Search results for: 'offspring'

Watch Later 1:18

By: HWC, Views: 5592

A monohybrid cross is a cross between two parents that breed true for different versions of a single trait. In this example, that trait is flower color. The allele that specifies purple flowers is dominant over the allele that specifies white flowers. The purple-flowered plant has two domin...

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Darwin's Observation (Fossils, Galapagos Islands & Africa ) and Natural Selection (Adaptive Traits)

By: HWC, Views: 7622

Along Darwin's voyage, he made many observations. Each one added to his understanding of how organisms change over time. Darwin was already familiar with fossils and knew that many fossils were very different from living organisms. But, also there were some fossils that were very similar to li...

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Mendel's Principles of Dominance, Segregation and Independent Assortment

By: HWC, Views: 7255

Mendel selected true-breeding parents with contrasting traits, for example, purple and white flower color, and performed reciprocal crosses by choosing pollen from one parent and hand pollinating the seed-forming parent with this pollen. A cross-fertilization resulted from this procedure. In t...

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Helper T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 7826

• Most cells which have CD4 on their surface become Helper T cells (TN cells). • The CD4 1 cells only recognize a foreign antigen when it is presented with an antigen presenting immune cell (APC) that includes MHC-II protein. • The Helper T cell antigen receptor must match the presented...

Watch Later 2:56

Diversity of Living Creatures - Charles Darwin & the Beagle's Voyage

By: HWC, Views: 7481

As we look around at the living creatures on Earth, we see a great amount of diversity. In some cases, the differences are quite noticeable, like the differences between plants and animals. Some differences are not as easy to see, like the differences between two species of lizard. How did all...

Watch Later 1:29

Spermatogenesis Animation

By: Administrator, Views: 11092

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. T...

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Mendel's Pea Experiment

By: HWC, Views: 7166

Sugar snap peas were common garden plants during Mendel's lifetime and many varieties undoubtedly grew in the abbey gardens. An avid gardener. this is where Mendel first made observations about pea plants. He noticed that certain characteristics of peas were passed from generation to generation. ...

Watch Later 1:08

Introduction to Genetics

By: Administrator, Views: 10651

Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms. Gregor Mendel, a scientist and Augustinian friar, discovered genetics in the late 19th-century. Mendel studied "trait inheritance", patterns in the way traits are handed down from p...

Watch Later 2:35

Cytotoxic T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 8052

• Most cells which have CD8 on their surface become cytotoxic T cells (Tc cells). • CD8 T cells recognize a foreign antigen when it is presented in conjunction with the protein, MHC-I. • Nearly all nucleated cells in the body express MHC-I molecules. • T cells that recognize self-pe...

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