- Define the function of Helicase in DNA replication.
Helicase unwinds the double helix of DNA
- Define the function of Binding Proteins in DNA replication.
Binding proteins stabilize each strand
- Define the function of Primase in DNA replication.
Primase adds short RNA primer to template strand
- Define the function of DNA polymerase in DNA replication.
Binds nucleotides to form new strands.
- Define the function of Ligase in DNA replication.
Creates covalent bond between adjacent DNA segments
- Why DNA replication is considered semiconservative.
DNA is split into 2 template strands and new DNA is added to the old strands. The replicated DNA then contain 1 new strand and 1 old strand. Because each DNA double helix conserves half the original molecule it is considered semi-conservative.
- What is the role of Primase during DNA replication?
Primase adds short RNA primer to template strand
- What are the events of binary fission?
The parent cell contains one chromosome. The DNA replicated and attaches to the cell membrane. Membrane growth between the two attachment points moves the DNA molecules apart as new cell wall material is deposited. The cell finishes separating and there are two daughter cells identical to the original.
- Describe the events associated with Prophase?
Chromosomes condense and become visible, the nucleolus disappears and the two centrosomes migrate toward opposite poles and the spindle begins to form.
- Describe the events associated with Prometaphase?
The nuclear envelope breaks enabling the spindle fibers to reach the chromosomes and attach to kinetochores which are assembling on centromeres.
- Describe the events associated with Metaphase?
The spindle aligns the chromosomes down the equator of the cell.
- Describe the events associated with Anaphase?
The centromeres split, and the sister chromatids (now chromosomes) are pulled towards opposite poles of the cell by shortening microtubules. Unattached fibers elongate, stretching the cell.
- Describe the events associated with Telophase?
The spindle disassembles, the chromosomes decondense, and a nucleolus and nuclear enverlope form at both ends of the stretched cell. Cytokinesis starts.
- Describe division of the cytoplasm (cytokinesis) in plant cells - be detailed.
In plant cells, Vesicles from Golgi travel along microtubules delivering structural materials such as cellulose fibers, polysaccharides, and other proteins to the midline of the dividing cell. A cell plate forms midway between the spindle poles; it partitions the cytoplasm when it reaches and connects to the parent cell wall
- Describe division of the cytoplasm (cytokinesis) in animal cells - be detailed.
In an animal cell, the first sign of cytokinesis is the cleavage furrow. The cell membrane contracts as the contractile ring of actin and myosin proteins forms beneath the cell membrane. The proteins contract like a drawstring, separating the daughter cells.
- What are the 4 major checkpoints in the eukaryotic cell cycle? 1.1.3.2
The G1 checkpoint screens for DNA damage. The S phase checkpoints ensure that DNA replication occurs properly. Before mitosis, the G2 checkpoint checks if all the DNA has replicated, if damaged DNA can be repaired, and if the spindle making machinery is in place. The metaphase checkpoint ensures that all chromosomes are aligned and if the spindle fibers are attached properly to the kinetochores/chromosomes.
Tumor suppressor gene?
gene that normally prevents cell division but when inactivated or suppressed causes cancer - P53
Proto-oncogene?
a gene involved in the signalling or regulation of cell growth - BRCA1, BRCA2
Okazaki fragments?
Short stretches of DNA synthesized on the lagging strand
Template strand is read?
3’-5’
Newly synthesized strand is formed?
5’-3’
