meiosis and sexual reproduction

meiosis is a form of cell division that ------- the number of chromosomes when forming specialized reproductive cells or spores

halves

sperm or egg cells are examples of…

gametes

plants and fungi are examples of…

spores

what are the 2 forms of nuclear division?

meiosis I and meiosis II

DNA in the original cell is replicated once during….

interphase

meiosis begins with

homologous chromosomes pairing up

what are chromosomes that are alike in size, shape, and genes. one homologue from each parent in a cell

homologous chromosomes

in prophase I, loose ------ coils up into visible chromosomes (replicated chromosomes)

chromatin

when homologous chromosomes pair it is called

synapsis

what is the exchange of genes between a chromatid on one homologous chromosome and another chromatid of the other homologous chromosome

crossing over

what is the result of crossing over

genetic recombination

what is genetic recombination

new gene combinations

what is a group of 2 homologous chromosomes (4 chromatids)

tetrad

in prophase I, ------ form

tetrads

in prophase I, ------- breaks down

nuclear envelope

in prophase I, ----- disappears

nucleolus

in prophase I, ------- forms

spindle

in metaphase I, ------- line up along the equator with the help of ------- fibers

tetrads, kinetochore

in metaphase I, where does kinetochore fiber attachment occur?

on each side of a tetrad

in anaphase I, ---------- pairs seperate toward opposite poles of the cell (------- splits)

homologous chromosomes, tetrad

each homologous chromosome still contains…..

2 sister chromatids

do centromeres divide in anaphase I?

no

in telophase I, ----------- gather at the poles.

individual replicated chromosomes

--------- divides the original cell into 2 cells

cytokinesis

each daughter cell is ---------- because it only contains one chromosome from each pair of homologous chromosomes

haploid

do chromosomes replicate between meiosis I and meiosis II?

no

in prophase II, chromosomes ------ only if they uncoil between meiosis I and meiosis II

recoil

in prophase II, new ----- forms around the chromosome in both cells.

spindle

in metaphase II, ------- chromosomes (not tetrads) align at the equator of both cells.

individual

in metaphase II, each chromosome still contains - sister chromatids

2

in anaphase II, ------ divide and ------ chromatids seperate

centromeres, sister

in anaphase II, sister chromatids are now called -------.

individual chromosomes

in telophase II, ----------- reforms around chromosomes

nuclear envelope

in telophase II, ------- reappears in each nuclei

nucleolus

in telophase II, -------- dissolves

spindle

in telophase II, chromosomes uncoil into ------

chromatin

cytokinesis occurs resulting in - total new cells. each is ------ and unique

4, haploid

n + 1 or n - 1 is an example of a….

bad gamete

formation of gametes

gametogenesis

formation of sperm via meiosis in male animal testes

spermatogenesis

creation of a ovum (egg) during meiosis in female ovary

oogenesis

random distribution of homologous chromosomes during meiosis (metaphase I)

independent assortment

in humans, - million gametes with different gene combinations could result

8

other than independent assortment, what are 3 other mechanisms that contribute to genetic variation?

crossing over, random fertilization, and mutations

in ---------- each pair of chromosomes sorts its maternal and paternal homologoues into daughter cells independently of the other pairs

independent assortment

the process of producing offspring

reproduction

produces recombinant chromosomes that carry genes derived from two different parents

crossing over

in asexual reproduction, - parent passes all of its genes to its offspring.

1

in asexual reproduction, their is no fusion of -------- cells

haploid

asexual reproduction produces ------

clones

organisms that are genetically identical to its parent

clones

how do prokaryotes produce asexually

binary fission

how do eukaryotes produce asexually

mitosis

an advantage of -------- reproduction is that it produces many offspring in short time, no need to find a mate or produce gametes

asexual

a disadvantage of ---------- reproduction is that DNA stays the same, not good in a changing enviroment

asexual

separation of a parent into 2 or more individuals of about equal size

fission

what is an example of fission

bacteria

body breaks into several pieces, developing into complete adults

framentation

what is an example of fragmentation

planarian

new individuals split off from existing ones, bud may break off or remain attached.

budding

what are examples of budding

hydra and sponges

fission, fragmentation, and budding are all examples of -------- reproduction

asexual

in sexual reproduction, - parents are present

2

in sexual reproduction, their is fusion of --------

haploid gametes

in sexual reproduction, offspring have traits of both parents, but are not --------- to either parent,

identical

--------- reproduce sexually

eukaryotes

an advantage of ------ reproduction is that they have genetic variation

sexual

------------ is key to evolution

genetic variation