AP Bio - Ch. 7 - Cell - Cell structure a Tour of the Cell

What is the cell theory?

1. All organisms are made of cells. 2. The cell is the simplest collection of matter that can be alive. 3. All cells come from pre-existing cells.

What are the two main types of cells?

Prokaryotic and Eukaryotic cells.

What features are common to all cells?

Plasma membrane, semifluid cytosol, chromosomes (carry genes), and ribosomes (make proteins).

Which domains consist of prokaryotic cells?

Bacteria and Archaea.

What are the characteristics of prokaryotic cells?

No nucleus; DNA is unbound in cytosol; no membrane-bound organelles.

What are the characteristics of eukaryotic cells?

DNA in a nucleus bounded by a membranous nuclear envelope; many membrane-bound organelles; generally larger than prokaryotic cells.

What is the function of the plasma membrane?

It is a selective barrier that allows passage of oxygen, nutrients, and waste.

What is the general structure of a biological membrane?

A double layer of phospholipids.

Why is the surface area to volume ratio important for cells?

It is critical for obtaining nutrients, eliminating waste, and exchanging chemicals and energy with the environment.

How does cell size affect metabolic efficiency?

Smaller cells have a greater surface area relative to volume, enhancing efficiency in nutrient absorption and waste elimination.

What adaptations do desert animals like jack rabbits have for thermoregulation?

Large ears that increase surface area for heat dissipation.

How do root hairs increase absorption efficiency?

They provide a large surface area to volume ratio for better absorption of minerals and water.

What role do alveoli play in gas exchange?

They increase surface area for rapid oxygen diffusion into capillaries.

What is the function of villi in the small intestine?

They increase surface area to enhance nutrient absorption.

What is the formula for calculating surface area (SA) of a sphere?

SA = 4πr².

What is the formula for calculating volume (V) of a sphere?

V = (4/3)πr³.

What is the significance of the surface area to volume ratio (SA:V)?

A higher SA:V ratio allows for more efficient transport of materials in and out of the cell.

How does the shape of a cell affect its efficiency?

Different shapes can optimize surface area to volume ratios, affecting metabolic efficiency.

What happens to the surface area as cell size increases?

Surface area increases by a factor of n², while volume increases by a factor of n³.

What is the SA:V ratio for a eukaryotic cell with a surface area of 130 um² and a volume of 50 um³?

SA:V = 130:50, which reduces to 2.6:1.

What is the SA:V ratio for a prokaryotic cell with a surface area of 20,096 um² and a volume of 267,947 um³?

SA:V = 20,096:267,947, which reduces to approximately 0.07499991:1.

What is the importance of compartmentalization in eukaryotic cells?

It minimizes competing interactions and increases the surface area for reactions.

How do internal membranes enhance cellular processes?

They compartmentalize functions, increasing efficiency and reaction surfaces.

What is the relationship between cell size and diffusion?

Larger cells experience slower diffusion rates, which can lead to inefficiency and potential cell death.

What is the role of ribosomes in cells?

Ribosomes are responsible for protein synthesis.

What is cytosol?

A semifluid substance within the cell where organelles are suspended.

What are the main differences between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.

What is the formula for the volume of a cylinder?

V = (π)(radius²)(height)

What is the volume of a cylinder with a radius of 2 um and height of 8 um?

V = 100 um³

What is the surface area to volume ratio (SA:V) for a cylinder with SA = 125 um² and V = 100 um³?

SA:V = 1.25:1

How can SA:V ratios be simplified?

By dividing both SA and V by V, reducing the ratio to its simplest form.

What is the surface area of a cylinder with a radius of 10 um and height of 80 um?

SA = 5,652 um²

Why is a smaller prokaryotic cell more efficient at transporting materials?

Because it has a higher SA:V ratio.

What is the SA:V ratio for a prokaryotic cell with SA = 5,652 um² and V = 25,120 um³?

SA:V = 0.225:1

What is the SA:V ratio for a eukaryotic cell with SA = 54 um² and V = 27 um³?

SA:V = 2:1

What is the primary function of ribosomes in a cell?

To carry out protein synthesis.

What are the two locations where ribosomes can be found?

Free ribosomes in the cytosol and bound ribosomes on the rough endoplasmic reticulum.

What is the role of the nucleolus?

It is the site of ribosomal RNA (rRNA) synthesis.

What does the endomembrane system consist of?

Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and plasma membrane.

What are the two distinct regions of the endoplasmic reticulum?

Smooth ER (lacks ribosomes) and Rough ER (studded with ribosomes).

What are the main functions of the smooth endoplasmic reticulum?

Synthesizes lipids and detoxifies drugs, alcohol, and poisons.

What is the nuclear envelope?

A double membrane that encloses the nucleus and separates it from the cytoplasm.

What is chromatin?

DNA organized with proteins, which condenses to form chromosomes during cell division.

What is the function of nuclear pores?

To regulate the entry and exit of molecules from the nucleus.

What is the significance of a higher surface area to volume ratio?

It allows for more efficient transport of materials in and out of the cell.

What is the surface area of a cylinder with a radius of 3 um?

SA = 54 um²

What is the volume of a cube with a side length of 3 um?

V = 27 um³

What is the SA:V ratio for a eukaryotic cell with SA = 38,400 um² and V = 512,000 um³?

