Life Science

Introduction to Cells All life forms on our planet are made up of cells.

In ALL organisms, cells have the same basic structure.

The scientist Robert Hooke was the first to see cells under a microscope.

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

2. Cells are the basic unit of structure and function in organisms.

3. All cells arise from existing cells.

Looking at Cells Cells vary greatly in size and in shape.

There are over 200 different types of cells in your human body.

Brain cells look and function differently than muscle cells, although their parts on the inside of the cell are the same.

Although these cells are somewhat different, they are all very SMALL!!!

Cell Size All substances (FOOD) that enter or leave a cell must

pass through the surface of the cell.

Substances must move farther to reach their destination if the cell is LARGE.

Cell size must be limited by a cells surface area-to-volume ratio.

Prokaryotic and Eukaryotic Cells Although ALL cells are very similar in structure and

function, they are not all exactly the same.

Single celled organisms are made of prokaryotic cells, while multicellular organisms (YOU) are made of eukaryotic cells.

Prokaryotic Cells A prokaryotic cell is simple, they make up

UNICELLULAR organisms (single celled) (bacteria)

The genetic material is a single loop of DNA floating in the cytoplasm.

Ribosomes and enzymes share the cytoplasm with the DNA.

A cell wall surrounds the plasma membrane, this is similar to plant cells, but nothing like an animal cell.

A Prokaryotic Cell

Prokaryotic Cells

Eukaryotic Cells Eukaryotic Cells are cells found in multicellular

organisms (YOU)

Eukaryotic Cells are more complex than prokaryotic cells.

Because of their complex organization, eukaryotic cells can carry out more specialized functions than prokaryotic cells can.

Unlike the prokaryotic cell, the DNA in a eukaryotic cell is found in the nucleus.

All eukaryotic cells have membrane bound organelles (you’ll learn what these are very soon)

A Eukaryotic Cell

A Eukaryotic Cell

DNA inside of a eukaryotic cell is found in the :

Nucleus

Ribosome

Cytoplasm

Mitochondria

Bacteria are made up of:

Eukaryotic Cells

Prokaryotic Cells

Animal Cells are made up of:

Eukaryotic Cells

Prokaryotic Cells

Plant Cells are made up of:

Eukaryotic Cells

Prokaryotic Cells

A cell is discovered that contains a nucleus and no flagella. It is most likely a:

Eukaryotic Cell

Prokaryotic Cell

Identify the following cell type Prokaryotic Cell

Eukaryotic Cell

Identify the following cell Type:

Eukaryotic, Animal

Eukaryotic, Plant

Prokaryotic, Bacteria

Prokaryotic , Plant

Both prokaryotic and eukaryotic cells contain

A nucleus

DNA

Mitochondria

Nuclear envelope

Inside the Prokaryotic Cell DNA is located in an area of the cytoplasm called the

NUCLEOID. THIS IS NOT A NUCLEUS! It is NOT bound by a membrane!

Small hair-like structure are attached to the outside of the prokaryotic cell called FIMBRIAE or PILI. Allows bacteria to attach to some surfaces.

Inside the Prokaryotic Cell The membrane that immediately surrounds the

cytoplasm is known as the PLASMA MEMBRANE. Controls what enters and leaves the cell. (INNER LAYER)

Bacteria also have a CELL WALL that lies just outside the PLASMA MEMBRANE. (MIDDLE LAYER)

A jelly-like CAPSULE forms the outer coating of many prokaryotes. (OUTER LAYER)

Inside the Prokaryotic Cell RIBOSOMES: Make Proteins. These structures will be

talked about more inside the Eukaryotic Cell.

Some bacteria have the ability to move around and are propelled by FLAGELLA!

Prokaryotic Cell DNA is located in an area of the cytoplasm called the:

Nucleus

Ribosome

Plasma Membrane

Nucleoid

In the prokaryotic cell, ribosomes make:

Carbohydrates

Nucleic Acids

Lipids

Proteins

Inside the Eukaryotic Cell The Cytoplasm

The region of the cell within the plasma membrane.

The Cytoskeleton

A web of protein fibers

The cytoskeleton supports the cell like bones support your body

Inside the Eukaryotic Cell The Nucleus

Houses the DNA

The brains of the cell Tells the cell what to do!

Nuclear Envelope

A double layered membrane that surrounds the nucleus

Ribosomes

These structures take info from DNA and link amino acids together.

What do we create when we link amino acids together?

Inside the Eukaryotic Cell The Endoplasmic Reticulum

A system of internal membranes

Rough ER-Ribosomes attached send vesicles with proteins to the Golgi Apparatus and then to other parts of the cell

Has Ribosomes attached to it so that after proteins are produced, they can send them out of the cell.

