Introductory Science
Introduction to Biology
Cells
●
In this tutorial you will…
– Distinguish Between Prokaryotic and Eukaryotic Cells
– Describe Transport Mechanisms
– Describe Basic Metabolic Reactions – Explain Mitosis
– Describe Functions of Specialized Cells
Distinguish Prokaryotic
and Eukaryotic Cells
● This means that all living things are composed of one or more cells.
● There are two major classifications of cells.
– Prokaryotic – Simple Cells
(say Pro-carry-ah-tic)
– Eukaryotic – Complex Cells
(say You-carry-ah-tic)
● Organisms will be composed
of either Prokaryotic or Eukaryotic cells but not both.
● The Cell Theory states that the cell is the basic unit of life.
1 of 23
Distinguish Prokaryotic
and Eukaryotic Cells
2 of 23
Components of Prokaryotic Cells
● Prokaryotic are the simplest cells.
● The only organisms composed of prokaryotic cells are bacteria.
● A typical prokaryotic cell will have the following components.
Cell Wall
Cell
Membrane Protoplasm
Ribosome DNA
Distinguish Prokaryotic
and Eukaryotic Cells
3 of 23
Components of Prokaryotic Cells.
Cell Wall
● The cell wall is composed of proteins and carbohydrates.
Distinguish Prokaryotic
and Eukaryotic Cells
4 of 23
Components of Prokaryotic Cells.
● The membrane is composed of two layers of lipids. Scattered within the lipid bilayer are proteins.
Cell Membrane
2 layers of Lipids
Protein
Distinguish Prokaryotic
and Eukaryotic Cells
5 of 23
Components of Prokaryotic Cells.
Protoplasm
● Protoplasm is a water solution containing materials the cell needs to carry on its life processes.
Distinguish Prokaryotic
and Eukaryotic Cells
6 of 23
Components of Prokaryotic Cells.
Ribosome
● The ribosome is a small structure composed of RNA and Protein.
● There are many ribosomes in every cell.
Distinguish Prokaryotic
and Eukaryotic Cells
7 of 23
Components of Prokaryotic Cells.
DNA
● DNA is the genetic information for a cell
● DNA codes for the production of proteins.
Proteins are the structural components of the cell and they control many reactions in the cell.
Distinguish Prokaryotic
and Eukaryotic Cells
8 of 23
Components of Prokaryotic Cells.
Flagella
● The flagella is a whip-like tail on prokaryotic cell.
● Bacteria can have one, many or no flagella.
Distinguish Prokaryotic
and Eukaryotic Cells
9 of 23
Components of Prokaryotic Cells.
● Draw a prokaryotic cell and include the six components discussed.
Cell Wall
Cell
Membrane Protoplasm
Ribosome DNA
Distinguish Prokaryotic
and Eukaryotic Cells
10 of 23
Components of Eukaryotic Cells.
● Only bacteria are composed of prokaryotic cells. All other organisms; animals, plants, protozoa, and fungi are composed of Eukaryotic cells.
● Eukaryotic cells are much more complex.
● Eukaryotic cells have many of the structures found in prokaryotic cells.
● All eukaryotic cells have a membrane, DNA, ribosomes,
and protoplasm (called cytoplasm in eukaryotes).
● Although they are structurally different, plant and fungal
Distinguish Prokaryotic
and Eukaryotic Cells
11 of 23
Components of Eukaryotic Cells.
● The primary difference between Prokaryotic cells and Eukaryotic cells are organelles.
● Organelles are structures inside the eukaryotic cell that are enclosed within their own membrane.
● The nucleus is an organelle. It is separated from the rest of cytoplasm by a membrane similar to the
cell membrane. Cell
Membrane
Cytoplasm Nucleus
Distinguish Prokaryotic
and Eukaryotic Cells
12 of 23
Components of Eukaryotic Cells.
● The terms Prokaryotic and Eukaryotic allude to this distinction.
● Karyon means organelle (especially the nucleus)
● Pro means before
● Eu means true or real
● Prokaryotic refers to cells that existed before the evolution of organelles.
Distinguish Prokaryotic
and Eukaryotic Cells
13 of 23
Components of Eukaryotic Cells.
Cell Wall
(in Plant, Protozoan, & Fungal Cells)
Cell Membrane
Chloroplast
(in Plants Cells)
Cytoplasm
Nucleus
Endoplasmic Reticulum Ribosome
Distinguish Prokaryotic
and Eukaryotic Cells
14 of 23
Components of Eukaryotic Cells.
