BIO 457: Cell Phys - Week 2 Vocab

Gamete

a haploid cell specialized for sexual reproduction

Ovum

egg/mature oocyte, female gamete (in some animals fertilization occurs at this stage)

Ova

plural of ovum

Sperm

male gamete

Zygote

the diploid cell resulting from the fusion of gametes (only lasts until it divides)

Oocyte

the cell that will become the egg after completing meiosis (not the same as an egg)

Spermatocyte

the cell that will become a sperm after completing meiosis

Maturation

a process including meiosis that leads to the development of a mature sperm or egg cell

Fertilization

union of egg and sperm, which leads to the formation of a new organism

Cytoskeleton

a set of protein filaments that gives shape and structure to living cytoplasm

Plasma Membrane

the outermost boundary surrounding living cytoplasm, consisting of a lipid bilayer where high concentrations of protein are dissolved

Cell Cortex

specialized film of cytoplasm associated with the plasma membrane in which organelles are scarce and the cytoskeleton (especially actin) is enriched

Golgi Apparatus

membrane-bound organelle that receives, sorts, modifies, and packages proteins and lipids in vesicles for transport

Acrosome / Acrosomal Vesicle

membrane-bound organelle located at the front of a sperm containing enzymes to help penetrate the outer layers of an ovum (derived from the golgi apparatus)

Acrosomal Reaction

reaction where the acrosome fuses with the sperm plasma membrane when sperm binds an egg, and releases its enzymes

Acrosomal Process

part of the acrosomal reaction in some species; a specialized protuberance formed at the apex of the sperm head, supported by a core of actin filaments

Acrosomal Filaments

actin structures within sperm acrosomes that extend during the acrosome reaction

Actin

a protein that acts as the central agent in cell shape change and contractility, among the most abundant cellular proteins in eukaryotes (ATPase)

Barbed End / Pointed End

due to polarity, actin filaments assemble more rapidly at the barbed ends

ATPase

an enzyme that hydrolyzes ATP (e.g. actin)

Cortical Granule

exocytotic (secretory) vesicles in the cortex of an unfertilized egg, which contain hyalin, enzymes, and mucopolysaccharides (derived from the golgi apparatus)

Regulated Secretory Pathway

Cortical Reaction

process triggered by fusion of sperm and egg plasma membranes, in which the cortical granules fuse with the egg plasma membrane and release their contents between the plasma membrane and vitelline envelope

Polyspermy

a condition in which more than one sperm enters the egg

Hyalin

protein released from the cortical granules, forming a coat around the egg and holds blastomeres together during early development

Vitelline Envelope

an extracellular coat which contains glycoproteins and is bound to the egg plasma membrane (important in species-specific interactions with sperm)

Fertilization Envelope

membrane which surrounds the fertilized egg of an urchin and is the product of the vitelline envelope, cleaved off and raised from the surface of the egg and hardened by the cortical reaction

Pronucleus

distinguishes the haploid gamete-derived nuclei from the diploid zygote nucleus

Microtubule

tubular protein polymer; the second major eukaryotic cytoskeletal filament. Larger, stiffer, and typically longer than actin filaments, but polar with plus and minus ends

Tubulin

building blocks of microtubules composed of dimers of alpha and beta tubulin (GTPase)

Protofilaments

nearly straight tubulin dimers stacked one atop the next

GTP Cap

the plus end of a growing microtubule consists entirely of tubulin bound to GTP (GTP-tubulin). Eventually tubulin hyrdolized GTP and becomes GDP-tubulin

GTP-tubulin

microtubules composed of GTP-tubulin are stable and tend to add more subunits

GDP-tubulin

created when tubulin hydrolyzes GTP, microtubules composed of GDP-tubulin are unstable and tend to disassemble rapidly

Dynamic Instability

character behavior epitomized by individual microtubules, conferred by the coupling of assembly to GTP hydrolysis, composed of three steps: nucleation, catastrophe, and rescue

Nucleation

beginning step of actin filament and microtubule formation, often prompted by specific protein complexes

Catastrophe

when growth slows, GTP hydrolysis can catch up to the plus end and obliterate the GTP cap, causing the unstable ends to rapidly disassemble

Rescue

a shrinking microtubule can be rescued and grow again if growth can be stimulated or the ends are stabilized

Treadmilling

Microtubule-organizing Centers (MTOC)

areas in cell in which nucleation of microtubules is tightly localized

Centrosome

an MTOC which typically defines the cell center, composed of a cloud of material where the centriole can be found

Centriole

Highly-structured microtubule-containing structure that seems to organize the centrosome

Basal Body

a centriole, located at the base of the ciliary axoneme, that serves as the template and anchor for microtubules in the cilium

Centromere

a chromosome region that controls the assortment of chromosomes during division by nucleating the assembly of kinetochores

Kinetochore

large-scale protein complex that assembles around the centromeric chromatin on each replicated chromosome during mitosis, serving as the attaching point for microtubules of the mitotic apparatus

Kinetochore Fiber

the set of microtubules that attach to the kinetochore to one spindle pole

Mitotic Apparatus

chromosome-sorting machine that ensures daughter cells receive one copy of each chromosome during cell division. It differs between branches of eukaryotic life, but in animals, it typically consists of a spindle, two spindle poles, and asters

Spindle

the densest bit with the chromosomes attached to K-fibers

Spindle Poles

basically the centrosomes plus a bunch of other mitotic-specific stuff added

Asters

radial arrays of microtubules that extend in every direction through the cytoplasm

Astral Mictrotubules

not directly visible in a transmitted light microscope

Astral Rays

visible in a transmitted light microscope because microtubules organize cytoplasm wherever they go

Mitosis

normal way that eukaryotic cells divide: DNA replicates, condenses, aligns on the mitotic apparatus, then partitions into the two daughter cells

Interphase

centrosome maintains the cell center by feeling around with microtubules

Prophase

chromatin condenses, poles separate, microtubules experience more frequent catastrophe and therefore get shorter

Prometaphase

nucleus is broken down, chromosomes not yet aligned, many short-lived microtubules

Metaphase

chromosomes aligned at future division plane, captured by dense bundles of microtubules

Anaphase

Sister chromatids separate along the spindle, few microtubules are nucleated, but last long and therefore reach further

Telophase

Chromosomes are pulled far apart, nuclei reform, cell divides, few but very long microtubules remain in each cell

Cytokinesis

coupled to telophase, the physical partitioning of the cytoplasm in which the cell pinches itself in two

Cleavage Furrow

form of cytokinesis that takes place in animal cells, furrow occurs around equator of cell and constricts

Contractile Ring / Cytokinetic Apparatus

actin-filament structure that causes the ingression of the furrow

Cleavage

series of mitotic cell divisions whereby the volume of the egg cytoplasm is divided into numerous progressively smaller cells

Blastomere

cleavage stage cell, which can form a blastula when enough are present