The correct statement(s) about absorption is (D) Amino acid transport is linked to sodium transport.
Amino acids are transported across the villus epithelium in the small intestine, and this process is linked to sodium transport.
Amino acids, not proteins, are absorbed; proteins rely on prior digestion to amino acids. Most absorption of amino acids occurs in the jejunum; there is a lesser contribution from the ileum.
Amino acids are absorbed by a co-transport mechanism with sodium ions. Both sodium ion and amino acid combine with a cell surface protein receptor.
There are different receptors for the groups: neutral amino acids, basic amino acids, acidic amino acids
In addition, certain amino acids may have there own specific transporter e.g. proline. The receptor then conveys both molecules to the inside of the cell.
The energy for this transport is derived from the concentration gradient for sodium across the cell membrane. Na-K ATPase transporters actively and continuously pump sodium ions outwards to maintain the gradient.
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hich gas began to increase in the atmosphere as a result of photosynthesis by autotrophic prokaryotes approximately 2.7 billion years ago?
Oxygen began to increase in the atmosphere as a result of photosynthesis by autotrophic prokaryotes approximately 2.7 billion years ago. This process, called oxygenic photosynthesis, uses energy from sunlight to convert carbon dioxide and water into organic matter (carbohydrates) and oxygen gas. This new source of oxygen led to an increase in atmospheric oxygen, which had previously been low, and allowed for the evolution of more complex forms of life.
Oxygenic photosynthesis is carried out by autotrophic prokaryotes, or “oxygenic phototrophs”, which are organisms that use energy from sunlight to convert inorganic molecules into organic molecules. These phototrophs use light to break down carbon dioxide molecules, and form simple organic molecules, such as glucose. The byproducts of this process are organic molecules and oxygen gas. As a result of this reaction, the amount of oxygen in the atmosphere began to increase.
This increase in oxygen allowed for the evolution of more complex life forms. Before the rise of oxygenic photosynthesis, the atmosphere was largely composed of carbon dioxide and nitrogen, which prevented the evolution of complex organisms. With the rise of oxygen, more complex organisms could thrive, as oxygen allowed for respiration, which is the process of breaking down food molecules to create energy. As a result, the diversity of organisms increased and eventually led to the evolution of multicellular organisms.
In conclusion, oxygen began to increase in the atmosphere approximately 2.7 billion years ago as a result of oxygenic photosynthesis carried out by autotrophic prokaryotes. This allowed for the evolution of more complex forms of life and the development of multicellular organisms.
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do not add any more lactose and watch what transpires. note what happens and why this occurs. how could you re-activate the lacz gene?
The lacZ gene is responsible for the enzyme β-galactosidase which breaks down lactose. When no more lactose is added, the lacZ gene is not activated and the β-galactosidase enzyme does not break down lactose. To re-activate the lacZ gene, you would need to add lactose back in so that the β-galactosidase enzyme is activated and lactose is broken down.
Lactose is a disaccharide sugar composed of glucose and galactose, which is found in milk. Lactose can be hydrolyzed into glucose and galactose through the catalytic action of lactase enzymes. This reaction occurs in the small intestine, and the glucose and galactose are then absorbed and used as energy by the body.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
To re-activate the lacZ gene, it is necessary to add lactose or a lactose analog such as IPTG to the culture medium. IPTG is an inducer of the lac operon that does not bind to the repressor protein, allowing the genes involved in lactose metabolism to be expressed even in the absence of lactose.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
Therefore, if no more lactose is added to the culture medium, the lac operon will turn off, and the genes involved in lactose metabolism will not be expressed. This occurs because the repressor protein binds to the operator site of the operon, preventing RNA polymerase from transcribing the genes involved in lactose metabolism.
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1. some of the age-related changes in the articular cartilage that contribute to osteoarthritis include
Some of the age-related changes in the articular cartilage that contribute to osteoarthritis include increased stiffness and decreased elasticity, reduced water content and a decrease in proteoglycan content within the matrix, and loss of structural integrity.
Osteoarthritis (OA) is a chronic degenerative joint disease that affects both the cartilage and the underlying bone, with a growing prevalence and a major impact on people's lives.
The articular cartilage, which is the cartilage that covers the ends of bones in a joint, deteriorates in OA, causing joint pain, stiffness, and disability.
As the population ages, OA is projected to become a leading cause of disability, making it a significant public health concern.
The age-related changes in the articular cartilage that contribute to osteoarthritis include the following:
Increased stiffness and decreased elasticity. The articular cartilage, like other body tissues, loses its elasticity and becomes stiffer as we age.
This loss of elasticity and increased stiffness causes the joint to become less mobile, limiting motion and leading to joint pain and discomfort.
Reduced water content. The cartilage matrix has a high water content, which provides cushioning and shock absorption, particularly during joint movement. However, with age, the water content of the matrix reduces, leading to a loss of this cushioning effect.
Loss of proteoglycan content within the matrix. Proteoglycans are large molecules found in the cartilage matrix that help to maintain the structural integrity of the cartilage. The age-related loss of proteoglycans weakens the cartilage matrix and makes it more prone to damage and deterioration.
Loss of structural integrity, Age-related changes, such as changes in the joint shape or the alignment of the bones, can lead to uneven distribution of weight within the joint, causing additional stress on the cartilage.
This uneven weight distribution, combined with the age-related changes in the cartilage matrix, contributes to the loss of structural integrity of the articular cartilage, which is a hallmark of osteoarthritis.
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