Unit 2: Cells and Cell Transport

What is the number one tool in cell biology?

Microscopes

What did microscopes help in the development of?

The cell theory

What are the two different types of microscopes?

Electron and light microscopes

What are the characteristics of an electron microscope?

They use beams of electrons and magnets, can magnify up to 10 million times, are used for viewing dead cells, and do not show color.

What are the characteristics of a light microscope?

Uses light and lenses, magnifies up to 1500 times, is used for viewing living cells, and requires stains to see color.

How do light microscopes work?

They shine light from a source, have a specimen mounted on a slide placed on the stage, use an objective lens near the stage to magnify the specimen, utilize adjustment knobs for focus, and have an ocular eyepiece lens for further magnification.

How do electron microscopes work?

They use electron beams to produce images with higher magnification and resolution than a light microscope.

What are the three laws of cell theory?

All organisms are made of one or more cells, the cell is the basic unit of life, and cells come from pre-existing cells.

Who contributed to the invention of the microscope?

Robert Hooke and Antoine van Leeuwenhoek.

What did Robert Hooke do?

Looked at cork and called the little spaces he found 'cells'.

What did Antoine van Leeuwenhoek do?

Looked at pond water and identified cells.

What limits cell size and shape?

Surface area to volume ratio.

How do cells absorb nutrients?

Through their membranes.

What happens to the surface area of a cell as it gets bigger?

The surface area gets smaller relative to volume.

What does a cell’s membrane represent?

The cell surface area (SA).

What within the cell represents the cell's volume?

The cytoplasm and all the organelles.

How do you calculate the surface area for a cell using representative cubes?

SA = length times width times number of sides.

How do you calculate the volume for a cell using representative cubes?

V = length times width times height.

What do cells require to absorb enough nutrients to stay alive?

A high ratio of surface area to volume.

What are the two types of cells?

Prokaryotic and eukaryotic cells.

What are the characteristics of prokaryotic cells?

They are bacteria, unicellular, have no membrane-bound organelles or nucleus, have circular DNA, and may have flagella, pili, and a capsule.

What are the characteristics of eukaryotic cells?

They include plant, animal, protist, and fungal cells, may be unicellular or multicellular, have membrane-bound organelles, and contain linear DNA.

What is endosymbiosis?

A theory used to explain how eukaryotic cells could have evolved from prokaryotic cells.

What do 'endo', 'sym', and 'bio' mean?

Inside, together, life.

What does the endosymbiotic theory use as evidence?

Mitochondria and chloroplasts were originally free-living bacteria.

Why is it hypothesized that mitochondria and chloroplasts were once free-living bacteria?

Because they have circular DNA, reproduce like bacteria, and have similar ribosomes and size.

What are the characteristics of plant cells?

They have a cell wall, chloroplasts, and a large central vacuole.

What are the characteristics of animal cells?

They lack a cell wall and chloroplasts, and have small vacuoles that may have cilia/flagella.

What is a nucleus and what does it contain?

It contains DNA with instructions for making proteins, a nuclear membrane, and a nucleolus that makes ribosomes.

What are ribosomes?

Structures that turn amino acids into proteins.

What are characteristics of ribosomes?

They look like small dots, can float in the cytoplasm or attach to the endoplasmic reticulum, and their number can vary with the protein needs of the cell.

What is the Endomembrane system?

A system of folded membranes inside eukaryotic cells that divide the cell into compartments.

In which type of cells is the Endomembrane system found and why?

In eukaryotic cells, because prokaryotic cells lack organelles.

What is the endoplasmic reticulum?

A membrane that twists and folds to create compartments for chemical reactions.

What are the two types of ER?

Smooth ER and rough ER.

What are the characteristics of smooth ER?

It does not have ribosomes, makes lipids, and detoxifies drugs and poisons.

What are the characteristics of rough ER?

It has ribosomes attached, which synthesize proteins that then enter the rough ER for folding and packaging.

What does the Golgi apparatus do?

Packages and sends proteins to different parts of the body.

What are transport vesicles?

Membrane-bound spheres that move unfinished products from the ER to the Golgi.

What do lysosomes do?

Digest old or broken cell organelles and pathogens.

What are vacuoles?

Phospholipid membranes that serve as temporary storage in cells for food, water, and toxins.

What do chloroplasts do?

Convert energy through photosynthesis using pigments.

What does a cytoskeleton do?

Maintains cell shape, holds and moves organelles, and enables some cells to move.

What are cilia?

Short, hair-like microtubules that move fluids and particles.

What are flagella?

Long, whip-like structures used for cell movement.

What do most animal and plant cells have in common?

Most do not move; animal cells may move, but plant cells do not.

Where are cell walls found and what do they provide?

Found in plants and fungi, they provide protection, shape, and strength.

Which type of organism is the only one without a cell wall?

Animals.

What are the different components of plant, fungal, and bacterial cell walls?

Cellulose (plants), chitin (fungi), and peptidoglycan (bacteria).

What does a cell membrane serve as?

A protective barrier that regulates what enters and exits the cell.

What is the cell membrane made of?

Phospholipids.

What are the different types of membrane proteins?

Transport proteins (move substances), recognition proteins (identify cells), and receptor proteins (involved in communication).

What does cholesterol do in the membrane?

Helps maintain fluidity and flexibility of the membrane.

What is passive transport?

Movement of molecules from high to low concentration without using energy.

What is diffusion?

The movement of uncharged molecules from high to low concentration.

What is osmosis?

The diffusion of water.

What is facilitated diffusion?

The movement of molecules with the help of proteins, but no energy required.

Does passive transport require ATP?

No.

What is active transport?

The movement of molecules from low to high concentration using energy.

What is an example of active transport in the nervous system?

Na+/K- pump.

What is exocytosis?

The removal of large molecules from the cell.

What is endocytosis?

The process of large molecules moving into a cell.

Does active transport require ATP?

Yes.

What is a solute?

The substance being dissolved.

What is a solvent?

The substance doing the dissolving.

What is water known as?

The universal solvent.

What are the different types of solutions?

Hypertonic (high solute), hypotonic (low solute), isotonic (equal solute).