● Cell walls are found in Eukaryotic; plant, fungal, and protozoan cells.
● They are composed of carbohydrates and proteins.
● Cell walls provide structural support.
Distinguish Prokaryotic
and Eukaryotic Cells
15 of 23
Components of Eukaryotic Cells.
● The membrane is composed of two layers of lipids. Scattered within the lipid bilayer are proteins.
Cell Membrane
2 layers of Lipids
Protein
Distinguish Prokaryotic
and Eukaryotic Cells
16 of 23
Components of Eukaryotic Cells.
● Cytoplasm is a water solution containing materials the cell needs to carry on its life processes.
● There are nutrients the cell acquires from the environment, substances the cell produces, and waste products the cell must eliminate.
Distinguish Prokaryotic
and Eukaryotic Cells
17 of 23
Components of Eukaryotic Cells.
Ribosome
● The ribosome is a small structure composed of RNA and Protein.
● Ribosomes are not organelles because they are not enclosed in a membrane
● There are many ribosomes in every cell.
Distinguish Prokaryotic
and Eukaryotic Cells
18 of 23
Components of Eukaryotic Cells.
Nucleus
● The Nucleus contains the cell’s genetic information (DNA)
● The nucleus is an organelle because it is enclosed by a membrane.
Distinguish Prokaryotic
and Eukaryotic Cells
19 of 23
Components of Eukaryotic Cells.
Endoplasmic Reticulum (ER)
● Endoplasmic Reticulum (ER)is a system of tubes or sacks in the cell. It may be rough or smooth
● Rough E.R. is studded with ribosomes. It is used to process the proteins produced by the ribosomes.
20 of 23
Distinguish Prokaryotic
and Eukaryotic Cells
Components of Eukaryotic Cells.
Chloroplast
● Chloroplasts are found in plant cells and some protozoa.
● Chloroplasts are organelles where photosynthesis takes place.
21 of 23
Distinguish Prokaryotic
and Eukaryotic Cells
Components of Eukaryotic Cells.
Mitochondria
● Mitochondria are the organelles where respiration takes place.
● Respiration is the process where sugar is burned to produce energy.
22 of 23
Distinguish Prokaryotic
and Eukaryotic Cells
Components of Eukaryotic Cells.
Lysosome
● Lysosomes are organelles that contain a variety of digestive enzymes.
● These enzymes can break down nucleic acids,
protein, complex carbohydrates, etc within the cell
Distinguish Prokaryotic
and Eukaryotic Cells
23 of 23
Components of Eukaryotic Cells.
● Draw a eukaryotic cell and include the nine components discussed.
Cell Wall
(in Plant, Protozoan, & Fungal Cells)
Cell Membrane
Chloroplast
(in Plants Cells)
Cytoplasm
Nucleus
Endoplasmic Reticulum Ribosome
Mitochondria Lysosome
Describe Transport
Mechanisms
1 of 18
Home
● A cell is a busy place; similar to a factory
● Raw materials are constantly being delivered, products are being made, and waste products are generated.
Describe Transport
Mechanisms
2 of 18
● There are four basic mechanisms by which substances are transported:
● Diffusion
● Facilitated Diffusion
● Osmosis
Describe Transport
Mechanisms
3 of 18
Diffusion
● Diffusion is the process of a substance moving
from an area where it is in high concentration to an area where it is in low concentration.
● Diffusion happens naturally.
The cell does not have to make diffusion happen.
● When you take the top off a bottle of perfume, it diffuses into the air.
Describe Transport
Mechanisms
4 of 18
Diffusion
● Imagine putting a drop of food coloring in a glass of water.
● Even if you don’t stir the water or touch glass…
● The food coloring will
Describe Transport
Mechanisms
5 of 18
Diffusion
● Diffusion helps to get oxygen into your blood stream.
● Oxygen which is in high concentration in lungs diffuses into the blood where it is low
concentration.
● Carbon Dioxide which is in high concentration in the
blood diffuses into the lungs
Describe Transport
Mechanisms
6 of 18
Osmosis
● Osmosis is really just a special type of diffusion.
● Osmosis is the movement of water from high concentration to low concentration across a membrane.
● The difference is that osmosis deals strictly with the movement of water across a membrane.
● Osmosis is similar to diffusion in that the water is moving from high concentration to low
Describe Transport
Mechanisms
7 of 18
Osmosis
● Water is a relatively small molecule and is able to move across the cell’s membrane fairly easily.
● The water moves because it is high concentration on one side and low concentration on the other.
