Chapter 3- Cell Structure

Outline & Notes

Section 2: Cell Features (pg. 55)

The Cell Theory *18

The observations of Schleiden, Shwann, and Virchow form the cell theory.

The Cell Theory has three parts:

All living things are made of one or more cells.

Cells are the basic units of structure and function in organisms.

All cells arise from existing cells.

Cell Size

Small cells function more efficiently than large cells.

If a cell’s surface area–to-volume ratio is too low, substances cannot enter and leave the cell well enough to meet the cell’s needs.

Summary

Ch. 3 Section 2: Cell Features (pg. 56-57)

Common Cell Features

Cells share common structural features, including:

an outer boundary called the cell membrane,

cell interior substance called cytoplasm,

structural support suspended in a system of microscopic fibers called the cytoskeleton,

Ribosomes are the cellular structures that make proteins,

All cells also have DNA, which provides instructions for making proteins, regulates cellular activities, and enables cells to reproduce.

Prokaryotes

Prokaryotes are single-celled organisms that lack a nucleus and other internal compartments.

The familiar prokaryotes that cause infection and cause food to spoil belong to the subset of all prokaryotes that is commonly called bacteria.

Characteristics of Prokaryotes

Prokaryotes can exist in a broad range

of environmental conditions.

In prokaryotes, the genetic material is a

Single, circular molecule of DNA.

Prokaryotic cells have a cell wall surrounding the cell membrane that provides structure and support.

Many prokaryotes have cilia or flagella, which are long, threadlike structures that protrude from the cell’s surface and enable movement.

Summary

Ch. 3 Section 2: Cell Features (pg. 58)

Eukaryotic Cells

A eukaryote is an organism whose cells have a nucleus.

A nucleus is an internal compartment that houses the cell’s DNA

Other internal compartments, or organelles, enable eukaryotic cells to function in ways different from prokaryotes.

An organelle is a structure that carries out specific activities in the cell.

LABEL the major organelles in an animal cell shown in Figure 7.

Summary

Ch. 3 Section 2: Cell Structure (pg.59)

The Cytoskeleton

The cytoskeleton provides the interior framework of an animal cell.

The cytoskeleton is composed of an intricate network of proteins anchored to the inside of the plasma membrane.

By linking one region to another, they support the shape of the cell, much as steel beams anchor the sides of a building to one another.

There are three different kinds of cytoskeletal fibers.

Microfilaments: long slender microfilaments made of the protein actin.

Microtubules: hollow tubes made of the protein tubulin.

Intermediate fibers: thick ropes made of protein.

LABEL the major parts of the cytoskeleton shown in Figure 9.

Summary

Ch. 3 Section 3: Cell Structure (pg. 62-63)

The Nucleus

Most functions of a eukaryotic cell are controlled by the cell’s nucleus.

The nucleus is surrounded by a double membrane called the nuclear envelope.

Scattered over the surface of the nuclear envelope are many small channels called nuclear pores.

Ribosomes and the ER

Cells make proteins on ribosomes.

The Endoplasmic Reticulum or ER is an extensive system of internal membranes that move proteins and other substances through the cell.

The part of the ER with attached ribosomes is called the rough ER.

The rough ER helps transport proteins that are made by the attached ribosomes.

The portion of the ER that contains the completed protein pinches off to form a vessicle.

A vesicle is a small, membrane-bound sac that transports substances in cells.

The smooth ER is called smooth because it lacks ribosomes and thus appears smooth when viewed.

Summary

Ch. 3 Section 3: Cell Structure (pg. 64-65)

Packaging and Distribution of Proteins

Vesicles that contain newly made proteins move through the cytoplasm from the ER to an organelle called the golgi apparatus.

The Golgi apparatus is a set of flattened, membrane-bound sacs that serve as the packaging and distribution center of the cell.

Below is the order in which proteins are processed:

Mitochondria

Mitochondria are organelles that harvest energy from organic compounds to make ATP.

