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From: gagen@bgsuvax.UUCP (kathleen gagen)
Newsgroups: sci.bio
Subject: Re: Dumb Questions about Mitochondria
Message-ID: <1260@bgsuvax.UUCP>
Date: Mon, 17-Aug-87 13:36:55 EDT
Article-I.D.: bgsuvax.1260
Posted: Mon Aug 17 13:36:55 1987
Date-Received: Wed, 19-Aug-87 04:03:04 EDT
References: <52@citcom.UUCP>
Organization: Bowling Green State University B.G., Oh.
Lines: 35
Summary: Mitocondrial DNA

In article <52@citcom.UUCP>, jack@citcom.UUCP (Jack Waugh) writes:
> Which species have mitochondria?

So far as is known, all cellular organisms have mitochondria.  Virus 
lack them.
> 
> Do mitochondria always have their own DNA and hence
> genetic line independent of nuclear DNA?

Yes.
> 
> In sexually reproducing species, do the mitochondrial
> genes always come from the mother (I understand that
> this is the case for humans).

To the best of my knowledge, this is always the case for 
organisms for which one parent can be called the "mother".
There are, however, organisms in which the gametes that
fuse are of similar size (some of the blue-green algae,
for example) and unicellular organisms, such as yeast, that
fuse.  I am not familiar with blue-green algae.  However,
in yeast two haploid cells (cells with one set of chromosomes), an "a" and
an "alpha" cell fuse to form a diploid cell (with two sets of chromosomes)
referred to as an "a-alpha" cell. This a-alpha cell contains mitochondria
from both parent cells.  This cell or its genetically identical progeny
can then sporulate to produce four daughter cells: two "a" cells and
two "alpha" cells.  To the best of my knowledge, the mitochondria of
these cells can be a mixture of that from the original "a" and "alpha"
cell that fused to form their parent.

-- 
 Kathleen Pausic Gagen                       ...!cbosgd!osu-eddie!bgsuvax!gagen
 Dept. of Biological Sciences                          gagen@research!.bgsu.edu 
 Bowling Green State University               gagen%bgsu.csnet@csnet-relay.arpa
 Bowling Green Ohio 43403                 gagen%andy.bgsu.edu@csnet-relay.csnet