1.1 遗传的细胞与分子基础 英文版

There is no particular functional grouping to their order, it is mostly evolutionary chance that determines their location.
(5) In prokaryotes, the DNA loop replicates before fission ( 分裂), with both loops still attached to the cell membrane.
• Prokaryotes lack a defined nucleus and have a simplified internal structure
(细菌)
• Eukaryotes have membrane limited nucleus and more complicated internal structure
• Three branches of life
(真核生物界)
(ell
Prokaryotes: which include the archaea (古细菌) and bacteria, are the simplest, oldest, and most common organisms on the planet.
(3) Prokaryotes do not have sexual reproduction, though they have several forms of gene exchange.
These include swapping (交换的) plasmids (质粒).
(4) The various genes, about 1200 in a typical bacterium, are arranged along the length of the chromosome, like beads on a string.
(3) Eukaryote DNA (except plastid 质体DNA, which is very similar to bacterial DNA because of its evolutionary origin) is usually linear, not circular.
The cellular and molecular basis in Genetics
The Cell
• Basic component of life
• Two main categories,
prokarytic
and
eukaryotic cells
• Differences in the nucleus
During fission, as the cell membrane splits in two, one loop of DNA ends up in each new “daughter cell”
Animal cell
Plant cell
This is the basic structure of all living things. Animals, plants, and to some extent even bacteria (they are made up of cells too, but the cells have a different structure,). The mitochondria (as well as chloroplasts in plants) are thought to be ancient bacteria that were somehow swallowed by the cell, and these mitochondria (including chloroplasts) carry some DNA of their own, but it’s the DNA in the nucleus of the cell we’ll be focusing on.
(1) A typical prokaryote has a much smaller genome than a typical eukaryote.
Nearly always, it is in the form of a simple loop of DNA.
This loop is attached to the cell membrane.
(2) Like prokaryotes, eukaryote genes are arranged along the length of a chromosome like beads on a string.
There is no particular functional reason for their location, either within a chromosome, or with respect to what chromosome they are on, it is mostly an evolutionary accident.
Eukaryotes:
-including plants, animals, fungi, protists (原生生物), often multicellular.
(1) Most eukaryotes have several orders of magnitude more DNA than a typical prokaryote. DNA is contained within a membrane-bound nucleus.
(2) Even though the structure simple, there is a lot of DNA in a single bacterium.
Stretched out, the DNA in an E. coli would be 500 times longer than the cell itself.