0:05 this is an extra video on rhizopus
0:08 reproduction rise of us is a type of
0:10 fungus and it's mostly associated with
0:12 bread mold however we do know that it
0:14 grows on particular types of fruit you
0:16 can often see it growing on tomatoes and
0:18 on strawberries for example when they're
0:20 decaying or going off it looks like this
0:22 white furry stuff and this is because
0:24 Manny - these two black filaments will
0:27 form a mycelium rise of us is
0:30 saprophytic this means that it feeds off
0:32 dead organic matter therefore it acts as
0:35 a decomposer and decomposers are really
0:37 important in returning nutrients to the
0:39 soil remember from ecology most of the
0:43 time rhizopus reproduces asexually by
0:45 means of spar ulation so producing
0:48 spores to understand reproduction in the
0:50 rhizopus you need to know its structure
0:52 we know that it's a fungus and it's made
0:54 up of these two black filaments known as
0:56 haifa there are three types of haifa
0:59 which you have to know very well so the
1:01 first type of haifa that we talk about
1:03 are the rhizoids and you can see them
1:05 here in the picture
1:06 I always remember them because I think
1:07 of them as roots even though they're not
1:09 but I just say or furrows oh it's or for
1:11 roots their main role is Anchorage
1:14 they're there to anchor the fungus but
1:16 they also play a very important role in
1:18 digestion extracellular digestion
1:20 because they secrete those digestive
1:23 enzymes which are going to break down
1:25 the substrate and then the nutrients are
1:27 absorbed back into the rhizoids the next
1:29 type of haifa is a stolen it grows above
1:32 the substrate and it creeps along
1:33 horizontally its main role is in helping
1:36 this fungus to spread the final type of
1:39 haifa is known as a sporangia for it
1:41 grows vertically upwards into the air so
1:44 this Brown Geo for which is filled with
1:46 manny haploid nuclei develops a swelling
1:49 near the end which fills with many more
1:51 haploid nuclei and cytoplasm and these
1:54 are all formed by means of mitosis
1:56 across wall called the columella forms
1:58 and this is formed to block off or to
2:01 separate all of these nuclei and the
2:03 cytoplasm in the swollen tip from the
2:05 rest of the haifa just below the
2:07 columellar is the a puff Isis which is
2:09 this swelling of the haifa both the
2:12 columellar forms this structure
2:13 known as the sprang Geum and it's here
2:15 that those haploid nuclei together with
2:17 some cytoplasm are now going to become
2:19 those haploid spores eventually the
2:22 sporangium splits and releases all of
2:24 these haploid spores and if they land on
2:27 a suitable substrate well then they will
2:28 germinate to form a new haifa rhizopus
2:31 will mostly reproduce asexually by means
2:34 of sporulation producing spores
2:36 however under adverse conditions such as
2:38 dehydration sexual reproduction takes
2:41 place sexual reproduction occurs in
2:44 Haifa which look very similar but are
2:46 chemically different so one is a plus
2:48 strain and the other is a minus strain
2:50 swellings begin to grow between the plus
2:52 and the minus strain as if they're
2:54 growing towards each other and into the
2:56 swelling's on both sides flow mani
2:58 haploid nuclei and this now forms
3:01 progamme tangia after this cross walls
3:04 form essentially blocking in those
3:06 nuclei and forming these structures
3:08 known as gamma tangia and supporting the
3:10 gamma tangia are the suspense errs the
3:13 wall between the gamma tangia dissolves
3:15 allowing both the cytoplasm and the
3:18 haploid nuclei from both sides both
3:20 strains to mix eventually what happens
3:22 are many fertilizations
3:24 so forming manney diploid zygote nuclei
3:27 these diploid zygote nuclei get encased
3:30 in a tough walled zygous 4 and this can
3:33 remain dormant for quite a long time
3:35 eventually it will germinate by meiosis
3:37 so when does I guess for germinates
3:39 and undergoes meiosis a haploid haifa
3:42 emerges and this Haifa is filled with
3:44 manney haploid nuclei which in turn can
3:47 become haploid spores the spores
3:49 released are haploid but they are
3:51 genetically different meiosis has
3:53 introduced genetic variation this video
3:56 was only about rhizopus remember that we
3:59 covered the asexual and sexual
4:00 reproduction of this fungus we learned
4:03 that it's a Sam prophetic fungus meaning
4:05 that it feeds on dead organic matter we
4:08 also learned that it's economically not
4:10 that great why because it causes food
4:13 spoilage so the very best of luck with
4:15 your exams make sure you're using your
4:17 textbook you're doing pass papers and
4:19 you're listening to your teachers
4:20 guidance good look
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