The phrase to fit into the blank is "sexual reproduction"!
In sexual reproduction each of the parents produces a gamete and contributes to half of the offspring's genes. This means that the offspring is a unique composition of the two parents.
In contrast, in a asexual reproduction, the offspring would likely have the same genetic code as the parent.
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Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated.
In proteins that have segments extending extracellularly, the extracellular segments are also often glycosylated. Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system without of reversible cytosolic/nuclear glycosylation. Glycoprotein of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residues that is consider reciprocal to phosphorylation and the functions of these are likely to be additional regulatory mechanism that controls phosphorylation-based signalling.[2] In contrast, classical secretory glycosylation can be structurally essential. For example, inhibition of asparagine-linked, i.e. N-linked, glycosylation can prevent glycoprotein folding and full inhibition can be toxic to an individual cell. In contrast, perturbations of terminal processing, which occurs in the Golgi apparatus, is dispensable for isolated cells(as evidence by survival with glycosides inhibitors) but can lead to human disease (Congenital disorders of glycosylation) and can be lethal in animal models. It is therefore likely that the fine processing of glycans is important for endogeneous functionality, such as cell trafficking, but that this is likely to have been secondary to its role in host-pathogen interactions. A famous example of this latter effect is the ABO blood system.
Answer:
D. muscularis externa
Explanation:
The gastrointestinal tract or digestive tract consist of four main layers:
• Mucosa- consists of the epithelium together with glandular tissue and the lamina propria (connective tissue)
• Submuscosa- consists of fibrous connective tissue with larger blood vessels, lymphatics, nerves..
• Muscularis externa-smooth muscle layer that consists of three layers, responsible for movement (propulsion) and physical break down of the food
• Serosa-consists of connective tissue continuous with the peritoneum.
