nucleic acids. certain proteins. cell membranes. certain carbohydrates.
Complete question:
A geneticist crossed fruit flies to determine the phenotypic ratio. The geneticist crossed a fly with blistery wings and spineless bristles (bbss) with a heterozygous fly that had normal wings and normal bristles (BbSs). Which proportion of offspring that are dominant for both traits in would you not expect based on Mendel's law of independent assortment? 1/2 , 4/16, 25% , or 1/4
Answer:
1/2 is the proportion of the offspring that is NOT expected among individuals that are dominant for both traits.
4/16 = 1/4 = 25% of the progeny and the correct expected proportion of individuals that are dominant for both traits.
Explanation:
<u>Available data</u>:
- Cross: a fly with blistery wings and spineless bristles with a heterozygous fly that had normal wings and normal bristles
- Recessive trait: blistery wings and spineless bristles
- Dominant trait: normal wings and normal bristles
Let us say that:
- B is the dominant allele for normal wings
- b is the recessive allele for blistery wings
- S is the dominant allele for normal bristles
- s is the recessive allele for spineless bristles
Parentals) bbss x BbSs
Gametes) bs, bs, bs, bs BS, Bs, bS, bs
Punnett square) BS Bs bS bs
bs BbSs Bbss bbSs bbss
bs BbSs Bbss bbSs bbss
bs BbSs Bbss bbSs bbss
bs BbSs Bbss bbSs bbss
F1) 4/16 = 1/4 = 25% of the progeny is expected to be BbSs, dyhibrid individuals, expressing normal wings and normal bristles
4/16 = 1/4 = 25% of the progeny is expected to be Bbss, expressing normal wings and spineless bristles
4/16 = 1/4 = 25% of the progeny is expected to be bbSs, expressing blistery wings and normal bristles
4/16 = 1/4 = 25% of the progeny is expected to be bbss, expressing blistery wings and spineless bristles
A pathogen is a microorganism that is able to cause disease in a plant, animal or insect. Pathogenicity is the ability to produce disease in a host organism. Microbes express their pathogenicity by means of their virulence, a term which refers to the degree of pathogenicity of the microbe. Hence, the determinants of virulence of a pathogen are any of its genetic or biochemical or structural features that enable it to produce disease in a host.
The relationship between a host and a pathogen is dynamic, since each modifies the activities and functions of the other. The outcome of such a relationship depends on the virulence of the pathogen and the relative degree of resistance or susceptibility of the host, due mainly to the effectiveness of the host defense mechanisms. Staphylococcus aureus, arguably the most prevalent pathogen of humans, may cause up to one third of all bacterial diseases ranging from boils and pimples to food poisoning, to septicemia and toxic shock. Electron micrograph from Visuals Unlimited, with permission.
The Underlying Mechanisms of Bacterial Pathogenicity
Two broad qualities of pathogenic bacteria underlie the means by which they cause disease:
1. Invasiveness is the ability to invade tissues. It encompasses mechanisms for colonization (adherence and initial multiplication), production of extracellular substances which facilitate invasion (invasins) and ability to bypass or overcome host defense mechanisms.
2. Toxigenesis is the ability to produce toxins. Bacteria may produce two types of toxins called exotoxins and endotoxins. Exotoxins are released from bacterial cells and may act at tissue sites removed from the site of bacterial growth. Endotoxins are cell-associated substance. (In a classic sense, the term endotoxin refers to the lipopolysaccharide component of the outer membrane of Gram-negative bacteria). However, endotoxins may be released from growing bacterial cells and cells that are lysed as a result of effective host defense (e.g. lysozyme) or the activities of certain antibiotics (e.g. penicillins and cephalosporins). Hence, bacterial toxins, both soluble and cell-associated, may be transported by blood and lymph and cause cytotoxic effects at tissue sites remote from the original point of invasion or growth. Some bacterial toxins may also act at the site of colonization and play a role in invasion. Acid-fast stain of Mycobacterium tuberculosis, the agent of tuberculosis (TB). The bacteria are the small pink-staining rods. More than one-third of the world population is infected. The organism has caused more human deaths than any other bacterium in the history of mankind. Although its ability to produce disease is multifactorial, it is not completely understood. American Society of Microbiology, with permission.
Answer:
A, G2.
Explanation:
G2, the second gap, occurs directly after S phase, the synthesis of new DNA.
The answer is <span>Chytridomycota.</span>
