MeiFUCKINGosis

Question 1

Clonal Reproduction in single celled and multicellular organisms

Answer 1

• single celled organsisms usually reproduce by binary fission: amoeba, paramecium, yeasts, algae
• multicellular plants and animals can also use vegetative means:
  Runners, bulbs, tubers, rhizomes; hydra, anemone, sponge, starfish

Question 2

Where does the sexual cycle occur

Answer 2

In almost all eukaryotes

Question 3

Haploid

Answer 3

• sperm
• egg
• single set of chromosomes
• half the genetic information
• after fertilisation, two haploids make a diploid

Question 4

Diploid

Answer 4

• two copies of genetic information - one from mum, one from dad
• 2n

Question 5

What would happens if gametes were produced by mitosis

Answer 5

• they would be 2n and result in embryos with 4n
• meiosis is a process of cell division that halves the number of chromosomes going into gamete’s (n), so that the diploid number (2n) is retained into zygote.

Question 6

Interphase of meiosis:

Answer 6

• goes from a pair of homologous chromosomes in diploid parent cells
• to then being duplicated
• creating a pair of duplicated homolohous chromosomes, each containing two genetically identical sister chromatids

Thus creating a diploid cell with duplicated chromosomes

Question 7

Prophase 1

Answer 7

• homologous chromosifned align and synapse
• crossing over between non-sister chromatids occurs at chiasmata
• crossing over breaks DNA in a chromosome and regions it with a non-sister chromatid (from a different parent)
• crossing over results in chromatids now being a mic of pieces from each homologous chromosome
  -nuclear envelope disintegrates
• spindle aparatus and spindles form from either side of the asters
• centrosomes start to move to opposite poles

Question 8

What is an aster

Answer 8

A centrosome with a centriole pair

Question 9

Metaphase 1

Answer 9

• paired homologous chromosomes move to metaphase plate
• chiasmata lines up EXACTLY on the metaphase plate
• kinetochore microtubules still attach via the keneticore at the centromere

Question 10

Anaphase 1

Answer 10

• keneticore microtubes shortnen - non keneticore lengthen
• recombined homologous chromosomes sperate (disjoin)-
  pulled apart - disjunction
• sister chromatids remain attached at the centromere
  (Unlike in mitosis where the sister chromatids separate))

Question 11

Telophase 1 and cytokinesis

Answer 11

• haploid cells with duplicated chromosomes (the pairs f sister chromatids) from
• haploid because only half the genetic information was in each new cell
• cleavage forrow

Question 12

Meiosis 2 what does it do?

Answer 12

Sepearates sister chromatids

Question 13

Meiosis 2 process:

Answer 13

LITTERALLY EXACLY THE SAME AS MEIOSIS REFER TO THE OTHER 40 FUCKING CUE CARDS I MADE

Except because the two haploid cells produced from meiosis 1 it forms 4 haploid daughter cells

But is called prophase 2, metaphase 2, anaphase 2, etc

(There is no prometaphase either - all process occur in prophase 2 except the keneticore microtubules conencting to the centromeres via the keneticore structures)

Question 14

Key differences between mitosis and meiosis 1

Answer 14

Mitosis :
- chromosomes align independently
- no chiasmata
- centromeres on metaphase plate
Chromatids disjoin

2n —-> 2n

Meiosis 1:
- homologous chromosomes synapse
- chiasmata (holds homologous pairs of chromosomes together)
- chiasmata on metaphase plate
- chromosomes disjoin

2n —-> n

• the structures that move to the spindle poles at anaphase 1 in meiosis differ from those that move to the poles at anaphase 2 with respect to:
  
  • chromatid number
  • gene copy number
  • the ratio of maternal to parental genes (bc of crossing over)

Question 15

Asexual reproduction vs sexual reproduction

Answer 15

Asexual - one gender
Sexual - 50% chance of getting a boy or girl

Question 16

Sexual reproduction produces genetic diversity through

Answer 16

• independent assortment of chromosomes (random which chromosomes go in which gamete)
• crossing over
• random fertilisation of gametes

Question 17

Genetic diversity allows selective responses to:

Answer 17

Spatially variable environments (e.g climate, ecology)
Changing environments (e.g parasites, seasons)
Sib-sib competition ??????

Question 18

Segregation and indecent advent assortment

Answer 18

Two equally probable arrangements of chromosomes at metaphase 1
- could produce one of 4 equally probable comabation of chromosomes

Question 19

How to determine the number of possible gamete’s (or other things?) when dealing with chromosome Paris

Answer 19

2 ^n
Where n = number of homologous chromosome pairs

Question 20

Process of crossing over: (rewatch this part of lecuture)

Answer 20

Prophase 1 of meiosis:
- non-sister chromatids of a pair of homologs held together during synapsis - synapsis and crossing over occurs
- movement to the metaphase 1 plate
?????? REDO THUISN SLIDE