Download Basics of What You Need to Know About Carbohydrates, Cells

Proteins, Nucleotides, Metabolism and the
Cell 8/29







What is the hierarchy of protein folding?
What happens when proteins denature?
What are nucleotides and what do they do?
ATP is the universal energy currency of cells!
How are catabolic and anabolic reactions the “Ying and
Yang” of metabolism?
What is “Cell Theory”?
What limits cell size and determines cell shape?
For the test/quiz: Draw two peptide
bonds that would be required to link
three amino acids into a tripeptide.
Proteins also have shapes and levels of
folding that are important considerations
with respect to function and denaturation.
Levels of Protein Structure:
 PrimarySecondaryTertiaryQuaternary
 Primary: This is amino acid order and location of dissulfide
bonds in chain sequence
 Secondary: H-bond interactions between adjacent backbone
of amino acids. 2o structure can create sheets, globular
structures and tubes
 Tertiary: H-bond and ionic interactions between R-groups on
the amino acids. 1o dissulfide bonds may “stabilize” tertiary
structure (Consider a hair perm)
 Quaternary: Sometimes two or more protein chains stabilize
each other when they fit together….consider Hemoglobin.
 Prosthetic Groups: iron and the “heme”
 Co-factors: vitamins, Calcium, etc
Each color is a different protein chain
“denaturation” causes loss of enzyme function!
1) The more unfolded a protein becomes the less
of its original function REMAINs!
2) Once a protein is unfolded it may or may not
be able to return to its original shape and
function.
Pepsin and Trypsin are digestive enzymes that
cut the peptide bonds of proteins.
Why does pepsin work in the stomach?
Why does trypsin work in the intestine?
What happens if an enzyme is turned “ON” in
the wrong place? (i.e. trypsin in the lung)
Why can’t a diabetic take insulin as a pill?
Insulin actually consists of two small segments of protein held
together by disulfide bonds (-S-S-) in a very special shape.
Enzymes only become/stay active within a specific pH or
temperature! Enzymes also have a specific environment where
they are optimally active. Each enzyme has unique optima that
may be unique to each different enzyme.
Has an understanding of protein structure improved your
understanding of how function and structure are linked?
Why does a small change in pH have a large effect on
enzyme function?
pH = -log(H+)
pH=-log(0.0000001)= 7
pH= 7.5 = 0.00000032 moles H+/liter
Nucleotides are important for energy
metabolism, production of proteins
and storing genetic information.
Parts of a nucleotide:
 Ribose– Without -OH = DNA
– With-OH = RNA
 High energy phosphate
chain Nitrogenous BASE:
Adenine (ATP)
Thymine (TTP)
Guanine(GTP)
Cytosine(CTP)
Uracil (UTP)
 “Cyclic”AMP
 Single vs. Chain
NUCLEIC ACIDS ARE THE STUFF OF LIFE!
DNA: deoxyribonucleic acid RNA: Ribonucleic acid
RNA and DNA are both made from nucleotides


DNA stores our genetic information and is used to make RNA
4 Bases: Adenosine, Thymine, Cytosine and Guanine
(Not Uracil)
ATGC
– Ribose has a hydrogen instead of a hydroxyl group
– Hydrogen changes solubility and causes two
complimentary strands to form a double helix
RNA is used to make proteins AUGC
4 Bases: Adenine, Cytosine, Guanine, Uracil (Not Thymine)
– Ribose has the hydroxyl group and cannot form stable
double helix
– Pattern of nucleotides is used to make a protein with a
unique primary sequence
– DNA or RNA: Which has ribose? Which has Uracil?
What does DNA or RNA look like?
RNA makes: Protein
Has –OH on ribose
No double helix
DNA makes: RNA
Ribose has no –OH
“deoxyribose”
Double stranded Helix
ATP is broken down to sequentially
release energy!
Enzymes tightly control this process.

ATP ADP + Pi + Energy

ADP AMP + Pi + Energy

AMP  Adenine + Pi + Energy
These two important reactions that create “information” in the
cell:
 ATP cAMP + PPi + Energy + Information
– Effect in lung:
 GTP cGMP + PPi + Energy + Information
– Effect in reproductive organs:
ATP is the energy currency of the body. Most of our ATP is
produced in the mitochondria, but some cells (red blood cells)
lack mitochondria and can only generate ATP anaerobically.
Energy is released when ATP is broken down to ADP and PO4.
The energy can be used to overcome the activation energy for
many (but not all) enzyme catalyzed chemical reactions.
The name of an “enzyme” usually has “–ase” at the end
“Kinases” attach phosphate from a nucleotide to a target (add
energy). Phosphorylation= Pi attachment to a substrate
“Phosphatases” remove the phosphate from a target (release
energy). Dephosphorylation= Pi removal from a substrate.
Consider energy in a muscular contraction or the movement
of a flagella that permits a sperm to “swim”:
Energy can also be carried/delivered in the form of a highenergy electron that is temporarily “stored/stabilized” by
important co-factor molecules such as FADH2 or NADH
NADH is used to shuttle energy rich electrons to the
mitochondria where most of our ATP is produced!
Catabolism (breakdown) of lipids, carbohydrates and proteins
yields energy via aerobic or anaerobic routes.

Glucose is cleanest burning fuel in the body>>CO2

Fat can also be used to produce ATP

Aerobic Requirements

Anaerobic Fallback:

Conversion of substrates to glucose before entering
metabolic routes:
Anabolic Reactions in the body use energy to make
more complicated molecules (energy storage).

Carbohydrate monomers are stored as polysaccharides for
later use

Energy is used to make fatty acids which are stored for use
later (Triglycerides) or used to make plasma membranes of
cells
 Energy is used to create peptide bonds between amino
acids….this makes proteins
Your metabolism (Metabolic Rate) is the sum of all the
catabolic (energy releasing) and anabolic (energy storing)
reactions occurring in your body at any given time.
What is metabolism?



Sum of all catabolic and anabolic reactions in a cell.
Sum of all catabolic and anabolic reactions in a body.
The Ying and Yang of the chemical reactions that make up our
metabolism seek to maintain homeostasis in a cell and the whole body!
Are you using Catabolic or Anabolic Reactions?
 If you are “gaining” weight?
 If you are “losing” weight?
 If you sitting quietly?
 If you are exercising?
The cell is the functional unit of all life. Organisms
can consist of a single cell or groups of cells with
varying degrees of specialization.
Cell Theory:
 Organisms are composed of cells
 Cell is simplest single unit of life
 Cell structure/function relate to activity
 All cells come from pre-existing cells
 Cells share common similarities
Folks that Examine Cells for a Living:
 “Cytologist”:
 “Hematologist”
 “Oncologist”
Why do cells have a specific size,
shape and function?

Shape is often dependent on the needs of the cells specialized
activity:

Size Range: 0.01-0.1 mm diameter (Huge= 1mm oocyte)
What limits cell size?






Plasma membrane holds things in a cell!!
Membrane proteins control movement in/out of a cell!!
Organelles allow for specialization within a cell!
Second messengers are chemicals that allow for information
movement in a cell.
Hormones/neurotransmitters carry information between cells!