Cell Structure and Function

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotes have no nucleus or membrane-bound organelles eukaryotes have a nucleus and membrane-bound organelles

How do cell structures provide evidence that all life shares a common ancestor?

Similar structures, such as ribosomes, DNA, and cell membranes, suggest that organisms evolved from a common ancestor

Ribosomes

Make proteins

Rough ER

Makes and transports proteins

Smooth ER

Makes lipids and helps detoxify substances

Golgi

Modifies, sorts, and packages proteins and lipids

Mitochondria

Produce ATP through cellular respiration

Lysosomes

Break down waste and worn out cell parts

Vacuoles

Store water, food, and other materials

Vesicles

Transport materials around the cell

Chloroplasts

Carry out photosynthesis

What is the endomembrane system

A group of membranes and organelles that make, modify, transport, and process proteins and lipids.

What materials does a cell exchange with its enviroment?

Nutrients, water, oxygen, carbon dioxide, ions, and waste

How does the cell size affect surface area to volume ratio?

As a cell gets larger, its volume increases faster than its surface area, so the ratio decreases

Why is a large surface area to volume ratio important?

It allows materials to enter and leave the cell more effciently

How do you calculate surface area to volume ratio?

Calculate surface area and volume, then divide surface by volume

Why do some cells have specialized structures for exchanging materials?

To increase surface area and make the exchange of nutrients and wastes more easier

What are examples of specialized exchange surfaces?

Root hairs absorb water/minerals, intestinal villi absorb nutrients, and alveoli exchange gases

What is the relationship between body size and metabolism?

Larger organisms generally have a lower metabolic rate per unit of body mass because they gave a smaller surface area to volume ratio

Why is plama membrane important?

It seperates the cell from its enviroment and controls what enters and leaves

What is a phospholipid made of?

A hydrophilic phosphate head and hydrophobic fatty acid tails

How do phospholipids form a bilayer?

They arrange with hydrophillic heads facing water and hydrophobic tails facing inward

What is the fluid mosaic model?

The membrane is a flexible phospholipid bilayer with proteins and other molecules embedded in it

What are the functions of proteins, cholesterol, and carbohydrates in membranes?

Proteins transport and communicate, chloesterol helps maintain fluidity, and carbohydrates help with cell recognition

What is the difference between peripheral and integral proteins

Peripheral proteins are attached to the membrane surface, integral proteins are embedded in the membrane with transmembrane proteins crossimg

What does selectively permeable mean?

The membrane allows some substances to pass while preventing others from passing

What types of molecules can pass directly through the phospholipid bilayer?

Small, nonpolar molecules such as oxygen and carbon dioxide

How can molecules that cannot cross the bilayer directly enter or leave cells?

They can move through membrane proteins by facilitated diffusion or active transport.

How does a cell wall function as a structural boundary?

It provides support, protection, and helps maintain cell shape

What are plasmodesmata?

Channels through plant cell walls that allow materials and signals to move between cells

What are cell walls made of, and which organisms have them?

Plants have cellulose, fungi have chitin, and bacteria have peptidoglycan

What is a concentration gradient?

A difference in the concentration of a substance between two areas

What does it mean to move with or against a concentration gradient?

With: high concentration → low concentration. Against: low concentration → high concentration

What is passive transport?

Movement across a membrane without using cellular energy. Facilitated diffusion uses protein channels or carriers

What is active transport?

Movement against a concentration gradient that requires energy, usually ATP

What are exocytosis and endocytosis?

Exocytosis: vesicles release materials outside the cell. Endocytosis: the cell takes materials in using vesicles

How is cotransport a type of active transport?

One substance moving down its gradient provides energy to move another substance against its gradient

What does it mean when a membrane is polarized?

There is an unequal distribution of electrical charge across the membrane

How does the sodium-potassium pump maintain membrane potential?

It uses ATP to pump 3 Na⁺ out and 2 K⁺ in, creating an electrical gradient

What is osmosis?

The diffusion of water across a selectively permeable membrane

What are osmolarity and solute?

concentration of dissolved particles in a solution. Solute: a substance dissolved in a solvent

What do hypotonic, hypertonic, and isotonic mean?

• Hypotonic: Lower solute concentration

• Hypertonic: Higher solute concentration

• Isotonic: Equal solute concentration

How can you predict which way water will move?

Water moves toward the side with the higher solute concentration

What is osmoregulation?

The control of water and solute balance in an organism

Why do animal and plant cells prefer different osmotic environments?

Plant cells have cell walls and benefit from water entering, while animal cells can burst if too much water enters

How do you calculate solute potential and water potential?

Use the equations on the equation sheet to calculate solute potential and then combine it with pressure potential to find total water potential

How does water move between solutions with different water potentials?

Water moves from higher water potential to lower water potential

Which organisms have membrane-bound organelles?

Eukaryotes, including plants, animals, fungi, and protists

What are the benefits of cell compartmentalization?

It separates different processes, increases efficiency, and allows specialized conditions for different reactions

How did the nucleus and other internal membranes most likely evolve?

The plasma membrane likely folded inward, eventually forming internal membranes and the nucleus

What is the theory of endosymbiosis, and which organelles came from it?

It states that mitochondria and chloroplasts were once free-living prokaryotes that were engulfed by another cell and formed a symbiotic relationship

What evidence supports the theory of endosymbiosis?

Mitochondria and chloroplasts have their own DNA, ribosomes, double membranes, and reproduce similarly to bacteria