7.2 – Cell Structure Plant Cell Animal Cell

Cell Membranes All cells contain a cell membrane that controls what enters and leaves the cell.

Cell Walls Plants (and prokaryotic cells) have cell walls. The main function of the cell wall is to provide support and protection for the cell. Cell walls lie outside the cell membrane and are porous enough to allow certain substances to pass through easily.

Cell Organization The eukaryotic cell can be divided into two major parts: the nucleus and the cytoplasm. The cytoplasm is the fluid portion of the cell outside the nucleus that the organelles “float” around in (think jello…).

Many cellular structures act as if they are specialized organs Many cellular structures act as if they are specialized organs. These structures are known as organelles, meaning “little organs.”

The Cytoskeleton The cytoskeleton gives cells their shape and helps with movement. Is a network of microfibers and microtubules made of protein

The Nucleus In the same way that the main office controls a large factory, the nucleus is the control center of the cell. The nucleus houses and protects the cell’s DNA – all the instructions for the cell to function correctly. Where’s the nucleus?

The nuclear envelope (nuclear membrane) surrounds the nucleus and is dotted with thousands of nuclear pores.

The nuclear pores in the nuclear envelope (nuclear membrane) allow material to move into and out of the nucleus.

The nucleus also contains a small, dense region called the nucleolus. The nucleolus is where ribosomes are made.

Vacuoles Many cells contain large, saclike structures called vacuoles that store materials such as water, salts, proteins, and carbohydrates. Plants have a very large central vacuole that stores water and helps to keep plants rigid.

Lysosomes Lysosomes are small organelles filled with enzymes that function as the cell’s cleanup crew. Lysosomes perform the vital function of removing “junk” that might otherwise accumulate and clutter up the cell.

Ribosomes Ribosomes are small particles of RNA and protein found throughout the cytoplasm in all cells. Ribosomes make proteins by following coded instructions that come from DNA.

Endoplasmic Reticulum Eukaryotic cells contain an internal membrane system known as the endoplasmic reticulum, or ER. The ER is the transport system of the cell, moving materials along for later packaging.

Rough ER The part of the ER attached to the nucleus that’s involved in making proteins is called the rough ER. It’s looks rough because of the ribosomes found on the surface.

Smooth ER The other part of the ER is known as the smooth ER because ribosomes are not found on its surface & contains mostly enzymes.

Golgi Apparatus Proteins made in the rough ER move next into the Golgi apparatus (Golgi), which looks like a stack of flattened pancakes.

The Golgi is the delivery service of the cell. It modifies, sorts, and packages proteins or other materials from the ER for use inside or outside of the cell.

Mitochondria Mitochondria are the power plants of the cell. They change the energy stored in food into the only form of energy a cell can use – ATP!

You get your mitochondria from Mom! One of the most interesting aspects of mitochondria is the way in which they are inherited. In humans, all of our mitochondria come from the cytoplasm of the egg cell. You get your mitochondria from Mom! Looks like a kidney bean with a folded inside.

Chloroplasts Plants contain chloroplasts. Chloroplasts are like solar power plants. They capture the sun’s energy and change it into food (glucose!) through photosynthesis.

Mitochondria & Chloroplasts Chloroplasts and mitochondria contain their own DNA that is different from the rest of the cell. Scientists believe that chloroplasts and mitochondria may have come from independent microorganisms.