chapter 11

gene expression

information in genes is expressed as proteins

gene regulation

turning on/off gene expression

because it allows cells to produce specific kinds of proteins when and where they are needed

why control gene expression?

differentiation

differences between cell types due to selective gene expression

x chromosome inactivation

in female mammals, one of two X chromosomes is chemically modified and highly compacted
> either the maternal or paternal chromosome is randomly inactivated

barr body

an inactivated x chromosome is also called…

inactivation of x chromosomes

tortoiseshell fur colouration is due to __________________________ in heterozygous female cats

DNA microarrays

genome-wide expression studies made possible by _________
> consists of thousands of different kinds of single-stranded DNA fragments

flourescent cDNA

___________ is produced from mRNA

> helping to identify which chemotherapies will be most effective
> personalized to each patient

DNA microarrays can assist with what?

small percentage

most cells express only a __________ of their genes
> one way to approach these questions is to determine if a differentiated cell can be stimulated to generate a whole new organism

clone

an organism produced through asexual reproduction from a single parent

regeneration

regrowth of lost body parts

nuclear transplantation

animal cloning can be achieved using _____________

reproductive cloning

a type of cloning that results in the birth of a new living individual

Dolly the sheep

what mammal was first used to clone in 1996 in Scotland?

embryonic stem cells

blastocyst can provide it
> can differentiate in an embryo to give rise to all specialized cell types of the body
> divide indefinitely when grown in a lab culture
> pluripotent

therapeutic cloning

goal = produce embryonic stem cells to use in therapeutic treatments

adult stem cells

farther along the road to differentiation than ES cells, they can give rise to only a few related types of cells

cancer

set of diseases in which the control mechanisms that normally limit cellular growth have malfunctioned

oncogene

tumor

HPV

this disease can be transmitted through sexual contact and is associated with several types of cancer, most frequently cervical cancer

two

mutations in ___ types of genes can cause cancer

proto-oncogenes

normal genes that promote cell division
> stimulate cell division

tumor-suppressor genes

normally inhibit cell division or function in the repair of DNA damage
> mutations inactivate the genes and allow uncontrolled division to occur

colon cancer

this type of cancer is one of the best understood types of human cancer and illustrates an important principle about how cancer develops

second

cancer is the _____-leading cause of death in the most industrialized nations

carcinogens

these things are cancer-causing agents that alter DNA
> most mutagens (substances that promote mutations) are __________

>X-rays
> ultraviolet radiation in sunlight

two of the most potent carcinogens are:

lung cancer

one substance known to cause more cases and types of cancer than any other single agent is tobacco — which can result in this type of cancer