Smooth ER produces enzymes that break down LIPIDS, and detoxify drugs.

Secretes sex hormones

Stores Calcium ions

Endoplasmic Reticulum (ER)

Inside the Eukaryotic Cell Cont. The Golgi Apparatus

We can think of the golgi apparatus as a center of manufacturing, warehousing, sorting, and shipping.

Often receives proteins from ER and transports them around the cell.

Inside the Eukaryotic Cell Cont Lysosomes

Contains specific enzymes that break down large molecules.

Can digest food to provide nutrients for the cell.

Digests waste products in the cell and helps send them out.

Inside the Eukaryotic Cell Cont Mitochondria

The power house of the cell

The MIGHTY MITOCHONDRIA!!!

Takes sugar molecules and makes ATP (energy)

Do muscle cells or skin cells contain more mitochondria organelles?

Inside the Eukaryotic Cell Cont. Microfilaments

Similar to the cytoskeleton, but are mainly involved in CELL DIVISION.

These “tubes” grow out of CENTRIOLES

Centrioles

Located in a region of the cell called the centrosome.

Centrioles produce the microfilaments that organize the cell before CELL DIVISION.

Inside the Eukaryotic Cell Cont Central Vacuole

ONLY FOUND IN PLANT CELLS!

Stores WATER, ions, nutrients, waste

Chloroplasts ONLY FOUND IN PLANT CELLS!

Uses light energy from the sun to make sugar.

Cell Wall ONLY FOUND IN PLANT CELLS!, also prokaryotic

Cells!

Provides stability for the cell.

A Plant Cell.

The Plasma Membrane So important that it gets a slide to itself!

Also known as the CELL MEMBRANE.

A double layered phospholipid membrane that separates the inside of the cell from the outside of the cell.

The plasma membrane is selectively permeable.

What do you think selectively permeable means?

The “fluid mosaic model” describes the plasma membrane. (This is discussed in the Cell Function notes.)

The Fluid Mosaic Model

Naomi adds cycloheximide to cells grown in a test tube. Within minutes, she identifies short, incomplete segments of proteins in the cell. On which organelle does cycloheximide act?

Endoplasmic Reticulum

Golgi Apparatus

Nucleus

Ribosome

After Harrison adds a chemical to cells, proteins begin to accumulate in the endoplasmic reticula. The chemical prevents movement of proteins from the endoplasmic reticulum to which organelle?

Golgi Apparatus

Lysosome

Mitochondrion

Ribosome

The presence of which structure indicates that cells are NOT photosynthetic bacteria.

Cell Wall

Ribosome

Nucleus

Cytoplasm

Cellular Division Cells divide by the process of mitosis.

One cell becomes two identical daughter cells.

These daughter cells are exactly the same

Have exactly the same genetic material.

The Cell Cycle

Cell Cycle Out of Control Cells have genes (DNA) that regulate the cell cycle.

Some of these genes tell the cell cycle to stop and some of these genes tell the cell cycle to proceed.

If either of these genes are mutated, it causes the cell cycle to go to fast.

When this occurs, the cell is CANCEROUS!

This is a loss of control of the cell cycle.

Cancer When cell growth and mitosis is out of control tumors

develop.

When a cancer tumor develops, cells from the tumor can break off, enter the blood stream, and move to other parts of the body

The process by which cancer spreads is called metastasis.

Cancer Pictures CAUTION: THESE PICTURES ARE EXTREMELY

GRAPHIC.

If you are comfortable viewing actual pictures of cancerous lesions, click here.

The Steps of Mitosis!

Interphase: DNA has already been replicated,

but has not condensed. Two centrosomes have formed with centriole pairs.

The Steps of Mitosis!

Prophase: DNA begins to coil and is observable

with sister chromatids. Nuclear envelope disappears. Centrosomes move away from each other propelled by lengthening microtubules.

The Steps of Mitosis!

Metaphase : The longest stage of mitosis.

Centrosomes now at complete opposite ends of the cell. Chromosomes held at the middle of the cell by microtobules.

The Steps of Mitosis!

Anaphase: Shortest stage of mitosis. Sister

chromatids are pulled apart to opposite ends of the cell. Pulled apart by microtubules.

The Steps of Mitosis!

Telophase: Two new daughter nuclei begin to

form. Nuclear envelope reappears. The division of one nucleus into two genetically identical nuclei, is now complete!!!

Cytokinesis: complete division is underway.

Formation of cleavage

Furrow.