Sex-Linked Inheritance PDF

Sex-Linked showing how Morgan’s experiment turned out: Inheritance What is Sex-Linked Inheritance? The inheritance of traits from the parents to the offspring through sex chromosomes. Males have X and Y chromosomes, whilst Females...

Sex-Linked showing how Morgan’s experiment turned out: Inheritance What is Sex-Linked Inheritance? The inheritance of traits from the parents to the offspring through sex chromosomes. Males have X and Y chromosomes, whilst Females have [Figure 1] both X chromosomes (X and Y chromosomes carry alleles at their gene loci) Sex-linked genes located on the X chromosome are referred to as X-linkage. Y-linkage, on the other [Figure 1.2] hand, is more present on the Y chromosome and is transmitted in males only. Discovery of Sex Linkage Thomas Hunt Morgan, an [Figure 1.3] embryologist, worked on an experiment involving fruit flies Types of Sex-Linked (Drosophila melanogaster) due to its Inheritance unique breeding inside his lab known as the “fly room”. Below are pictures There are two types of sex-linked inheritance: X-linked and Y-linked. Moreover, X-linked inheritance can X-linked X-linked either be recessive or dominant. Recessive Dominant Inheritance Inheritance X-Linked Recessive Genes This trait is more Both males and common in females are Commonly affects the males as one males as they affected by this contain only one type of disorder. copy of the affected X-linked X chromosome. recessive gene is enough for the trait Haemophilia A Examples of to be expressed., It can affect and haemophilia X-linked females if they are homozygous B are examples dominant of X-linked inheritance recessive. recessive include inheritance. Incontinentia X-Linked Dominant Genes pigmenti. This type is considered rare and embryonically lethal in male. One There are certain diseases which are copy of an allele is enough to cause linked to the X chromosome but are the mutation. recessive, where females act as a carrier if they have only one copy of defective genes (e.g. colour blindness, haemophilia) Males are heterozygous; hence, they are more prone to get sex-linked disorders because only one defective copy of genes is sufficient to cause diseases. [BYJU] Y-Linked Genes [Figure 1.3] ___________________________________________________________________ Word Notes: Carrier is an individual who seems normal but carries the mutant allele Haemophilia is a trait among royals in which minor cuts and bruises are considered fatal (excessive bleeding and death) due to the lack of blood-clotting trait. Mutated genes are present at the Y chances of passing or getting the chromosome. Since the Y disease, and animal and plant chromosome is found in males only, breeding. disorders are passed from father to offspring (e.g. hypertrichosis of the ears, webbed toes, porcupine man) [Figure 2] Table on the interpretation on parts of a Pedigree chart Types of Analysis [Figure 1.4] There are 5 types: Autosomal Dominant (AD), Autosomal Recessive Pedigree Analysis (AR), X-Linked Dominant (XD), It is a genetic representation of the X-Linked Recessive (XR), and family tree showing the flow of Y-Linked (Y). inheritance of traits over generations. Not only that, it also shows the Autosomal Dominant talks about relationship between members of the having one copy of the allele needed family and which carries or expresses in which the trait appears in every the trait. generation for both sexes (male and female are equally affected). All This was applied to discover natures offspring will contain at least one of new rising diseases, trace the affected parent, no carriers. ___________________________________________________________________ Pedigree - late Middle English: from Anglo-Norman French pé de grue ‘crane's foot’, a mark used to denote succession in pedigrees.  Assuming to have a normal mother, an affected male will not have any affected sons, but all daughters are affected. No carriers. [Figure 2.1] Huntington’s disorder This time, Autosomal Recessive, two copies are required in which two carrier parents (male and female equally affected) have the possibility [Figure 2.3] Fragile X Syndrome to produce an affected offspring. X-Linked Recessive contains a requirement that two allele copies on an X chromosome is needed. An affected male is considered Hemizygous (one copy rather than the usual two). For an affected woman, all sons are affected and daughters are carriers (assume [Figure 2.2] Tay Sachs disease normal husband). Additionally, in X-Linked Dominant, both male and female are affected, however, it is more prominent in males. Each pregnancy of an affected female will result in a 50 percent chance for the trait to be inherited. [Figure 2.4] Color Blindness Lastly, in Y-Linked, the Y chromosome Synthesis and Breakdown of ONLY will have an allele for the gene Polymers in which the trait is transmitted from Polymers are made through a process father to son only. called polymerization. Polymerization happens in which monomers, may it be alike or representing two or more compounds, are chemically bonded. Under this process is dehydration synthesis, also known as condensation. Dehydration synthesis [Figure 2.5] Hypertrichosis Pinnae or reaction, meaning “to put together Auris while losing water”, involves the release of H2O during the Macromolecules combination between monomers as byproducts. It