Water in High Conc. Water in Low Conc.
Describe Transport
Mechanisms
8 of 18
Osmosis
● Let’s say we put a cell from your body in a solution of sea water.
● Your cell has a higher concentration of water than the sea water. (Sea water is saltier than your cell)
● Water will move from high concentration (The Cell) to low concentration
(The Seawater)
● Water moves out of the cell and the cell shrinks.
Describe Transport
Mechanisms
9 of 18
Osmosis
● Let’s say we put a cell from your body in a solution of distilled (pure) water.
● Your cell has a lower concentration of water than the distilled water.
● Water will move from high concentration (The Distilled Water) to low
concentration (The Cell)
● Water moves into the cell and the cell swells.
Describe Transport
Mechanisms
10 of 18
Osmosis
● You body works to maintain an equal
concentration of water in the fluid surrounding the cells as the water concentration in your cells.
● This way the amount of water moving into the cells is equal to amount of water moving out of the cells.
● So the cells don’t shrink or swell.
● The kidney is one organ responsible for maintaining this water balance
H2O
Describe Transport
Mechanisms
11 of 18
Facilitated Diffusion
● In Facilitated Diffusion substances move from high concentration to low concentration using special
molecules or channels in the cell membrane.
● Remember, the natural tendency of substances is to move from high conc. to low conc.
Describe Transport
Mechanisms
12 of 18
Facilitated Diffusion
● Molecules that are small enough can diffuse right through the cell membrane.
● Large molecules require help of transport proteins to get them across.
High Conc. Low Conc.
Diffusion
Facilitated Diffusion
Describe Transport
Mechanisms
13 of 18
Facilitated Diffusion
● Glucose (sugar) molecules are in high demand because glucose is the cell’s main energy source.
● Glucose is constantly being used up by the cell so it is always in low concentration inside.
● However, glucose is in high conc. in the blood because it is constantly absorbed from your food.
● The problem is glucose is too large to diffuse
directly through the cell membrane so it gets into the cell by facilitated diffusion using special
Describe Transport
Mechanisms
14 of 18
Facilitated Diffusion
● In facilitated diffusion, substances still move from High Conc. to Low Conc. They are just using
special channels to get across the membrane.
● Since the substances are moving with the natural tendency (high to low) no energy is required.
● Imagine you are rafting and you want to go down stream. You don’t have to
expend any energy because you are going with the
Describe Transport
Mechanisms
15 of 18
Active Transport
● Active Transport is the movement of substances across a membrane using special transport proteins from an area of low conc. to high conc.
● This is similar to facilitated diffusion because special proteins transport substances across the membrane
Describe Transport
Mechanisms
16 of 18
Active Transport
Low Conc. High Conc.
Active Transport
Transport Protein
● Substances move naturally from high conc. to low conc. This occurs independently without any help.
Describe Transport
Mechanisms
17 of 18
Active Transport
● An example of active transport is the calcium
pump. Some cells actively pump out calcium ions.
● This keeps the calcium concentration inside the cell many times lower than concentration outside.
● Active transport pumps like these are important.
Home
Describe Transport
Mechanisms
18 of 18
Active Transport
● Remember, in active transport, substances move from Low Conc. to High Conc. using special
channels to get across the membrane.
● Since the substances are moving against the natural tendency (low to high) energy is required.
● Imagine you are rafting and you want to go up stream. You have to expend
Describe Basic
Metabolic Reactions
1 of 12
● Metabolism is the broad term that covers all the chemical reactions that go on in a living organism.
● Metabolic reactions allow a cell to get the
nutrients, generate the energy, and produce the substances it needs.
● Metabolic reactions fall into two broad categories.
● Catabolism – (say ca-Tab-o-lism)
This is the process of breaking substances down into their constituent parts.
● Anabolism – (say an-Ab-o-lism)
This is the process of putting small molecules together to create larger or more complex molecules.
Describe Basic
Metabolic Reactions
2 of 12
Photosynthesis
● Photosynthesis is an anabolic reaction.
● It is probably the most important metabolic reaction.
● Photosynthesis is performed by primarily by plants but also by some bacteria and protozoa
● In Photosynthesis sugar
Describe Basic
Metabolic Reactions
3 of 12
Photosynthesis
● Plants use sunlight as energy to build sugar molecules from carbon dioxide and water molecules.
● Photosynthesis happens in the chloroplast of the plant cell.
● In addition to sugar, plants produce oxygen as a by-product of photosynthesis.
● Photosynthesis is important for at least two reasons.
