To produce, degrade, store, and export biological molecules, and to degrade potentially harmful substances.
Short DNA fragments synthesized on the lagging strand during replication.
Act as receptors for chemical messengers, transport proteins, and in cell-to-cell recognition.
S phase.
An elaborate network of rods running through the cytosol, providing support and enabling cell movement.
Enzymes and proteins needed for division are synthesized and centriole replication is completed.
They interact with myosin to generate contractile forces.
Basal bodies are centrioles that form the bases of cilia and flagella.
The '9 + 2' pattern consists of nine doublets of microtubules encircling one central pair.
They cannot reproduce and live for only three to four months before deteriorating.
It generates microtubules and organizes the mitotic spindle during cell division.
Endoplasmic reticulum (ER), Golgi apparatus, secretory vesicles, lysosomes, and the nuclear envelope.
Interphase and the mitotic phase.
To move substances across the free cell surface.
DNA replication occurs during the S subphase.
The cell typically cannot survive because the nucleus contains the genetic material necessary for cell function.
Stable cytoskeletal elements that resist mechanical forces acting on the cell.
Hollow tubes of spherical protein subunits called tubulin.
Packages, modifies, and segregates proteins for secretion, lysosomes, and plasma membrane incorporation.
A flagellum is longer than a cilium; the only example in humans is the sperm tail, which propels the cell.
A double membrane barrier that surrounds the nucleus.
The cell is metabolically active, synthesizing proteins rapidly and growing.
Flagella are longer projections formed by centrioles, while cilia are shorter and occur in larger numbers. Flagella propel the cell itself, whereas cilia propel substances across a cell's surface.
Bundled actin filaments.
Sites of protein synthesis.
Synthesis of proteins and phospholipids, and transport of proteins to the Golgi apparatus.
They determine the overall shape of the cell and the distribution of cellular organelles.
They move 'hand over hand', gripping and releasing at new sites.
It positions complementary free nucleotides along the template strands.
A double layer of phospholipids with embedded cholesterol and proteins.
The cell undergoes autolysis, digesting itself.
The cellular region between the nuclear and plasma membranes, containing cytosol, organelles, and inclusions.
To greatly increase the speed of replication.
Ribosomal RNA and proteins.
A cell that has many nuclei, often found in skeletal muscle and some liver cells.
The centrosome or cell center.
Ciliated cells in the respiratory tract propel mucus laden with dust particles and bacteria upward away from the lungs.
Nucleoli are dark-staining spherical bodies within the nucleus where ribosomal subunits are assembled.
Power stroke and recovery stroke.
A rare neurodegenerative disorder caused by lysosomes lacking an enzyme needed to break down a specific glycolipid in nerve cell membranes.
It acts as the control center, containing genetic instructions for protein synthesis.
Fine filaments composed of actin; involved in muscle contraction and intracellular movement.
Cilia move substances in one direction through a rhythmic alternating motion of a propulsive power stroke and a recovery stroke.
The cell divides into two cells.
DNA must be replicated exactly.
Punctures in the nuclear envelope that regulate entry and exit of molecules.
It acts as a microtubule organizing center.
Nine triplets of microtubules.
Histone proteins package and regulate DNA, playing an important role in gene regulation.
Twisted units of tetramer fibrils.
To act as internal cables that resist pulling forces on the cell.
It is a critical point where the cell checks for DNA damage and ensures all DNA is replicated before mitosis.
5 μm.
Tubular extensions of the plasma membrane that increase surface area for absorption.
The point at which the DNA strands separate as hydrogen bonds are broken.
Forms an aqueous transport channel and regulates molecular transport.
Chromatin coils and condenses to form short, barlike bodies called chromosomes.
Increase the plasma membrane surface area.
Cylindrical structures made of tubulin proteins; support the cell, give it shape, and are involved in intracellular movements.
They degrade glycogen at a relatively constant rate.
It contains a proximal centriole and a distal centriole with an atypical structure.
Because early cytologists thought cells were inactive, but it is actually a period of metabolic activity.
Detoxify toxic substances and break down hydrogen peroxide using catalase.
Nuclear envelope, nucleoli, and chromatin.
Chromatin is composed of approximately 30% DNA, 60% globular histone proteins, and 10% RNA chains.
Microfilaments, intermediate filaments, and microtubules.
Actin.
They move and reposition organelles along the microtubules powered by ATP.
It separates the nucleoplasm from the cytoplasm and regulates the passage of substances to and from the nucleus.
Cilia and flagella.
Oriented at right angles to each other.
Site of lipid and steroid synthesis, lipid metabolism, drug detoxification, and Ca2+ storage.
Varied substances including stored nutrients like lipid droplets and glycogen granules.
The largest organelle, surrounded by the nuclear envelope; it controls the cell and transmits genetic information.
They function as the cell's 'demolition crew' by digesting particles, degrading stressed or dead cells, and performing metabolic functions.
Nucleosomes are the fundamental units of chromatin, consisting of clusters of eight histone proteins connected by a DNA molecule.
Membranous sacs containing acid hydrolases; sites of intracellular digestion.
Site of ATP synthesis; known as the powerhouse of the cell.
Extended chromatin segments are active and expose different DNA segments for synthesizing proteins or RNA species.
Dynein arms are motor proteins that produce the movement of the cilium or flagellum by gripping and pushing adjacent doublets.
Nuclear envelope, nucleolus, and chromatin.
Maintains the shape of the nucleus and organizes DNA.
The degradation of stressed or dead cells and worn-out organelles by lysosomes.
The jellylike fluid enclosed by the nuclear envelope.
It is selectively permeable but allows substances to pass more freely.
The sperm cell, which has one propulsive flagellum commonly called a tail.
A 'cherry red spot' on the macula of the retina.
Soluble transport proteins.
Methyl groups can shut down nearby DNA, while acetyl groups expose different DNA segments for gene expression.
Centrioles multiply and line up beneath the plasma membrane at the cell's exposed surface, leading to the sprouting of microtubules.
The cell ensures that all DNA is replicated and damaged DNA has been repaired before division.
Small molecules, protein molecules, and RNA molecules.
Enzymes unwind the DNA molecule, forming a replication bubble.
DNA and histone proteins.
Paired cylindrical bodies that organize the microtubule network and form the spindle and asters during cell division.
They constantly grow, disassemble, and reassemble.
Short cell-surface projections that create a unidirectional current to propel substances across cell surfaces.
