Cells: Organization and Communication (February 11, 2025)

Cytology

The study of cells.

Prokaryotic Cells

Cells that have no internal membrane-bound organelles and whose genetic material is confined to a nucleoid region.

Eukaryotic Cells

Cells that have a nucleus and membrane-bound organelles, evolved from prokaryotic ancestors.

Glycocalyx

Layer formed by glycoproteins and glycolipids on the cell membrane, defining cells as belonging to a specific organism.

Osmosis

The diffusion of water across a semipermeable membrane to equalize solute concentrations.

Active Transport

The movement of molecules or ions across a cell membrane against their concentration gradients, requiring energy.

Endocytosis

Process by which extracellular molecules and particles are taken into the cell via vesicle formation.

Exocytosis

Process by which secretory products or waste products are removed from the cell.

Cilia

Short hair-like structures that aid in locomotion or the movement of substances across the cell surface.

Flagella

Long whip-like structures that propel a cell forward; the sperm is the only human cell that moves this way.

Rough Endoplasmic Reticulum (RER)

Endoplasmic reticulum that processes and sorts proteins synthesized by ribosomes.

Smooth Endoplasmic Reticulum (SER)

Endoplasmic reticulum responsible for the synthesis of fatty acids and steroid hormones, with no attached ribosomes.

Lysosomes

Organelles containing hydrolytic enzymes that break down waste materials and cellular debris.

Mitochondria

Organelles that convert nutrients into usable energy in the form of ATP during cellular respiration.

Cell Signaling

The process through which cells communicate with one another via chemical messengers or physical contact.

Passive Transport

Movement of substances across a cell membrane without the need for energy input.

Chloroplasts

Organelles in plant cells that produce sugars through photosynthesis.

Cell Membrane

The semipermeable membrane that separates and protects the cell, composed of a phospholipid bilayer.

Cytoskeleton

Support structure within the cytosol that provides shape and structural support, composed of filamentous proteins.

Microfilaments

Part of the cytoskeleton, responsible for cellular locomotion and muscle contractions, made of actin protein.

Intermediate Filaments

Strong cables of protein providing structural integrity to cells, protecting from mechanical stress.

Microtubules

Hollow tubes made of tubulin proteins, important for chromosome movement during cell division.

Nucleus

Organelle containing a cell’s genetic library, surrounded by a double membrane called the nuclear envelope.

What characterizes the process of active transport across the cell membrane?

Active transport includes the use of ATP to move substances.

What accurately describes prokaryotic cells?

Prokaryotic cells can live in extreme environments.

What is a key concept regarding eukaryotic cells?

Eukaryotic cells evolved from prokaryotic ancestors.

How many cells are estimated to be in the human body?

The human body has billions of cells.

How do cells communicate with one another according to the notes?

cell communication occurs through direct physical contact and chemical signals.

What is true regarding cell-to-cell junctions and communication?

Cell-to-cell junctions allow for instantaneous communication.

What is the primary assertion about cells according to the notes?

Cells are the fundamental units of living organisms.

What is the role of the Golgi complex?

The Golgi apparatus processes proteins and fatty acids.

What is the role of lysosomes within a cell?

Lysosomes contain hydrolytic enzymes for digestion.

Which organelle is responsible for synthesizing proteins in the cell?

Ribosomes are responsible for protein synthesis.

What does current cell theory state regarding the origin of cells?

All cells arise from preexisting cells.

What type of signaling affects cells in the immediate vicinity?

Paracrine signaling affect neighboring cells.

What is a function of microfilaments in cellular structure?

Microfilaments are responsible for muscle contractions.

What is the primary function of microfilaments in the cytoskeleton?

Microfilaments allow for movement and shape change.

What is the primary function of mitochondria in a cell?

Mitochondria convert nutrients into ATP

During osmosis, how does water typically move across the cell membrane?

Water moves down its concentration gradient during osmosis.

What distinguishes plant cells from animal cells?

Plant cells have additional organelles compared to animal cells.

What role does the glycocalyx play on the surface of cells?

Glycoproteins help in cell recognition.

