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Lecture 2 Chemistry, Cytology, DNA, Cellular Respiration, Protein Synthesis. Chemistry, Matter and Life. Chemical Bonding of Matter Atoms are the simplest forms of matter Elements are composed of the same type of atoms
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Chemistry, Cytology, DNA,
Chemical Bonding of Matter
Atoms are the simplest forms of matter
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.
a. When a chemical reaction occurs, bondsbetween
atoms are broken(energyis released)orformed,
(energy is stored).
b. Two kinds of chemical reactions are:
1.) Synthesis – in which smaller atoms or smaller
molecules combine to from larger
2.) Decomposition – in which larger molecules are
broken down to form smaller
1.Compounds that ionize when they dissociate in water
and can conduct an electric current are called
2. Electrolytes that release hydrogen ions (H+)are
acids, and those that release hydroxide ions (OH-)
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).
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 organicand are usually nonelectrolytes;
Those lacking carbon atoms are inorganic and are usually electrolytes.
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.
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++)
a. Carbohydrates provide much of the energy needed
by cells; their basic building blocks are simple sugar
molecules of glycerol and 3 fatty acids.
Cholesterol, also includes the sex hormones, vitamin D and others
source and enzymes.
1.) Enzymes initiate and accelerate metabolic
reactions in the body.
2.) The building blocks of protein are the 20 common
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.
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
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.
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
5. Cell organelles “little organs” are often composed of
membrane material or granular arrangements of
1. Cell membrane – “molecular traffic cop”, it regulates
materials that enter and leave the cell.
a. Rough, has attached ribosomes, synthesis of proteins
for export (secretion).
b. Smooth, lacks attached ribosomes, synthesizes lipids,
carbohydrates, detoxifies medications &
3. Golgi apparatus- “protein packaging factory” 5 to 8 flattened sacs that package, address and modify secretions,
4. Lysosome – “Stomach” of the cell. Contains enzymes that can digest all organic compoundswithinthe 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
membrane organelle. Inner folded membranes
(cristae) are the locations of cellular respiration. O2,
ADP, and food material enter, ATP, H2O and CO2 are
1. Cytoplasmic microtubules – compose part of the
cytoskeleton, cilia, flagella, form the mitotic spindle
and provide a path for movement of organelles within
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.
1. 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.
the cell is synthesizing large and small
ribosomal subunits from ribosomal RNA
and polypeptides made in the cytoplasm.
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.
The information in the DNA is “read” by the RNA molecules
Types of RNA (3)
Messenger RNA (mRNA)= produced from the DNA molecule by transcribing the genetic code
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
Ribosomal RNA ( rRNA)= part of the ribosome,
Each triplet codon specifies 1 amino acid
By changing the order or length of the you get a different protein
transcription – in nucleus (DNA code messenger RNA
translation – in cytoplasm (mRNA code read by ribosome)
to construct a protein (a chain of individual amino acids
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
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.
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