Lecture 2Chemistry, Cytology, DNA,

Cellular Respiration, Protein Synthesis

Chemistry, Matter and Life

A. Chemical Bonding of Matter1. Atoms are the simplest forms of matter 2. Elements are composed of the same type of

atoms 3. Molecules – formed when 2 or more atoms

become chemically bonded.

4. Compounds – formed when atoms of different kinds become chemically bonded.

5. Formula – a representation of the number and kinds of atoms in a molecule or compound.

6. Chemical reactions a. When a chemical reaction occurs, bonds between atoms are broken(energy is released) or formed, (energy is stored). b. Two kinds of chemical reactions are: 1.) Synthesis – in which smaller atoms or smaller molecules combine to from larger ones. (Anabolism). 2.) Decomposition – in which larger molecules are broken down to form smaller ones, (Catabolism)

B. Acids, Bases and pH 1.Compounds that ionize when they dissociate in water and can conduct an electric current are called electrolytes. 2. Electrolytes that release hydrogen ions (H+) are acids, and those that release hydroxide ions (OH-) are bases. 3. The concentration of hydrogen ion (H+) in a solution is represented on a scale of 0 to 14 and is known as pH (potential hydrogen). A pH of 0.0 6.99 is acidic A pH of 7.0 is neutral A pH of 7.01 14 is basic (alkaline).

7.4

4. Solutions with equal numbers of H+ and OH- = neutral Solutions with more H+ than OH- = acidic pH<7.00 Solution with fewer H+ than OH- = base. pH>7.00

C. Chemical constituents of Cells

Molecules containing carbon and Hydrogen atoms are organic and are usually nonelectrolytes;

Those lacking carbon atoms are inorganic and are usually electrolytes.

1. Inorganic substances: common examples a. Water is the most abundant compound in cells and serves as a substance in which chemical reactions occur; it also transports chemicals and heat. (universal solvent) b. Oxygen (O2) is used in releasing energy from glucose and other molecules. (oxidation) c. Carbon dioxide (CO2) is produced when energy is released from glucose and other molecules. e. Inorganic salts provide ions (charged particles) needed in metabolic processes. (Na+, K+, Cl-, Ca++)

2. Organic substances a. Carbohydrates provide much of the energy needed by cells; their basic building blocks are simple sugar molecules (monosaccharides)

Disaccharides:=2 simply sugars

Polysaccharides =many simple sugars

b. Lipids supply energy; their basic building blocks are molecules of glycerol and 3 fatty acids.

Steroids

Cholesterol, also includes the sex hormones, vitamin D and others

c. A phospholipid, major lipid of cell membranes.

c. Proteins serve as structural materials, an energy source and enzymes. 1.) Enzymes initiate and accelerate metabolic reactions in the body. 2.) The building blocks of protein are the 20 common amino acids.

3.) Different kinds of proteins vary in the number and kinds of amino acids they contain, and in the sequences (linear order) in which these amino acids are arranged.

4.) Protein molecules can be denatured by heat, strong acid, etc. When denatured, protein shape changes and the protein becomes nonfunctional.

Denatured

Heat

d. Nucleic acids control cell activities. 1.) The two kinds: a.) RNA – ribonucleic acid. b.) DNA – deoxyribonucleic acid. 2.) They are composed of building blocks called

nucleotides. Nucleotides contain: a.) A 5 carbon sugar, either ribose (in RNA) or deoxyribose (in DNA). They differ from each other by one oxygen atom! b.) A phosphate group (PO4) c.) one of five different nitrogen bases. RNA – Guanine, Cytosine, Adenine, Uracil DNA - Guanine, Cytosine, Adenine, Thymine

Cellular Anatomy and Physiology

A. General Cell Features 1. The cell is the basic unit of structure and function in all organisms. The study of cells is Cytology. Cells are the smallest part that is considered alive. 2. Cells range in size from 1/12,000 of an inch to

over3 feet for the neurons that help you wiggle your toes!

3. Cells vary widely in shape and form which is related to its function.

4. Kinds of cells a. Prokaryote “before a nucleus” lack a membrane surrounding their DNA and are said to lack a distinct nucleus, they have a “nucleoid”. 1.) Bacteria are common prokaryotes.

b. Eukaryotes are cells that have a distinct nucleus. 1.) Plant – has chloroplasts and a thickened

cellulose cell wall. 2.) Animal – has centrioles which plants lack, but lacks the rigid cell wall and chloroplasts.

5. Cell organelles “little organs” are often composed of membrane material or granular arrangements of microtubules.

B. Membranous Organelles 1. Cell membrane – “molecular traffic cop”, it regulates materials that enter and leave the cell.

