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Sickle Cell Anemia
Ms. Liu
Biology
5/11/12
Textbook p. 458
• You will be working on steps #1-3.
• Work with a partner to answer the questions in your notebook.
• These will serve as your notes for your poster.
Sickle cell anemia = genetic diseaseCaused by genotype: HbSHbS
Crescent
shaped
Red Blood
Cell (RBC)
Hemoglobin
• A protein in blood that…
–Gives blood it’s red color
–Carries oxygen to all the organs
In sickle cell anemia…
• The hemoglobin inside the red blood cell (RBC), clumps under low oxygen conditions.
• This causes the RBC to lose it’s flexibility and change its shape.
Readings/Qs
• Step #1: Need to Know Box p. 459
• Step #2: Incomplete Dominance p.510
• Step #3: Answer questions a-d
Step 3
A) What medical symptoms might a person with sickle cell disease experience?
Answer: Sickle cell disease can cause extreme pain and organ damage
Why?
Step 3
B) What problem in the red blood cells causes these symptoms to happen?
Answer: The red blood cells are sickle shaped (like a crescent moon)
Why?
Step 3
C) What problem in the hemoglobin molecules is associated with these changes in an individual’s red blood cells?
Answer:
• When the concentration of oxygen is low, the abnormal hemoglobin protein molecules clump together,
• This causes the red blood cells to change their shape, preventing blood flow
Step 3
D) Thinking back to your knowledge of the DNA structure…
What might be the molecular basis for phenotype of sickle cell anemia?
Answer:
• Since phenotype is determined by the genotype…
• An error in the base pairing in the DNA structure of the gene can cause the disease
p. 460
• Work on questions #4-5
• Begin posters
FACTSDNA is the genetic material of all cellular
organisms that make us who we are.
But having DNA does not explain how DNA becomes a trait such as brown eyes.
***That DNA info needs to be translated and transcribed into a cell to create a gene.
DNA is USELESS…
Unless…–There are “helpers” that can
translate DNA (make a complimentary copy) and send it out to be expressed as a phenotype.
–But 1st:
DNA RNA protein gene
RNA = ribonucleic acid• Long polymer chain like DNA but single
stranded
• Has 4 subunits/bases:
– A, C, G, and U (uracil). NO thymine (T)
• 3 types of RNA:
– mRNA (send message)
– rRNA (ribosomal makes amino acids)
– tRNA (transfers info to make protein)
RNA
• DNA is read by
a complimentary molecule
called RNA
• RNA is what translates
info from DNA to express
genes/traits
Translating DNA RNA info
• DNA: A T C A G G A C
• RNA: U A G U C C U G =brown hair
1. Write the complimentary base (opposite base)
2. Replace T with U
Posters p. 460
• Do questions #4-5
• Refer to p. 459 and 510 for readings
• Focus on poster topics #1, 5-8
What is the mRNA strand copied from this DNA strad?
DNA:
GGC TAT CTG CGC TAT ACG CTA
CCG AUA GAC GCG AUA UGC GAU
RNA:
p. 460-461
• Work on Part C: Changing mRNA protein
• Reading: p. 510, 524 and 527
Amino acids are building blocks that make up polypeptides
Polypeptides are long chains that make up protein