New one Flashcards
When a particular gene
is expressed, one of the two DNA strands in the gene is tran
scribed to produce a complementary RNA strand, which is
then processed to produce:
Messenger RNA (mRNA)
In eukaryotic cells, the —– travels from the nucleus to the cytoplasm, where it is translated into a polypeptide
mRNA
Which RNA determines the ordered sequence of amino acids in the polypeptide chain and what is this chain built by>
mrna
built by ribosomes
What is a ribosome and what is it composed of?
its essentially a protein synthesis factory and is composed of multiple proteins and several ribosomal RNAs.
What do the RNA’s in peptide bonds do?
they catalyze peptide bond formation between amino acids, to form a polypeptide.
What 2 things can tRNA do?
1) it can bind a specific amino acids
2) it can recognize specific sequences of nucleotides in MRNA
Which type of RNA can recognize which amino acid should be added to a growing polypeptide chain?
tRNA
where does transcription take place at?
the nucleus
Where does translation take place at?
the cytoplasm
what is translation
the process of using mrna to assemble amino acids into a protein
What enzymes does saliva contain?
salivary amylase and lipase
what is the esophagus
a muscular tube that connects the pharynx to the stomach
what 2 glands do the mucosa of the stomach contain?
Gastric glands and pyloric glands
Which nerve does the gastric gland respond to?
vagus nerve
Gastric glands have 3 different type of cells:
mucous cells, chief cells, and parietal cells
Chief cells produce —– , the inactive form of pepsin
pepsinogen
Hydrogen ions in the stomach, secreted by —– cells as hydrochloric acid, cleave pepsinogen to pepsin
parietal cells
Mucous cells produce
the bicarbonate rich mucus that protects the muscular wall from from teh harshly acidic and proteolytic environment of the stomach
The pyloric glands of the stomach contain G cells that secrete —-, a peptide hormone
gastrin
What does Gastric do?
induces the parietal cells in the stomach to secrete more HCl and signals that stomach to contract, mixing its contents
Talk about the 3 segments of the small intestine and their roles briefly:
The 3 segments are the duodenum, jejunum and ileum
The duodenum is responsible for the majority of the chemical digestion and has some minor involvment in absorption.
However, most of the absorption in the small intestine takes place in the jejunum and ileum
the presence of chyme in the duodenum causes the release of what class of enzymes?
Brush-border enzymes like disaccharidases and peptidases
Examples of disaccharidases
maltase, isomaltase, lactase and sucrase
Examples of peptidases
dipeptidase
What hormones does the duodenum secrete
secretin and cholecystokinin
what does secretin do
it causes pancreatic enzymes to be released into the duodenum
it also regulates the pH of the digestive tract by reducing HCl secretion from parietal cells and increasing bicarbonate secretion from the pancreas
What does cholecystokinin do
it stimulates the secretion of bile and pancreatic juices and also acts in the brain where it promotes satiety
What are the accessory organs of digestion
pancreas, liver and gall bladder
what are the pancreatic enzymes
-pancreatic amylase
-pancreatic peptidase (trypsinogen, chymotrypsinogen, and carboxypeptidases A and B)
-pancreatic lipase
where is bile produced in
the
