Introduction to the Cell

Chapter 7.1

Introduction to the Cell

Cell- smallest unit of matter that can carry on all of the processes of life

Hooke and Leeuwenhoek used microscopes to see first images of cells in the 1600-1700’s.

The Cell Theory…a. All living things are composed of cells

b. Cells are the basic units of structure and function in an organism (smallest living unit).

c. Cells come only from the reproduction of existing cells (cells come from cells).

Cells Size…

Limited in size because of surface to area ratio– If a cell gets too big the nutrients and

wastes do not have enough surface area to come into / out of the cell

Shape…

A cells shape is usually associated with its job.

Internal Organization…

Cells contain many organelles– Def: cell component that performs specific

functions for the cell• Like mini organs

– Cell membranes surround cell and decides what goes in and out of the cell.

– Nucleus contains genetic information (DNA), which controls the cell.

Eukaryotic vs. Prokaryotic Eukaryotic

– Cell that has membrane bound organelles

– More complex

– Plant and animal cells

-YOU are a eukaryote!

Prokaryotic– Has membrane

around entire cell

– No organelles

– No nucleus

– bacteria

Eukaryotic vs. Prokaryotic

Bill Nye: Discovery of Cells

Organelles

Inside the Eukaryotic Cell

7.2

Cell Membrane

The lipid bilayer that surrounds the cell

Cell Membrane cont.

Controls what enters/leaves the cell Selectively permeable – allows some

substances to enter while not allowing others to enter

Sometimes have proteins integrated into the layer, some are on either side of the bilayer

All cells have: Cytoplasm-a jelly like substance that

fills the cell within the cell membrane. Ribosomes- the cellular

structure where proteins

are made.

Nucleus

Contains DNA, hereditary info.

Surrounded by the nuclear membrane

Also has a nucleolus where ribosomes are made.

The cell’s “brain.”

Mitochondria Site of chemical

reactions that produce ATP (energy).

Have folded center to allow for more surface area for production of ATP

Have their own DNA Many of them in the

cell

Ribosomes Numerous; some

are free floating others are attached to Endoplasmic Reticulum

Play a large role in the production of proteins

Endoplasmic Reticulum Act as highway for

proteins and other substances, has many different channels

Rough ER – ribosomes make proteins, ER ships them off

Smooth ER – makes steroids, regulates calcium, and breaks down toxins

Lysosome Uses enzymes to digest/break down organic

compounds, old cell parts and other materials

Golgi Apparatus Processes and packages cells proteins

Cytoskeleton ~ Provides support and allows movement like a

human’s skeleton.

Cilia and FlagellaCilia Found on outside of

the cell Aid in movement Hair-like structures Cilia are short and

come in large numbers

Flagella Found on out side of

the cell Aid in movement Hair-like structures Flagella usually

come in 1-3.

Plant vs. Animal Cells

Both plants and animals have more complex eukaryotic cells.

However there are some differences in there structure.

Plant Cells…

Have cell wall for structural support- like plant bones

Has large vacuoles for storage of water and toxins

Have Chloroplasts that convert light into chemical energy

Animal Cells

No cell wall, just a cell membrane.

No chloroplasts. No vacuole.

Levels of Organization

From Cells to Organisms

7.3

Multicellular Organization

Cell

Tissue

Organ

Organ System

Organisms

Multicellular OrganizationCell=The smallest unit of life.

Tissue= A group of similar cells that are working together. Examples: Muscle tissue or bone tissue.

Organ= Similar tissues organized into a structure with a specific function. Examples: Heart, bones, liver.

Multicellular Organization

Organ system- Various organs working together to carry out a major body function. Examples: digestive system, urinary system, reproductive system.

Organism-Any living thing that can carry out life processes independently.