Thursday 11/21/13. AIM: Why do we eat proteins DO NOW: What are biomolecules? Why are biomolecules organic compounds? HW:Read page 62. reading check on page 62 and question 4 on page 63. Review. What are the 4 categories of biomolecules? Why are biomolecules called polymers?
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What are the 4 categories of biomolecules?
Monomers form larger molecules by condensation reactions called dehydration reactions
Dehydration removes a watermolecule, forming a new bond
(a) Dehydration reaction in the synthesis of a polymer
Hydrolysis adds a watermolecule, breaking a bond
(b) Hydrolysis of a polymer
Carbon, Hydrogen, oxygen, nitrogen, sulfur
Structure for tissues and organs
How are amino acids related to proteins?
There are only 20 amino acids which account for all of the proteins in all organisms
Polymers made of subunits called amino acids
Amino acids: form 1 or more chains which fold extensively to form a functional protein
Protein or polypeptide: 50 or more amino acids bonded togetherPeptide: shorter chains
Shape of protein is determined by exact type, position and number of it’s amino acids
In many cases 2 or more amino acid chains join
Amino acid chain undergoes a series of folds
If the shape of protein is denatured, the protein may no longer be able to function properly
ProteinsProtein structure Primary structure
ProteinsProtein structure Secondary structure
folding of polypeptide chain
ProteinsProtein structure Tertiary structure
ProteinsProtein structure Quaternary structure
Speed up chemical reactions without being consumed by the reaction
Built from amino acids
Lower activation energy: the amount of energy needed for a chemical reaction to occur
Enzyme names end with the -ase suffix,
the -ase suffix is added to the substrate name.
For example, sucrase is the enzyme that breaks down the substrate sucrose, a disaccharide, into the monosaccharides glucose and fructose.
Protease: the enzyme that catalyzes the break down of proteins into amino acids
How Do Enzymes Work?
Enzymes are substrate specific
Substrate is the reactant
Active site: part of the enzyme capable of recognizing and binding to substrate
Actually the "fit" of the substrate and the active site is not a "perfect fit”
enzyme slightly changes shape to fit the substrate
At the enzyme substrate complex
1. Amount of enzyme
2. Amount of substrate
If the amount of substrate remains
As increase amount of enzyme,
the rate of an enzyme action also increase
All enzymes become saturated
At this point all enzymes are working at maximum capacity
If the amount of enzyme
remains the same:
at low concentrations,
Enzyme activity is low
Because all enzymes are NOT working
As you increase the amount of substrate, you increase enzyme activity until all substrates are bound to enzymes
At this point, enzymeactivity is steady
Each enzyme works best at a certain pH
2. At optimal (best) pH:
enzyme has the right shape
to fit substrate
3. Changes in pH change the shape of enzymes and their ability to fit with substrates
4. Most enzymes work best at pH’s near 7 (neutral)
Enzymes work best at a
2. Optimum (best) temp. for human enzymes is near normal body temp. (37C)
3. Changes in temp. alter shape of enzyme
4. At extreme temp’s enzyme can ‘t fit with substrate
5. high temperatures denature the enzyme
If I changed the shape of the active site, how would the enzyme activity change?
In this picture, name the products.
When is the activation energy lowered?
The most likely result of mixing both enzymes with their substrates in a single test tube is that:
A- only gastric protease would be active if the pH of the mixture was basic
B- gastric protease would be more active than intestinal protease at pH 6
C-both enzymes would exhibit some activity at pH 5
Which enzyme shows the greatest change in its rate of action with the least change in pH?
What type of chemical reaction is this and how do you know?
What builds nucleic acids?
Passed down from parent to offspring
DNA and RNA
Deoxyribose Nucleic Acid
Ribose Nucleic acid
5 carbon sugar
James Watson and Francis Crick
DNA is a double helix
2 strands of nucleotides connected at nitrogen bases
Weak Hydrogen Bonds hold Nitrogen bases together
Hydrogen bonds hold nitrogen bases together
Ribose- 5 Carbon sugar
The sequence of Nitrogen bases A,T,C,G are what build a gene.
Genes: sequences of nitrogen bases that hold the code to build a protein
DNA carries genes
Chromosomes are condensed forms of DNA
Many genes are found on 1 chromosome
Specific sequences of nuleotides form genes
Genes code for proteins
EVERY SINGLE chromosome is copied before the cell divides
ALL cells contain the same genes
So how then are cells different
Cells are different because they express different genes
Therefore different cells build different proteins