● First, the oxygen released by plants through
photosynthesis is Earth’s only source of Oxygen.
● Second, all animals use the sugar produced by
plants either directly or indirectly as a food source.
● Animals can’t make their own food so they rely on plants as their food source.
● If there were no plants,
there would be no animals.
Describe Basic
Metabolic Reactions
4 of 12
Describe Basic
Metabolic Reactions
5 of 12
Digestion
● Digestion is a catabolic reaction.
● During digestion large complex molecules are broken down into smaller subunits.
● Your digestive system breaks down the food that you eat so it can be processed and used by the body.
Describe Basic
Metabolic Reactions
6 of 12
Digestion
● Proteins for example are broken into amino acids
● Polysaccharides are broken into simple sugars (monosaccharides).
● The products of digestion are generally used in one of two ways.
● They are broken down further to produce energy.
● They are reassembled to create new structures.
Describe Basic
Metabolic Reactions
7 of 12
Respiration
● Respiration is a catabolic reaction.
● Your digestive system breaks down the food you eat so it can be processed and used by the body.
● Carbohydrates are digested producing sugar molecules.
● During respiration these sugar molecules are
broken down further to produce energy.
Sugar
Describe Basic
Metabolic Reactions
8 of 12
Respiration
● Energy is released during respiration because it is a catabolic (or breaking) reaction.
● The sugar is broken down by combining it with oxygen and producing carbon dioxide and water.
Sugar + O2 CO2 + H2O
● Respiration is a
combustion reaction.
● In the mitochondria, sugar is burned to
Describe Basic
Metabolic Reactions
9 of 12
Protein Synthesis
● Protein synthesis is an anabolic (building) reaction.
● During digestion, food is broken into its constituent parts. Proteins are broken into amino acids.
● In protein synthesis, these amino acids are
Describe Basic
Metabolic Reactions
10 of 12
Protein Synthesis
● Energy is required for Protein synthesis because it is an anabolic or building reaction.
● Whenever a substance is built energy is required to do the work.
● In protein synthesis large proteins are built from small amino acids.
Describe Basic
Metabolic Reactions
11 of 12
● What are the 2 categories of metabolic reactions?
● Categorize each of the metabolic reactions below.
Photosynthesis Digestion
Respiration
Protein Synthesis
A Anabolic = Building Reactions Catabolic = Breaking Reactions
= Anabolic = Catabolic
= Catabolic
Describe Basic
Metabolic Reactions
12 of 12
● Summarize the four basic metabolic reactions.
Α In photosynthesis, plants use energy from the sun to build sugar molecules from CO2 and H2O.
In digestion, biomolecules are broken into their
constituent parts. Carbohydrates are broken down into simple sugars and proteins into amino acids.
Respiration further breaks down sugar molecules to release energy that will be used by the cell.
Protein synthesis builds new proteins needed by the cell using energy released by respiration.
Explain Mitosis
1 of 15
● Another process in which virtually all cells engage is cell division
Home
● Cell division is also called Mitosis (say my-Toe-sis)
Explain Mitosis
2 of 15
● There are three main reasons why cells need to divide (go through mitosis)
1. Growth
When an organism grows its cells do not become larger instead it produces more cells.
2. Repair
If cells are damaged they must be replaced with new cells capable of taking over for the originals. 3. Replacement
Skin cells for example have a limited life
Explain Mitosis
3 of 15
● What part of a cell controls how the cell will function?
Α The DNA is the blueprint for making all cell
4 of 12
● Mitosis is the process for making new cells
● To insure that the new cells function like the
original, we need to make sure they have identical DNA.
● For this reason, copying the DNA is the most important part of mitosis
● The next few slides will lead you through mitosis.
● To make it easier to study, mitosis is broken into five phases.
5 of 12
Explain Mitosis
Interphase
● During interphase the cell is going about its normal activities. (Making proteins, producing energy etc)
● In the nucleus, the DNA is unwound like a tangled string.
Nucleus
DNA Note:
In eukaryotic cells, the DNA is NOT in one single strand.
It is divided into pieces. Humans have 46 pieces of DNA in the nucleus of each
cell. There are 4 chromosomes in this cell When these pieces of DNA
are unwound, as they are during interphase, they are
called chromatin.
When these pieces of DNA coil up, as the do before the
cell divides, they are called chromosomes.
Human beings, therefore, have 46 chromosomes in the
nuclei of every cell in their bodies.
Just before the next phase, normal activities stop and the
DNA is copied so the number of chromosomes doubles.
