heredity - cell replication Flashcards
How important is it for genetic material to be replicated exactly
- changing the sequence can alter or stop the protein from being produced
- the exact replication of genetic material that occurs during mitosis
allows for the exchange of alleles between homologous chromosomes during meiosis, which incorporates variation into the species.
model advantages
- simplify complex concepts
- have predictive power
- lead to increased understanding and future research
model disadvantages
- may not be accurate
- oversimplification can be misleading
- lack detail
mitosis
- growth and development and repair for an individual
- parent cell gives rise to two identical daughter cells
meiosis
- produces genetically unique haploid cells which is essential to maintain genetic diversity within the species
- parent cell giving rise to four genetically unique daughter cells
mitosis interphase
period of cell growth and normal activity, The DNA is duplicated during interphase creating two copies of each chromosome
mitosis prophase
first and longest stage. Chromosomes become visible and the centrioles seperate and move to opposite poles of the cell
mitosis metaphase
second stage of mitosis. The chromosomes line up across the centre of the cell and become connected to the spindle fibres at their centriole
mitosis anaphase
third stage of mitosis. Sister chromatids are pulled apart and are separated into individual chromosomes
mitosis telophase + cytokinesis
chromosomes gather at opposite ends of the cell and lose their distinct rod-like shapes. Two new nuclear membranes form around each set of chromosomes and the spindle fibres disappear
cytokinesis follows telophase. The cell membrane pinches and divides the cytoplasm in half. The result is two identical daughter cells, each containing a complete copy of the original DNA and all organelles
meiosis prophase I
the complex of DNA and protein known as chromatin condenses to form chromosomes. The pairs of replicated chromosomes are known as sister chromatids, and they remain joined at a central point called the centromere.
meiosis metaphase I
the alignment of the duplicated chromosomes at the equatorial plate known as the metaphase plate. One of the sister chromatids is attached to one pole of the cell by microtubules attached to its kinetochore and the other sister chromatid gets attached to the opposite pole.
meiosis anaphase I
begins when homologous chromosomes separate. The nuclear envelope reforms and nucleoli reappear. The chromosomes coil up, the nuclear membrane begins to disintegrate, and the centrosomes begin moving apart. Spindle fibers form and sister chromatids align to the equator of the cell.
meiosis telophase + cytokinesis I
the chromosomes are enclosed in nuclei. The cell now undergoes a process called cytokinesis that divides the cytoplasm of the original cell into two daughter cells. Each daughter cell is haploid and has only one set of chromosomes, or half the total number of chromosomes of the original cell.
watson and crick model
- double stranded
- helical
- two sugar phosphate backbones
- held with hydrogen bonds between each nitrogenous base
