Grade 9 Proteins and Nucleic Acids Group Activity
https://www.youtube.com/watch?v=Bsk9hvXDJp8
1. List the elements found in all proteins:
Carbon ,hydrogen , nitrogen , oxygen , sulfur , phosphorus
2. What are the monomers of proteins? Polymers?
Amino acid , pholypeptide
3. How many standard amino acids are there?
20
4. In one amino acid, circle and label the Amino
terminus and Carboxyl terminus.
For each amino acid, draw a square around the
R group.
Grade 9 Proteins and Nucleic Acids Group Activity
https://www.youtube.com/watch?v=Bsk9hvXDJp8
5. R groups can be classified by their chemical properties. Identify the three classifications
for R groups and then discuss how the R groups affect the structure and function of a
protein.
Hydrophobic , hydrophilic , or amphiphatic (both polar and nonpolar)
6. When a protein is folded, which classification of R groups would orient outwards
(towards the surface/aqueous cellular environment)? Which would orient inwards
(away from the aqueous cellular environment)? Why?
Hydrophilic outside because it is water solube/ polar. Hydrophobic inward because they are
nonpolar/ water insoluble.
7. Examine the three pairs of amino acids above. Which pair of amino acids is in the
optimal position to form a dipeptide? Justify your choice by identifying and describing
the reaction that takes place to form peptide bonds.
The third pair (extreme right) is the right one. The process is dehydration synthesis where one
molecule of water is released. The bond between the monomers is called peptide
bond(covalent bond)
8. The image below represents a growing polypeptide chain. What does directionality refer
to in terms of polypeptides? Label the image below accordingly.
The amino group is positive and the cardoxylic is negative.
Grade 9 Proteins and Nucleic Acids Group Activity
Polar amino acids
Nonpolar amino
acids
Serine, threonine, cysteine,
asparagine, glutamine,
tyrosine, lysine, arginine,
histidine, aspartate, glutamate
Glycine, alanine, valine,
leucine, methionine,
isoleucine, phenylalanine,
tyrosine, tryptophan
Use the chart to the left to help answer
questions 9-12
9.
If an amino acid substitution
occurred in a polypeptide chain, predict
which option would have the most
significant impact on the structure and
function of the final protein? Why?
a.
Serine is replaced by glutamate.
b.
Alanine is replaced by lysine.
c.
Glycine is replaced by valine.
https://www.youtube.com/watch?v=ZSpFVPBEeLk
Sickle cell anemia is an inherited disorder that affects the shape of red blood cells (see figures 1
and 2). Individuals who have sickle cell anemia have blood that is chronically low in oxygen and
they suffer from frequent infections and chronic pain. Sickle cell anemia is caused by a single
nucleotide substitution in the hemoglobin-Beta gene found on chromosome 11. This mutation
causes one adenine nucleotide on the hemoglobin-Beta gene to be switched to the nucleotide
thymine. This in turn causes a change in a single amino acid in the protein produced that helps
form red blood cells. Normal red blood cells should have glutamic acid (glutamate) as the sixth
amino acid position in their polypeptide chain, but the mutation switches this glutamic acid to
valine. Use this information and the chart above to answer questions 10-12.
10. What codes for proteins?
DNA
11. In the case of sickle cell anemia, what happens to the gene?
To the protein?
Figure 1: Normal red blood cell (left)
The mutation in the HBB gene in sickle cell anemia changes
one of the amino acids, the building blocks of proteins, in
the beta chain of hemoglobin. This defect causes the
hemoglobin protein to stick together and form stiff fibers.
These fibers distort the shape of the red blood cells and
make them more fragile.
12. Propose an explanation for how a single amino acid
substitution could cause such a dramatic difference in the
final shape of red blood cells.
versus sickle cell (right)
Figure 2: Microscopic image of a blood
smear
One of the common genetic disorders is sickle cell anemia, in
which 2 recessive alleles must meet to allow for destruction and alteration in the morphology
of red blood cells. This usually leads to loss of proper binding of oxygen to hemoglobin and
curved, sickle-shaped erythrocytes.