6 of 12
Explain Mitosis
Prophase
● During prophase, the nuclear membrane begins to breakdown.
● In addition, the chromatin begins to coil up and shorten forming recognizable chromosomes.
Notice:
We have 8 chromosomes total. Our original 4 plus a copy of each,
made at the end of Interphase Notice:
Explain Mitosis
7 of 12
Metaphase
8 of 12
Explain Mitosis
Anaphase
Notice:
The original cell had 4
chromosomes. Each resulting cell also has 4 chromosomes
Explain Mitosis
9 of 12
Telophase
● During Telophase, a new cell membrane forms splitting the cell in two.
● Finally, the cells divide completely and a new
nuclear membrane forms around the chromosomes.
Notice:
Through Mitosis, two cells are created that are genetically
10 of 12
Explain Mitosis
● How is mitosis like making a photocopy?
Α When you make a photocopy you start with one page and end up two pages that are identical to original. In mitosis, we start out with one cell and we end up with two cells that are identical to the original cell.
● If a human cell (with 46 chromosomes) went through mitosis, what would be the result.
Α If a human cell goes through mitosis the result will be 2 cells each of which will have 46
chromosomes.
Describe Functions
of Specialized Cells
1 of 10
● We begin our lives as a single cell
Home
● That cell divides by mitosis producing two cells.
● Those two cells divide producing 4, then 8, then 16 and so on….
2 of 10
Describe Functions
of Specialized Cells
● Complex organisms are composed of millions of cells and each cell has the same DNA,
● Even though every cell has the same DNA they are not identical.
● A human being is composed of hundreds of different types of cells.
● These different types of cells arise through a process called differentiation.
Describe Functions
of Specialized Cells
3 of 10
● The body of a complex organism is responsible for many different functions.
● These functions are best carried out by cells that are specifically designed for the task.
● Muscle cells have a much different job to do than nerve cells or blood cells
● Consequently, different types of cells are structurally different.
4 of 10
Describe Functions
of Specialized Cells
Red Blood Cells
● Red blood cells are relatively small cells, the
majority of their cytoplasm is occupied by a protein called hemoglobin
● Red blood cells’ main job is to carry O2 and CO2 throughout the body.
● Hemoglobin readily bonds to O2 and CO2. Therefore, it allows the blood to carry
a lot more oxygen and carbon
Describe Functions
of Specialized Cells
5 of 10
Red Blood Cells
● In order to maximize the amount of room available for hemoglobin, mammalian red blood cells don’t have a nucleus.
● Because of this red blood cells are fairly short lived. They last only about 4 months.
● Red blood cells must be continually produced from nucleated stem
cells in the bone marrow.
6 of 10
Describe Functions
of Specialized Cells
Muscle Cells
● Muscle cells are much larger than red blood cells. They may be several centimeters long as opposed to a few micrometers.
● Skeletal muscle cells’ primary job is to move the structures to which they are attached (like bones).
● To accomplish this muscle cells are filled with proteins that have the ability to
contract.
Describe Functions
of Specialized Cells
7 of 10
Muscle Cells
● Muscle contraction is an energy intensive business so muscle cells contain a lot of mitochondria
● The nuclei are pushed to the edge of the cell to make room for the contractile proteins.
Nuclei
● Skeletal muscle cells have many nuclei. This is because they form from a number
8 of 10
Describe Functions
of Specialized Cells
Nerve Cells
● The main job of a nerve cell is to receive and send information from one place to another.
● Nerve cells have a cell body with a nucleus but their other features are more prominent.
Cell Body Nucleus
● One end of the nerve cell resembles the branches of a tree. These are called the Dendrites.
Dendrites
● The long, single
projection at the other end of the cell is
Describe Functions
of Specialized Cells
9 of 10
Nerve Cells
● The nerve cell’s job is to move information.
Cell Body Nucleus
Dendrites
Axon
● It is the dendrites’ job to collect information.
● This information may come from receptors (pain pressure, heat, etc) or from other nerves.
● The signals collected by the dendrites are then passed on through the axon.
● The axon terminates on whatever the nerve effects.
Describe Functions
of Specialized Cells
10 of 10
Review
● The cells of complex organisms start out looking and functioning the same.
● In differentiation, the stem cell’s structure changes and therefore its functions are modified as well.
● Differentiated cells are much better at their job than an undifferentiated stem cell.
● Once a cell has differentiated it can’t go back or become something else.
● A blood cell will stay a blood cell. It can’t become a muscle cell or go back to being a stem cell.
