Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cells—the fundamental unit of life...

Larry M. Frolich, Ph.D.Biology Department, Yavapai College

Cells—the fundamental unit of life

• What is life?What is life?

• Molecules of lifeMolecules of life

• Cell as fundamental unitCell as fundamental unit

• Cell membranes and organellesCell membranes and organelles

• Cell metabolismCell metabolism

• Cells organized into tissuesCells organized into tissues

• Types of tissuesTypes of tissues


Cells—the fundamental unit of life

•What is lifeWhat is life??• Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


What is Life? • Life needs energy• Life reproduces• Life grows and

develops• Life maintains a

stable condition—homeostasis

• Life responds to stimulus

• Life is organized because it has evolved


Humans Evolve• Life is organized

hierarchically• Evolution explains

organization at every level of hierarchy

• Humans can be understood at every level of hierarchy

• Humans have evolved and are evolving


• Cells are the basic and fundamental unit of life

• The first life was cellular life

• The Molecules of Life are what cells and all their internal parts are made up of

Cells are fundamental unit of life


Cells—the fundamental unit of life• What is life?What is life?

•Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


The Carbon-chain Molecules of Life

MOLECULE MADE OF FUNCTION

Carbohydrates Simple Sugars Energy

Proteins Amino Acids Catalyze reactions

Fats Fatty Acids Cell membranes

DNA/RNA Nucleotides (bases)

Information


Carbohydrates• Components are

simple sugars• Used for energy

storage in complex form

• Broken down to simple sugars to fuel cellular metabolism in mitochondria

• So, why are simple sugars bad for us? And why do we love them so much? (p. 29 in text)


Proteins• Components are

amino acids• Very complicated• Amino acid chain

folds up to give complex form

• Complex form allows for catalyzing very specific chemical reactino

• GenBlue


Fats/Lipids• Fundamental to life and

origins—separate cell interior from environment as cell membrane

• Mammals and other vertebrates—long-term energy storage

• Role in diet=big controversy!


DNA/RNA (Nucleic Acids)

• DNA and RNA store and use information• Components are nucleotides or “bases” (A,C,T/U,G)• One DNA molecule can be very long and complex—millions of bases

long• DNA duplicates to pass on information• Transcription to mRNA to be translated into protein’s amino acid chain• What do proteins do?


Cells—the fundamental unit of life• What is life?What is life?• Molecules of lifeMolecules of life

• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


Two types of cells• Prokaryotic cells

– Relatively Simple– Relatively Small– No organelles with Molecules of Life

distributed throughout cytoplasm– Bacteria are all prokaryotic cells

• Eukaryotic cells– More complex– Much bigger (100 x size of prokaryotic

cells)– Internally organized with membrane-bound

organelles– Multi-cellular organisms, like plants and

animals, are all made up of eukaryotic cells


Eukaryotic cell


Endosymbiotic origin of mitochondria and chloroplasts

• Eukaryotic cells evolved from fusion or integration of prokaryotic cells

• Best evidence is in bacterial or prokaryotic appearance of mitochondria and chloroplasts

• These organelles are like little bacterial cells within our cells, now fully functionally integrated

• They perform fundamental cell functions. Mitochondria process sugars to produce energy; chloroplasts make sugars by photosynthesis

• But they maintain their own DNA and genetic control


Prokaryotic cells have:

• Cell membrane• DNA molecule loose in cytoplasm• Small Ribosomes where proteins are

assembled from DNA information• Microtubule structures like flagella and

cilia• Mitochondria and chloroplasts share most

of these features, including their own independent DNA


WHAT EUKARYOTIC CELLS HAVE:

• Cell membrane• Nucleus• Mitochondria (and sometimes chloroplasts for

photosynthesis) • Larger ribosomes for protein assembly from DNA

information• Internal membranes that organize cellular spaces and

distribution of Molecules of Life within cell (“cytoskeleton”)

Eukaryotic cells (like our human cells) have:


WHAT CAN EUKARYOTIC CELLS DO?

WHAT STRUCTURES ARE INVOLVED?

Separate inside of cell from external environment and control what substances pass across membrane

Cell Membrane

Produce proteins/enzymes that catalyze chemical reactions or control movement across membrane

Nucleus (DNA), Ribosomes on rough endoplasmic reticulum

Break down sugars to form energy which is stored in phosphate bonds of ATP

Mitochondria

Organize distribution of Molecules of Life (macromolecules) and ions throughout cell

Internal membrane system and “cytoskeleton” (ER, lysosomes, vessicles, microtubules)

Move Flagella, cilia, pseudopods


Cells—the fundamental unit of life• What is life?What is life?• Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit

• Cell membranes and Cell membranes and organellesorganelles

• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


A cell membrane or plasma membrane separates cell from outside world—creates ability to regulate internal environment (homeostasis)


cell membrane


What are some characteristics of the plasma membrane?

