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0
Q

meiosis

A

crossing over and independnt assortment and fertilization

1
Q

2 ways to get genetic variagtion

A

mutaion and sexual reproduction… mutation only way to get new information

2
Q

the production of haploid gametes

A

meiosis

3
Q

the fuiosn of haploid gametes

A

fertilization

4
Q

consequences of meiossi

A

genetic variation

5
Q

interphase

A

DNA synthesis and chromosomes replication phase

6
Q

seperation of homologous chromosome pairs, and reduction of the chromosome number by half

A

meiosis 1

7
Q

seperation of sister chromatids, also known as equational division

A

meiosis II

8
Q

major results of meiosis

A

increase in cell numbers sometimes, duaghter cells are not genetically identical, daugther cells are haploid, formation of gametes… compare to mitosis

9
Q

gametognesis

A

spermatogensis. oogenesis… produces sperm and eggs

10
Q

synapsis

A

pairing of homologous chromosmes

11
Q

crossing over

A

in meiosis

12
Q

meiosis requires

A

two consectutive cell divisions but only one cycle of DNA replication

13
Q

crossing over

A
  1. once chromosome possesses the A and B allele
  2. and the homologous chromosomes possesses the a and b allele
    DNA SYNTHESIS
  3. DNA replication in the S phase produces identical sister chromatids
    CROSSING OVER
  4. During crossing over in prophase I, segments of nonsister chromatids are exchanged.
    MEIOSIS I AND II
  5. after meiosis I and II, each of the resulting cells carries a unique combination of alleles
14
Q

produces variation without crossing over

A

independent assortment… needs more than on pair of chromsomes… line up as homologous pairs in varies ways.

15
Q

reduction divison

A

meiosis I…. Diploid to haploid

16
Q

equational division

A

Meiosis II… haploid

17
Q

prophase I

A
Leptotne
zygotene
pachytene... synaptonemal complex
diplotene.. bivalent or tetrad, chiasmata
diakinesis
18
Q

leptotene

A

exteneded state, microscopically can’t be discerned as indviduals… thread like, very thin, each chormosome still two chromatids(replication has already occured)… start to condense…

19
Q

zygotene

A

start ot pair up, homologous chromsomses pair(synapsis).. synaptonemal complex forms, results in bivalents(tetrads)

20
Q

pachytene

A

thick… starting to condense.. shorter and thicker… crossing over begins

21
Q

synaptonemal complex

A

later like structure btw to chromosomes… alignment mechanims… if this does not work correctly duplicaiton and deletion occurs… equal crossing overs.

22
Q

diplotene

A

start to see tetrads(bivalents)

seee cross over points, chiasmata(pt where crossover occurs) are well defined

23
Q

diakinesis

A

cross over points start to move toward the end… homoloug pair and crossing over. termilalization occurs. spidle apparatus in place. nuclear memnbrane disrupted

24
Q

metaphase I

A

Centromeres DONOT divide, random alignment of homologus pairs of chromosomes along the metaphase plate

25
Q

prophase I

A

synopsis… pair up.

26
Q

anaphase I

A

move to opposite poles… not idintical bc of crossing over… haploid…. second mechanism of generating genetics variation in the newly formed gamates

27
Q

Telephase I

A

cytokinesis occurs, neclear membrane reforms. spinndle apparatus disassembles… HAPLOID…. INterkinesis…

28
Q

interkinesis

A

nucler membranes reform, spindle apparatus disassembles, chromsomes may uncoil to vaying degress… spindle usually breaks down…. no DNA synthesis takes place

29
Q

prophase II

A

chromsomes condense… each chromosmes has 2 chromatids… nuclear membrane disapears, each chromosmes has two chromatids …e ach daughter cell has one complete set of chromosomes (haploid)

30
Q

metaphase II

A

chromosmes line up on equtorial plate… kinetochoroes face opposite poles…

31
Q

anaphase II

A

centromeres have split… sister chromatids seperate… chromosmes move to opposite poles… each consists of single chromatid

32
Q

telophase II

A

chromosmes uncoil, Four geneticall unique haploid cells!!! 4. is one compelte set… cytokinesis is complete. nuclear membre reforms.spindle aparatus disintigrates … chromosomes arrive at the spindle poles.

33
Q

cytokinesis meiosis

A

the cytoplasm divides to produce tow cells, each having half the orginal number of chromosomes

34
Q

cohesion.

A

holds chromatids together during early parts of mitosis… break down allows sister chromatids to spearate during mitosis anaphase

35
Q

cohesion during meiosis

A

chromosomes arms holds homologous chromsomes together at chiasmata through metaphase I

36
Q

meiosis specific cohesions at centromere …

A

keeps sister chromatids together during anaphase…

37
Q

the cohesion that protects anaphase of sister chromatids during meiosis is

A

shugoshin

38
Q

separase

A

kept inactive during interphase and early mitosis, breaks down cohesion at end of metaphase, breakse down meiosis-specific cohesion at centromere during end of metaphase II

39
Q

Keeps separase inactive during interphase and early mitosis

A

securin

40
Q

keeps sists kinetochores oriented toward same pole during metaphase i

A

monopolins

41
Q

48 mins

A

in lecture 2

42
Q

spermatogonia—>

A

43
Q

spermatogenesis… primordial germ cells

A

diploid… divide mitotically to produce dipoloid spermatogonia

44
Q

spermatogonia are

A

diploid
can undergo repereated rounds of mitosis to produce more spermatogonia
may initiate meiosis and enter into prophase I to give rise to primary spermatocyte

45
Q

Sour of genetica variation

A

mutation and sexual reproduction

46
Q

meiosis includes

A

crossing over and independent assortment and fertilization

47
Q

Spermatogonia–>

A

primary spermatocytes 2N

48
Q

primary spermatocytes 2N 1–>

A

secondary spermatocytes N 2… haploid, undergo meiosis II to produce haploid spermatids

49
Q

secondary spermatocytes 2…. N–>

A

4 spermatids N… haploid, differentiate into haploid sperm

50
Q

oogonia–>

A

2n primary oocytes…. arrests at diploteme of prophase I

51
Q

Primary ooctye 2N–>

A

seondary oocyte…. willl also divide off polar body… will go to 2nd metaphase that is ovulated and stop unless fertilized…

52
Q

secondary oocyte fertilized

A

ootid and polar body

53
Q

primary oocyte

A

lg ovum and small polar body, meiosis will not re