Grade 9 Proteins and Nucleic Acids Group Activity
https://www.youtube.com/watch?v=PPJ7C3hcnPw
13. How many levels of protein structure exists? 4 levels
14. Fill in the protein structure level that is most relevant to each statement:
Statement
Representative Image
Protein Level
includes α-helix and β-pleated sheet
secondary
the unique three-dimensional structure
of a polypeptide
Tertiary
interactions among several polypeptide
subunits
quaternary
disulfide linkages are covalent bonds
Tertiary
Structure is held together by hydrogen
bonds that occur between the atoms of
the polypeptide backbone
Secondary
the unique sequence of amino acids
primary
hydrophobic R groups of nonpolar
amino acids become positioned inside
of the protein
Tertry
Nucleic acids
15. What 5 elements are found in nucleic acids?
carbon
hydrogen
oxygen
phosphate
nitrogen
https://www.youtube.com/watch?v=XELQnfXmNYE
16. DNA has different levels of organization within a eukaryotic cell. Order these images
from least dense (1) to most dense (4):
3
1
2
4
17. What are the monomers of nucleic acids called? nucleotide
Grade 9 Proteins and Nucleic Acids Group Activity
18. Consider the name ‘de-oxy-ribose’ and study the structure of each nucleotide above.
Which image is the ribose nucleotide? Which is the deoxyribose nucleotide? Highlight
the single difference between them.
Ribose nucleotide , deoxyribose nucleotide.
19. For each nucleotide monomer, circle and label the phosphate, sugar, and nitrogen base.
Which part actually carries the coded biological information? Nitrogen carries the coded
biological information.
20. Choose a color for the phosphate groups and a different color for the sugars - color each
of them. This is the sugar – phosphate backbone.
21. Label the 5 ’and 3 ’end of each strand.
22. Add a ‘nucleotide’ to each strand by drawing a rectangle to represent it - be sure you
add them to the appropriate end (5’ or 3’)!
The nucleotide is added to the 3 end.
23. What bond did you just draw to connect your new nucleotides? Covelnt bond.
Blue:
phosphate
Green : hydrogen
Yellow: sugar
24.Choose a color for hydrogen bonds. Highlight the two bonds between the A - T and
the three bonds between the G - C.
Grade 9 Proteins and Nucleic Acids Group Activity
https://www.youtube.com/watch?v=pEwvhUVCEe4
24. Which set of base pairs do you predict would be more structurally stable? Why?
G-C base pairs have 3 hydrogen bonds , G-C base pairs will be more strongly bonded
together, more stable.
When DNA is heated the double strands unwind and separate into single strands due to the
breaking of hydrogen bonds between the bases. This process is called denaturation. An
experiment was performed where two molecules of DNA were placed in a solution and heated.
Both sets of DNA contained 40 base pairs, but each DNA molecule was modified such that one
DNA molecule contained only adenine and thymine bases and the other contained only
cytosine and guanine bases. Examine the data in the chart below.
DNA with only A/T
DNA with only C/G
Temp
(℃)
37
% single strand
Temp (℃)
% single strand
0
37
0
47
23
47
5
57
52
57
17
25. Describe the effect that temperature had on each DNA molecule.
If the temperature increase , the DNA with only A/T will start denaturing faster because A/T has
hydrogen double bond.
26. Propose an explanation for the results in the table above by discussing how changes in
structure affect functionality.
If the three- dimensional structure of the protein is altered because of the change In the
structure of the amino acids, the protein becomes denatured and does not perform its function
as expected.
27. Using the image to the right, create a list of similarities and differences between the two nucleic
acids (consider location, size, function).
Similarities
Four nitrogen bases
each
Both DNA and RNA
store genetic
information.
Differences
DNA is found mainly in the
nucleus of the cell RNA) is found
mainly in the cytoplasm of the
cell
DNA is longer that RNA
DNA and RNA are both
large biological
polymers.
RNA
DNA