Structure and Function Chromosomes Structure and Function Title Pic of chromosome structure

Chromosomes & DNA DNA is a long, thin molecule that stores genetic Information and is located in the nucleus of eukaryotic cells. During cell division, this DNA is coiled around proteins into very compact structures called chromosomes DNA wraps around proteins called histones that keep the shape of chromosomes and help to pack DNA tightly

From DNA  Chromosome

Chromosome Structure consists of identical halves (sister chromatids) which form after DNA replication centromere holds the two chromatids together until they split during cell division (mitosis/meiosis) centromeres aid in chromosome movement during cell division

Chromatin vs. Chromosomes When cells are not dividing, DNA is not coiled up tightly into chromosomes. Why? Uncoiled DNA can be easily read so the information can give your cells directions on how to carry out activities. Only during cell reproduction is DNA in chromosome form. The rest of the time DNA is called chromatin (uncoiled DNA).

Chromosome Numbers of Different Organisms Each species has a specific number of chromosomes in each of their cells, which is NOT based on complexity. Organism #of Chromosomes Camel 70 Bat 44 Chicken 78 Apple 34 Fruit Fly 8 Pea 14 Dove 16 Fox 34 Earthworm 36 Cat 38

Chromosome Numbers in Organisms Animals (including humans) have two categories of chromosomes: 1. sex chromosomes (determine gender) XX - female, XY - male 2. autosomes (all other chromosomes, determine the rest of your traits) IMPORTANT POINT: Cells have a copy of each autosome (one from each parent) called homologous chromosomes (pairs/diploid). Homologues are the same size, shape and carry genes for the same trait. THEREFORE… Humans have 46 chromosomes (2 sex chromosomes, 44 autosomal) in autosomal (body) cells and 23 in germ (sex) cells. Complexity Sex chrom Autosomes Homologous Karyotype

Haploid versus Diploid Cells with pairs of homologous chromosomes entact/together are diploid (2n), they have both parents’ sets of chromosomes. Germ (sex) cells are haploid (1n), having one chromosome of each homologous pair and one sex chromosome. For example: human somatic (body) cells - 46 human germ (sex) cells - 23 Why must egg and sperm cells be haploid?

Using this karyotype, what is the sex of this person? What is a Karyotype? a picture of an organism’s chromosomes it can tell help answer questions such as: -What is the gender of the child? -Will an unborn baby have a genetic disorder? -What kind of genetic disorder? -Which chromosome(s) is effected? Using this karyotype, what is the sex of this person?