cell function exam 4

Cytoskeleton

Supports cell shape and facilitates transport.

Intermediate filaments

Fibrous proteins providing tensile strength to cells.

Desmosomes

Anchors intermediate filaments between adjacent cells.

Nuclear lamina

Mesh of intermediate filaments surrounding the nucleus.

Keratin filaments

Intermediate filaments found in epithelial cells.

Vimentin

Intermediate filaments in connective tissue and muscle.

Neurofilaments

Intermediate filaments specific to nerve cells.

Accessory proteins

Assist in the stability and function of filaments.

Plectin

Protein that links intermediate filaments to other components.

Microtubules

Hollow tubes made of tubulin dimers.

Centrosome

Microtubule organizing center near the nucleus.

Centrioles

Cylinders of microtubules within the centrosome.

GTP hydrolysis

Process affecting microtubule stability and growth.

GTP cap

Stabilizes microtubules during rapid growth.

Microtubule fishing

Process of microtubules attaching to cell components.

Phosphorylation

Modification controlling nuclear lamins during cell division.

Epidermolysis bullosa simplex

Genetic disorder affecting keratin filament formation.

Butterfly children

Nickname for patients with epidermolysis bullosa simplex.

Mechanical stress

Force that intermediate filaments help cells withstand.

Polar microtubules

Microtubules with distinct plus and minus ends.

Stable microtubules

Microtubules that resist disassembly in certain cells.

Cell division

Process involving breakdown of nuclear lamina.

Cilia

Hair-like structures for motion and food collection.

Flagella

Longer than cilia, used for cell movement.

Motor proteins

Transport cargo along microtubules in cells.

Kinesins

Motor proteins moving towards plus end of microtubules.

Dyneins

Motor proteins moving towards minus end of microtubules.

Microtubules

Cylindrical structures that position organelles.

Axoneme pattern

9 double microtubules surround a central pair.

Actin filaments

Thin filaments crucial for cell movement and division.

Actin subunit

Monomeric units that form actin filaments.

Actin polarity

Filaments have distinct plus and minus ends.

Actin growth

Faster at plus ends, unstable when unsupported.

Actin binding proteins

Regulate actin polymerization and filament stability.

Cell cortex

Dense actin network beneath plasma membrane.

Crawling cells

Cells using actin for movement and attachment.

Myosin I

Universal myosin with one head for actin movement.

Myosin II

Muscle myosin with two heads for contraction.

Bipolar myosin filaments

Formed by myosin II dimers for muscle contraction.

Sliding mechanism

Process by which myosin II contracts muscles.

Skeletal muscle contraction

Involves myosin II activated by calcium ions.

Sarcomere shortening

Muscle contraction mechanism involving actin and myosin.

Smooth muscle variations

Different myosin II mechanisms important for function.

Myosin heads

Walk along actin filaments in opposite directions.

Sliding mechanism

Occurs in muscles and during cell division.

Muscle contraction

Shortening of sarcomeres without changing filament length.

Sarcomeres

Structural units of muscle contraction.

Cross bridge cycle

Myosin heads walk on actin, requires ATP.

Cytosolic Ca2+

Triggers muscle contraction by activating myosin.

Cardiac muscle

Heart muscle cells that do not divide.

Familial hypertrophic myopathy

Genetic mutation causing heart issues and sudden death.

Smooth muscle

Involuntary muscle activated by Ca2+ phosphorylation.

Extracellular signals

Stimulate smooth muscle contraction.

Baculovirus

DNA virus that replicates in the nucleus.

Nuclear lamina

Protective barrier composed of intermediate filaments.

B type Lamin

Building blocks of the nuclear lamina.

A-type Lamin

Contributes to nuclear stiffness and function.

Mitosis

Nuclear division during the M phase.

Cytokinesis

Cell division following mitosis.

Interphase

Long phase including G1, S, and G2.

S Phase

DNA replication occurs during this phase.

G1 Phase

Cell growth and preparation for DNA synthesis.

G2 Phase

Final preparations for mitosis and cell division.

Cell Cycle Checkpoints

Regulatory points that pause cell cycle progression.

G1/S checkpoint

Checks DNA damage and cell readiness.

Cleavage divisions

Rapid cell divisions in early embryonic development.

Phosphorylation

Increases during infection, disrupting nuclear lamina.

G2/M checkpoint

Checks DNA replication before mitosis starts.

Spindle checkpoint

Ensures chromosomes are attached before separation.

Cdk

Cyclin-dependent kinases activate cell cycle progression.

Cyclin-CDK complex

Activates target proteins for cell cycle regulation.

Cyclins

Regulatory proteins that activate Cdks.

APC

Ubiquitinates cyclins for degradation.

Proteasome

Degrades ubiquitinated proteins in the cytosol.

Mitogens

Stimulate cell division through extracellular signals.

MAP signaling

Pathway triggered by mitogens for cell growth.

P53

Transcription factor activating p21 in response to damage.

P21

Cdk inhibitor preventing entry into S phase.

DNA damage response

Activates p53 leading to cell cycle arrest.

Aneuploidy

Abnormal number of chromosomes due to cohesion failure.

M-CDK

Activates M phase after dephosphorylation by Cdc25.

Condensins

Proteins that condense chromosomes during mitosis.

Cohesions

Proteins holding sister chromatids together.

Cytokinesis

Division of cytoplasm following mitosis.

Contractile ring

Actin and myosin structure facilitating cytokinesis.

Phragmoplast

Guides cell wall formation in plant cytokinesis.

Apoptosis

Programmed cell death, tightly regulated process.

Necrosis

Cell death due to injury, causing inflammation.

Caspases

Proteases that execute apoptosis by cleaving proteins.

Intrinsic apoptosis

Triggered by internal signals like DNA damage.

Bcl2

Regulates apoptosis by inhibiting pro-apoptotic factors.

Cytochrome C

Activates apoptosome in intrinsic apoptosis pathway.

Fas receptor

Initiates extrinsic apoptosis upon ligand binding.

Positive signal proteins

Promote cell survival and inhibit apoptosis.

Growth factors

Stimulate cell growth and prevent degradation.

Cell cycle phases

Includes G1, S, G2, and M phases.

S phase checkpoint

Ensures complete DNA replication before mitosis.

Separase

Cleaves cohesions to allow sister chromatid separation.

Securin

Inhibits separase until targeted for degradation.

Flow cytometry

Measures DNA content in cells.