Nucleic Acids Flashcards
Nucleic Acids
- like proteins, they are also polymers
- made of repeating NUCLEOTIDE subunits
- CONTAIN THE INSTRUCTIONS FOR PROTEIN SYNTHESIS
- DNA and RNA
Polymer
a mol made up of repeating subunits (monomers)
eg: Proteins are made of amino acids
Monomer
repeating subunit in polymer made of simple chemical units
eg: Amino Acids (monomer)- made of- C, H, Amino group (-NH2), Carboxyl group (-COOH), R group (variable side chain)
Monomer of DNA
Monomer: Nucleotide
Monomer of: Polysaccharides
Monomer: Monosaccharide
Monomer of: Lipids
Monomer: Glycerol + Fatty acids
Polymer: Triclyceride
Monomer of: Protein
Monomer: Amino Acid
Polymer: Polypeptide Chain/ protein
Types of RNA
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
the replication of a double stranded DNA molecule begins when the strands separate at the
hint: what bond keeps base pairs bonded
hydrogen bonds
which pair of molecules, when bonded together, would most likely be found in a nucleotide of DNA?
Deoxyribose sugars+ Nitrogenous base (bonded at 1’ carbon)
Polymer
a mol made up of repeating subunits (monomers)
Monomer
repeating subunits of polymer made of simpler chemical units
Monomer and Polymer of DNA/ RNA?
Nucleotide, Nucleic Acids
Monomer of proteins?
Amino acids
makes- polypeptide chain/protein
Monomer of polysaccharides?
Monosaccharide
Monomer of lipids (fats)?
Monomer: Glycerol + Fatty acids
Polymer: Triglyceride (e.g., fats, oils)
Types of RNA
mRNA (messenger RNA)
tRNA (transfer RNA)
rRNA (ribosomal RNA)
Subunits of RNA
made up of nucleotides
- Phosphate group
- Ribose sugar
- Nitrogenous base: A, U, G, C
Subunits of DNA
made up of nucleotides
- Phosphate group
- Deoxyribose sugar
- Nitrogenous base: A, T, G, C
Roles of DNA and RNA
DNA → contains the instructions coding for synthesis of proteins
RNA → different types of RNA are involved in bringing the different components required for protein synthesis to the organelle that performs this process
RNA ROLES
Ingredients- Amino acids- tRNA
Recipe- Instructions- mRNA
Chef- Organelle-ribosome- rRNA
DNA replication is a __
Conservative Process
Semi-Conservative Process
not Conservative Process
Semi-Conservative Process
Each new DNA molecule has one original, old (parent) strand and one newly synthesised (daughter) strand.
parent strand= template strand
daughter strand= coding strand
DNA backbone
The alternating chain of sugar and phosphate to which the nitrogen bases are attached
Hydrogen Bonds
These connections are weak between the nitrogen bases that form the “rungs” of the DNA ladder.
These connections are weak between the nitrogen bases that form the “rungs” of the DNA ladder.
Hydrogen Bonds
helicase
An enzyme that unzips the DNA double helix during DNA replication
DNA polymerase
- Adds nucleotides to the growing DNA strand in the 5’ → 3’ direction.
- Proofread for errors to ensure accuracy.
- DNA Polymerase I: Replaces RNA primers with DNA.
- DNA Polymerase III: Main enzyme for strand elongation.
primer in DNA replication?
- A short RNA sequence made by primase.
- Provides a starting point for DNA polymerase to add nucleotides.
- Later replaced by DNA Polymerase I with DNA nucleotides.
What is the leading strand in DNA replication?
- Synthesized continuously in the 5’ → 3’ direction.
-Moves toward the replication fork.
-Requires only one primer.
Built by DNA Polymerase III.
replication fork
- Y-shaped structure where DNA unzips.
- Formed by helicase breaking hydrogen bonds.
Leading strand
Continuous synthesis
3’ to 5’ end (toward the replication fork)
when a new strand is created, it goes 5’ to 3’.
always synthesized in the 5’ → 3’ direction, but the direction of the template strand (3’ → 5’ or 5’ → 3’) determines how replication occurs (continuously or in fragments).
Lagging strand
Discontinuous (Okazaki fragments)
5’ to 3’ end (moving away from the replication fork)
when a new strand is created, it goes 3’ to 5’.
always synthesized in the 5’ → 3’ direction, but the direction of the template strand (3’ → 5’ or 5’ → 3’) determines how replication occurs (continuously or in fragments).
5’ end of deoxyribose sugar
The part of the new DNA strand that DNA polymerase is UNABLE to build from. Can be identified by the phosphate end of the backbone.
3’ end of deoxyribose sugar
the end to which free floating nucleotides can be added, the sugar end of the nucleotide.
Ligase
An enzyme that connects portion of DNA during replication
“glue” that joins the Okazaki fragments on the lagging strand by forming phosphodiester bonds, making the strand continuous.
Why does DNA replication occur?
DNA replication occurs before a cell divides so each new cell can have a complete copy of the DNA enabling growth, repair, and reproduction.
DNA replication
Purines
nitrogenous bases that include adenine (A) and guanine (G). They are double-ringed structures in DNA and RNA.
Pyrimidines
nitrogenous bases that include cytosine (C), thymine (T), and uracil (U). They have a single-ring structure in DNA and RNA.
Semi-conservative replication
In semi-conservative replication, each half of the original DNA strand serves as a template for a new strand. The result is two new DNA molecules, each with one old strand and one new strand.
DNA replication steps
- Unwinding: Helicase breaks hydrogen bonds between bases- unzips the double helix
- Priming: Primase adds a short RNA primer to the template strand to start replication.
- Elongation:
leading strand, DNA polymerase adds nucleotides continuously in the 5’ → 3’ direction.
lagging strand, DNA polymerase adds nucleotides in short fragments (Okazaki fragments) in the 5’ → 3’ direction. - Joining: DNA ligase seals the gaps between Okazaki fragments on the lagging strand to make a continuous strand.
- Proofreading: DNA polymerase checks for errors and corrects them.
