Intro to Cells: Cell Theory and Cell Structure

Modern Cell Theory

1. All organisms are composed of one or more cells 2. The cell is the basic unit of structure and function of life. 3. Cells only come from preexisting cells

Robert Hooke

1665, first scientist to see a cell, cork, compound light microscope, saw tiny boxes and named it cells which means "little rooms" in Latin

Leeuwenhoek

A Dutch merchant, who in the late 1600s made the first simple microscope and observed microscopic life from pond water and teeth scrapings.

cell membrane

A cell structure that controls which substances can enter or leave the cell. Also known as the plasma membrane.

eukaryote or eukaryotic

A cell that contains a nucleus and membrane bound organelles. YOU are made of this type of cell.

chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria.

flagellum (pl) flagella (s)

A long, whiplike structure that helps a cell to move. They only animal cell with a flagellum is the sperm cell. Single cell organisms rely on this structure for movement.

organelles

A membrane-enclosed structure with a specialized function within a cell.

mitochondrion (singular) mitochondria (plural)

A membrane‐bound organelle found in most eukaryotic cells; site of cellular respiration. It contains its own ring of DNA which supports the theory of endosymbiosis of the eukaryotic cell.

cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement.

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction. It is often referred to as the "control center of the cell."

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell. Plant, bacteria and fungi all have cell walls. Animal cells do not.

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells that controls what enters and exits the cell. This is another name for cell membrane.

virus

A tiny, nonliving particle that invades and then reproduces inside a living cell.

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes.

eukaryotic cell

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Examples of organisms with these cells are protists, plants, fungi, and animals.

macromolecule

A type of giant molecule formed by joining smaller molecules which includes proteins, carbohydrates, lipids, and nucleic acids.

chloroplast

An organelle found in plant and algae cells where photosynthesis occurs, contains the chlorophyll.

Golgi body (Golgi apparatus)

An organelle that receives proteins and other newly formed materials from the endoplasmic reticulum, packages them, and transports them out of the cell by vesicles. Think of this structure as a Fedex Truck -- shipping packages out of the cell.

If a cell contains a nucleus, no cell wall and no chloroplasts, then what type of cell might it be?

Animal cell

vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

nucleolus

Found inside the nucleus and produces ribosomes

cytoplasm

Gel-like fluid where the organelles are found

central vacuole

LARGE "holding container" in plant cells for water; helps maintain turgor pressure in plants.

Compound Microscope

Magnifies the image using two lenses at once. This is the type of microscope we use in class.

multicellular

Many cells

unicellular

One cell

ribosome

Organelle where proteins are synthesized (made).

If a cell contains a nucleus, cell wall, chloroplasts, and a large central vacuole, then what type of cell could it be?

Plant cell

phospholipid bilayer

Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.

differentiation

Process in which cells become specialized in structure and function. The human body is composed of trillions of cells and has about 200 different types of cells, examples: red blood cell, white blood cell, muscle cell, neuron.

If a cell has NO nucleus, a flagella, no mitochondria and chlorophyll, then what type of cell could it be?

Prokaryotic -- there is no nucleus! Some bacteria DO contain chlorophyll (but not chloroplasts).

Bacteria are what type of cells?

Prokaryotic cells (small and simple cells that lack membrane-bound organelles)

Which type of cell does NOT have membrane-bound organelles (ex. golgi bodies, endoplasmic reticulum, mitochondria, chloroplasts, etc.)?

Prokaryotic cells, ex. bacteria

vesicle

Small membrane-bound sac that functions in moving products into, out of, and within a cell.

organelle

Small structures within cells that perform specific functions (ex. mitochondria, nucleus, ER).

True or False? All cells contain ribosomes, because all cells must be able to produce proteins.

TRUE!

semi-permeable

The characteristic of a cell membrane which allows some molecules to pass through but not others. Water, oxygen and carbon dioxide can simply diffuse across the cell membrane, but salt, protein and sugar molecules cannot.

fluid mosaic model

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

cilia

The hairlike projections on the outside of cells that move in a wave-like manner.

endoplasmic reticulum (rough)

The organelle that transports proteins around the cell,located near the nucleus and and covered by ribosomes. Think of this organelle like a major highway system within your cell where proteins are transported to the Golgi.

Lysosome

This organelle is primarily found in an ANIMAL CELL. It contains enzymes that break down old cell parts and dead cells. Think of this structure as a recycling truck.

True or False? The cell membrane is considered semi-permeable because it only allows some substances in.

True

prokaryote

Unicellular organism that has NO nucleus.

Hydrophobic

Water fearing

hydrophobic

Water fearing

hydrophilic

Water loving

pro-

before

cyto-

cell (prefix) cell; cytoplasm

What structures (cell organelles) do ALL cells have?

cell membrane, ribosomes, DNA and cytoplasm

chloro-

green

eu-

true

bilayer

two layers

bi-

two, double