ATP is the main energy currency of cells. Most ATP is made inside the mitochondria.

Summary

Ch. 3 Section 3: Cell Structure (pg. 65-66)

Mitochondria

Mitochondria have two membranes. The outer membrane is smooth. The inner membrane is greatly folded, and has a large surface area.

Mitochondrial DNA

Mitochondria have their own DNA.

Mitochondrial DNA is passed on directly by your mother. This means your mitochondrial DNA is identical to your mothers.

Structures of Plant Cells

Plants have three additional structures that are not found in animal cells: cell wall, the chloroplasts and the central vacuole.

Cell wall helps support and maintain the shape of a cell, protects the cell from damage, and connects it with adjacent cells.

Chloroplasts are organelles that use light energy to make carbohydrates from carbon dioxide and water.

Central Vacuole is a large membrane-bound space that stores water, nutrients, and wastes.

Summary

Ch. 3 Section 3: Cell Structure (pg. 61)

The Cell Membrane

The fluidity of cell membranes is caused by lipids, which form the foundation of membranes.

The lipids form a barrier that separates the inside of the cell from the outside of the cell.

This selective permeability of the cell membrane determines which substances enter and leave the cell.

The Cell Membrane as a Barrier

The selective permeability of the cell is mainly caused by the way phospholipids interact with water.

A phospholipid is a lipid made of a phosphate group and two fatty acids.

In a cell membrane, the phospholipids are arranged in a double layer called a lipid bilayer.

A phospholipid’s “head” is polar (Loves Water)

A phospholipid’s “tails” are non-polar (Hate Water)

Summary

Ch. 3 Section 2: Cell Structure (pg. 61)

Membrane Proteins

As shown in Figure 12, cell membranes contain different types of proteins.

Marker protein attaches to a carbohydrate on the cell’s surface advertise cell type-such as a liver cell or a heart cell.

Receptor proteins bind specific substances, such as signal molecules, outside the cell.

Enzymes embedded in the cell membrane are involved in important biochemical reactions in the cell.

Transport proteins aid the movement of substance into and out of the cell.

Summary

Cell Organelles and Functions

(Please check mark which type of cell has each structure)

Structure	Prokaryotes

(bacteria)	Eukaryotes	Function	Real-life Example
Animal	Plant
Cell membrane

√	√	√	Barrier; lets certain things in and out.	*US Border*
Cytoplasm

√	√	Filling of the cell.	* People in a town*
Cytoskeleton

√	√	Support	*Scaffolding*

Bricks and Lumber
Ribosomes

√	√	√	Where proteins are made	*Factory*
Nucleus

42
√	√	Holds DNA (info)	*Library*
Endoplasmic

Reticulum
√	√	Transports materials throughout the cell	*Subway System*

Vesicle

√	√	This sac transports things in/out to organelles. (Think of organelles like stores.)

*Airplane*

Can take packages outside of the cell.
Golgi Apparatus (body)

49
√	√	Packages and distributes proteins from inside and outside the cell

*UPS*

Post office
Lysosome

51
√	√	Contains digestive enzymes which get rid of waste & foreign bodies.

*Garbage Truck*
Mitochondria

55
√	√	Supplies power to the cell. This “power house” of the cell contains its own DNA.	*Power Plant*
Cillia

√	√	√	Feel & Sense things.

Moves substances across the cells surface. (reproduction).	*Radar*

Senses things
Flagella

√	√
Propels the cell.	*Propeller*

Cell wall

√
√	Made of cellulose. Gives the cell structure and support.	*Brick Wall*
Chloroplast

61

√	Contains pigment that helps convert light energy to glucose.

Site of photosynthesis	* Solar Panels*
Central Vacuole

63
√	Contains water, gives cells turgor pressure that helps plant stand upright.	*Water Tower*

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Biology Ch

Belton Schools

2012-11-27

Crystal Venable

Belton School District #124