DNA_ The Human Body Recipe by Slidesgo.pptx

its a ppt on the topic genetics, very detailed explaination about the relative topics.

1. BY FAIZAN KHAN G E N E T I C S

2. • contents: Terminologies Defination of chromosomes Structure of chromosomes Types of chromosomes based on the position of centromere Functions of chromosomes Sex determination Autosomes Allosomes Bar bodies Human blood groups - A, B, AB, O Rh factor

3. GENETICS - branch of biology which deals with the study of heredity, variation, and factors responsible for the characterisitics. DNA - Deoxyribonucleic acid, is the genetic code in living organisms, a biological instruction manual found in the cells. DNA is composed of two strands forming a double helix structure. Essentially, DNA is the blueprint of life, passing on hereditary information from one generation to the next generation. RNA - ribonucleic acid, is a versatile molecule crucial for various cellular tasks. A messenger that carries instructions from DNA to guide protein synthesis. RNA is single-stranded. CHROMATIN - is the complex of DNA and proteins in a cell's nucleus, resembling a thread-like structure that holds genetic information. Terminology:

4. CHROMOSOME - A chromosome is a thread-like structure in a cell's nucleus that carries genetic information in the form of genes. CHROMATIDS - Chromatids are identical halves of a duplicated chromosome, joined at the centromere, that separate during cell division. CENTROMERE - The centromere is the centralized region of a chromosome where the two chromatids are joined, facilitating their separation during cell division.

5. CHROMOSOMES Defination: Chromosomes are thread-like structures composed of DNA and proteins found in the nucleus of a cell, carrying genetic information in the form of genes and playing a crucial role in the inheritance of traits during cell division. Chroma - colour and Soma - body. Chromosomes are made up of strands of a DNA tightly wrapped around proteins called histones, this makes the DNA compact and able to fit inside the cells nucleus.

6. These chromosomes have multiple centromeres. These chromosomes have a single centromere. These chromosomes have two centromeres. Monocentric Chromosomes: Dicentric Chromosomes: Diffused or non-located Chromosomes: Polycentric Chromosomes: These chromosomes lack a centromere. • Types of chromosomes based on the number of centromeres: The term "diffused chromosomes" is less commonly used and may refer to a state where the centromeric region is not as well-defined or concentrated in a specific area. Acentric Chromosomes:

7. The centromere is slightly off-center, resulting in one longer arm (q) and one shorter arm (p). The centromere is positioned near the center, creating arms of roughly equal length. The centromere is located almost towards the end region, leading to a long arm (q) and a very short arm (p). Metacentric chromosomes: Acrocentric Chromosomes: Submetacentric Chromosomes: The centromere is at the terminal end of the chromosome. • Types of chromosomes based on the posistion of centromere Telocentric Chromosomes:

8. DNA: Chromosomes are primarily composed of deoxyribonucleic acid (DNA), a molecule that encodes genetic instructions. Histones: DNA is wrapped around histone proteins, forming nucleosomes. These histones help in organizing and compacting the DNA. Nucleosomes: The basic repeating unit of chromatin, consisting of DNA wound around a core of histone proteins. Chromatids: Chromosomes consist of two identical chromatids, which are the result of DNA replication during the cell cycle. Centromere: The point where chromatids are joined is called the centromere. It serves as an attachment site during cell division. Structure of chromosomes:

9. Telomeres: Protective caps at the ends of chromosomes, consisting of repetitive DNA sequences. They prevent deterioration and fusion of neighboring chromosomes. Replication Origins: Specific DNA sequences where the process of DNA replication begins. Genes: Segments of DNA on chromosomes that encode specific traits or functions. Sister Chromatids: The two identical copies of a chromosome that are connected by the centromere. Kinetochore: A protein structure on the centromere that plays a role in the separation of chromatids during cell division. P and Q Arms: Chromosomes have two arms, labeled as the short (P) arm and the long (Q) arm. The centromere divides the chromosome into these arms.

