ch. 2 cellular and molecular physiology Flashcards
carbohydrates
monosaccharides [ie glucose] & polysaccharides [ie glycogen, cellulose]
lipids
fatty acids, phospholipids, cholesterol
proteins
composed of amino acids
highly complex 3d structures
nucleic acids
composed of nucleotides
deoxyribonucleic acid [DNA]
ribonucleic acid [RNA]
major subdivisions of eukaryotic cells
plasma membrane [cell membrane] - separates cell’s contents from the surrounding environment & selectively controls movement of molecules between intracellular fluid [ICF] and extracellular fluid [ECF]
nucleus - contains DNA; materials for genetic instructions and inheritance& control center of the cell
cytoplasm - contains organelles and cytoskeleton dispersed within the cytosol
DNA
packed with histones to form chromosomes
contains codes [genes] for making RNAs and proteins through transcription and translation
functions:
provide a code of info for RNA & protein synthesis
serves as a genetic blueprint during cell replication
transcription
gene is copied into a pre-messenger RNA by RNA polymerase
pre-messenger RNA is processed into messenger RNA [mRNA] by removing noncoding sequences and adding signal sequences
translation
mRNA leaves the nucleus and delivers a coded message to a ribosome
ribosomal RNA [rRNA] translates the mRNA code into amino acid sequences
transfer RNA [tRNA] transfers the appropriate amino acids from cytoplasm to ribosome to be added to the protein under construction
endoplasmic reticulum [ER]
elaborate, fluid-filled membranous system distributed throughout the cytoplasm
rough ER
ribosomes bound to the outer surface give rough ER its granular appearances
new proteins synthesized by ribosomes are released into lumen of rough ER
smooth ER
no ribosomes
synthesis of lipids [ie steroid hormones]
detoxify toxic compounds in liver cells
ribosomes
synthesize proteins under direction of nuclear DNA
free ribosomes dispersed throughout cytosol
bound ribosomes are found on membranes of rough ER
golgi complex
newly synthesized molecules from smooth ER enter
modifies proteins to final form
sorts finished products and directs them to final destination
lysosomes
break down organic molecules
contain hydrolases, enzymes that catalyze hydrolysis reactions
remove worn-out organelles
process of endocytosis
pinocytosis, receptor mediated endocytosis, phagocytosis
proteosomes
break down internal proteins into amino acids
peroxisomes
membrane-enclosed sacs smaller than lysosomes
contain oxidative enzymes
mitochondria
power plants of the cell, produce 90% of energy cells need
aerobic vs anaerobic
aerobic pathways require consumption of O2
anaerobic pathways can proceed in absence of O2
major steps in generation of ATP
glycolysis
citric acid cycle
electron transport chain associated with oxidative phosphorylation
ATP [adenosine triphosphate]
carries high-energy bond in the terminal phosphate
glycolysis
chemical process that breaks down glucose into two pyruvate molecules
can proceed in anaerobic conditions [no O2]
releases 2 electrons that are transferred to NAD+ to form NADH
not very efficient; 1 molecule of glucose yields 2 molecules of ATP
citric acid cycle
key purpose of the cycle is to produce hydrogens for entry into the electron transport chain
cyclical series of 8 reactions catalyzed by enzymes in the mitochondrial matrix
pyruvate produced by glycolysis enters the mitochondrial matrix
pyruvate is converted to acetyl CoA by removal of a carbon and formation of CO2
acetyl CoA combines with oxaloacetic acid to form citric acid
2 carbons released for each turn of the cycle
electron transport chain [respiratory chain]
electron carrier molecules are located in inner mitochondrial membrane
electrons are transferred through chain of reactions with electrons falling to lower energy levels at each step
O2 is final electron acceptor of the electron transport chain; O2 combines with electrons and hydrogen to form H2O
some energy released during transfer of electrons is used to synthesize ATP
total ATP yield is 30 ATPs per molecule of glucose
food + O2 => CO2 + H2O + ATP
