Search Results

Nerve Impulse Transmission Animation

By: Administrator, Views: 11119

How nerves transmit impulses. Stimulation of a nerve occurs at a receptor. Sensory receptors Specialized to specific types of stimulation such as heat, cold, light, pressure, or pain. React by initiating a chemical change or impulse. All-or-none principle Means that no transmission occ...

Sister chromatids of a metaphase chromosome animation

By: HWC, Views: 5790

At metaphase, the chromosomes are duplicated and are at their most condensed. In each chromosome. two identical sister chromatids are held together at a constricted region called the centromere. When a chromosome is condensed, interactions among chromosomal proteins keep loops of DNA tightly ...

Transcription—A molecular view

By: HWC, Views: 3332

Transcription, as related to genomics, is the process of making an RNA copy of a gene's DNA sequence. This copy, called messenger RNA (mRNA), carries the gene's protein information encoded in DNA. During transcription, a DNA molecule is copied into RNA molecules that are then used to translate...

Genetic distance between human groups

By: HWC, Views: 4596

One proposed family tree for modern humans. This family tree is based on nucleic-add hybridization studies of many genes and immuno-logical comparisons. Branch points show presumed genetic divergences. This data indicates that the greatest genetic distance separates humans native to Afri...

Pressure Flow Model Animation

By: HWC, Views: 7012

This apparatus of beakers A and funnels simulates the flow of a sucrose solution in the phloem of a plant. The funnels and connecting tube represent a sieve tube of the phloem. Differentially permeable membranes cap the funnels at the source and sink ends, allowing water, but not sucrose, to cros...

Sperm Formation

By: HWC, Views: 5746

Spermatogenesis takes place inside the seminiferous tubules. Diploid spermatogonia located near the outer edge of the tubule divide mitotically to form primary spermatocytes. The first meiotic division produces secondary spermatocytes with a haploid number of duplicated chromosomes. T...

Nerve Type Animation (Part 1)

By: Administrator, Views: 330

Used to describe neuronal processes conducting impulses from one location to another. Nerve fibers: - Nerve fibers of the PNS are wrapped by protective membranes called sheaths. - Myelinated fibers have an inner sheath of myelin, a thick fatty substance, and an outer sheath or neurilemma compo...

Optic Nerve and Optic Disk Animation (Part 1 of 2)

By: Administrator, Views: 10934

Inner Layer Blind spot: the absence of rods and cones in the area of the optic disk creates a blind spot on the retina's surface; the only part of the retina that is insensitive to light. Inner Layer The eye contains approximately 120 million rods that are sensitive to dim light. The rods ...

Nerve Type Animation (Part 2)

By: Administrator, Views: 316

Used to describe neuronal processes conducting impulses from one location to another. Nerve fibers: - Nerve fibers of the PNS are wrapped by protective membranes called sheaths. - Myelinated fibers have an inner sheath of myelin, a thick fatty substance, and an outer sheath or neurilemma compo...