is also called Macromolecules are considered large condensation as two molecules are and complex, paving way to unique condensed to create a larger properties that arise depending on molecule in exchange for a loss of a the arrangement of atoms. smaller molecule. Not only that, biomolecules contain Moreover, hydrolysis, meaning to Carbon along with H and O. “split water”, compared to Composed of 4 outer shell electrons, dehydration, puts polymers into a carbon is able to form stable covalent process that is then broken down. bonds. ___________________________________________________________________ Functional Groups - group of atoms within a molecule with the same chemical properties Polymer - molecule consisting of many similar monomers Monomers - buildings blocks “All dehydration reactions are polymerization, but all polymerization are not dehydration” The polymer is broken into two considered to be the source of energy components, one gains a H- atom (e.g. glucose, fructose), storage of (un-ionized) and the other gains a energy (e.g. starch, glycogen), and OH-. structure (e.g. cellulose, chitin). Monosaccharides (CH2O), known as the simplest form of carbohydrate, is a single sugar molecule. It can be classified through the location of the carbonyl group (Aldose, Ketose), number of carbon atoms, and the major nutrients for the cells. Most common under monosaccharides is glucose. [Figure 3] Synthesis and breakdown of carbohydrate and protein polymers All living things are made up of four classes of large biological molecules: carbohydrates, lipids, [Figure 3.1] proteins, and nucleic acids. Carbohydrates include sugar and polymers of said sugar (CH2O)n. It is ___________________________________________________________________ Polymers are diverse and are different in each organism, both in the cell and in between species. Starch - glucose molecules broken down by amylase Meat - polypeptides broken down by pepsin DNA - broken down by deoxyribonuclease  glycosidic linkage (covalent bond). It can be linear or branched. Oligosaccharides consist of 3-10 monosaccharides similarly joined by a covalent glycosidic linkage. This however, must be broken down into [Figure 3.2] monosaccharides for energy use. Polysaccharides range from a few hundred up to a few thousand monosaccharides joined together. It is mainly used for storage and structure. Examples of storage Polysaccharides are starch and glycogen. Starch is made up entirely [Figure 3.3] of glucose in plants with two types: Amylose (unbranched structure) and Amylopectin (branched structure). Glycogen, on the other hand, is made up of glucose from animals and is [Figure 3.4] mainly stored in the liver and muscle cells to be depleted in about a day. In Disaccharides are a combination of 2 addition, structural polysaccharides monosaccharides joined by a are cellulose and chitin. ___________________________________________________________________ Disaccharides paired: Galactose + Glucose + Fructose = Raffinose Glucose + Fructose = Sucrose Glucose + Glucose = Maltose Glucose + Galactose = Glucose Cellulose is made entirely of alpha each carbon. Fatty acid is a and beta glucose molecules and is the combination of a carboxyl group most abundant organic compound on attached to a carbon skeleton. An Earth and major component in plant example of a fat is triglyceride, cells. Chitin, this time, are found in common fat found in foods and our arthropods (exoskeleton). Not only body. that, it is also found in fungi with the role as a building material for its cell Fatty acids can be branched into wall. saturated and unsaturated fats. Saturated is the max number of Moving onto lipids, Lipids are a hydrogen atoms possible with no diverse group of hydrophobic double bonding. Unlike unsaturated, it molecules in which it is also part of consists of one or more double bonds, the class of large biological molecules less hydrogen oils. that doesn’t include true polymers. They mix poorly and in some cases, do not mix with water. Lipids are also hydrophobic as they contain mostly hydrocarbons (which form nonpolar [Figure 4] covalent bonds). Most important lipids are: fats, phospholipids, and steroids. Fat is constructed of glycerol and [Figure 4.1] fatty acids. Glycerol is a three-carbon with a hydroxyl group attached to ___________________________________________________________________ Unsaturated is better than saturated fat since your condition might worsen. Lipid function: energy storage Adipose cells/ adipocytes: long term food reserves storage Adipose tissue: cushions the organs and insulation The process in which hydrogen is added to an unsaturated acid and is left to harden (margarine) is called hydrogenation. This makes unsaturated fat into trans fat double bonds (can lead to cardiovascular disease like atherosclerosis). Some unsaturated fats cannot be not synthesized inside the body and are only supplied through eating (Omega-3). Phospholipids are two fatty acids and a phosphate group attached to glycerol (hydrophobic and hydrophilic). Steroids is a carbon skeleton with four fused rings. [Figure 4.2] ___________________________________________________________________ Cholesterol in mammal cell membrane helps in creating other steroids. High cholesterol, more probability of getting cardiovascular diseases Roid Rage - unbalanced hormones due to steroid use