A muscle fiber contains many myofibrils, which are cylinders of muscle proteins. These proteins allow a muscle cell to contract. Myofibrils contain two types of filaments that run along the long axis of the fiber, and these filaments are arranged in hexagonal patterns. There are thick and thin filaments.hese proteins allow a muscle cell to contract. Myofibrils contain two types of filaments that run along the long axis of the fiber, and these filaments are arranged in hexagonal patterns. There are thick and thin filaments.
Cocklebur (Xanthium strumarium L.) is a large, annual broad-leaved weed with an erect, branched stem and broadly triangular leaves (Figure 1). The stem is rough-hairy, spotted with purple and up to 1.5 m high. The leaves are alternate on the stem, with toothed or lobed margins and rough-hairy surfaces.
1. Ladybugs aren't really bugs at all, they're beetles! Entomologically speaking, the term bugs applies to insects of the order Hemiptera. Ladybugs belong to the order Coleoptera, or beetles. Europeans have called these dome-backed beetles by the name ladybirds, or ladybird beetles, for over 500 years. In America, the name ladybird was replaced by ladybug. Scientists usually prefer the common name lady beetles.