2. Define the term enzyme and discuss the
general characteristics of an enzyme. Be sure to discuss the mechanism by which
most enzymes function (i.e. how do they react with their substrate and
cofactor/coenzyme), and explain how most enzymes are named, giving examples
when applicable.
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An
enzyme is a biological protein catalyst that increases the rate of a chemical
reaction without being consumed by the reaction. |
|
An
enzyme has a very specific shape and fits together with its substrate
like a lock and key through the enzyme’s active site. |
|
The
enzyme and substrate come together to form the enzyme - substrate complex. |
|
Then
the reaction occurs and the end-products are released and the unaltered enzyme is released |
|
and
can be used over and over again. |
|
The
enzyme’s active site may not always be exposed, and a substance called
a coenzyme or cofactor
may be required to activate the enzyme. B vitamins are examples of coenzymes and minerals are example of cofactors. |
|
Enzymes
are named for the substrate they act
upon. The root of the enzyme name |
|
typically
comes from the substrate and
the suffix -ASE is added at the
end. |
|
For
example, the enzyme lactase acts upon the substrate lactose.
|
|
And
the enzyme lipase acts upon a substrate lipid or fat. |
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In
extreme conditions, enzymes can be denatured
which results in loss of function. |
|
Enzymes
typically occur in a particular sequence within metabolic pathways. |
DIAGRAM: See
your notes from class!!!!
3. Define
the term substrate.
|
A substrate
is acted upon by an enzyme in a metabolic reaction. For example, the enzyme lactase acts upon the substrate lactose. |
4. Explain
why most enzymes need a vitamin (coenzyme) or mineral (cofactor) to function,
and name the site where this coenzyme or cofactor bind the enzyme.
|
The enzyme’s
active site may not always be exposed, and a substance called a coenzyme
or cofactor may be required to activate
the enzyme. B vitamins are examples
of coenzymes and minerals are example of cofactors |
5. Name
the three components of ATP and describe its function in living cells.
|
Ribose |
adenine |
3 phosphates |
6. Write
a simple chemical equation showing the reversible reaction of ATP/ADP.
|
ATP ß----à
ADP + Pi |
8. Compare
the two major steps in cellular respiration in terms of:
a. name
b. their
location in the cell;
c. whether
oxygen is required;
d. initial
compounds and end-products;
e. number
of ATP molecules produced.
And draw an overview diagram of
CR including this information
|
|
ANAEROBIC |
AEROBIC |
|
Name of step(s) |
GLYCOLYSIS |
KREB’S
CYCLE (CITRIC ACID CYLE) AND ELECTRON TRANSPORT CHAIN |
|
LOCATION
in cell |
CYTOPLASM |
MITOCHONDRION |
|
Is
Oxygen Required? |
NO |
YES |
|
Starting Product(s) |
GLUCOSE (6-C) |
2
PYRUVIC ACIDS 2
ATP |
|
End- Products |
2 PYRUVIC ACIDS |
36
ATP WATER CARBONDIOXIDE |
|
|
|
|
CELLULAR
RESPIRATION
ANAEROBIC RESPIRATION
AEROBIC RESPIRATIION
CYTOPLASM MITOCHONDRIA
GLYCOLYSIS (KC, ETC)
GLUCOSE
(6C )→→→→→→→ PYRUVATE (2X3C)
→→→→→→CO2, H2O. 36 ATP
+
2ATP
fermentation
Lactic
acid ←←←←←←←←←←
10. Describe
the fate of pyruvic acid in the absence of oxygen.
|
It
is fermented to lactic acid in animal cells. |
11.
Distinguish between aerobic and
anaerobic respiration in terms of energy production.
|
|
anaerobic
respiration |
aerobic
respiration |
|
Energy
released |
2
ATP |
36
ATP |
12. Name the greatest reserve fuel in the
body. FAT
13. Name
the specific substance that is required for each and every step of metabolism.
An
ENZYME
is required for each and every step of
metabolism.
14. Explain
why an enzyme that catalyzes a step in glycolysis would not be required for a
step in Beta-oxidation (i.e. fat metabolism)
|
Because
enzymes are specific for their substrates. |
15. Construct
a molecule of DNA. Be sure to label
parts fully (if using abbreviations, make sure to provide a key).
