Comprehensive Cell Biology & Anatomy Flashcards

A set of 100 question-and-answer flashcards covering key concepts from plasma membrane structure to skeletal anatomy for exam preparation.

What is the semipermeable structure that separates cytoplasm from the extracellular environment in all cells?

The plasma (cell) membrane.

Which molecules form the core selective barrier in the fluid-mosaic model?

Phospholipids.

How does cholesterol affect membrane fluidity at high temperatures?

It restrains excess phospholipid movement, preventing a leaky membrane.

What is cholesterol’s effect on the membrane at low temperatures?

It prevents phospholipid tails from packing too tightly, preserving flexibility.

Which membrane proteins span the entire bilayer to act as channels, carriers, pumps, or receptors?

Integral (transmembrane) proteins.

What is the primary function of the glycocalyx formed by membrane carbohydrate chains?

Cell recognition and immune "self/non-self" discrimination.

Which type of molecules cross the plasma membrane most easily by simple diffusion?

Small non-polar molecules such as O₂ and CO₂.

Aquaporins facilitate the passage of what substance across the membrane?

Water (H₂O).

Name the three major filament systems of the cytoskeleton.

Microtubules, intermediate filaments, and microfilaments (actin).

Which cytoskeletal filaments form the mitotic spindle and serve as tracks for kinesin and dynein?

Microtubules.

Mutations in keratin intermediate filaments cause which blistering skin disorder?

Epidermolysis bullosa.

Which cytoskeletal element interacts with myosin to power muscle contraction?

Actin (microfilaments).

Which fibrous protein provides most of the tensile strength in the extracellular matrix?

Collagen.

Which ECM protein permits elastic recoil in tissues such as skin and large arteries?

Elastin.

Proteoglycans and GAGs attract water to create what property of ground substance?

A hydrated gel for shock absorption and nutrient diffusion.

Which Ca²⁺-dependent adhesion molecules create strong cell-to-cell junctions, and their loss promotes tumor invasion?

Cadherins.

Integrins link cells to what external structures while transmitting survival signals inside the cell?

Extracellular matrix proteins (e.g., fibronectin, collagen, laminin).

During inflammation, what is the role of selectins on endothelial cells?

They mediate transient rolling of leukocytes along the vessel wall.

What bulk-transport process engulfs large particles into phagosomes for lysosomal degradation?

Phagocytosis.

Which protein coats the pits involved in receptor-mediated endocytosis?

Clathrin.

Exocytosis of neurotransmitters occurs primarily in which type of cell?

Neurons.

Which enzyme synthesizes mRNA during transcription?

RNA polymerase.

What post-transcriptional modification at the 3′ end protects mRNA from degradation?

Addition of a poly-A tail.

What codon signals the start of translation and codes for methionine?

AUG.

Which organelle’s trans face sorts and packages proteins for final destinations?

The trans-Golgi network of the Golgi apparatus.

Proteins tagged with mannose-6-phosphate are directed to which organelle?

Lysosomes.

Which mitochondrial membrane houses the electron transport chain complexes?

The inner mitochondrial membrane.

Approximately how many ATP are produced by oxidative phosphorylation per molecule of glucose?

About 26–28 ATP.

Release of cytochrome c from mitochondria initiates which cellular process?

Intrinsic (mitochondrial) apoptosis.

Peroxisomes primarily oxidize which category of fatty acids?

Very long-chain fatty acids (VLCFAs).

Which peroxisomal enzyme decomposes hydrogen peroxide into water and oxygen?

Catalase.

What is the typical internal pH of a lysosome?

Approximately 4.5–5.0.

Deficiency of hexosaminidase A leads to which lysosomal storage disease?

Tay-Sachs disease.

What structures perforate the nuclear envelope to regulate molecular traffic?

Nuclear pores.

Where are ribosomal subunits assembled within the nucleus?

In the nucleolus.

What term describes loosely packed, transcriptionally active chromatin?

Euchromatin.

Which level of protein structure consists of alpha helices and beta sheets stabilized by hydrogen bonds?

Secondary structure.

What name is given to an independently folding region of a protein that performs a specific function?

A functional domain.

Which membrane proteins are loosely attached to the cytoplasmic or extracellular face and can detach easily?

Peripheral proteins.

How do increased unsaturated fatty acid tails affect membrane fluidity?

They increase fluidity.

Activation of adenylate cyclase increases the concentration of which second messenger?

cAMP (cyclic AMP).

Protein kinase C is activated by DAG together with an increase in which ion released by IP₃?

Calcium (Ca²⁺).

The Na⁺/K⁺-ATPase pumps how many Na⁺ out and K⁺ in per ATP hydrolyzed?

3 Na⁺ out and 2 K⁺ in.

Secondary active transport uses energy stored in what to drive uphill solute movement?

An ion gradient, usually the Na⁺ gradient.

Which buffer system is the body’s first-line defense against changes in blood pH?

The carbonic acid–bicarbonate buffer system.

At blood pH 7.4, what is the approximate bicarbonate-to-carbonic-acid ratio?

About 20 : 1.

Acidosis caused by elevated CO₂ from hypoventilation is classified as what?

Respiratory acidosis.

What is a carbohydrate composed of two monosaccharides linked by a glycosidic bond called?

