Chemistry, Cellular Structure, and

FunctionSurgical A&P for Surgical Technologists

Frey and Price

Describe the basic concepts of chemistry Compare and contrast the structures and

functions of the cell Evaluate the importance of cell movement

and responsiveness Compare and contrast the elements of cell

reproduction Compare and contrast glycolysis and the

Krebs cycle

Objectives

Surgical technologists deal with tissue and organs on a daily basis.

The foundation for tissues is cells. We have to understand cells so that we

understand sterility (the destruction of certain cells)

Surgical technologists come into contact with cancerous cells on a near daily basis

Refer to case study 1 p. 17

Why do we have to study chemistry?

Anything that takes up space and has mass

Weight and mass are different.◦ Weight represents the gravitational pull on an

object◦ Objects in space still have mass even though they

are weightless

Matter

All matter is made of atoms

Different matter is made of different types of atoms

Matter constantly changes, physical states can change, but it will retain fundamental characteristics◦ Water in solid form is ice, liquid is water, and gas

is steam

Matter, cont’d

Energy causes change in matter Light, electricity, sound, heat, and

mechanical energy Mechanical energy makes objects move or

change course Objects can store energy as “potential

energy” Kinetic energy is the energy of motion

◦ Total mechanic energy is the sum of potential and kinetic energy

Energy

Made of subatomic particles◦ Protons are positively charged◦ Electrons are negatively charged◦ Neutrons are neutral

Atoms

Atomic mass is the mass of the protons and neutrons that make up the nucleus

Atomic number is the number of protons in the nucleus

An isotope is two elements that have the same number of electrons, but different number of neutrons. The difference in the number of neutrons changes the atomic mass, but the atomic number is still the same.

Electrons orbit around the nucleus like the planets orbit the sun◦ Valence electrons are in the outermost orbit

Atoms, cont’d

Each energy level can only hold a certain number of electrons◦ 1st level has the capacity for only 2 electrons◦ 2nd-4th level can hold up to 8 electrons

The valence (outermost) electrons determine how atoms behave

Ionization is the gain or loss of an electron◦ Positive ions LOST an electron (remember, electrons

have a negative charge◦ Negative ions GAINED an electron

Electrons

Elements are made of only one type of atom◦ Oxygen is made only of oxygen atoms◦ Hydrogen is made only of hydrogen atoms

COHN- 96% of living things are made from Carbon, Oxygen, Hydrogen and Nitrogen

Elements

Can be broken down into smaller substances

Represented by formulas

◦ For example: water is a compound made of two hydrogen atoms and one oxygen. The formula is H2O

Compounds

Atoms joined by chemical bonds

Molecular weight is the sum of the atomic weights

Molecules

Inorganic compounds do not contain carbon◦ Salts, CO2, water, acids and bases

Organic compounds contain carbon-hydrogen bonds◦ Proteins, fats and carbohydrates

Inorganic vs. Organic

A charged atom (one that has given up or taken an electron) is called an ion

A compound that dissociates (breaks apart) in water and forms positive and negative ions is an electrolyte◦ Salt in water is an electrolyte because the salt

breaks apart and forms sodium and chlorine ions

Ions and Electrolytes

Acids are substances that increase the number of H+ ions in a solution

Bases decrease the number of H+ ions in a solution

Acids and Bases

The scale ranges from 0-14

7 is neutral

0-6.9 is an acid; the closer to 0, the stronger the acid

7.1-14 is a base; the closer to 14, the stronger the base

Blood must remain in very strict limits; 7.35-7.45

pH Scale

The smallest living unit of the human body

Cancer is a cell that malfunctions and reproduces itself

Cells

1. All known living things are made of cells

2. The cell is the structural and functional unit of all living things

3. All cells come from preexisting cells by division (no spontaneous generation)

4. Cells contain hereditary info, which is passed from cell to cell

Cell Theory

5. All cells are basically the same in chemical composition. (Same types of organelles)

6. All energy flow of life occurs within cells.

Cell Theory, cont’d

Animal cells posses specific structures

Cells may vary by shape, location, and function

Cell Strucutre

Cells are not always perfect spheres. The shape can be controlled by substances outside the cell, or the contents of the cell.

