celsius in human body)
active site deforms above that
decreasing successful collisions as bonds are broken
get to a point where there are no successful collisions
enzymes and pH
optimum pH:
most successful collisions
this value depends on the enzyme
moving away:
become denatured
fewer successful collisions
extreme pH:
no activity- completely denatured
metabolism
sum of all the reactions in a cell/organism
examples of synthesis in humans
starch, glycogen, cellulose from glucose
proteins from amino acids in ribosomes
lipids from fatty acids and glycerol
examples of synthesis in plants
glucose from carbon dixode and water
amino acids from glucose and nitrate ions
anabolic reaction
synthesis reaction
catabolic reaction, example
breaking down reaction (big to small)
eg digestion
cellular respiration (glucose -> water and co2)
deamination (excess amino acids -> urea)
reactions that happen in plants and humans
respiration and protein synthesis
what happens to excess proteins/amino acids
converted to urea- excreted in urine
what is the point of digestion
make molecules smaller and SOLUBLE to be absorbed into blood
investigating breakdown of starch by amylase:
why is it better to measure concentration of starch rather than just if it is present
more accurate, quantitive, less subjective
what will happen to enzymes at 80 degrees??
THEY WILL DENATURE AND SO WONT COLLIDE etcetc!! AT ALL.
in biology, how to do describe graph questions
PUT DATA FROM GRAPH IN
why/how does small intestine absorb nutrients
into blood by active transport
what affects metabolic rate
genetics, age, gender, body mass
how to determine concentration of solution inside an egg using solutions of water
put egg inside at least 4 solutions of different water potentials, record changes in mass and plot each eggs results on a graph. then see where graph crosses x axis (no change in mass), would tell each eggs concentration)