A disaccharide.

Which polysaccharide is the principal glucose-storage molecule in animals?

Glycogen.

A fatty acid with no carbon–carbon double bonds is termed what?

A saturated fatty acid.

Why is HDL often called "good" cholesterol?

It removes excess cholesterol from tissues and returns it to the liver.

Which amino acid is the precursor for the neurotransmitter serotonin?

Tryptophan.

At physiological pH, amino acids predominantly exist in what dipolar form?

As zwitterions (bearing both positive and negative charges).

According to Bronsted–Lowry theory, how is a base defined?

As a proton (H⁺) acceptor.

Why is acetic acid a stronger acid than ethanol?

Its conjugate base (acetate) is resonance-stabilized, whereas ethanol’s is not.

Which epithelial junction of claudins and occludins forms an impermeable seal between cells?

Tight junctions.

Which epithelial type lines alveoli to allow rapid diffusion of gases?

Simple squamous epithelium.

The epidermis is composed of what specific epithelial classification?

Keratinized stratified squamous epithelium.

Which skin gland releases its product by holocrine secretion (cell rupture)?

Sebaceous (oil) gland.

Adipose tissue is classified as which subtype of connective tissue proper?

Loose connective tissue dominated by adipocytes.

Dense regular connective tissue forms which structures that attach muscle to bone?

Tendons.

Which cartilage type, rich in collagen I, forms intervertebral discs and menisci?

Fibrocartilage.

Bone mineral is primarily composed of crystals of what compound?

Hydroxyapatite (calcium phosphate).

Which glial cells act as immune sentinels and phagocytes in the CNS?

Microglia.

Demyelination in multiple sclerosis primarily damages which CNS glial cells?

Oligodendrocytes.

What property allows muscle tissue to return to its original length after being stretched?

Elasticity.

Cardiac muscle cells are electrically coupled through what specialized junctional structures?

Intercalated discs (containing gap junctions and desmosomes).

Which bone-resorbing cell type is stimulated by vitamin D and PTH?

Osteoclasts.

Intramembranous ossification produces most of which bones in the body?

The flat bones of the skull (and the clavicles).

In the epiphyseal plate, which zone contains rapidly dividing chondrocytes responsible for lengthening?

The proliferative zone.

Weight-bearing exercise increases the activity of which bone-forming cells?

Osteoblasts.

Skull sutures are examples of which structural class of joint?

Fibrous joints.

The elbow primarily functions as which type of synovial joint?

A hinge joint.

Which movement decreases the angle between arm and forearm at the elbow?

Flexion.

Turning the sole of the foot inward is called what movement?

Inversion.

What is the anatomical term for lying face-down on a surface?

Prone position.

Which anatomical plane divides the body into anterior and posterior portions?

The frontal (coronal) plane.

Relative to the little finger, the thumb is positioned how?

Lateral.

What term describes the jumping conduction of nerve impulses along myelinated axons?

Saltatory conduction.

Which part of an adult long bone holds yellow marrow?

The medullary cavity of the diaphysis.

Blood vessels enter bone through small openings called what?

Nutrient foramina.

Articular cartilage at synovial joint surfaces is composed of which cartilage type?

Hyaline cartilage.

Which hormone raises blood calcium by stimulating bone resorption?

Parathyroid hormone (PTH).

How many net ATP are produced during glycolysis before the Krebs cycle?

2 ATP.

Which buffer system is most important inside cells and in renal tubules?

The phosphate buffer system.

Marfan syndrome results from mutations in which elastic-fiber scaffold protein?

Fibrillin-1.

In intestinal epithelial cells, the Na⁺/glucose cotransporter moves Na⁺ and glucose in which directions?

Both Na⁺ and glucose are moved into the cell (symport).

Peroxisomal beta-oxidation generates which reactive oxygen species that must be detoxified?

Hydrogen peroxide (H₂O₂).

What is the primary role of the Golgi apparatus’s cis face?

Receiving newly synthesized proteins from the rough ER.

Which post-translational modification tags misfolded proteins for proteasomal degradation?

Ubiquitination.

Hemoglobin buffering of H⁺ in red blood cells is an example of what general buffer category?

The protein buffer system.

Which class of arteries contains abundant elastic connective tissue to accommodate pressure pulses?

Elastic arteries (e.g., the aorta).

What specialized ECM sheet anchors epithelia and functions in filtration?

The basement membrane.

Which muscle type is non-striated and contracts via the Ca²⁺–calmodulin pathway?

Smooth muscle.

The neuromuscular junction is the synapse between a motor neuron and which muscle type?

Skeletal muscle.

Which neurodegenerative disease is closely associated with mitochondrial dysfunction and loss of dopamine neurons?

Parkinson’s disease.

Which secondary active transporter rapidly extrudes Ca²⁺ from cardiac myocytes in exchange for Na⁺?

The Na⁺/Ca²⁺ exchanger (antiporter).

Which inflammatory mediator released by mast cells causes vasodilation and increased permeability?

Histamine.

What mature bone cell, residing in lacunae, functions as a mechanosensor?

An osteocyte.

Coordinated contractions of which muscle type produce peristalsis in the gastrointestinal tract?

Smooth muscle.