Genetics CH12

the members of a chromosome pair that conatin the same genes and that pair during meiosis.

Chromosomes that contain diferent genes and that do not pair during meiosis.

The chromosomes that are represented differently in the two sexes in many eukaryotic organisims.

Chromosomes other than sex chromosomes

Is the constriction along the lengenth of the chromosome.

Has the centromere about the center so the chromosome appears to have two approximately equal arms.

Have one arm longer than the other

Have one arm with a stalk and often with a bulb on it.

have only one arm, because the centromere is at it end.

A complete set of all metaphase chromosomes in a cell is called the cell's karyotype.

• Q is the larger arm separated by the Centromere
• P is the smaller arm separated by the Centromere.

The cycle of growth AKA nuclear division of Karyokinesis

• The cycle of growth, Mitosis, and cell division.
• INterphase and Mitotic phase

Consists of 3 Stages

• G1- Gap Phase-Presynthesis phase- the cell prepares for DNA and Chromosome Replication in S phase
• S-Synthesis Phase- DNA is synthesized
• G2- Gap2- Post synthesis Stage - The cell prepares for cell division or the M stage.

Replicated DNA from the S phase which are 2 exact copies.

One of the two distinct longitudinal subunits of all replicated chromosomes that become visible between early prophase and metaphase of mitosis.

When the centromeres separate the sister chromatids alternative names.

• Prophase
• Prometaphase
• metaphase
• anaphase
• telophase

The successive division of a diploid nucleus after only one DNA replication cycle.

THe formation of male(sperm) and female(eggs) gametes (haploid) during meiosis.

• The chromosome number is reduced from diploid to haploid.
• Occurs during gameteogenesis in animal (production of gametes)
• Meiosis I results in the separation into sister Chromatids
• Meiosis II results in the separation of the sister chromatids.
• The Meiosis of a single diploid cell produces 4 haploid cells.

• Consists of 5 stages
• Prophase I
• Pro Metaphase I
• Metaphase I
• Anaphase I
• Telophase I

The important difference between Mitosis and Meiosis I is that homologus chromosomes pair with each other in Meiosis and Crossing over occurs.

Early Prophase I- Leptonema- Extended Chromosomes condense and become visible as long thin threads. once here a cell is comitted to meiosis.

Middle Prophase I - Zygonema- Chromosomes align and form a synapsis and synaptomeal complex.

Middle Prophase I- Pachynema- Crossing over occurs if the chromosomes are different they produce a recombinant chromosome. (most important step in genetics)

Late Prophase I- Diplonema- the synaptonemal Complex disassembles and the results of crossing over form a x called a chiasma and they move apart.

Later Prophase I- Diakinesis- The chromosomes condense even more, and the 4 members of the tetrads become visible.

• Results of crossing over become visible
• Nuclear Envelope breaks down.
• Meiotic Spindle enters the former nuclear area.
• Kinetochore microtubules attach to chromosomes