Lesson 6_Chromosomes.pdf

Lesson 6: Chromosomes Autosomal Chromosomes Chromosome  22 pairs  From the word  1-22 chromosome o “Chroma” - Color  Contain genes that...

Lesson 6: Chromosomes Autosomal Chromosomes Chromosome  22 pairs  From the word  1-22 chromosome o “Chroma” - Color  Contain genes that are responsible in our o “Soma” - Bodies somatic characteristics  Thread like structures o Inside the nucleus Sex Chromosome o Contains DNA and genes  23rd pair  Contains Genes  X and Y  Colored Bodies  XX - Female  XY - Male Chromosome Structures  Contain genes that encodes for our sexual characteristics that will identify the sex of an individual Classification based on Centromere Metacentric  Two arms are roughly equal in length  Centromere is exactly in the middle Centromere  Chromosomes:  Found in the middles o 1,3,16,19,20  Used during cell division as the attachment point o During cell division, spindle fibers Submetacentric attached here, specifically the  Short and long arms of unequal kinetochore length with the centromere more o Kinetochore - the protein in the towards one end centromere  Usual morphology of chromosomes Telomere  Chromosomes:  Both ends o 2,4,6,7,8,9,10,11,12,17,18  Use to maintain chromosomal integrity by o X capping off the ends Acrocentric Short arm  p arm is hard to observe but still  P present  Clue: P for petite  Centromere is very near to one  Upper end and have very small short arm Long arm  Chromosomes  Q o 13,14,15,21,22  Lower o Y Telocentric  Centromere is located at the terminal end of the chromosome  Do not exist in humans Primary and Secondary Constrictions Chromosome Classification  Primary Constriction  Autosome Chromosomes o Centromere  Sex Chromosomes  Secondary Constriction  Centromere Location o Satellite / Stalk  Stalk/Satellite (with Secondary Constriction) Group B  Contains genes which code for rRNA  Chromosome: 4-5 o rRNA produced in nucleolus, that  Large is why it is responsible in the  Submetacentric with 2 arms very different nucleolus formation in size  Responsible in nucleolus formation  SAT Chromosomes o Chromosome that contains satellite o Most of the chromosomes that have satellite in humans they are Chromosome 4 acrocentric  Submetacentric  191 million base pairs Chromosome 5  Submetacentric Chromosome Identification  181 million base pairs Group A  Chromosomes: 1-3  Largest  Metacentric: 1,3  Subcentric: 2 Group C  Chromosome: 6-12, X  Medium size  Submetacentric Chromosome 1  Largest chromosomes  Metacentric  246 million base pairs Chromosome 2  Largest submetacentric  Second largest chromosome  243 million base pairs Chromosome 6  Medium submetacentric  Largest among the group C chromosomes  170 million base pairs Chromosomes 3  Metacentric  Second largest metacentric  199 million base pair Chromosomes 7  Medium submetacentric  158 million base pairs X Chromosome Chromosome 13  Medium submetacentric  Medium Acrocentric  153 million base pairs  With stalk  113 million base pairs Chromosome 14  Medium Acrocentric Chromosome 8  With stalk  Medium Submetacentric  105 million base pairs  146 million pairs Chromosome 15  Medium Acrocentric Chromosome 9  With stalk  Medium submetacentric  100 million base pairs  136 million base pairs Group E Chromosome 10  Chromosome: 16-18  Medium submetacentric  Small  135 million base pairs  Metacentric: 16  Submetacentric: 17,18 Chromosome 11  Medium submetacentric  134 million base pairs Chromosome 16  Small metacentric  90 million base pairs Chromosome 12  Medium submetacentric  132 million base pairs Chromosome 17  Small submetacentric  81 million base pairs Group D  Chromosomes: 13-15 Chromosome 18  Medium size  Small submetacentric  Acrocentric with satellites  76 million base pairs  Group F Y Chromosomes  Chromosome: 19-20  Small Acrocentric  Small  Without satellites  Metacentric  Largest in Group G  50 million base pairs Chromosome 19  Small metacentric  63 million base pair Euploidy  Condition of having a normal number of Chromosome 20 structurally normal chromosomes  Small Metacentric  59 million base pair Aneuploidy  Any abnormal number of chromosome that is not a multiple of the haploid number (23 chromosomes)  Result of nondisjunction o Nondisjunction  Failure of chromosomes to Group G separate normally during  Chromosomes: 21-22, Y cell division (meiosis)  Small  Acrocentric Trisomy  21 and 22 with satellites  Presence of an extra chromosomes Monosomy  Absence of a single chromosome Chromosome 21  Smallest chromosome  Smallest human chromosome o Chromosome 22 was discovered later, and more genes or base pairs were added to it after discovery, making chromosome 22 larger compared to chromosome 21 Polyploidy  Acrocentric with satellite  Chromosome number is higher than 46  46 million base pairs but is always exact multiple of the haploid chromosomes number of 23 Triploidy (3n)  A karyotype with 69 chromosomes Chromosome 22 Tetraploidy (4n)  Small Acrocentric  A karyotype with 92 chromosomes  Second smallest human chromosomes  With stalk  49 million base pairs  Types of Chromosomal Banding G-Banding  Giemsa Stain  Dark bands: A-T  Light bands: G-C R-Banding  Reverse pattern of G bands  Staining with Giemsa dye  Dark bands: G-C  Light bands: A-T Chromosomal Banding  Staining technique for chromosomes Q-Banding  Comprised of alternating light and dark  Quinacrine stain stripes (bands)  Fluorescent pattern  Appear along it length after being stained  Dark (neon green) bands: A-T with a dye  Light (neon yellow) bands: G-C C-Banding  Dark bands: Constitutive heterochromatin  Centromeric T-Banding  Staining telomeric regions  Giemsa stain or Acridine orange NOR-Staining Euchromatin  Identifies genes for ribosomal RNA that  Lightly packed chromatin were active in a previous cell cycle  Enriched in genes  Nucleolar Organizing Region  Active transcription  Silver Staining method Note: NORs are located on the short arms of the acrocentric chromosomes 13,14,15,21,and 22 Heterochromatin  Tightly packed chromatin  Low gene density  Constitutive heterochromatin  Facultative heterochromatin