What is operon ?
It's a unit of genetic regulation common in prokaryotes; cluster of of genes with related functions, along with the promoter and operator that control their transcription.
How is DNA packed ?
Crucial role in DNA packing play proteins called histones. They protect packed DNA from being expressed. Also the DNA itself is wrapped around these proteins in formations called nucleosome.
What is cloning ?
Cloning is a process of creating new individual with genetic informations same as from the donor. There are two types of cloning : reproductive and therapeutic. Reproductive cloning creates a new individual with the same genetic informations as the donor. Therapeutic cloning uses embryonic stem cells to create specialized cells that are needed.
Diagram :
This diagram shows the process of cloning.
5facts:
Female mammals have one inactive X in each somatic cell.
Cascades of gene expression direct the development of an animal.
Stem cells are cells with no specialization.
Stem cells have a great medical potential.
Human reproductive cloning raises a lot of ethical issues. For example : to get stem cell we have to destroy embryo which in some cultures represents life.
Key terms :
gene expression - process by which genetic information flows from genes to proteins
histones - small proteins associated with DNA packing
differentiation - process of becoming specialized in function and structure
silencers - DNA sequence that stimulates the gene transcription
enhancers - DNA sequence that functions to inhibit the start of gene transcription
homeotic gene - master control gene
DNA microarray - glass slide with thousands of different kinds of single-stranded DNA fragments
regeneration - regrowth of lost body part
adult stem cells - cells capable of giving rise to many but not all the types of cells
oncogene - gene that can cause cancer
Video :
Summarize :
This chapter was mainly about gene expression. The way genes are turned on a off and also this chapter described the process of cloning.
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