Some cells will maintain their shape, others will vary

The mass of organs is due to the number of cells, not the volume of the cells

Cell Size and Shape

All cells contain:◦ Carbohydrates

◦ Proteins

◦ Lipids (fats)

◦ Nucleic acids

Cell Composition

Aka sugars

Carbon, hydrogen and oxygen form long chains to make carbohydrates

Monosaccharide-single sugar Disaccharide- double sugar Polysaccharide- many sugars

Carbohydrates

Made of amino acids attached to one another by peptide bonds

20 types of amino acids

Proteins

The fats

Fats are solid at room temperature, oils are liquid at room temperature

Lipids

RNA- ribonucleic acid

DNA- deoxyribonucleic acid

RNA and DNA are made of nucleotides

Each nucleotide has a nitrogenous base, a sugar and a phosphate

The nitrogenous bases are:◦ Adenine-thymine◦ Cytosine-guanine◦ Uracil replaces thymine in RNA

Nucleic Acids

The material that lies within the boundaries of the cell

Contains no genetic material

Contains the organelles

Cytoplasm

Surrounds the cell and separates the inside of the cell from the outside

Allows cells to interact with their surroundings if needed

Phospholipids and proteins compose the membrane◦ The phosphate end of the phospholipids love

water, the 3 fatty acid tails repel water

Cell (Cytoplasmic) Membrane

Keeps cytoplasm in

Osmosis is a process where water equilibrates on both sides of the cell membrane. The cell membrane is selective about what comes in and out. Nutrients in, waste out.

Functions of Cell Membrane

Some substances are too big or polar, and cannot cross the membrane. To allow the entry of certain substances, there are 4 transport systems◦ Passive diffusion◦ Facilitated diffusion◦ Group translocation◦ Active transport

Transportation through the membrane

Passive diffusion- no energy is required

Facilitated diffusion- no energy is required, a molecule binds to a specific protein in the cell membrane. It is selective.

Group Translocation- most requires energy. The target molecule is chemically changed as it enters the cell.

Active transport- pumps are used to move substances up the concentration gradient. Energy in the form of ATP is required.

Transport Processes

Largest structure within a cell. Eukaryotic cells are animal cells. They

possess a true nucleus surrounded by a nuclear membrane.

Prokaryotic cells are any cells not found in animals. They do not have a true nucleus.

Nucleus houses DNA See functions on pg 25

Nucleus

Endoplasmic reticulum is continuous with the membrane.

Nuclear envelope is similar to the cell membrane, but it surrounds the nucleus

The envelope has small holes that will allow a few substances to move into and out of the nucleus

Nuclear Membrane

Contains ribosomes, RNA, DNA, and proteins

rRNA is transcribed and processes and assembled into ribosomes

Ribosomes leave through the nucleus and they aid in protein synthesis

Nucleolus

Chromatin contains the genetic code and is stored in chromosomes

Two types of chromatin◦ Heterochromatin is condensed chromatin◦ Euchromatin is most abundant in active,

transcribing cells. The DNA must uncoil before the code can be read.

Chromatin and Chromosomes

Lysosomes Vacuoles mitochondria ER Golgi apparatus Ribosomes Centrioles Cilia Flagella

Organelles

Lysosomes digest waste materials and food

Vacuoles are areas of the cell membrane that fold inward and trap substances on the outside of the cell. It will pinch off and bring the molecule inside. (Think Pac-Man)

Endoplasmic reticulum (ER) transports substances. Rough ER is covered in ribosomes. Smooth ER is not.

Organelles

Mitochondria convert food into ATP. They are the major source of energy for the cell. Mitochondria have their own DNA. All mitochondria are derived from the mother. This is a very useful tool in forensics or identification.

The Golgi apparatus modifies and refines proteins and packages them in vesicles.

Organelles, cont’d

Ribosomes are the protein factories and can be free in the cytoplasm or attached to ER. The main function is to serve as mRNA translation.

Centrioles are rod-shaped and play a role in cell division

Cilia are shorter than flagella and function to move fluid or materials past an immobile cell. Millions of cilia line the respiratory tract to keep substances from entering the lungs.

Organelles, cont’d

Flagella are whip-like and propel a cell. The only flagellated cell in the human is sperm.

Organelles, cont’d

Some cells must be able to move throughout the body.

Cancer cells are very capable of movement.

Understanding how cancer cells move may lead to the advancement in fighting cancer.

Cell Movement

There are 46 chromosomes inside the nucleus and 1000’s of genes are contained on each chromosome.

The nucleic acids (RNA and DNA) contain our hereditary info.

DNA is the cookbook, RNA translates the cookbook

Nucleic Acids

Adenine pairs with Thymine◦ Forms two hydrogen bonds

Cytosine pairs with Guanine◦ Forms three hydrogen bonds

Base Pairing

DNA is a double helix structure

RNA is single stranded

DNA will “unzip” and a copy of one side will be made. This copy is called messenger RNA or mRNA.