SA:V = 0.000075:1

What do ribosomes produce when bound to the rough ER?

Proteins for outside the cell or for the cell membrane.

What is the main role of the Golgi apparatus?

To modify, sort, and package proteins for secretion or delivery to other organelles.

What is the function of lysosomes?

To digest macromolecules and recycle cellular components.

What is the function of vacuoles in plant cells?

To store nutrients, waste products, and help maintain turgor pressure.

What is the significance of the plasma membrane?

It regulates the movement of substances in and out of the cell.

What is the primary function of the rough endoplasmic reticulum (Rough ER)?

The Rough ER is a site for protein synthesis and compartmentalizes the cell.

What are glycoproteins?

Proteins that have carbohydrates covalently attached, formed in the Rough ER.

What is the role of the Golgi apparatus?

The Golgi apparatus sorts, modifies, and ships products of the Rough ER.

What is the structure of the Golgi apparatus?

It consists of flattened membranous sacs.

What is the cis face of the Golgi apparatus?

The receiving side of the Golgi apparatus.

What is the trans face of the Golgi apparatus?

The shipping side of the Golgi apparatus.

What is a lysosome?

A membranous sac of hydrolytic enzymes that digests macromolecules.

What pH do lysosomal enzymes work best in?

An acidic environment.

What is autophagy?

The process by which lysosomes recycle the cell's own organelles and macromolecules.

What is the function of lysosomes in digestion?

Lysosomes fuse with food vacuoles to digest molecules.

What is the primary function of vacuoles?

Vacuoles serve various functions, including storage and maintaining ion concentration.

What is the function of contractile vacuoles?

They pump excess water out of cells to maintain suitable ion concentrations.

What is the central vacuole's role in plant cells?

It stores ions and water, enabling the cell to become larger.

What is the endosymbiont theory?

It proposes that mitochondria and chloroplasts originated from engulfed prokaryotic cells.

What are two similarities between mitochondria, chloroplasts, and bacteria?

They are enveloped by a double membrane and contain circular DNA.

What is the main function of mitochondria?

They are the sites of cellular respiration, generating ATP using oxygen.

What are the two compartments created by the inner membrane of mitochondria?

The intermembrane space and the mitochondrial matrix.

What is the role of chloroplasts?

Chloroplasts are the sites of photosynthesis, capturing light energy.

What are thylakoids?

Membranous sacs in chloroplasts that contain chlorophyll and are the site of the light-dependent reactions.

What is the stroma in chloroplasts?

The internal fluid where the light-independent reactions, or Calvin cycle, occur.

What is the role of ribosomes on the Rough ER?

They synthesize proteins that are secreted or used in the cell membrane.

What type of proteins do free ribosomes produce?

Proteins that function within the cytosol.

What is the function of lysosomes in white blood cells?

They digest bacteria.

What is the significance of the cristae in mitochondria?

They increase the surface area for ATP synthesis.

What is the main difference between bound and free ribosomes?

Bound ribosomes synthesize proteins for secretion or membrane use, while free ribosomes synthesize proteins for use within the cell.

What is the function of the smooth endoplasmic reticulum (Smooth ER)?

It is involved in lipid synthesis and detoxification processes.

What is the role of the cytoskeleton in cells?

It provides structural support and facilitates cell movement and transport within the cell.

What pigment do chloroplasts contain that captures light energy?

Chlorophyll

Where are chloroplasts primarily found?

In leaves and other green organs of plants and in algae.

What is the function of the outer and inner membranes of chloroplasts?

They are not involved in photosynthesis.

What is the Endosymbiotic Theory?

The theory that mitochondria and chloroplasts are descendants of ancient free-living bacteria that were engulfed by ancestral eukaryotic cells.

What are the three types of fibers that make up the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments.

What is the primary role of the cytoskeleton?

To organize the cell's structures and activities, anchoring many organelles.

How do microtubules contribute to cell motility?

They create 'monorails' on which vesicles and organelles can move, aided by motor proteins.

What are cilia and flagella?

Locomotor appendages of some cells controlled by microtubules.

What is the function of the cell wall in plants?

To protect the plant cell, maintain its shape, and prevent excessive uptake of water.

What are the main components of plant cell walls?

Cellulose fibers embedded in other polysaccharides and proteins.

What is the extracellular matrix (ECM) in animal cells?

An elaborate structure that provides support, adhesion, movement, and regulation.

What are plasmodesmata?

Channels that perforate plant cell walls, allowing water and small solutes to pass from cell to cell.

What are tight junctions?

Intercellular junctions that prevent fluid from moving across a layer of cells.

What are desmosomes?

Intercellular junctions that provide mechanical stability by anchoring cells together.

What are gap junctions?

Communicating junctions that provide cytoplasmic channels between adjacent cells.

What is the role of motor proteins in the cytoskeleton?

They aid in the movement of vesicles and organelles along microtubules.

What is the primary function of chloroplasts?

To perform photosynthesis, converting inorganic molecules into organic compounds.

What is the significance of the circular DNA found in chloroplasts and mitochondria?

It indicates their evolutionary origin from free-living prokaryotes.

What is the role of the cytoskeleton in maintaining cell shape?

It provides structural support and helps maintain the cell's shape.

What are microfilaments also known as?

Actin filaments.