meiosis

Question 1

inheritance/heredity

Answer 1

transmission of traits from one generation to the next
parent —> offspring

Question 2

traits

Answer 2

variants of a character
heritable feature that may vary among individuals

Question 3

gene

Answer 3

unit of hereditary information

Question 4

locus

Answer 4

gene’s specific location along the length of a chromosome
chromosomes consist of dna and associated proteins

Question 5

somatic cells

Answer 5

body cells
humans have 46 chromosomes in the nuclei of these diploid(2n) cells
two sets of 23 chromosomes from parent 1 and parent 2

Question 6

gametes

Answer 6

sex cells
egg or sperm haploid (1n) cells that fuse to pass on genes to the next generation

Question 7

asexual reproduction

Answer 7

less common version
individuals pass on genetically identical copies of its genes to its offspring without fusion of gametes (mitosis only)
produces a clone

Question 8

sexual reproduction

Answer 8

two individual parents pass on genetically different copies of their genes to its offspring with fusion of gametes
fertilization plus meiosis

Question 9

synaptonemal complex

Answer 9

join two chromatids together

Question 10

gametogenesis

Answer 10

diploid (2n) cell in ovary and testis go through meiosis to produce haploid (n=23) gametes (egg or sperm cell)

Question 11

fertilization

Answer 11

union of gametes leading to a fusion of their nuclei to produce a diploid (2n) zygote

Question 12

mitosis

Answer 12

zygote and descendent cells generate all the somatic cells of the body (2n=46)

Question 13

similarity between reproductive cycle in animals, plants/algae, and fungi/protists

Answer 13

meiosis, mitosis, fertilization all happen
zygotes produced in all three

Question 14

difference between reproductive cycle in animals, plants/algae, and fungi/protists

Answer 14

plants have something called alternation of generations
go from diploid multicellular organism to haploid multicellular organism
sporophytes produce spores
gametophytes produce gametes

fungi haploids can be multicellular or unicellular
can produce both multicellular or unicellular haploids depending on environmental factors/stresses

Question 15

chromosome sets during meiosis

Answer 15

meiosis reduces the number of chromosome sets from diploid(2n) to haploid(n)

Question 16

meiosis interphase generally what is accomplished

Answer 16

stage before meiosis where DNA is replicated to produce paired chromatids in diploid cell
go from one chromatid to paired chromatids (2n)
similar to mitosis

Question 17

meiosis I generally what is accomplished

Answer 17

homologous chromosomes are separated into two haploid cells with duplicated chromosomes
different from mitosis

Question 18

meiosis II generally what is accomplished

Answer 18

paired chromatids are separated into haploid cells with unduplicated chromosomes
4 haploid cells with unduplicated chromosomes
different from mitosis

Question 19

meiosis step by step
interphase what is produced

Answer 19

1 diploid cell 2n=4
2 pairs of homologous chromosomes X X
DNA replicated during S phase of cell cycle
DNA and chromosomes doubled

Question 20

meiosis I
in depth step by step

Answer 20

prophase 1 - homologous chromosomes pair up forming X shapes (bivalent) –> crossign over occurs here –> chromosomes condense

metaphase I – pairs of homologous chromosomes line up along metaphase plate–> spindle poles connect to kinetochores of each paired chromatid (independent assortment happens here)

anaphase I – pairs of homologous chromosomes start separating towards the poles

telophase I and cytokinesis – nuclear envelope reforms, cytoplasm divides, results in 2 haploud cells n=2

Question 21

meiosis II
in depth step by step

Answer 21

start w 2 haploid cells n=2
prophase II – homologous chromosomes condense and spindles connect

metaphase II – sister chromatids line up along metaphase plate

anaphase II – poles pull one chromatid from each paired chromatid towards it
sister chromatids are separated and pulled as one chromatid

telophase II and cytokinesis – nuclear envelope reforms
cytoplasm divides
4 haploid cells with unduplicated chromosomes that are genetically different

Question 22

mechanisms that contribute to genetic variation during sexual reproduction

Answer 22

crossing over
independent assortment
random meeting of gametes(fertilization)
dependent on chromosome behavior

Question 23

crossing over

Answer 23

synapsis during early stages of prophase I
DNA molecules of nonsister chromatids are broken by a protein and physical exchange occurs between a pair of homologous chromosomes

leads to exchange between homologs and generates new combination of alleles

Question 24

chiasma

Answer 24

point where crossing over occurs

Question 25

independent assortment

Answer 25

pairs of homologous chromosomes orient randomly at metaphase I
each pair sorting its homologs into cells independently of every other pair
number of possible combinations for resulting gamete is 2^n
n = haploid number of the species
humans (n=23), results in 2^23 or 8.4 million possible combinations of chromosomes

Question 26

random meeting of gametes (fertilization)

Answer 26

any sperm can fuse randomly with any ovum (unfertilized egg)
fusion of gametes produces a zygote with 70 trillion diploid combinations (2^23 x 2^23)