• It is a phospholipid bilayer• It is embedded with

proteins that move in space

• It contains cholesterol for support

• It contains carbohydrates on proteins and lipids

• Selectively permeable

cell membrane


What does selectively permeable mean?

• The membrane allows some things in while keeping other substances out

cell membrane


How do things move across the plasma membrane?

1. Diffusion

2. Osmosis

3. Facilitated transport

4. Active transport

5. Endocytosis and exocytosis

cell membrane


What are diffusion and osmosis?

• 1. Diffusion is the random movement of molecules from a higher concentration to a lower concentration

• 2. Osmosis is the diffusion of water molecules

cell membrane


How does tonicity change a cell?

• Hypertonic solutions have more solute than the insideof the cell and lead to lysis (bursting)

• Hypotonic solutions have less solute than the inside of the cell and lead to crenation (shriveling)

• Isotonic solutions have equal amounts of solute inside and outside the cell and thus does not affect the cell

cell membrane


What are facilitated diffusion and active transport?

• 3. Facilitated transport is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier

• 4. Active transport is the movement of molecules from a lower to higher concentration using ATP as energy; requires a protein carrier

cell membrane


What are endocytosis and exocytosis?

• 5. Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle

• 6. Exocytosis transports molecules outside the cell via fusion of a vesicle with the plasma membrane

cell membrane


Protein synthesis• Remember that proteins control cell

metabolism—how and where are they made, or synthesized in the cell?


What structures are involved in protein synthesis?

• Nucleus

• Ribosomes

• Endomembrane system

Protein synthesis


What is the structure and function of the nucleus?

• Bound by a porous nuclear envelope

• Houses DNA and associated proteins called chromatin

• Contains nucleoplasm• Nucleolus region(s)

that contain ribosomal RNA (rRNA)

Protein synthesis


What is the structure and function of ribosomes?

• Organelles made of RNA and protein

• Found bound to the endoplasmic reticulum and free floating in the cell

• Site of protein synthesis

Protein synthesis


What is the endomembrane system?

• A series of membranes in which molecules are transported in the cell

• It consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes and vesicles

Protein synthesis


How does the endomembrane system function and appear?

Protein synthesis


Summary of the parts of the endomembrane system?

• Rough endoplasmic reticulum – studded with ribosomes used to make proteins

• Smooth endoplasmic reticulum – lacks ribosomes but aids in making carbohydrates and lipids

• Golgi apparatus – flattened stacks that process, package and deliver proteins and lipids from the ER

• Lysosomes – membranous vesicles made by the Golgi that contain digestive enzymes

• Vesicles – small membranous sacs used for transport

Protein synthesis


What are cilia and flagella?

• Both are made of microtubules

• Both are used in movement

• Cilia are about 20x shorter than flagella


What do mitochondria do and what do they look like?

• A highly folded organelle in eukaryotic cells

• Produces energy in the form of ATP

• They are thought to be derived from an engulfed prokaryotic cell


Cells—the fundamental unit of life• What is life?What is life?• Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles

• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


What is cellular respiration?• Occurs in the

mitochondria• Production of ATP

in a cell• Usually glucose is

main “energy” molecule enters cellular respiration

• Includes:– Glycolysis – Citric acid cycle – 3. Electron

transport chain


What other molecules besides glucose can be used in cellular respiration?

• Other carbohydrates

• Proteins

• Lipids


How can a cell make ATP without oxygen?

• Fermentation– Occurs in the cytoplasm– Does not require oxygen– Involves glycolysis– Makes 2 ATP and lactate in human cells– Is important in humans for a burst of energy

for a short time


All of cell metabolism• Cell metabolism is much more than simply making

ATP, or cellular respiration, which is just how the cell has an energy supply.

• What does the cell do with that energy?• Get ready for what you are about to see…• The cell runs all the reactions that make it alive—

see the first part of this presentation: grow, reproduce, develop, move, maintain internal homeostasis, respond to stimuli.

• This involves a LOT of chemical reactions. • Here it is: most of the reactions involved in

keeping the simplest of cells—an E. coli bacteria—alive!


Ecocyc—database of complete E. coli metabolism


What’s it all mean?• Every little box represents a stage in a particular

chemical reaction. The sum of those reactions is the total cell metabolism—what makes the cell alive!

• You’ll actually visit the ecocyc database under the web links for this section as the last thing you do

• Remember three things:1. every one of these reactions is catalyzed by a protein

2. The amino acid sequence for those proteins are coded for in the DNA

3. The world’s biggest super-computers are trying to figure out how, based on their unique amino acid sequence, all the different cellular proteins take on the particular shape they have, and control the particular reaction they catalyze. (You’ll also visit the Blue Gene IBM super-computer website in the web links for this section.)


Blue Gene


Cells—the fundamental unit of life• What is life?What is life?• Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles• Cell metabolismCell metabolism

• Cells organized into tissuesCells organized into tissues• Types of tissuesTypes of tissues


What is a tissue?• Multi-cellular organisms are composed of

millions and millions of cells whose metabolism is organized to work together.

