Cell Physiology

3 major subdivisions of cells

plasma membrane, nucleus, and cytoplasm

function of the plasma membrane

separates ICF and ECF and controls movement

what is the sacrolemma

consists of the plasma membrane plus proteoglycans and type IV collagen on the outer surface facing ECF

structures in the cytoplasm

ribosomes, organelles, and cytoskeleton

ribosome function

translates mRNA code into chains of amino acids

ribosomes contain specific sites for ___ which do what

tRNAs that that vary specified amino acids

where are ribosomes found?

freely in the cytosol or attached to the RER

four functions of ER

protein synthesis, synthesis of lipids and steroids, packaging of newly synthesized materials into transport vesicles, and storage and release of intracellular calcium

main function of RER

protein synthesis

main function of smooth ER

central packaging and discharge site

function of Golgi apparatus

modifies products from SER into final form and sorts, packages and directs molecules to their appropriate destinations

how are products released from golgi

via exocytosis in secretory cells

function of proteasome

degradation of unfolded protein

what are the two categories of organelles

non-membranous and membranous

lysosomes

membrane bound organelles that contain acid hydrolytic enzymes

functions of lysosomes

degrade endocytosed material, destroy materials internalized by the cell, degrade membrane receptors, remove worn-out parts (autophagy)

peroxisomes

small, intracellular, membrane bound organelles containing oxidative enzymes

function of peroxisomes

oxidizes fatty acids and amino acids and produces hydrogen peroxide

what happens to hydrogen peroxide since it is toxic to cells?

rapid conversion to water and oxygen by catalase

catalase function

protective enzyme that prevents cells from injury by free radicals

cytoskeleton

complex, intracellular protein network in the cytosol that acts as muscle and bone of the cells

three elements of cytoskeleton

microtubules, microfilaments, and intermediate filaments

microtubules are made of

tubulin

microtubule function

maintenance of asymmetric cell shapes, serves as highways for intracellular transport, make up main component of cilia and flagella, and make up mitotic spindle

microfilaments are made up of

actin

function of microfilaments

important role in cellular contractile systems

intermediate filaments function

help cells resist mechanical stress

intermediate filaments composition in skin

keratin

IF composition in skeletal muscle

desmin

three types of endocytosis

pinocytosis, receptor-mediated endocytosis, and phagocytosis

how does endocytosis work

endocytic vesicle is pulled into the cell by clathrin

how do secretory vesicles know where to go?

when secretory vesicle leaves the Golgi, a coat-protein is lost, exposing v-SNAREs

what do v-SNAREs bind to

t-SNAREs on the inner surface of the plasma membrane

long distance transport is the function of

microtubules

kinesin

forward motor movement toward positive end / out of cell

dynein

reverse motor; movement of debris vesicles to lysosomes for degradation

what is contained in the cytosol

enzymes involved in intermediary metabolism and ribosomes

how are unused nutrients stored in cytosol

in the form of glycogen granules or fat droplets

what is the function of mitochondria

energy production

Cristal of the mitochondria

inner membrane

matrix of the mitochondria

gel-filled cavity

how does mitochondria make energy

conversion of glucose and fatty acids into ATP

what does mitochondria require for cellular respiration

oxygen

what are the stages of cellular respiration?

glycolysis in the cytosol, citric acid cycle in the mitochondrial matrix, and oxidative phosphorylation at the mitochondrial inner membrane

glycolysis

breakdown of glucose into 2 pyruvate molecules resulting 2 ATP

does glycolysis use oxygen?

no

citric acid cycle

conversion of pyruvate into acetyl CoA

does citric acid cycle require oxygen?

yes

major function of citric acid cycle?

preparing hydrogen carrier molecules (NAD and FAD) to enter oxidative phosphorylation

net ATP production in citric acid cycle

2

oxidative phosphorylation

ATP synthesis through energy released by electrons they are transferred to O2

what two groups of proteins are involved in oxidative phosphorylation

electron transport system and ATP synthase

electron transport system

extracts electrons from hydrogen ions generated during glycolysis and the citric acid cycle

transfer electrons

lower energy levels

the energy released in the inner mitochondrial membrane is used to create

a H+ gradient

chemiosmosis

movement of protons down their gradient to synthesis ATP using ATP synthase

how much ATP does oxidative phosphorylation generate

30

cells generate more ATP in what conditions?

aerobic