10. Primary Constriction: The primary constriction is the region on a chromosome where the centromere is located. It plays a crucial role during cell division, helping to ensure proper separation of chromatids. Secondary Constriction: Secondary constrictions are additional narrowings or constricted regions on a chromosome. They may contain important genetic material and are often associated with the location of ribosomal RNA genes. Secondary constrictions are sometimes called "nucleolar organizers" because they are involved in the formation of nucleoli (structures within the nucleus where ribosomes are produced). Satellite: A satellite is a small, bulbous extension connected to the main body of a chromosome, usually near the secondary constriction. It is formed by a portion of the chromosome that breaks away but remains attached. The satellite is often rich in repetitive DNA sequences and may have specific functions related to gene regulation.

11. Functions of chromosomes:

12. chromosomes control cell differentiation. chromosomes forms a link between off spring and parents. sex chromosomes determines the sex of an individual. Chromosomes provide structural support for the DNA molecule. Chromosomes play a crucial role in cell division, ensuring that genetic material is accurately distributed to daughter cells. Chromosomes carry genes, which are segments of DNA containing instructions for building and maintaining an organism.

13. Sex determination is the process by which an organism's biological sex, whether male or female, is established. The mechanisms of sex determination vary among different species. In humans and many mammals, sex determination is influenced by the combination of sex chromosomes inherited from the parents. • SEX DETERMINATION:

14. The total number of chromosomes in the human body is 46. These chromosomes are organized into 23 pairs. Each parent contributes one chromosome to each pair, resulting in a total of 23 chromosomes from the mother and 23 chromosomes from the father. The chromosomes are divided into two main types: autosomes and allosomes ( sex chromosomes ) . Autosomes (Non-Sex Chromosomes): There are 22 pairs of autosomes, numbered from 1 to 22. These chromosomes contain genes that influence general body characteristics and functions. Allosomes ( Sex Chromosomes ) : The 23rd pair of chromosomes is known as the sex chromosomes. Females have two X chromosomes (XX). Males have one X and one Y chromosome (XY). The combination of sex chromosomes determines an individual's biological sex.

15. The X-chromosome was first observed by a German biologist, Henking in 1891 during the spermatogenesis in male bug and was described as X-body. The chromosome theory of sex - determination was worked out by E.B. Wilson and Stevens (1902-1905). They named the X and Y chromosomes as sex chromosomes or Allosomes and other chromosomes of the cell as autosomes. Sex chromosomes carry genes for sex of an individiual. X-chromosomes carries female determining genes and Y-chromosomes have male determining chromosomes. The number of X and Y chromosomes determines the female or male sex of the individual. Autosomes carry genes for the somatic characters- These characteristics encompass various aspects of the body's structure, appearance, and function. CHROMOSOMAL THEORY OF SEX DETERMINATION:

16. • Different types of mechanisim of sex determination: XX and XY Chromosomes (Humans): In humans, sex determination is based on the presence of sex chromosomes. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The sex chromosomes are inherited from the parents during fertilization. The mother always contributes an X chromosome, while the father contributes either an X (resulting in a female offspring) or a Y chromosome (resulting in a male offspring). Other Mechanisms: In some organisms, environmental factors can influence sex determination. For example, in reptiles like turtles, the temperature during a critical period of egg incubation can determine the sex of the offspring. In certain insects, the presence or absence of a specific chromosome, rather than the combination of sex chromosomes, determines sex.

17. • Different types of mechanisim of sex determination: Genetic Control: Genes on the sex chromosomes play a critical role in the development of sexual characteristics. These genes control the production of hormones and other factors that guide the development of reproductive organs and secondary sexual characteristics. Exceptions: While the XX/XY system is common in mammals, some species have different sex determination systems. For example, birds have a ZW/ZZ system, where females have Z and W chromosomes, and males have two Z chromosomes.