• A tissue is a collection of cells of the same type that perform a common function

• There are 4 major tissue types in the body:1. Connective

2. Muscular

3. Nervous

4. Epithelial


How many cell types?How many cells?

• Each class of tissue might include a number of different cell types. In total, our bodies have a few hundred different types of cells

• How many total cells are in our body?


How many cells are in an adult human? Lots. More than anyone could count, and the bigger you are the more cells there would be. Growth is a process of cellular reproduction, so as you grow bigger you are made up of more cells. Following a similar logic, a larger person is larger because they have more cells, not because their cells are larger. In fact, cell types have a fairly uniform size across the entire human species.

The largest and smallest cells in the human body are the gametes, or the sex cells. The female sex cell, the oocyte, is about 35 microns in diameter, which puts it just on the edge of being visible if you have real good eyes. The male sex cell, spermatozoan, cell is only about 3 microns in diameter, and therefore is the smallest cell of the human body. Various other cell types have various other sizes within this range.

Although no exact number can be given, the order of magnitude of the number of cells in a human body can be approximated to 10 14 or one hundred trillion cells.

Source: MadSci Network http://www.madsci.org/posts/archives/mar98/889221957.An.r.html


Cells—the fundamental unit of life• What is life?What is life?• Molecules of lifeMolecules of life• Cell as fundamental unitCell as fundamental unit• Cell membranes and organellesCell membranes and organelles• Cell metabolismCell metabolism• Cells organized into tissuesCells organized into tissues



1. Epithelial tissue

• A groups of cells that form a tight, continuous network

• Lines body cavities, covers body surfaces and found in glands

• Cells are anchored by a basement membrane on one side and free on the other side• Different types of epithelial cells are named

after the appearance of cell layers and the shape of the cells

• There is transitional epithelium that changes in appearance in response to tension


What does epithelial tissue look like?


2. Connective tissue

• Binds and supports parts of the body• All have specialized cells, ground substance

and protein fibers • Ground substance is noncellular and ranges

from solid to fluid• The ground substance and proteins fibers

together make up the matrix of the tissue• There are three main types of connective

tissue: A. fibrous , B. supportive and C. fluid


Connective tissue holds things together

• Tendon, fascia• Bone• Cartilage• Throughout body

supporting blood vessels, nerves, cell populations (like in bone marrow, blood)


3. Muscle tissue• Allows for movement in the body

• Made of muscle fibers/cells and protein fibers called actin and myosin

• There are 3 types of muscle tissue in humans: A. Skeletal

B. Smooth

C. Cardiac


4. Nervous tissue• Allows for communication

between cells through sensory input, integration of data and motor output

• Made of 2 major cell types: A. Neurons—carry

messages

B. Neuroglia—support neurons


Cells—the fundamental unit of life (review)

• What is life?What is life?

• Molecules of lifeMolecules of life

• Cell as fundamental unitCell as fundamental unit

• Cell membranes and organellesCell membranes and organelles

• Cell metabolismCell metabolism

• Cells organized into tissuesCells organized into tissues



What is Life? • Life needs energy• Life reproduces• Life grows and

develops• Life maintains a

stable condition—homeostasis

• Life responds to stimulus

• Life is organized because it has evolved


The Carbon-chain Molecules of Life

MOLECULE MADE OF FUNCTION

Carbohydrates Simple Sugars Energy

Proteins Amino Acids Catalyze reactions

Fats Fatty Acids Cell membranes

DNA/RNA Nucleotides (bases)

Information


WHAT CAN EUKARYOTIC CELLS DO?

WHAT STRUCTURES ARE INVOLVED?

Separate inside of cell from external environment and control what substances pass across membrane

Cell Membrane

Produce proteins/enzymes that catalyze chemical reactions or control movement across membrane

Nucleus (DNA), Ribosomes on rough endoplasmic reticulum

Break down sugars to form energy which is stored in phosphate bonds of ATP

Mitochondria

Organize distribution of Molecules of Life (macromolecules) and ions throughout cell

Internal membrane system and “cytoskeleton” (ER, lysosomes, vessicles, microtubules)

Move Flagella, cilia, pseudopods


A cell membrane or plasma membrane separates cell from outside world—creates ability to regulate internal environment (homeostasis)


Protein synthesis• Remember that proteins control cell

metabolism—how and where are they made, or synthesized in the cell?


Ecocyc—database of complete E. coli metabolism


What is a tissue?• Multi-cellular organisms are composed of

millions and millions of cells whose metabolism is organized to work together.

• A tissue is a collection of cells of the same type that perform a common function

• There are 4 major tissue types in the body:1. Connective

2. Muscular

3. Nervous

4. Epithelial


This initial review of life and cells is crucial!

• Please read your book chapters, review the web links and get this part of the course.

• We’ll come back to cells and how they work again and again.

• I am aware this is a LOT of information!

• But master this, and the rest of the course will seem easy.

Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cells—the fundamental unit of life...

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