Biochemistry Nucleic Acids Flashcards
(26 cards)
What elements are nucleic acids made from?
Carbon, hydrogen, oxygen, nitrogen, and phosphorous
What are the building blocks of nucleic acids?
Nucleotides made up of a phosphate group, pentose sugar and a nitrogenous base combined through condensation reactions
How do nucleotides form polynucleotides and nucleic acids?
Through condensation reactions that form phosphodiester bonds. They from between the phosphate of one nucleotide and the Pentose sugar of the next nucleotide forming long chains of polynucleotides.
Nucleic acids are formed from further condensation reactions of these polynucleotide chains
Name an important nucleotide in our bodies and give its function
ATP, which supplies and carries energy in cells
Name 2 important nucleic acids
DNA and RNA
Describe DNA
A double helix composed of two antiparallel polynucleotide chains joined via hydrogen bonds between their nitrogenous bases
What sugar is found in the nucleotides that make up DNA?
Deoxyribose
Which nitrogenous bases pair in DNA?
Adenine with Thymine and Guanine with Cytosine
What type of bond forms between the phosphate of one nucleotide and the pentose sugar of the next?
Phosphodiester bond
What process reverses the formation of polynucleotides?
Hydrolysis
Fill in the blank: Nucleotides consist of a phosphate group, a pentose sugar, and a _______.
Nitrogenous base
What is RNA?
RNA is a single polynucleotide chain made up from nucleotides containing the sugar, ribose.
The nitrogenous bases in RNA are Adenine, Uracil, Guanine, and Cytosine.
What are the 3 types of RNA?
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
mRNA carries DNA code from nucleus to ribosome, tRNA carries amino acids to mRNA on ribosome, and rRNA forms the ribosome, made in the nucleolus.
What is the role of DNA?
Carries the genetic code; the bases form triplet codes (codons) that code for amino acids forming proteins.
The sequence of bases in DNA determines the structure and function of proteins.
Describe the semi-conservative theory of DNA replication.
The DNA double helix unwinds and a new strand is formed when free nucleotides join up with exposed bases of each template strand by base-pairing, resulting in 2 new DNA molecules.
Each new DNA molecule contains one original (template) strand and one new strand. (Coding)
What happens during base-pairing?
Nucleotides containing Adenine bond with Thymine, and those with Guanine bond with Cytosine, forming hydrogen bonds.
This process is crucial for the accuracy of DNA replication.
What does DNA helicase do?
Causes the DNA double helix to unwind by breaking the hydrogen bonds between the bases.
DNA helicase is essential for replication as it separates the strands.
What does DNA polymerase do?
Helps the new complementary DNA strands to form by catalyzing the attachment of nucleotides via phosphodiester bonds.
DNA polymerase is crucial for synthesizing new DNA strands during replication.
What did the conservative theory/model propose?
The parental/original DNA does not unwind but is simply copied to form a new double strand.
Name the famous experiment which proved that the method of DNA replication is semi-conservative.
The Meselson-Stahl Experiment
What were the radioactive isotopes that were used in the Meselson-Stahl experiment?
N15 (heavy isotope) and N14 (light isotope).
Why were these specific radioactive isotopes used?
To differentiate between the heavy and light DNA during the experiment.
Why was bacterial DNA (E.coli) used in this experiment?
Bacteria reproduce very quickly and easily, enabling results to be obtained quickly.
What did centrifugation show about the make-up of the DNA after one generation of replication in a medium containing N14?
The bacterial DNA was now hybrid DNA, made of half N15 and half N14 (this is GENERATION 1).
