Chromosomes

• Chromosomes are threadlike structures that contain genes and are colored bodies.
• Centromere is found in the middle of chromosomes and is used during cell division as an attachment point.
• Telomere is located at both ends of chromosomes and is used to maintain chromosomal integrity by capping off the ends.
• Short arm of chromosomes is p and long arm is q.
• Autosomes or Sex chromosomes are classified based on centromere location.
• Metacentric chromosomes have two arms of roughly equal length, examples include 1,3,16, 19, 20.
• Submetacentric chromosomes have one arm that is shorter and one that is longer with the centromere more towards one end, examples include 2,4,5, 6,7,8,9,10,11,12,17,18 and X.
• Acrocentric chromosomes have a short arm that is hard to observe but still present, the centromere is very near to one end and has a very small short arm, examples include 13,14,15,21,22 and Y.
• Telocentric chromosomes have the centromere located at the terminal end of the chromosomes and do not exist in humans.
• Stalk/Satellite chromosomes contain genes which code for RNA and are responsible in nucleolus formation, examples include chromosomes that contain satellite.
• Chromosome 1 is the largest chromosome and is metacentric with 246 million base pairs.
• Chromosome 2 is submetacentric and the second largest with 243 million base pairs.
• Chromosome 3 is metacentric and the third largest with 199 million base pairs.
• Chromosomes 4-5 are the largest and are submetacentric with two arms very different in size, examples include 4,5.
• Chromosome 4 is submetacentric and the largest among the group c chromosomes with 191 million base pairs.
• Chromosome 5 is submetacentric and the second largest with 181 million base pairs.
• Chromosomes 6-12, X are medium size and submetacentric, examples include 6,7,8,9,10,11,12, X.
• Chromosomes 13-15 are medium size and acrocentric with satellites, examples include 13,14,15.
• Chromosome 13 is medium acrocentric with stalk and 113 million base pairs.
• Chromosome 14 is medium acrocentric with stalk and 105 million base pairs.
• Chromosome 21 is the smallest chromosome, acrocentric with satellite, and contains 46 million base pairs.
• Aneuploidy is any abnormal number of chromosomes that is not a multiple of the haploid number (23 chromosomes).
• Group G chromosomes are 21-22, small, and acrocentric.
• Group E chromosomes are 16-18, small, and submetacentric.
• Chromosome 17 is small submetacentric and contains 81 million base pairs.
• Chromosome 15 is medium acrocentric, has stalk, and contains 100 million base pairs.
• Euchromatin is lightly packed chromatin enriched in genes and active transcription.
• Chromosomal banding is a staining technique for chromosomes, comprised of alternating light and dark stripes (bands), which appear along its length after being stained with a dye.
• Chromosome 19 is small metacentric and contains 63 million base pairs.
• Chromosome 16 is small metacentric and contains 90 million base pairs.
• Group F chromosomes are 19-20, small, and metacentric.
• NOR banding identifies genes for ribosomal RNA that were active in a previous cell cycle.
• Polyploidy is when the chromosome number is higher than 46 but is always an exact multiple of the haploid chromosome number of 23.
• Chromosome 20 is small metacentric and contains 59 million base pairs.
• The Y Chromosome is small acrocentric and contains 50 million base pairs, making it the largest chromosome in Group G.
• Types of chromosomal banding include G-banding, R-banding, Q-banding, and C-banding.
• Euploidy is the condition of having a normal number of structurally normal chromosomes.
• Chromosome 22 is small acrocentric and contains 49 million base pairs.
• Chromosome 18 is small submetacentric and contains 76 million base pairs.
• Heterochromatin is tightly packed chromatin with low gene density and constitutive heterochromatin.