meiosis quiz

another name for meiosis

reduction division

meiosis occurs in

gamete cells

gamete cells

testes or ovaries

mitosis happens in all _________ cells

somatic

meiosis

cell division where the number of chromosomes is halved to produce sex cells

meiosis produces

4 haploid cells

genes

sections of DNA that control a specific trait

how many divisions does meiosis have?

2

diploid human cell has

46 chromosomes

haploid human cell has

23 chromosomes

diploid

the total number of chromosomes which consists of 2 sets

haploid

half the number of chromosomes, only one set

homologous chromosomes

chromosomes that have the same length and centromere position

homologous chromosomes have the same _______ in the same __________

genes, location

alleles

alternative forms of genes

genes in homologous chromosomes are same but have

different alleles

non-homologous chromosomes have

different genes

sister chromatids

same genes and alleles, held together at centromere

autosomal chromosomes

chromosomes that don’t determine sex, humans have 22 pairs

female sex chromosomes

xx

male sex chromosome

xy

2 main parts of meiosis

Meiosis 1 and Meiosis 2

Interphase occurs in _____ but not in _______

meiosis 1, meiosis 2

T/F: There are 92 chromosomes after DNA replicates in S-phase.

false, only 46 with sister chromatids

what separates in meiosis 1?

homologous chromosomes

after meiosis 1 and 2, cells have

haploid chromosomes

in meiosis 2, what separates?

sister chromatids

sperm and egg each contain

23 chromosomes

duplication happens before/after meiosis

before

which meiosis is similar to mitosis?

meiosis 2

what happens in prophase 1

crossing over

crossing over

non sister chromatids exchange genetic material

when non sister chromatids cross over,

they make a chiasma

result of crossing over

increase genetic diversity, chromatids no longer identical

after crossing over, chromosomes pull apart and

recombinant chromatids form

independent assortment

after metaphase 1, homologous chromosomes separate independently and randomly

metaphase 1

homo chromos lined up on metaphase plate

how many possible combos for one person?

2²³

fertilization increases

genetic variation

anaphase 1

homologous chromosomes pulled apart, sister chromatids remain attached

Telophase

cleavage furrow develops and cell separates

there is no interphase after

meiosis 1

at the beginning or meiosis 2, cells are

haploid, cells contain sister chromatids

Prophase 2 does not have

crossing over

end of cytokinesis

4 haploid daughter cells with unique DNA

benefits of meiosis

cells are genetically different and don’t have to rely on mutations alone to evolve

2 causes of genetic variation

crossing over and independent assortment

benefits of genetic variation

better chance for species to survive and evolutionary advantage

each sperm cell can produce

4 sperms

zygote

diploid cell formed by fertilization of an egg

out of 4 mature haploid eggs,

3 are smaller polar bodies

in ovaries, after meiosis 1

1 of the 2 cells get smaller in size and produces 2 polar bodies

after meiosis 2, the larger cell

produces 1 polar body and 1 egg

how many sperms can enter an egg

1

sperm have enzymes on head of body that

break down the outer membrane of egg

after one sperm fertilizes the egg

the egg releases chemicals that inhibit sperm

karyotype

visual display of chromosomes arranged by shape, size and banding pattern

band on chromosomes show

genes

non-disjunction

failure of chromosomes to separate

result of nondisjunction

gain or loss of chromosomes

which phase does nondisjunction occur during?

anaphase

aneuploidy

change in chromosome number (higher or lower)

euploidy

avg number of chromosomes in a species (46 for humans)

types of aneuploidy

trisomy or monosomy

which is worse trisomy or monosomy?

monosomy, bc genes are missing

nondisjunction is worse if it happens in

meiosis 1 bc more daughter cells are affected

monosomy

missing one homologous chromosome in a homologous pair

trisomy

extra chromosome in a homologous pair

how many trisomys are viable beyond birth?

three

which trisomys are viable beyond birth?

trisomy 13, 18 and 21

trisomy 13 name

patau syndrome

effects of trisomy 13

major circulatory, eye and brain defects, children rarely live more than a few months

trisomy 18 name

edward’s syndrome

trisomy 18 effects

small heart, all organs effected

trisomy 21 name

Down syndrome

what is the most common type of trisomy

21, down syndrome

trisomy 21 effects

slight mental handicaps, short, flat face, heart problems

prevalence of down syndrom increases with

mother’s age

XO name

turner’s syndrome

XO effects

short, wide neck, ovaries don’t develop correctly, infertile, small breasts, low hairline, short life expectancy

XXY name

kleinfelter’s syndrome

XXY effects

less muscle, body hair, small d, big breasts, infertile, insufficient puberty

XXX syndrome

female

XXX effects

tall, low IQ, anxiety, motor skill issues, delayed speech, fertile

XYY syndrome

male

XYY effects

tall, mental handicap, acne, feminine physique, fertile

SRY gene

stimulates growth of the male reproductive system