mating in filamentous ascomycota

Question 1

a typical ascus contains

Answer 1

8 ascospores

Question 2

operculum

Answer 2

at the tip of the ascus where the spores are released from

Question 3

what controls the mating process of Saccharomyces cerevisiae

Answer 3

a complex genetic locus called MAT at which two linked genes are located

Question 4

which two linked genes are located at MAT a complex genetic locus which controls mating in Saccharomyces cerevisiae

Answer 4

a1,a2 for mating type a and alpha 1 and alpha2 for mating type alpha

Question 5

MATa locus encodes for

Answer 5

a1 and a2 polypeptides, the messengers for which are transcribed in opposite direction.

Question 6

a and alpha

Answer 6

join to produce a zygote from two septette ascomycota

- in one ascomycota there will be genes for a and in others gene for alpha

Question 7

basidiomycetes have..

Answer 7

thousands of sexes

Question 8

name some of the sexes of basidiomycetes

Answer 8

Homothalic (self fertile), heterthalic (partner required), monjaryon (uninucleate haploid), homokaryon (uni-or multi-nucleate haploid (n)_, dikaryon ( binucleate haploid (n+n)), heaterokaryon (multinucleate (n +n)), diploid (2n).

Question 9

homothallic

Answer 9

self fetile

Question 10

heterothallic

Answer 10

sex requires a partner

Question 11

monjarygon

Answer 11

uninucleate haploid

Question 12

homokaryon

Answer 12

uni or multi nucleate haploid (n)

Question 13

dikaryon

Answer 13

binucleate haploid (n+n)

Question 14

heterokaryon

Answer 14

multinucleate (n+n)

Question 15

diploid

Answer 15

2n

Question 16

for mating to be successful in basidiomycetes ..

Answer 16

all sexes HAVE TO BE DIFFERENT

Question 17

how many diff sexes in Schizophyllum

Answer 17

28,000

Question 18

what maintain dikaryon

Answer 18

clamp connections

- ensuring that every hyphal compartment within a mycelium is binucleate

Question 19

where are basiospores produced

Answer 19

on basidia

Question 20

sexual reproduction in Zygomycota

Answer 20

1) +ve and -ve mycelia make contact
2) gametangia with haploid nuclei and then plasmogamy
3) a young zygosporgangium (heterokaryotic) forms
5) the zygosporangia goes through karygoamy to produce a diploid nucleus
6) meiosis
7) forms into a sporangium
8) spore get released from sporangium and these spore are dispersed and germinate mycelia

Question 21

mycelia reproduction can either be..

Answer 21

asexual or sexual

- e.g. the spore produced my mycelia can either be used to germinate itself or other mycelia

Question 22

sexual reproduction in Ascomycota

Answer 22

1) +ve ascogonium and -ve ascogonium make contact
2) plasmogamy
3) DNA shared
3) an ascocarp is formed with ascus’ that are dikaryotic
4) karygamy–> forms a diploid nucleus (zygote)
5) meisois- four haploid nuclei
6) mitosis- eight ascospore
7) ascospore dispera
8) germinate mycelia

Question 23

sexual reproduction in ascomycota can be

Answer 23

sexual or asexual

Question 24

yeast can reproduce asexually by

Answer 24

budding

Question 25

sexual reproduction in Basidiomycota

Answer 25

1) positive and negative mating type
2) plasmogamy
3) dikaryotic mycelium is formed
4) gills of fungi lined with basidia which are dikaryotic
5) karyogamy- forming a diploid nuclei
6) meiosis
7) basidium containing four haploid nuclei dispersed as basidiospore
8) germination of haploid mycelia

Question 26

dikaryon/heterokaryons are established through ……. mating

Answer 26

SOMATOGAMOUS

Question 27

plasmogamy

Answer 27

is a stage in the sexual reproduction of fungi, in which the cytoplasm of two parent cells (usually from the mycelia) fuses together without the fusion of nuclei, effectively bringing two haploid nuclei close together in the same cell.

Question 28

karyogamy

Answer 28

is the final step in the process of fusing together two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei. Before karyogamy, each haploid cell has one complete copy of the organism’s genome.

Question 29

basidiospore are produced on

Answer 29

basidia

Question 30

in basidomycota spore discharge is

Answer 30

passive or mediated by bullers drop

Question 31

bipolar heterothallism

Answer 31

one mating-type gene,w with two alleles (e.g. A and a) are compatible. However A xA or a xa are incompatible (homogenise incompatibility)

Question 32

tetrapolar heterothallism

Answer 32

two mating types genes with two or more alleles (e.g.A and a with B and b). only combinations that differs at all four alleles are fully compatible e.g. AB x ab.

Question 33

secondary hoothallism

Answer 33

in some bipolar heterothallic species, spore can form that segregate both mating-types together. the mycelium is consequently self fertile.

Question 34

outcrossing

Answer 34

mating between different haploid strain

Question 35

outcrossing can either be

Answer 35

outbreeding or inbreeding

Question 36

outbreeding

Answer 36

mating between different haploid strains from different spore sources (non sib)

Question 37

inbreeding

Answer 37

mating between different haploid strains from the same spore source (sib)

Question 38

non-outcrossing

Answer 38

self mating between identical haploid strains

Question 39

outcrossing strategies require the opening up of

Answer 39

‘self’ to ‘non-self’ genetic info which can lead to cooperatives, mergers, takeovers and STDs