Cell Structure and Function

cell

a membrane covered structure containing all the materials necessary for life

the building block of life

all living things are made of one or more cells

Robert Hooke

First person to DESCRIBE and NAME cells.

He looked at a very thin slice of CORK under the microscope and saw tiny box-like structure that reminded him of the very small rooms where monks live. From this observation, he came up the word CELL to describe these basic units of life!

Cell Theory

Following the discovery of cells, 200 years of research (that was completed by many scientists) led to the following conclusions about cells:

1. All living things are made of one or more cells.

2. Cells are the basic units of structure and function in living things.

3. Living cells only arise from other living cells. (LIFE comes from LIFE.)

****REMEMBER: A scientific THEORY is supported by EVIDENCE. A theory is NOT a hunch or a guess.

microscope

• a tool using light and lenses that creates enlarged images.

• invented in the 1600s

• made possible the discovery of cells

cell wall

STRUCTURE: Strong, stiff, nonliving layer outside the cell membrane of plants, fungi and most bacteria.

In plants the cell wall is made of a carbohydrate called cellulose

FUNCTION: Provides shape, support and protection

cell membrane

STRUCTURE: Think, flexible covering made of phospholipids and proteins

FUNCTION: selectively regulates what eneters and leaves the cell

Nicknames: “border patrol”, “gate-keeper”, “guarded fence”

cytoplasm

region between the nucleus and the cell membrane

STRUCTURE:  consists of a jelly-like substance that contains many organelles; mixture of water and chemicals

FUNCTION:  site of metabolism (chemical reactions)

nucleus

STRUCTURE:

• largest and most visible organelle

• surrounded by the nuclear membrane, which controls what enters and leaves the nucleus

• contains one or more nucleoli

FUNCTION: Location of the genetic material (DNA)

NICKNAMES: “Boss”, “Brains”, “Control Center”

nucleolus (singular) / nucleoli (plural)

STRUCTURE: Dark spot within the nucleus

FUNCTION: Makes ribosomes

chromosomes

During cell division, the genetic material (DNA) is tightly coiled around proteins forming short thick structures.

chromatin

During routine cell activity, the genetic material is found in the form of chromatin, which is DNA loosely wrapped around proteins forming long, thread-like structures

ROUGH Endoplasmic Reticulum (RER)

STRUCTURE: Tubular channels or passageways covered with ribosomes

FUNCTION:  Transports materials (such as proteins ) around the cell

NICKNAME:  “Cell highway”

SMOOTH Endoplasmic Reticulum (SER)

STRUCTURE: Tubular channels that are NOT covered in ribosomes

FUNCTION: Synthesizes some types of lipids and detoxifies substances (breaks down substances that could damage the cell)

Ribosomes

STRUCTURE:

• not membrane-bound (so found in prokaryotes and eukaryotes

• smallest, most abundant organelle

• may be attached to the ER forming RER or free within the cytoplasm

• **produced by the nucleolus

FUNCTION: Place where proteins are made (site of protein synthesis)