Search results for: 'DNA'

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By: HWC, Views: 4687

DNA fingerprinting enables a scientist to compare the DNA from two biological samples, such as a blood stain and a suspect's blood. A restriction enzyme is added to the samples to be compared. The enzyme cuts the DNA into smaller fragments. The DNA fragments are placed on an electrophor...

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Bond in biological molecules (Ionic, Covalent and Hydrogen bonds)/ How atoms bond?

By: HWC, Views: 5075

Sodium atoms and chloride atoms have unfilled orbitals in their outer shells. The lone electron in the outermost shell of a sodium atom can be pulled or knocked out. This ionizes the atom. It is now a positively charged sodium ion. A chlorine atom has an electron vacancy in its outer shell and...

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HIV replication/ Replication cycle of HIV

By: HWC, Views: 4918

Replication cycle of HIV, one of the retroviruses. The HIV virus is surrounded by a lipid envelope with embedded proteins. A coat of viral proteins surrounds two strands of RNA and the enzymes used during replication. The virus attaches to and enters the host cell. Viral reverse trans...

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DNA Replication

By: HWC, Views: 4605

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell.

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Mutations and translation

By: HWC, Views: 4260

A mutation, which may arise during replication and/or recombination, is a permanent change in the nucleotide sequence of DNA. Damaged DNA can be mutated either by substitution, deletion or insertion of base pairs. Mutations, for the most part, are harmless except when they lead to cell death or t...

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Primate Evolutionary Tree Animation

By: HWC, Views: 3890

Presumed evolutionary branchings in the primate family tree. The first primates arose between 85 and 65 million years ago. The common ancestor of apes and hominids branched off from Old World monkeys about 23 million years ago. The hominid lineage, which includes humans and earlier humanlik...

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Subunits of DNA And Semi Conservative Replication

By: HWC, Views: 4065

Adenine is a purine with a double-ring structure. In double-stranded DNA, adenine base-pairs with thymine. Guanine is a purine with a double-ring structure. In double-stranded DNA, guanine base-pairs with cytosine. Thymine is a pyrimidine with a single-ring structure. In double-stranded DNA, th...

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Cell mediated immune response to a viral infection Animation

By: HWC, Views: 3760

Intracellular pathogens are the targets of cell-mediated immune response. The process begins when a virus infects a macrophage. Another macrophage engulfs the same virus or an antigen from it. In both cells, enzymes cleave the viral antigens into small bits. The fragments move to the cell sur...

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Chromosome structural organization/ Mechanisms for chromosome movement Animation

By: HWC, Views: 3886

How the chromosome is organized. 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 ...

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