Each 3 bases are called a triplet, and that is the specific code for one amino acid

DNA and RNA

Transfer RNA or tRNA lives in the cytoplasm. The tRNA picks up the appropriate amino acid

When all of the amino acids have been assembled and all of the peptide bonds have been formed, it is now a protein.

DNA and RNA

Before cells divide, the DNA must make a copy of itself.

The DNA will ‘unzip’ and one side serves as a template to make a complementary strand.

After complete division, each cell will have one old side and one new side.

DNA Replication

5 Stages◦ Prophase◦ Metaphase◦ Anaphase◦ Telophase◦ Interphase

Mitosis

Chromosome condense and distribute between the two cells

Centromere forms between two identical chromosomes

Microtubules from each side of the cell attach at the centromere.

Prophase

The chromosomes will line up in the middle of the cell

The microtubules will eventually pull the chromosomes apart.

Metaphase

The centromere is pulled apart.

One chromosome goes to one side, the other goes to the other side.

This equally divides DNA in the two cells

A cleavage furrow appears by late anaphase

Anaphase

Each chromatid is now a separate chromosome

New nuclear envelope starts to appear

Cell membrane will be completed for each cell.

Telophase

Used to be called “resting phase”, but there is no resting happening!!!

Organelles begin to form, nutrients are absorbed.

Interphase lasts until the next mitosis.

Interphase

Formation of gametes (sperm and ova)

Unlike mitosis, the cells divide twice in meiosis. Each resulting cell will have half of the genetic material (23 chromosomes)

In males, meiosis is spermatogenesis In females, oogenesis

Meiosis

Chromosomes become visible

Chromosomes have duplicated and become chromatids attached by a centromere

“crossing over” can occur

1st meiotic prophase

Chromosomes line up in the middle

1st meiotic metaphase

Chromosomes and chromatids will move to one end of the spindle

This results in each daughter cell only getting one copy

1st meiotic anaphase

Two daughter cells will appear

Nuclear membranes appear around the chromosomes

1st meiotic telophase

Chromosomes re-appear

Chromatids are joined by a centromere

2nd meiotic prophase

The chromosomes attach to spindle fibers

2nd meiotic metaphase

Centromeres separate

Chromatids move to opposite ends of the cell

2nd meiotic anaphase

The cell division is complete

Spermatogenesis results in the formation of 4 sperm cells with 23 chromosomes

Egg cells also contain 23 chromosomes

2nd meiotic telophase

Glycolysis and Kreb’s cycle

Cellular respiration is the process of oxidizing food molecules and turn them into carbon dioxide and water.

Glycolysis occurs in the cytoplasm, the Kreb’s cycle occurs in the mitochondria

Cellular Respiration

Aka anaerobic metabolism (no oxygen required)

Glyco= sugar Lysis= to break down

Glucose is broken down into pyruvate

Only 4 ATP particles can be made from one glucose

The pyruvate is taken to the mitochondria where it is converted to acetyl coenzyme A (acetyl coA)

Glycolysis

Aka aerobic oxidation, the citric acid cycle, or tricarboxylic acid cycle

Takes place in mitochondria

There are ten steps and the acetyl coA yeilds energy and CO2

Electrons are taken out of the food we eat to help produce ATP and other cellular functions

Kreb’s Cycle

Pyruvate enters mitochondria and CO2 is released. Acetyl coA is formed.

Acetyl coA joins a 4-carbon molecule called oxaloacetate to form citric acid

Citric acid is broken down and carbon and hydrogen ions are released.

The hydrogen ions are picked up NAD+ and FAD+ and ATP is released.

Kreb’s cont’d

CBC includes◦ White blood cell count◦ Red blood cell count◦ White blood cell types◦ Hematocrit◦ Hemoglobin◦ RBC indices◦ RBC distribution width◦ Platelet count◦ Blood smear

CBC

What is chemistry?

What is mass? Matter?

What are the subatomic particles?

What is atomic number? Atomic mass?

What is an element?

Summary

What is a compound?

What distinguishes an organic compound?

What is an ion?

What is the pH scale? What values are given to acids? Bases?

Summary

What are the 4 primary organic molecules?

What are proteins made of?

What are the organelles?

What are the four types of transport systems?

What are the nucleic acids?

Summary

What is mitosis?◦ What are the stages?

What is meiosis?◦ What are stages?

Summary