Cell Biology: Transport, Cell Cycle, and Specialization(3.3-3.7)

Comprehensive vocabulary flashcards covering membrane transport mechanisms, cell cycle phases, division control, stem cell differentiation, and cell death.

What does the cell membrane control?

Which substances enter and leave the cell.

What are the two major types of transport mechanisms?

Passive and active mechanisms.

What is passive transport?

Transport that does not require energy.

What are the types of passive transport?

Diffusion, facilitated diffusion, osmosis, and filtration.

What is active transport?

Transport that requires cellular energy in the form of ATP.

What are the types of active transport?

Primary active transport, endocytosis, exocytosis, and transcytosis.

What is diffusion?

Movement of atoms, molecules, and ions from an area of high concentration to low concentration.

When does diffusion occur?

Until diffusional equilibrium is reached.

What is a concentration gradient?

A difference in concentration between two areas.

What two things must be present for diffusion across a cell membrane?

The membrane must be permeable to the substance and a concentration gradient must exist.

Does diffusional equilibrium normally occur in organisms?

No

What is a physiological steady state?

Concentrations are unequal but stable.

What is facilitated diffusion?

Movement down the concentration gradient with help from protein carriers or channels.

Why is facilitated diffusion needed?

For substances that cannot cross the selectively permeable membrane because they are not lipid-soluble.

Does facilitated diffusion require ATP?

No, it is a passive transport.

What is osmosis

Movement of water across a selectively permeable membrane.

What is osmosis sometimes called?

“Diffusion of water.”

Where does water move during osmosis?

Toward the region with the higher impermeant solute concentration.

What does water move toward in terms of osmotic pressure?

A solution with higher osmotic pressure

What channels does water use to move through cell membranes?

Aquaporins.

Aquaporins

Water channels located between phospholipids in the cell membrane through which water moves during osmosis.

What is filtration?

Molecules are forced through membranes by pressure.

What is hydrostatic pressure?

The force that fluid exerts against a wall.

What happens when blood plasma leaves capillaries?

Water and small solutes are filtered, while large plasma proteins and blood cells are not.

How does active transport move substances?

Against a concentration gradient.

What does active transport require?

ATP

What does active transport use to move substances?

Specific membrane carrier proteins or pumps.

What is active transport often called?

pumps

What does secondary active transport use for energy?

Energy stored in an ion gradient established by active transport.

Does secondary active transport use ATP directly?

no

How can the Na⁺/K⁺ pump help other substances cross the membrane?

It changes the concentration gradient, allowing other substances to move through the membrane.

What is endocytosis?

Movement of a substance into the cell inside a vesicle.

Why is endocytosis used?

For substances too large to enter by other methods.

What are the three types of endocytosis?

Pinocytosis, phagocytosis, and receptor-mediated endocytosis.

What is pinocytosis?

“Cell drinking” — cells take in tiny droplets of liquid with solutes.

What is phagocytosis?

“Cell eating” — cells take in solid particles

What is receptor-mediated endocytosis?

A type of endocytosis that uses receptors to bring specific substances into the cell.

What is exocytosis?

Release of substances or particles from the cell.

How does exocytosis happen?

Vesicles containing particles fuse with the cell membrane and release their contents.

What is transcytosis?

Transport of substances across a cell using vesicles.

What happens during transcytosis?

The substance enters by endocytosis on one side, travels through the cell in a vesicle, and leaves by exocytosis on the opposite side.

What is the cell cycle?

The series of changes a cell undergoes until it divides.

What are the major stages of the cell cycle?

Interphase, mitosis, and cytokinesis.

What happens during interphase?

The cell grows and maintains normal functions.

What is mitosis?

Division of the nucleus

What is cytokinesis?

Division of the cytoplasm.

What happens during interphase?

The cell grows, maintains its functions, and prepares for cell division.

What are the three phases of interphase?

G1, S, and G2.

What happens during G1?

The cell grows and develops.

What happens during S phase?

DNA is copied

What happens during G2?

The cell checks the copied DNA and produces materials needed for division.

What is mitosis, where does it occur, and what does it produce?

Mitosis is division of the nucleus. It occurs in somatic (non-sex) cells and produces two identical daughter cells.

The four phases of Mitosis are

Prophase, Metaphase, Anaphase, Telophase.

What happens during Prophase?

Chromatin condenses into chromosomes, centrioles move to opposite sides, the nuclear envelope and nucleolus disperse, and microtubules assemble and attach to the chromosomes.

What happens during Metaphase?

The chromosomes move to and line up in the middle of the cell, with fibers attached to each centromere.

-nucleus is gone

What happens during Anaphase?

Centromeres separate, chromatids become individual chromosomes, and the chromosomes are pulled toward opposite sides of the cell. The cell begins to elongate and a furrow develops.

What happens during Telophase?

Chromosomes uncoil back into chromatin, new nuclear envelopes form around the chromosomes, and the cytoplasm begins pinching into two parts.

What is cytokinesis and when does it occur?

Cytokinesis is division of the cytoplasm. It begins during late anaphase, and a cleavage furrow forms as microfilaments contract, eventually producing two cells.

How is cell division controlled?

Cell division is strictly regulated by telomeres, cell size, hormones and growth factors, and contact inhibition. Healthy cells stop dividing when they become crowded. Too little division prevents growth, while too much can cause abnormal growth and tumors.

What are the two types of tumors?

Benign tumors remain in the local area and often enlarge. Malignant tumors are invasive, cancerous, and can spread or metastasize.

What genes are involved in cancer?

Oncogenes can increase the rate of cell division when overexpressed.

Tumor suppressor genes normally limit mitosis, so when they are inactivated or removed, they cannot regulate cell division.

What is differentiation and why is it important?

Differentiation guides cell specialization by activating and suppressing functions of many genes. It is essential for growth and repair.

What is a stem cell?

An undifferentiated cell that can divide to produce two daughter stem cells or one stem cell and one progenitor cell.

What is self-renewal?

The ability of a stem cell to produce at least one other stem cell.

What is a progenitor cell?

A daughter cell of a stem cell whose own daughter cells are restricted to specific lineages.

Apoptosis =

programmed cell death that is protective and helps sculpt organs from naturally overgrowing tissue.

Necrosis =

uncontrolled cell death caused by things like injury or infection.