Introduction
Good morning grade 12s, Welcome to webquest life sciences.
LESSON OUTCOMES
After today's lesson you should be able to know:
- The structure of DNA
- Role of DNA
- Replication of DNA
HISTORY OF DNA
Today's topic is about the human hereditary material known as deoxyribonucleic acid or DNA. It is a long molecule containing the information organisms need to both develop and reproduce. DNA is found in each and every cell in the body and it passes down from parent to child. The discovery of DNA occurred in 1869 by Swiss-born biochemist Fredrich Miescher. even today after more than 150 years it was discovered exciting research and technology continue to offer a more insight and a better answer as to why it is important.
STRUCTURE OF DNA
- DNA is a polymer and consists of two strands that are twisted to form a double helix.
- The monomers of DNA are known as nucleotides.
- Each nucleotide consists of a sugar molecule (deoxyribose), a phosphate group and a nitrogenous base.
- Deoxyribose combines with the phosphate group.
- One nitrogenous base combine with deoxyribose
- The sides of the DNA ladder consist of alternating deoxyribose molecules and phosphate groups.
- There are four types of nitrogenous bases in DNA i.e. Adenine (A), Guanine (G), Cytosine (C) and Thymine (T)
- Adenine always combines to Thymine • Guanine always combine to Cytosine
- There are equal numbers of adenine and thymine bases as well as equal numbers of guanine and cytosine bases in a DNA molecule. (A = T and G = C)
- Nitrogenous bases are joined by weak hydrogen bonds which are easily broken by enzyme action.
FUNCTIONS OF DNA
- Sections of DNA-forming genes carry hereditary information.
- DNA contains coded information for protein synthesis.
REPLICATION OF DNA
DNA replication is the process during which a DNA molecule makes an exact copy (replica) of itself. DNA replication takes place during interphase of the cell cycle.
- The DNA double helix unwinds
- Weak hydrogen bonds between nitrogenous bases break and the two DNA strands unzip
- Both DNA strands serves as templates
- Free nucleotides in the nucleoplasm are used to build a complementary DNA strand onto each of the original DNA strands (A to T and G to C)
- This results in two identical DNA molecules. Each molecule consists of one original and one new strand
Task
For today's task you are required to create a 3-D model demonstrating DNA coding. Use any recyclable material you can find, get creative while at it. After creating your model you and your group will present for class. You are required to work in groups or not more than four.
Process
- Amongst yourselves in a group allocate someone to be a leader, a scribe,time keeper, presenter etc.
- Refer to your textbook section in DNA. On digital resources refer to page 1-8 of the mind the gap study guide. The link will be done below.
- Revise what i already taught you about structure of DNA, how do you recognize a DNA molecule also and how it replicates.
- also take a look at this video for revision
https://www.youtube.com/watch?v=C1CRrtkWwu0
Evaluation
MAKE SURE YOU READ YOUR RUBRIC CAREFULLY BEFORE PROCEEDING WITH YOUR MODEL
|
CRITERIA: |
4 |
3 |
2 |
1 |
0 |
|
Model shows an understanding of base pair basics |
The model has two pairs of color-coded bases fitting like puzzle pieces. |
The model has two pairs of color-coded bases. |
The model has one pair of color-coded bases. |
The model has four bases but not color coded nor matched. |
Not present |
|
Model shows understanding of sugar and phosphate basics. |
Sugars and phosphates alternate on the sides of the DNA molecule. Bases are attached to the sugars. |
Sugars and phosphates alternate on the sides of the DNA molecule.
|
Sugars and phosphates are present but may not alternate correctly. |
The model contains the sides, but it is not clear if sugars and phosphates are present. |
Not present |
|
Model has a key. |
The key identifies all components of DNA. (sugar, phosphate, adenine, thymine, guanine, cytosine) |
The key identifies four bases (adenine, thymine, guanine, and cytosine). |
The key identifies two or three components of DNA. |
The key identifies one component of DNA. |
Not present |
|
Model has a double-helix shape. |
The model has a double-helical (3-D) shape. |
.the model is double helix but can be improved |
The model has a shape of a ladder (3-D) but not twisted |
The shape is unclear |
The model is not 3-D shaped |
|
Model has a required length. |
The model contains at least 16 base pairs. |
The model contains at least 14 base pairs. |
The model contains at least 10 base pairs. |
The model contains at least 8 base pairs. |
The model contains less than 8 base pairs. |
|
Model is neatly constructed. |
The model shows exceptional effort. |
The model is neatly done. |
Neatness of the model can be improved. |
The model is very carelessly done. |
The model is not neat and less attractive |
|
TOTAL POINTS |
________/24 |
Conclusion
Emphasize important points of the lesson. The completion of your model will be of good use as it will be used in the continuation of this topic. for more queries, you have my email also if you do not have it please find it on the teachers page. Thank you.