Biology Exam 2 Flashcards

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Questions and Answers

What are the components of a phospholipid and why are phospholipids important?

Phospholipids consist of two hydrophobic fatty acid tails and a hydrophilic head with a phosphate group. They are important as they form lipid bilayers, which are a major component of all cell membranes.

What do we mean by a 'selectively permeable membrane'?

A selectively permeable membrane restricts movement, allowing some materials to move freely while restricting others.

What are active and passive transport?

Active transport moves ions from low concentration to high concentration using metabolic energy, while passive transport moves ions from high to low concentration without using energy.

What is diffusion/osmosis?

Osmosis is the movement of water molecules from high water concentration to low water concentration through a selectively permeable membrane. Signup and view all the answers

What do the terms isotonic, hypotonic, and hypertonic mean?

Isotonic solutions have the same concentration of solutes inside and outside of the cell. Hypotonic solutions have a lower concentration of solutes outside the cell, and hypertonic solutions have a higher concentration of solutes outside the cell. Signup and view all the answers

What is the role of proteins in the cell membrane?

Proteins can function as enzymes, receptors for specific molecules, or transport materials across the membrane. Signup and view all the answers

How do cells bring materials in and out of the cell?

Cells utilize diffusion, including osmosis, to move simple molecules like water, carbon dioxide, and oxygen across the cell membrane. Signup and view all the answers

How are cells classified?

Cells are classified into two main types: prokaryotic and eukaryotic. Signup and view all the answers

What are the key differences between prokaryotic and eukaryotic cells?

Eukaryotic cells have membrane-bound organelles and a nucleus, while prokaryotic cells do not. Signup and view all the answers

Why is the size of cells constrained?

The surface area to volume ratio decreases as the cell size increases, which limits material movement across the membrane. Signup and view all the answers

What are the four things all cells have in common?

All cells have a plasma membrane, cytoplasm, ribosomes, and DNA. Signup and view all the answers

What is the function of the nucleus organelle?

The nucleus directs cell activities and contains genetic material called chromosomes made of DNA. Signup and view all the answers

What do mitochondria do?

Mitochondria make energy out of food. Signup and view all the answers

What is the role of ribosomes in cells?

Ribosomes make proteins. Signup and view all the answers

What does the Golgi apparatus do?

The Golgi apparatus makes, processes, and packages proteins. Signup and view all the answers

What is the cytoskeleton and what are its parts?

The cytoskeleton provides support in a cell and consists of a network of protein fibers. Signup and view all the answers

Study Notes

Phospholipids

Major components of all cell membranes.
Composed of two hydrophobic fatty acid tails and a hydrophilic phosphate head.
Amphiphilic nature allows them to form lipid bilayers.

Selectively Permeable Membrane

Controls the entry and exit of substances in and out of the cell.
Types of membranes: impermeable (no movement), permeable (free movement), selectively permeable (restricts certain materials).

Active and Passive Transport

Passive transport (or diffusion) moves substances from high to low concentration without energy.
Active transport moves substances from low to high concentration using ATP energy.
Both processes utilize ion channels for substance movement.

Diffusion and Osmosis

Osmosis is the diffusion of water across a selectively permeable membrane.
Water moves from areas of high water concentration to low concentration.

Tonicity: Isotonic, Hypotonic, Hypertonic

Isotonic solutions have equal solute concentrations inside and outside the cell.
Hypotonic solutions have lower solute concentrations outside the cell, potentially causing swelling.
Hypertonic solutions have higher solute concentrations outside the cell, potentially causing shrinkage.

Role of Membrane Proteins

Peripheral proteins reside on either side of the lipid bilayer.
Membrane proteins can act as enzymes, receptors, or transporters for materials.

Cellular Intake and Output

Simple molecules like water, CO2, and O2 cross the membrane via diffusion.
Diffusion facilitates movement of essential small molecules within cells.

Cell Classification

Living organisms are composed of cells, classified as prokaryotes and eukaryotes.
Prokaryotes lack a nucleus and membrane-bound organelles.

Prokaryotic vs. Eukaryotic Cells

Eukaryotic cells have membrane-bound organelles and a nucleus.
Prokaryotic cells, like bacteria, lack a nucleus and membrane-bound organelles.
Eukaryotes can be single-celled (e.g., yeast) or multicellular (e.g., plants, animals).

Constraints on Cell Size

As cells grow, their surface area-to-volume ratio decreases.
Larger cells may struggle to cross sufficient materials through the membrane to meet metabolic demands.

Common Features of All Cells

All cells possess a plasma membrane, cytoplasm, ribosomes, and DNA.
Plasma membrane encases the cell, controlling the internal environment.

Nucleus

Known as the "brain" of the cell, directing cellular activities.
Houses genetic material in the form of chromosomes made of DNA.

Mitochondria

Organelles responsible for converting food into energy.

Ribosomes

Sites for protein synthesis within the cell.

Golgi Apparatus

Functions in the processing, packaging, and distribution of proteins.

Cytoskeleton

Provides structural support within the cell.
Composed of a network of protein fibers that determine cell shape and organization.

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Description

Prepare for your Biology Exam 2 with these flashcards focusing on phospholipids and their significance in cell membranes. Understand the structure and functions of phospholipids, an essential topic in cell biology. Test your knowledge and ensure you're ready for exam day!