DNA Structure and Function
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Adenine and Guanine are purines (A-G)
What are the building blocks of DNA?
What are the three parts of a nucleotide?
- 5 Carbon sugar
- Nitrogen-containing base
What is the structure of DNA?
Each strand has a backbone made up of sugars and phosphate. In the double-stranded DNA, the two strands run in opposite directions and the bases pair up such that A always pairs with T and G always pairs with C. The nucleotides are the rungs. One strand binds with another forming a twisted ladder. The bind together based on complementary based pairing
What is DNA made from?
Chromosomes and proteins
What is DNA's function?
- Replicates itself for cell division
- Mutates occasionally
- Stores the instructions that control everything.
What is complementary based pairing?
How the T's always pair with A's (T and A) and the G's always pair up with the C's.
Describe DNA replication. Include all necessary building blocks and enzymes.
- Special enzymes unzip then untwist the ladder
- Each unzipped strand is now a template for replication
- DNA Polymerase brings in the correct complementary nucleotide
- Proofreading Enzymes check for error
- DNA Repair Enzymes repair any errors.
- Now there are two complete strands of DNA, both with half new, half old material (semi-conservative)
What are proofreading enzymes?
They check that the DNA Polymerase didn't make any mistakes during replication
What are DNA Repair Enzymes?
They make any repairs necessary to the new DNA
What is DNA Polymerase?
An enzyme that brings in the correct complementary nucleotide during replication
What is semi-conservative replication?
The fact that during DNA replication, one strand is of old material, while the other strand is new
What is RNA?
Ribonucleic acid. A helper to DNA made of one strand.
List the three types of RNA.
- Messenger RNA (mRNA)
- Ribosomal RNA (rRNA)
- Tranfer RNA (tRNA)
Reads the DNA and brings the message to the ribosome for the correct protein synthesis
Complementary triplet. If Codon triplet is GCT the anticodon is CGA. If is it GCA the anticodon is CGU (no t in rna)
Series of three nucleotides in the genetic code.
A three letter code that represents a specific amino acid
mRNA (aka RNA transcript) leaves the nucleus and moves out to the cytoplasm, protein made as a result of this transcript
What does translation need? Where does it happen?
mRNA, rRNA and rRna, in the cytoplasm
Type of RNA that delivers amino acids to a ribosome during translation.
The act of RNA reads and helps to create DNA replication
Same as the ribosome, the thing that actually produces the proteins needed for DNA replication
Compare and contrast DNA and RNA
- RNA helps DNA make proteins
- Has single strand of nucleotides
- Doesn't have T's (U's instead)so the U's pair with the A's
Make a single strand of DNA using letters then make the complementary or opposing strand to complete the DNA molecule.
- The instructions are in the sequences of
- the nitrogen containing bases
- •Each set of three, a triplet, is the instructions for a specific
- amino acid
- –BUT…protein making machinery is in
- •DNA never leaves the nucleus, so how do
- instructions get out to the cytoplasm?
This is where RNA, DNA’s helper, comes in
- •Using complementary base pairing, the
- code is passed to mRNA, which takes this message out to the cytoplasm
•mRNA synthesis is called transcription
The main enzyme responsible for transcription
When the DNA doesn't get put in right
Product of transcription
Product of translation
New strand for the DNA
Sickle cell anemia
Caused by DNA Substitution
Codon and Anticodon for CATGAG
- Codon= CAT GAG
- Anticodon= GUA CUC
Triplet for the CAUCAC anticodon
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