Cell Structure and Function Flashcards
plasma membrane structure and function
structure: phospholipid bilayer with embedded protiens,
primary function: protection and separation of intracellular components from extracellular environment
nucleus structure and function
structure: gel like matrix,
function: controls and regulates the activities of the cell
endoplasmic reticulum structure and function
structure: paired membranes and flat vesicles (canals) that connect nucleus to cytoplasm
function: The functions of the endoplasmic reticulum can be summarized as the synthesis and export of proteins and membrane lipids, calcium storage and release, mRNA is translated here to make protein of secretory cells like digestive enzymes and insulin
ribosome structure and function
structure:
function: site of protein synthesis
mitochondria structure and function
structure: tiny little bean in the cell
function: store energy as ATP and use ATP as energy for cellular activities with glucose a fuel, key regulator of apoptosis, has it’s own DNA and ribosomes
lysosomes and peroxisome structure and function
structure:
L function: lysosomes are the stomach of the cell and have enzymes that clean up the cell by breaking up potentially harmful products and then split into ECF. They do this by AUTODIGESTION
P function: peroxisomes contain enzymes that degrade peroxides, free radicals, and can break down fatty acids if needed
What are the three types of cell membrane receptors?
- Ligand-gated ion receptor
- G-protein linked receptor
- Enzyme-linked receptors
Describe the lock and key mechanisms of the ligand receptor
Enzymes are highly specific. They must bind to a specific substrate before they can catalyze a chemical reaction. In lock-and-key model, the enzyme-substrate interaction suggests that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.
define the cytoskeleton and it’s filaments
microtubules: develop and maintain cell form, support structure for organelles.
microfilaments: produce muscle contraction
myosin filaments
explain the importance of ATP for cells energy metabolism
ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes. ATP is a special carrier for cellular energy
compare glycolysis, Krebs cycle, and oxidative phosphorylation by location in cell and the amount of ATP produced
glycolysis: cytoplasm, ATP: 2 molecules
Krebs cycle: mitochondria, 34 ATP molecules
oxidative phosphorylation: 36 ATP molecules
compare and contrast membrane transport mechanisms such as diffusion, osmosis, active transport, endocytosis and exocytosis.
passive diffusion: water, Co2, ethanol can cross membrane with no energy needed
active diffusion: movement from high to low concentrations facilitated by a transport proteins
osmosis: when a semipermeable membrane separates two fluid spaces, water will flow from an area of lower solute concentration to one of higher solute concentration to achieve equilibrium so that the osmotic pressures are balanced.
active transport: requires energy for the transport of substances, ions are pumped against a concentration gradient (Na/K+ ase pump), energy comes from ATP splitting by enzyme ATPase.
endocytosis: Endocytosis occurs when a portion of the cell membrane folds in on itself, encircling extracellular fluid and various molecules or microorganisms. The resulting vesicle breaks off and is transported within the cell.
exocytosis: secretion of intracellular substances into extracellular space, opening in cell membrane allows for the release of substances.
explain how the sodium potassium pump works as an active transport mechanism and the role of ATP
- the pump pumps ions against a concentration gradient in order to move substances across the membrane.
- ATP provides the energy for the sodium and calcium to move across and transport the substances
describe the process of diffusion, osmosis, facilitated diffusion and active transport in the movement of particles and ions. Which requires energy?
simple diffusion: movement from high to low
osmosis: movement from low to high with a semi-permeable membrane.
facilitated diffusion: diffusion helped by a transport protien, ENERGY
active transport: ENERGY, ions are pumped against a concentration gradient (Na/K+ pump)
describe action potential and the role of the resting membrane potential RMP
an action potential is rapid changes in the membrane potential at voltage gated channels. This sudden change from a negative RMP to threshold causes and opening of the membrane channels. This allows large amounts of Na + ions to enter cells causing depolarization, then Na+ channels close and potassium exits cell and returns to RMP.
When RMP is above threshold, an action potential happens.
what are the general structures and function of the four main tissue groups?
Epithelial tissue forms sheets that function to cover the body’s surface, line internal surfaces, form glandular tissue. Structures: simple, stratified, pseudostratified Function: covering and protection
Muscle tissue: structure: striated function is contraction, types: cardiac muscle, smooth muscle, skeletal muscle
connective tissue:
Connective tissue is classified into two subtypes: soft and specialized connective tissue. Major functions of connective tissue include: 1) binding and supporting, 2) protecting, 3) insulating, 4) storing reserve fuel, and 5) transporting substances within the body.
nervous tissue: Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning.
explain the process of skeletal muscle contraction
- . Muscle activation: The motor nerve stimulates an action potential (impulse) to pass down a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to release calcium into the muscle cell.
- Muscle contraction: Calcium floods into the muscle cell binding with troponin allowing actin and myosin to bind. Calcium binds to troponin and moves tropomyosin so that myosin can bind to actin. Contraction then occurs.
define cell adaptation
cells adapt to changes in their environment
ex: atrophy, hypertrophy, hyperplasia, metaplasia
Not always good adaptations
describe cell changes that occur with atrophy, hypertrophy, hyperplasia, metaplasIa, dysPlasia, and give examples of each.
example demarcated by **
atrophy: decrease in cell size. disuse= **decreased skeletal muscle use.
hypertrophy: increase in cell size, **physiologic=exercise, cardiac=hypertension
hyperplasia: increase of cells in organ or tissue. Cells are capable of mitotic division, in the epidermis, intestinal epithelium, and gland tissue. **uterus, BPH, regeneration of Liver
metaplasia: one adult cell replaced by another type of cell, occurs in response to chronic Irritation and Inflammation **??
dysPlasia: deranged cell growth Producing cells that vary in size, shape and organization. Precursor of cancer. **cervical cells
describe the mechanism whereby physical agents like blunt trauma, electrical forces, and temperature extremes produce cell injury
blunt trauma leaves bruising and tearing of muscles and cells.
electrical forces can kill cells, as can temperature extremes because of getting out of homeostasis.
differentiate between the effects of ionizing and nonionizing radiation in terms of their ability to cause cell injury.
ionizing radiation has a shorter wavelength and can cause more cell injury because of it’s ability to destroy healthy cells.
non ionizing radiation is still somewhat toxic, but it does not cause cell death, only tissue damage. There is non-ionizing radiation in microwaves and etc.
Relate free radical formation and oxidative stress to cell injury and death
free radical formation is when an atom has an unpaired valence electron. Free radical injury disrupts and damages cells and tissues. This can lead to cell injury and death
oxidative stress is when reactive oxygen species are no neutralized by the body. this can cause endothelial dysfunction with heart disease (closing of arteries), and also is found with cancer.
explain the process of hypoxic cell injury and how it can be reversed.
hypoxic cell injury happens when there is inadequate amount of O2 in the air, Respiratory disease, ischemia anemia, edema, or inability of the cell to use oxygen as in sepsis.
the injury interrupts oxidative metabolism and generation of ATP. The cell then switches over to anaerobic metabolism. The sodium potassium pump fails and water accumulates in the cell.
TO REVERSE: get rid of the adverse influences on the cells homeostasis (give O2)
Irreversible cell injury: necrosis and apoptosis
apoptosis is programmed cell death and so the cells are injured and weak already and it’s okay if they die and get recycled under normal conditions.
necrosis is an inflammatory process that interferes with cell replacement and tissue regeneration. necrosis can be recognized by gangrene on the extremities.