2. Endoplasmic reticulum – two types; a. Rough, has attached ribosomes, synthesis of proteins for export (secretion). b. Smooth, lacks attached ribosomes, synthesizes lipids, carbohydrates, detoxifies medications & toxins.

3. Golgi apparatus- “protein packaging factory” 5 to 8 flattened sacs that package, address and modify secretions, forms lysosomes.

4. Lysosome – “Stomach” of the cell. Contains enzymes that can digest all organic compoundswithin the cell. Destroys worn out cells, organelles and foreign materials.

5. Vesicles – membranous sacs that form by pinching off from the cell membrane or an organelle membrane

These sacs can move solids or liquids into (endocytosis) or out of (exocytosis) the cell

6. Mitochondrion – “Powerhouse”, bean shaped double membrane organelle. Inner folded membranes (cristae) are the locations of cellular respiration. O2, ADP, and food material enter, ATP, H2O and CO2 are formed.

C. Microtubules and Related Organelles 1. Cytoplasmic microtubules – compose part of the cytoskeleton, cilia, flagella, form the mitotic spindle and provide a path for movement of organelles within the cell.

2. Centrioles – a pair of microtubular organelles in cytoplasm near the nucleus that are the microtubular organizing center, form spindle fibers, cilia and flagella. 3. Spindle fibers – visible during cell division, attach and move chromosomes to poles of daughter cells. 4. Cilia and Flagella – cilia are short, numerous and move material along cell surfaces. Flagella are long, few in number, propel entire cells, sperm.

D. Granular Organelles1. Ribosomes – “protein factory” for protein synthesis. a. Free ribosomes float in cytoplasm and produce proteins and enzymes for

use within the cell. b. Attached ribosomes - are

found on the surface of rough endoplasmic (Rough ER). They synthesize, package within transport

vesicles proteins for secretion out of the cell.

Ribosomes

2. Nucleolus – within the nucleus, its presence indicates the cell is synthesizing large and small ribosomal subunits from ribosomal RNA and polypeptides made in the cytoplasm.

E. Nucleus “control center” 1. Chromosomes (46) containing genes (25,000). A “gene” is a segment of a chromosome that codes for a protein. When DNA is controlling the cells activity it is stretched out, diffuse, and is called chromatin. When a cell is dividing it supercoils into the chromosomes we see as finger like structures. 2. DNA – double strand of complementary nucleotides based on the pairing rules A = T, C Ξ G. 3. RNA – usually a single strand of nucleotides; the nitrogen base Uracil sub for Thymine in its strands. RNA base pairing is; A = U, C Ξ G.

How information is carried in nucleic acid

1. Genetic information is organized into units called genes

2. The order of the bases in the gene called the genetic code

3. DNA has a coding and noncoding strand

4. Composed of nucleotides that form a double helix1. Sugars and phosphates hold the

bases in the right order2. The nucleotides pair with each

other5. The pairing of the bases with its

partner directs the copying process6. The order of the bases are read in

groups of 3 (codons)

How information is carried in nucleic acid

The information in the DNA is “read” by the RNA molecules

Types of RNA (3)

1. Messenger RNA (mRNA)= produced from the DNA molecule by transcribing the genetic code

2. Transfer RNA (tRNA)= binds to the codon (via an anticodon) this carries an amino acid, once bound it transfers the amino acid to the growing protein

3. Ribosomal RNA ( rRNA)= part of the ribosome,

Fig. 4.13

Each triplet codon specifies 1 amino acid

By changing the order or length of the you get a different protein

4. Protein synthesis – the making of a protein involves transcription – in nucleus (DNA code messenger RNA (mRNA). translation – in cytoplasm (mRNA code read by ribosome) to construct a protein (a chain of individual amino acids bonded together). a. DNA – master blueprint for proteins b. mRNA – receives a complementary code of DNA strand (transcription in the nucleus). c. Amino acids type and order of assembly are coded for on the mRNA strand (translation by the ribosome in the cytoplasm). mRNA code ribosome protein. d. Chain of specific A.A in a specific order protein e. tRNA – brings appropriate A.A. to ribosome during elongation of the chain that will become the protein.

F. Energy Production by the cell 1. Glycolysis “glucose splitting” is a chemical pathway in

the cytoplasm. 6 carbon glucose is split into two 3 carbon molecules called pyruvic acid. 2 ATP are also formed. Glycolysis is “anaerobic” no O2 needed. 2. Pyruvic acid enters the mitochondrion where the citric

acid cycle breaks the bonds of the 2 pyruvic acids and stores their energy (in carriers) while making 2 ATP.

3. The Electron Transport System (ETS) passes along the stored energy carriers from the citric acid cycle to make

34 ATP using the energy of H+ to recharge the ADP into ATP.