In hypertonic solutions, what condition is true regarding waters movement?

Water has a higher concentration of solutes than the cytoplasm in hypertonic environments.

What characteristic of the plasma membrane allows it to regulate the passage of substances?

Membranes allow selective permeability.

What allows plant cells to produce their own energy through photosynthesis?

Plant cells can perform photosynthesis due to chloroplasts

How do cells interact with one another in tissues?

Cells interact through junctions in tissues.

What is the primary function of cilia in human cells?

Cilia aid in the movement of mucous in the respiratory tract.

What distinguishes cellular respiration in prokaryotic and eukaryotic cells?

Eukaryotic cells perform energy production differently than prokaryotic cells.

Which statement about the cytoskeleton is true?

a) The cytoskeleton has no role in intracellular transport.

b) All protein filaments have identical roles in maintaining shape.

c) Microfilaments are responsible for transporting nutrients across cells.

d) Intermediate filaments are the strongest element of the cytoskeleton.

Intermediate filaments are the strongest element of the cytoskeleton.

Which statement best describes the process of osmosis?

a) The process of diffusion moves substances against their concentration gradient.

b) Water moves from areas of low solute concentration to high solute concentration.

c) An isotonic solution causes cells to swell.

d) Osmosis involves the movement of solutes across a membrane.

Water moves from areas of low solute concentration to high solute concentration.

According to current cell theory, what is true about cells?

Cells arise from existing cells.

What is the main function of mitochondria?

Mitochondria are responsible for cellular respiration.

What structure is found in all cells?

All cells have a plasma membrane.

What is the function of the glycocalyx?

The glycocalyx helps identify cells in organisms.

What is a key difference between cilia and flagella?

Flagella are longer than cilia and help in cell motility.

How do cells contribute to the formation of tissues?

Cells become tissues that then develop into organs.

Which of the following statements about cells is correct?

a) Only multicellular organisms have cells.

b) All cells are identical in function and structure.

c) Cells are the basic unit of life

d) Cells can spontaneously generate from non-living matter.

Cells are the basic unit of life.

What happens when a cell is placed in a hypotonic solution?

Hypotonic solutions may cause cells to burst.

What distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack membrane-bound organelles.

What role do ribosomes play in the cell?

Ribosomes synthesize proteins for other organelles.

Which statement correctly describes the plasma membrane?

a) Phospholipids form the basic structure of the plasma membrane.

b) The cell membrane is semipermeable and allows all substances to pass through freely.

c) Only eukaryotic cells possess a plasma membrane.

d) The main function of the plasma membrane is to protect the cell from viruses.

Phospholipids form the basic structure of the plasma membrane.

How do hormones function in cell communication?

Hormones can circulate throughout the body affecting distant cells.

Which statement about plant cells is correct?

a) Plant cells have chloroplasts for photosynthesis.

b) All cells contain the same organelles.

c) Bacterial cells can have multiple nuclei.

d) Eukaryotic cells do not require oxygen.

Plant cells have chloroplasts for photosynthesis.

What is true about active transport mechanisms in cells?

a) Facilitated diffusion moves substances through membrane proteins against their gradient.

b) Hypotonic solutions contain more solutes than cells.

c) Active transport processes require energy to move substances against their concentration gradient.

d) Passive transport requires ATP to operate.

Active transport processes require energy to move substances against their concentration gradient.

Which statement accurately describes cell communication?

a) Cell signaling can only occur through hormones.

b) All cell communications are instantaneous.

c) Cell-to-cell junctions exist only in plant cells.

d) Neurons release neurotransmitters for local communication.

Neurons release neurotransmitters for local communications.

What is the primary function of the Golgi complex?

The Golgi complex sorts and modifies proteins.

Which statement is true regarding cell structures?

a) Only prokaryotic cells have a cell membrane.

b) Plant and animal cells both have a plasma membrane.

c) Plant cells have a nucleus but no organelles.

d) Animal cells contain chloroplasts for photosynthesis.

Plant and animal cells both have a plasma membrane

What is the role of endocytosis in cellular function?

Endocytosis brings substances into the cell.