3
27.
Chromatin:
Nuclear Chapter material that gives rise to chromosomes during mitosis. Complex of
DNA, histones, and nonhistone proteins.
Chromosome:
Roadlike structure that appears in the nucleus of a cell during mitosis. Contains
the genes responsible for heredity. Structure composed of a long DNA molecule
and associated proteins that carries part or all of the hereditary info of an
organism.
Genetics:
The study of the mechanisms of transmission of genes from parents to offspring
Sex Chromosomes:
A chromosome that carries genes determining the genetic sex of an individual
Autosomes:
Chromosomes other than sex chromosomes
28. Gregor Mendel
Drosophila melanogaster
o Important laboratory model for over 100 years
Wild type characteristics
o A characteristic similar to that found in wild animals
29.
X-O System: Involves one kind of chromosome.
In females, all cells except gametes possess two X chromosomes
During meiosis, homologous X chromosomes segregate, and all eggs contain one
X chromosome
Males posses one X chromosome per cell
Meiosis results in half of all sperm cells having one X and half having no X
Fertilization results in half of all offspring having one X chromosome (males) and
half of all offspring having two X chromosomes (females)
X-Y System: Males females and have an equal number of chromosomes, but the male is
usually XY and the female is usually XX
Z-W System: Used in birds. The female is ZW.
30.
Diploid: Having 2 sets of chromosomes. The 2N chromosome number.
Haploid: Having one member of each pair of homologous chromosomes. Haploid cells
are the product of meiosis and are often gametes.
Polyploidy: Having more than 2 sets of chromosomes (3N, 4N, etc.)
Cytokinesis: The division of the cytoplasm of a cell into two parts, as distinct from the
division of the nucleus (mitosis)
Chromatid: One copy of a eukaryotic chromosome formed by DNA replication
Centromere: Constricted region of a mitotic chromosome that holds sister chromatids
together. Also, the site on the DNA where the kinetochore forms and then captures
microtubules from the mitotic spindle.
Kinetochore: A specialized group of proteins and DNA at the centromere of a
chromosome. Is an attachment site for the microtubules of the mitotic spindle and plays
an active part in the movement of chromosomes to the pole.
31. Responsible for growth, replacement, development and maintence . Without it, we
would be single celled.
32. Mitosis is typically followed by cytokinesis (division of the cytoplasm)
Exceptions: osteoclasts are multi-nucleated cells