Topic 2: Introduction to Genetics Flashcards
Mitosis
The process by which the chromosomes in the cell nucleus are separated into two identical sets of chromosomes, each in its own nucleus.
Meiosis
Process by which a cell divides its DNA when forming sex cells. Involves genetic recombination, forming new chromosomes and splitting pairs of these reducing the total amount of DNA assigned to a cell by half.
Diploid
Contain two sets of chromosomes (2n)
Haploid
Contain one set of chromosomes
Gametes
a cell that fuses with another cell during fertilization (conception) in organisms that sexually reproduce.
Chromosomes
a structure of DNA, protein, and RNA found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.
Homologous
a set of one maternal chromosome and one paternal chromosome that pair up with each other inside a cell during meiosis.
Non-homolougus
Chromosomes from different pairs
Sex chromosomes
X and Y
What is the cell cycle?
A series of developmental stages a cell goes through during its life. Consists of G1 (gap I) phase, NOTE G0, S (synthesis) phase, G2 (Gap 2) phase and M (mitosis) phase.
Explain Gap 1 phase.
The cell grows and accumulates materials and organelles. During this stage a commitment to divide is made and the cell must then go through the rest of the cell cycle. 5 hours.
Explain NOTE G0 phase.
A phase in which cells can be arrested and stay indefinetley. It is like G1 but no net growth occurs.
Explain S (synthesis) phase
DNA synthesis occurs and the chromosomes are replicated. 7 hours.
Explain Gap 2 phase.
The cell grows some more, synthesising proteins neccessary for mitosis. 3 hours.
Explain Mitosis phase.
Cell undergoes mitosis in which the duplicated genetic material is distributed equally into what will be two new cells. Each daughter cell receives an identical chromosome complement to the original cell. Cytokinesis occurs after mitosis and cycle starts again.
What are the four phases of Mitosis?
PEAS MAKE AWFUL TARTS.
Prophase. Metaphase. Anaphase. Telophase.
What is the centrosome?
The organising region from which microtubules radiate. They replicate about the same time as the DNA does.
What is a centromere?
The region of DNA.
Explain Prophase.
Chromosomes coil up and condense, centrioles divide and move apart.
Explain Metaphase.
Chromosomes are clearly doubled structures; centrioles reach the opposite poles; spindle fibres form. Centromeres align on metaphase plate.
Explain Anaphase.
Centromeres split and daughter chromosomes migrate to opposite poles.
Explain Telophase.
Daughter chromosomes arrive at the poles; cytokinesis commences.
Aneuploidy
Having one or two more (or less) chromosomes than normal. Eg down syndrome.
Polyploidy
Having multiple sets of chromosomes. (more than two)