18. •Difference between autosomes and allosomes: Characteristic Autosomes Allosomes (Sex Chromosomes) Definition Non-sex chromosomes Sex chromosomes Inheritance Equally inherited from both parents Inherited unequally, one from each parent Number Majority of an organism's chromosomes Typically two (one pair) Similarity in Males and Females Same in both males and females May differ between males and females Determination of Sex Do not determine the sex of the individual Determine the sex of the individual Role in Sexual Reproduction Contribute to general trait inheritance Play a role in determining sex Genetic Disorders Disorders can affect both males and females Some disorders are sex-linked Variation Contribute to genetic diversity Play a role in sex-related variations Types in Humans 22 pairs in humans One pair in humans (XX in females, XY in males) Evolutionary Perspective Involved in inheritance of general traits Play a role in evolution of sex determination mechanisms

19. • BAR BODIES: Barr bodies are condensed, inactive X chromosomes found in the nuclei of cells in females. In females, who have two X chromosomes (XX), one X chromosome in each cell is randomly inactivated through a process called X-inactivation. This ensures that both males (XY) and females have a similar dosage of X-linked gene expression. The presence of Barr bodies can be observed under a microscope

20. 1. Chromosomes and Sex Determination: Humans have 23 pairs of chromosomes, including one pair of sex chromosomes. Females have two X chromosomes (XX), and males have one X and one Y chromosome (XY). 2. X-Inactivation in Females: In females, to balance gene expression with males (XY), one X chromosome in each cell undergoes inactivation. This process is known as X-inactivation and occurs early in embryonic development. 3. Formation of Barr Bodies: The inactivated X chromosome condenses into a dense, drumstick-shaped structure called a Barr body. Named after Canadian researcher Murray Barr who discovered it. 4. Location in the Nucleus: Barr bodies are found within the nucleus of a cell. The number of Barr bodies in a cell corresponds to the number of inactivated X chromosomes. 5. Random X-Inactivation: X-inactivation occurs randomly in cells, leading to a mosaic pattern in females where some cells express genes from the paternal X, while others express genes from the maternal X.

21. 6. Function of X-Inactivation: X-inactivation ensures that the dosage of X-linked genes is the same in males and females. Prevents females from having double the expression of X-linked genes compared to males. 7 . Clinical Implications: Barr bodies can be observed in cells under a microscope, particularly in females. Abnormalities in X-inactivation can be associated with certain genetic disorders. 8 . Examples: In a normal female cell (XX), one X chromosome is randomly inactivated, forming a Barr body. In a female with Turner syndrome (XO), no Barr bodies are formed. 9 . Importance in Genetics: Understanding X-inactivation is crucial for comprehending the genetic basis of certain disorders and for appreciating the complexity of gene regulation in females.

22. • HUMAN BLOOD GROUPS: 1. Human blood grouping refers to the classification of blood based on the presence or absence of specific proteins (antigens & antibodies) on the surface of red blood cells. 2. The two main systems for blood grouping are the ABO system (which includes blood types A, B, AB, and O) and the Rh system (which categorizes blood as Rh-positive or Rh-negative). 3. The combination of these systems determines a person's blood type.

23. GROUP A GROUP B GROUP AB GROUP O ANTIGENS A B AB NIL ANTIBODIES B A NIL AB DONOR B, AB B, AB AB O, A, B, AB RECIPIENT O, A O, B O, A, B, AB O

24. The Rh factor, or Rhesus factor, is a protein that can be present on the surface of red blood cells. People are categorized as either Rh-positive (having the Rh factor) or Rh-negative (lacking the Rh factor). Rh-Positive (Rh+): If you have the Rh factor on your red blood cells. Rh-Negative (Rh-): If you lack the Rh factor on your red blood cells. Artificial antibodies are formed against Rh+. It indicates whether the blood of two different people is compatible. when mixed such as blood of a mother and her baby at birth. • Rh Factor: DONOR RECIEPIENT Rh+ Rh+ Rh- Rh- Rh- Rh+