cytology

What are the 3 parts of a cell?

• Cell membrane

• Cytoplasm

• Nucleus

What are the functions of the cell membrane?

• Physical barrier

• Protection

• Communication

• Transport of substances

What is the structure of the cell membrane?

Phospholipid bilayer with proteins scattered throughout

What is the main lipid in the cell membrane?

Phospholipid

What is the main function of membrane proteins?

• Transport and communication

Which molecules can freely pass through the membrane?

• Small nonpolar/lipid-soluble molecules

What does selectively permeable mean?

Allows some substances to pass while blocking others

What is passive transport?

• Transport that does NOT require ATP

What is diffusion?

Movement from high concentration to low concentration

What is another name for diffusion?

• Movement down the concentration gradient

What drives diffusion?

Concentration gradient

Molecules move until they reach what?

Equilibrium

What is facilitated diffusion?

Diffusion that requires transport proteins

What two proteins help in facilitated diffusion?

• Protein channels

• Protein carriers

What is osmosis?

• Movement of water across a selectively permeable membrane

In osmosis, water moves from ______ to ______.

• Low solute concentration → High solute concentration

What is a solute?

A dissolved substance

What drives osmosis?

• Solute concentration

What is active transport?

Transport that requires ATP

Why is ATP needed for active transport?

• Substances move against their concentration gradient

Active transport moves substances from ______ to ______.

Low concentration → High concentration

What are the two types of active transport?

• Pumps

• Vesicular transport

What do pumps do?

• Use transport proteins to move substances across the membrane

What is endocytosis?

What is exocytosis?

Releasing material from the cell

What are organelles?

Structures within a cell that perform specific functions

Function of the nucleus?

Control center; contains DNA

Function of ribosomes?

Protein synthesis

Function of rough ER?

Modifies and transports proteins

Function of smooth ER?

Lipid synthesis and detoxification

Function of Golgi apparatus?

• Modifies, packages, and ships proteins

Function of lysosomes?

Digestion and recycling of waste

Function of cytoskeleton?

• Cell support and shape

Function of centrioles?

Help organize cell division

Function of cilia?

Move substances across the cell surface

Function of flagella?

Cell movement

What does hydrophilic mean?

Water-loving; attracted to water

What does hydrophobic mean?

Water-fearing; repels water

Which part of a phospholipid is hydrophilic?

Phosphate head

Which part of a phospholipid is hydrophobic?

Fatty acid tails

In the cell membrane, where are the hydrophilic heads located?

Facing the water inside and outside the cell

In the cell membrane, where are the hydrophobic tails located?

Facing inward toward each other

Why does the phospholipid bilayer form?

Hydrophilic heads face water; hydrophobic tails avoid water

Does facilitated diffusion require ATP?

No

What is a channel protein?

A protein that forms a tunnel/pore through the membrane. 🚪 Channel = doorway

What is a carrier protein?

A protein that binds a molecule and changes shape to move it across the membrane. 🚕 Carrier = taxi service

Difference between channel and carrier proteins?

• Channel = tunnel

• Carrier = grabs molecule and changes shape

Isotonic solution

• Equal solute concentration inside and outside the cell

• No net water movement

• Cell stays the same size

Hypotonic solution

• lower solute concentration outside the cell

• Water moves INTO the cell

• Cell swells

hypo = hippo = gets bigger

Hypertonic solution

higher solute concentration outside the cell

• Water moves OUT of the cell

• Cell shrinks

Hyper = hyperactive = running away with the water

Function of Smooth ER

• Lipid (fat) synthesis

• Detoxification of drugs/toxins

Function of Lysosome

• Digests and recycles waste, old organelles, and foreign material