absorption of carbs and proteins Flashcards
starch is ……. branched
moderately
what is the smallest unit of sugar
monosaccharides
what is sucrose made from
glucose
fructose
glycogen is …. branched
highly
disaccharides
two single units joined together
polysaccharides are made from …..
monosaccharides
glucose + galactose
lactose
2 x glucose molecules form …..
maltose
define polysaccarhides
3 or many million units of sugar
examples of polysaccharides
what is the carbs storage in plants
starch
what is the carb storage in animals
glycogen
how to make a polysaccharide into a di
uses salivary amylase
pancreatic amylase
intestinal (brush border) enzymes
disaccharide into monosaccharide
intestinal (brush border) enzymes
-intestinal maltase
-intestinal sucrase
-intestinal lactase
dietary carbs/saccharides
-meet body’s energy needs - glucose
- proteins and fats are important components of cells and tissue - shouldn’t waste
- feed brain and nervous systems
- keep digestive system fit
- add bulk to foods
- ingestible carbs are beneficial
describe the enzymes involved in carb digestion + describe the process
poly -> di
- salivary amylase
- pancreatic amylase
- intestinal (brush border) enzymes
di -> mono
- intestinal (brush border enzymes)
- intestinal:
maltase, sucrase, lactase
where are some of the carb digestive enzymes located
intestinal villus brush border
desrcibe the stages of carb/monosaccharide absorption
- glucose, galactose, fructose absorbed
- fructose, galactose -> glucose
- glucose released into blood
- energy, glycogen, adipose tissue
dietary protein
-absorption is highly efficient
- body uses to build + repair
- provide essential am. acids for protein synthesis + nitrogen atoms for N compounds
-energy from protein when lipid + carbs aren’t available
-lose lots of proteins daily
where are proteins lost to daily
mucins
cell debris
proteins
levels of protein structure
- protein
- polypeptides
- peptides
- di- & tri- peptides
- amino acids
getting energy from proteins is …..
expensive + inefficient
how many different kinds of amino acids are there
20
what bond holds peptides together
peptide bond
di/tri amino acids can be absorbed by the ….. ….
small intestine
how many amino acids are essential
9
what type of digestion does the stomach provide
mechanical
what % of protein digestion occurs in the stomach
10-15%
what does pepsin do
convert larger proteins into smaller proteins
stomach for protein digestion - full explanation
- mechanical digestion
- HCl converts pepsinogen into active pepsin
- HCl denatures protein - INCREASE SURFACE ARE FOR PEPSIN
- pepsin - large proteins into smaller peptides
-10-15%
HCl converts pepsinogen into … …..
active pepsin
how is the surface area for pepsin increased
HCl denatures the protein
what are the 2 types of enzymes involved in protein digestion
endopeptidases
exopeptidases
intestines for protein digestion - full explanation
- receives denatured polypeptides from stomach
- pancreatic enzymes
- extensive and rapid digestion
- breaks small peptides into AA’s
-85-90%
endopeptidases - explain
attack bonds in the centre of peptide chains:
-gastric pepsin
-pancreatic trypsin
exopeptidases - explain
split AA’s one at a time:
-pancreatic enzymes
-intestinal (brush border) enzymes
-enterocyte cytoplasm enzymes
why are whole proteins rarely absorbed
no transporters on enterocytes + too big to ‘squeeze’ between cells
newborn - whole protein absorption
few days after birth
whole milk protein
maternal anitbodies
by pinocytosis
what is pinocytosis
invagination of cell membrane to form vesicles
monosaccharide absorption - full
- all 3 utilise same basolateral transporter GLUT2 - exit the enterocyte into blood by FACILITATED DIFFUSION
small peptide and AA absorption
FREE AA ABSORPTION
AA apical transporters in the brush border surface.
These free AA’s are
absorbed using Na+/K+ ATPase linked secondary active, facilitated diffusion
or simple diffusion
mechanisms.
PEPTIDE ABSORPTION
Di - & Tri-peptide apical transporters in the brush border surface AA transporters on the basolateral surface to allow exit of single AAs
examples of ways in which proteins enter the gut
diet
digestive enzymes
microoragnisms
mucus
plasma proteins
desquamated epithelial cells
