Biology 1.1 Chromosome and DNA Replication Flashcards
What are the four marcomolecules?
Proteins
Carbohydrates
Nucleic Acids
Lipids
What are each nucleotide composed of?
Sugar, phosphate, nitrogenous base
What are the differences between RNA and DNA?
Structure:
- RNA Single stranded helix
- DNA Double stranded helix
Bases:
- RNA Uracil
- DNA Thymine
Sugars:
- RNA Ribose
- DNA Deoxyribose
Prokaryotes and Eukaryotes
Simple prokaryotes have one, circular chromosome.
Complex eukaryotes have many, linear chromosome.
Prokaryotic Chromosome
The chromosome attaches to the cell membrane, as prokaryotes don’t have a nucleus. Prokaryotes may also carry other small, circular pieces of DNA called plasmids.
Eukaryotic Chromosome
Eukaryotic cells contain much more DNA than prokaryotes. They are many and linear. This is achieved by wrapping DNA molecules around proteins called histones. Chromosomes are only visible as discrete units when they are condensed during cell divison.
What happens before DNA Replication begins?
Before a cell divides, the DNA must be copied so that each new cell receives its own chromosome (prokaryotes) or set of chromosomes (eukaryotes).
What does Topoisomerase do?
Unwinds DNA
What does Helicase do?
Separates DNA Strands
What does the single strand binding proteins?
Keep strands from zipping back up
What does primase do?
Makes RNA primer to singal a starting point for replication
What does DNA Polymerase do?
Synthesis new DNA strands
What does ligase do?
Ligates newly synthesised DNA strands
Step 1 for Semi-conservative DNA Replication
The double helix unwinds (topoisomerase) and unzips (helicase) to separate strands and expose the nucleotide bases.
Step 2 for Semi-conservative DNA Replication
DNA polymerase synthesises a new strand of DNA, using free DNA nucleotides that will complementary base pair to both template strands from the original DNA molecule.
