3 Cell Structure and Function Free Online FlashCards

What are the three principles of cell theory?

All living organisms consist of one or more cells; the cell is the basic unit of structure and function; and new cells arise from pre-existing cells.

Which four features are shared by all cells?

All cells have a plasma membrane, cytoplasm, DNA, and ribosomes.

Where is DNA concentrated in a prokaryotic cell?

Prokaryotic cells lack a membrane-bound nucleus; their DNA is concentrated in a region called the nucleoid.

What distinguishes the internal organization of eukaryotic cells?

Eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles that specialize in particular tasks.

Are cell walls found only in prokaryotes?

No. Plants and fungi also have cell walls, so a cell wall is not unique to prokaryotes; its composition differs among these groups.

What is a key role of the rough endoplasmic reticulum?

The rough endoplasmic reticulum makes and begins processing many proteins destined for membranes or export.

What does the Golgi apparatus do to proteins and lipids?

The Golgi apparatus modifies, sorts, and packages proteins and lipids for delivery.

What is a major function of mitochondria?

Mitochondria carry out much of cellular respiration and produce much of the cell’s ATP.

How are phospholipids oriented in a cell membrane?

A phospholipid bilayer has water-attracting heads facing the watery environments inside and outside the cell, and water-repelling tails pointing inward.

How does membrane permeability differ for oxygen and charged ions?

Small nonpolar molecules such as oxygen can diffuse through the lipid bilayer, while charged ions and many large or polar molecules generally need membrane proteins.

How do passive and active transport differ?

Passive transport moves substances down their concentration gradient without the cell directly using energy for that movement. Active transport moves substances against a concentration or electrochemical gradient and requires energy.

How does facilitated diffusion move glucose into cells?

Facilitated diffusion uses a channel or carrier protein to move a substance down its concentration gradient without direct energy use; glucose can enter cells this way.