Chromosomes-General-Biology-1.pptx Science

Gen Bio

1. Chromosomes General Biology 1

2. Table of contents Introduction 01 05 04 02 06 03 Mitosis and Meiosis Chromatid Traditional Karyotyping Kinetochore Chromatin

3. Introduction

4. Chromosomes When you were born, you received your parents a complete set of DNA that carries the genetic information you have inherited and makes ypur body function normally throughout your life.

5. Deoxyribonucleic Acid DNA, a double stranded molecule, is tightly coiled in an organized structure called chromosome

6. Chromosomes A chromosome is simply a long, continuous thread of DNA wounded together by DNA-associated proteins, referred as histones. Each of our body consists of 46 chromosomes or 23 pairs.

7. Chromosomes contain tightly wound DNA. They are packaged by histone proteins into condensed structure called chromatin.

8. Cell Division Before the cell division, DNA is loosely organized like a scattered spaghetti on a plate. During cell division, chromosomes become tightly condensed.

9. Cell Division This step is required so the chromosome will not be entangled during cell division; that is why duplicated chromosomes must condense first before they divide into daughter cells.

10. Chromosome This figure shows how chromosome is transformed into linear strand of DNA from a highly condense structure. This is achieved by the proteins called histones where DNA wraps around.

11. Traditional Karyotyping

12. Traditional Karyotyping uses Giemsa stain to visualize chromosomes and then pairs and arranges homologous chromosomes, according to size and bonding pattens. This technique requires a fluorescent microscope to visualize the chromosomes labeled with specific probes that produce different fluorophores

13. Chromatin

14. Chromatin As mentioned earlier, before cellular division takes place, the DNA and proteins are loose like a spaghetti. The complex set of macromolecules that contains loose DNA, proteins and RNA is called chromatin.

15. Chromatin Chromatin is responsible for packaging the DNA efficiently into smaller volume so that it fits the nucleus of a cell to protect the DNA structure sequence, to prevent DNA damage, to control gene expression and DNA replication, and to reinforce the DNA molecule to allow mitosis and meiosis.

16. Mitosis and Meiosis

17. Mitosis Mitosis is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division. Mitosis is generally followed by equal division of the cell's content into two daughter cells that have identical genomes.

18. Meiosis Meiosis is a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes (the sex cells, or egg and sperm). In humans, body (or somatic) cells are diploid, containing two sets of chromosomes (one from each parent)

19. Chromatid

20. Chromatid As the cell progress in the cell division, chromatin further condenses, coiling more and more tightly around the proteins and eventually forming small, thick rods. Once the chromosom e has been copied, the chromosome now appears to be similar to a letter X in which the left and the right halves are identical.

21. Chromatid Chromatid refers to each strand of the duplicated chromosomes . Together they are called sister chromatids, which are held together by centromere, a region of condensed pinched chromosome.

22. Kinetochore

23. Kinetochore Located at the centromere is a group of proteins called kinetochore , which is attached to the long spindle fibers during cell division

24. Other information At the ends of the DNA molecule and structures referred to as telomeres that contain repeated nucleotides, which contain genetic information that do not translate into traits. Their role is to prevent their ends of chromosomes from accidentally attaching to one another and prevents the loss of genes.

25. DNA Replication The resulting two copies of DNA after replication consist of two identical copies of DNA connected to each other by the centromere

26. Thank you!