Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell Metabolism and Mitosis Cellular RespirationCellular Respiration Total cell metabolismTotal

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

Cell Metabolism and Mitosis

• Cellular RespirationCellular Respiration

• Total cell metabolismTotal cell metabolism

• MitosisMitosis

• Review of cellsReview of cells


Cell metabolism


Catabolic pathways: break down larger molecules in to smaller ones (starch into sugar, proteins into amino acids, for example) releasing energy, most of which is lost as heat, but some can be stored as ATP

Anabolic pathways: Build up larger molecules from smaller component parts (for example, assembling proteins from amino acids, assembling lipid membranes from fatty acids). These reactions use energy, usually provided by breaking high energy phosphate bonds of ATP


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 – Electron transport

chain


• Cells use carbohydrates to make ATP, which stores high energy bonds for anabolic pathways.

• Oxygen allows for complete "burning" or catabolic breakdown of sugars in Krebs Cycle

• But some ATP can be obtained in anaerobic, or pathways that are free of oxygen

Oxygen and "cellular respiration”


Glycolysis



Kreb’s cycle


Electron transport chain




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

• Other carbohydrates

• Proteins

• Lipids


"Raw material" for anabolic or synthetic pathways• amino acids • fatty acids • nucleotides • sugars

Some cells can make most of these from crude and even inorganic material. Some cells need to obtain these from environment


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


Fermentation is oxygen-free respiration where organic molecules are ultimate electron acceptor. Many groups of bacteria are fermenters.


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

http://www.research.ibm.com/journal/sj/402/allen.html


GENETICS (the quick view—much more later)

• Cells divide and pass on instructions coded in DNA of chromosomes

• Each chromosome is a huge DNA molecule with coded information– DNA replicates to pass on information– DNA is transcribed to make proteins

that run cell metabolism

• Cancer—example of what happens when genetic control goes awry

• Normal inheritance and meiosis


Mitosis—cell division

• Why do cells divide?– Growth—so tissues/structures can become

larger– Replacement—many tissues are constantly

being replaced because they get worn out or used up. E.g. blood, skin, lining of gut, sperm

– Repair—when tissues get damaged due to injury


Mitosis—what happens (overview)• DNA/chrosomes replicate

(make exact copies• Copies line up at center

of cell• Copies pulled to opposite

ends of cells by centromeres/spindles

• Cell membrane pinches off and splits cell into two


Mitosis—details/stages

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase


1. Mitosis: Prophase

• Chromosomes condense and become visible

• Nuclear envelope fragments

• Nucleolus disappears

• Centrosomes move to opposite poles

• Spindle fibers appear and attach to the centromere


2. Mitosis: Metaphase

• Chromosomes line up at the middle of the cell (equator)

• Fully formed spindle


3. Mitosis: Anaphase

• Sister chromatids separate at the centromeres and move towards the poles


4. Mitosis:Telophase and cytokinesis

• Chromosomes arrive at the poles

• Chromosomes become indistinct chromatin again

• Nucleoli reappear• Spindle disappears• Nuclear envelope

reassembles• Two daughter cells are

formed by a ring of actin filaments (cleavage furrow)


Mitosis—constant, fast, keeps body functioning

• Remember, mitosis produces two identical daughter cells

• Mitosis is constantly happening in your body to allow for growth, replacement and repair

• While you read this slide, millions of new cells were produced by mitosis in the tissues of your body!

• Don’t forget cellular scale and intelligence—it’s a whole planet happening at the sub-microscopic level


Review of class so far


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


• 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


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?


Cell metabolism


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


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 – Electron transport

chain


Ecocyc—database of complete E. coli metabolism

E. ColiMetaobolismwebsite


Mitosis—cell division

• Why do cells divide?– Growth—so tissues/structures can become

larger– Replacement—many tissues are constantly

being replaced because they get worn out or used up. E.g. blood, skin, lining of gut, sperm

– Repair—when tissues get damaged due to injury


Mitosis—what happens (overview)• DNA/chrosomes replicate

(make exact copies• Copies line up at center

of cell• Copies pulled to opposite

ends of cells by centromeres/spindles

• Cell membrane pinches off and splits cell into two


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.

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Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell Metabolism and Mitosis Cellular RespirationCellular Respiration Total cell metabolismTotal