DNA Structure and Replication, Protein Synthesis, Mutations & Genetic Engineering Flashcards
State Stargaff’s Rule
The amount of 4 bases are not equal
Bases are present in a characteristic are not a equal ratio
A=T and G=C (All in percentages)
Summarize Rosalind Franklin’s contribution to determining the structure of DNA
She used X-ray photography to analyze the structure of DNA and found that it is a helix w/ 2 repeating patterns. She found that nitrogen bases were on the inside and the sugar-phosphate was on the outside
Describe the double helix structure DNA discovered by Watson and Crick
The discovered it was like a twisted ladder. The handrails on the outside are the sugar-phosphate backbone. The rungs or steps of the ladder are the nitrogen bases that are arranged in complementary pairs (A-T and C-G). The two stands are NOT IDENTICAL and they are ANTI-PARALLEL (they run the opposite of one another- one strand is pointed up and the other down
Describe the antiparallel strands (twisted ladder)
The 5’ to 3’ ends run in opposite directions on each strand of nucleotides in a double strand DNA molecule the 5’ end points up strand and down the other
Compare DNA to RNA- sugar, nitrogen bases, # of stands and where it occurs
DNA: Deoxyribose, A-T and C-G, two strands, nucleus
RNA: Ribose, A-U and C-G, one stand, cytoplasm
Define gene:
A functional sub-unit of DNA that directs the formation of a protein (or polypeptide) molecule
Define genome:
is all of the DNA in each organism’s cells. It includes genes and non-coding sequences of DNA that do not direct the information of a protein
What is the first step for semi-conservative replication?
- Two stands of template DNA before replication in S Phase of interphase
What is the second step for semi-conservative replication?
- The DNA unwinds due to the helicase enzyme cutting the H bonds between matching nitrogen bases and the DNA polymerase enzyme adds in matching new bases to the template strand
What is the third step for semi-conservative replication?
- The ligase enzyme glues the DNA up to make two daughter strands: half old and half new
What does helicase do?
It breaks the weak H bonds between nitrogen bases to unwind the DNA molecule
What does DNA polymerase do?
Adds complementary bases to the template DNA to make a new stand
What does Ligase do?
Glues up the bases on the newly made DNA strands to join them together
In what way is the structure of a protein related to the genetic code?
The sequence (order) of the base pairs in a DNA molecule, the genetics code, decides the sequence of amino acids in a protein
Summarize the steps in Central Dogma or Transcription and Translation:
Transcription (Step 1): Occurs in the nucleus. Genes on DNA are made into an mRNA copy
Translation (Step 2): Occurs in the cytoplasm at a ribosome: the sequence of bases on the mRNA molecule determines the sequence of amino acids in a protein
Define Codon:
A set of three bases that codes for an amino acid or a stop codon. 3 bases= 1 codon