16.
Describe the function of deoxyribonucleic acid (DNA) and RNA.
|
DNA |
RNA |
|
Directs
protein synthesis |
Assists
DNA in protein synthesis |
17. Explain
why protein synthesis is so ultimately important in living things.
|
Proteins
have many functions in human metabolism including enzymes which regulate each
and every metabolic reaction. |
18. Define
the term gene, and give the
approximate number of genes that compose the human genome.
|
A
gene is the portion of a DNS molecule that codes for one particular protein. |
|
There
are approximately 34000 genes in the human genome. |
19. Distinguish
ribonucleic acid (RNA) from DNA, in terms of structure, where each is located
in a human cell, and the function of each.
|
|
DNA |
RNA |
|
STRUCTURE |
1. SUGAR = deoxyribose 2. BASES = adenine (A); thymine (T);
cytosine (C); and guanine (G) 3. DOUBLE OR SINGLE STRANDED? DS |
1. ribose 2. adenine (A); uracil (U)); cytosine (C);
and guanine (G) 3. SS |
|
LOCATION IN
CELL |
nucleus |
Made in
nucleus, but functions at ribosomes in cytoplasm or in rough endoplasmic
reticulum |
|
FUNCTION |
Directs
protein synthesis |
Assist in
protein synthesis |
20. Name the two major steps of protein
synthesis, and compare and contrast them in terms of where they occur in the
cell, start products, molecules (including enzyme names) involved in each step,
and end products. PROTEIN SYNTHESIS SUMMARY TABLE (outline page 15)
|
NAME
OF STEP |
TRANSCRIPTION |
TRANSLATION |
|
LOCATION
IN CELL |
Nucleus |
at a ribosome either that is either
free in the cytoplasm or on rough endoplasmic reticulum |
|
START PRODUCT |
DNA
(GENE) |
Messenger
RNA |
|
MOLECULES
INVOLVED AND HOW? |
DNA: unwinds & unzips RNA Polymerase (an enzyme) positions
the complementary RNA nucleotides along the DNA template and zips up their
backbone. |
mRNA carries the protein code to the
ribosome; Ribosome if the protein synthesizing
machinery; Transfer RNA (tRNA) brings the
appropriate amino acid to the ribosome to be incorporated into the protein.. |
|
END PRODUCT |
A strand of
mRNA |
A protein |
21.
Describe the role of messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal
RNA (rRNA) in protein synthesis.
|
mRNA |
tRNA |
rRNA |
|
Carries
the code for the protein to be made from the nucleus to the ribosome |
Brings
the appropriate amino acid to the ribosome to be incorporated into the
protein |
Composes
the ribosome along with proteins. |
22. Explain how amino acids are joined to
form a protein. Through a peptide
bond.
23. Given
the following DNA sequence (gene) and the mRNA codon chart that I distributed
in class, determine the peptide (protein) which will result.
|
DNA Base
Sequence (GENE) |
Messenger
RNA Base Sequence (mRNA) |
Amino Acid
Sequence (PROTEIN) |
tRNA anticodon
sequence |
|
T A C T A A C G T C C G T A A A T T |
A U G A U U G C A G G C A U U U A A |
MET ILE GLY ILE STOP |
U A C U A A C G T C C G U A A A U U |
24. Describe
the steps involved in DNA replication, name the location in the cell where DNA
replicates, name the enzyme required for DNA replication, and explain the
significance of the process.
|
DNA
replication steps |
TRANSCRIPTION |
TRANSLATION |
|
Location
in cell |
NUCLEUS |
AT
RIBOSOME EITHER IN CYTOPLASM OR ON RER |
|
Enzyme
that assists |
RNA
POLYMERASE |
N/A |
|
Significance |
Results
in mRNA that now carries code for protein to be made to ribosome. |
Results
in a protein. |
25. Describe
what is meant by "semi-conservative" replication.
|
The
two copies of DNA have been synthesized and each has one old
strand and one new strand of DNA. |
26.
Define the term mutation, and explain its significance
in protein synthesis.
|
A
mutation is an error in a gene (DNA sequence). |
|
Results
of mutations include an enzyme that is not made at all, a protein
with an altered structure/function, or a protein to be made in excess. |