ch 17

Human _____ have one X and one Y chromosome

males

homologs pairs matter in mitosis or meiosis ?

meiosis

Each set of 23 consists of 22 __________ and a single ____ chromosome

autosomes, sex

how many autosomes do we have from each parent and how many sex chromosomes do we have from each parent

22 autosomes and one sex chromosome from each parent

For humans, the haploid number is ___ (n = 23)

23

The 46 chromosomes in a human somatic cell are two sets of__: one from the mother and one from the father

23

egg and sperm cells only have ____ chromosomes each. when egg and sperm join to form you, you have ____ chromosomes and you're haploid or diploid?

23 46 diploid

whole process of spermatogenesis takes how long (days) for humans?

74

why is the polar body so small and the egg so big ?

Egg needs a lot of protein and food to grow into baby. Your egg needs to have all nutrients inside of it to turn nito a human body so it cant give more to the polar body (polar body is that little small circle)

Meiosis I is preceded by ____? -Interphase is identical to mitotic interphase, when the chromosomes are duplicated to form ____ ____.The sister chromatids are genetically identical and joined at the ______. -The single centrosome ________, forming two centrosomes -Division in meiosis I occurs in four phases, name them !

Interphase sister chromatids; centromere replicates -Prophase I -Metaphase I -Anaphase I -Telophase I and cytokinesis

errors in mitosis: ___________ :3 copies of a chromosome in a gamete ___________: 1 copy of a chromosome in a gamete you can determine if you have nondisjunction by ________ Karyotyping = looking at the ____________and appearance of chromosomes in the nucleus

Trisomy Monosomy karyotyping number

errors in mitosis: what is this disease? 47 chromosomes (XXX) In 1:1000 live births Little to no physical differences Can be infertile and/or have a learning disability Females are generally very tall Usually only discovered by karyotyping

Trisomy X

The sex chromosomes, which determine the sex of the individual, are called?

X and Y

name the phase: Like Mitosis: 1.Spindles ________, pulling chromosomes apart Unlike Mitosis: 1.Instead of single chromatids, _______ chromosomes are pulled apart (sister chromatids still remain together) 2.Proteins known as cohesins prevent sister chromatids from ____

anaphase shorten homologous separating

in ______ ________ a single individual passes genes to its offspring without the fusion of gametes

asexual reproduction

Germ cell division ends after ______. Therefore, once all of the germ cells are used up, there are no more eggs produced. (This rarely happens. Women are born with a lot of germ cells) As women age, these germ cells also _____. After 50+ years, most of these germ cells are no longer "healthy," and may have errors during _______/embryogenesis This is why babies born to older mothers have a higher risk of ______ defects.

birth age meiosis 2 genetic

Each pair of homologous chromosomes includes one ______ from each parent

chromosome

A _______ is a group of genetically identical individuals from the same parent

clone

In general, most pictures of chromosomes are during prophase, because at that point the chromosomes _______ and are visible under a microscope

condense

When tetrads are formed, homologous chromosomes can switch pieces. This is known as ______ ______, a type of genetic recombination, and produces offspring that are genetically _______ from parents. When does this stuff occur (what stage)?

crossing over; unique ; prophase

1.Unlike mitosis, at the end of meiosis I, the two daughter cells are NOT identical to each or to the parent cell due to _____ and _______ ______ 2.The daughter cells are now _______, meaning they have half the number of chromosomes as their parent cell (ex: daughter cells have 23 chromosomes in humans). This is a chromosomal _________

crossover ; independent assortment haploid reduction

mitosis is goos bc you can make a lot of the same cells when in need like when you

cut yourself

Spermatids do not have the "tails" usually seen on sperm. That is because spermatids later ________ into sperm cells. Cell differentiation is when a cell becomes a more _________ cell type. For human males, this differentiation occurs in the ______ cells.

differentiation specialized stertoli

A ______ cell (2n) has two sets of chromosomes

diploid

Through meiosis u take _____ cell and making it into haploid

diploid

meiosis : After chromosomes _______ (interphase), two divisions follow: -Meiosis I (reductional division): _______ pair up and separate, resulting in two haploid daughter cells with replicated chromosomes (bc cutting in half) -Meiosis II (equational division): sister ________ separate -The result is ____ haploid daughter cells with unique chromosomes

duplicate homologs chromatids 4

In an unfertilized ____ (ovum), the sex chromosome is X

egg

During meiosis I and II, the cell does not divide ________. One of the daughter cells is much larger and contains most of the ___________. This is the cell that will become the egg. The other daughter cells are known as ________ ________, contains chromosomes and very little else, and degenerate over time.

evenly; cytoplasm ; polar bodies

Three events are unique to meiosis, and all occur in meiosis I: -Synapsis and crossing over in prophase I: Homologous chromosomes physically connect and ______ genetic information -At the metaphase plate, there are paired homologous chromosomes (_______), instead of individual replicated chromosomes -At _______ I, it is homologous chromosomes, instead of sister chromatids, that separate

exchange tetrads anaphase 1

What is crossing over?

exchange of genetic material between homologous chromosomes

Human _______ have a homologous pair of X chromosomes (XX)

female

alternation of generations: Each spore grows by mitosis into a haploid organism called a ______ A gametophyte makes ________ gametes by mitosis _________ of gametes results in a diploid sporophyte

gametophyte ; haploid; fertilization

Plants and some algae exhibit an alternation of _____________ This life cycle includes both a diploid and haploid multicellular stage The diploid organism, called the ___________, makes haploid spores by meiosis

generations ; sporophyte

Mutations (changes in an organism's DNA) are the original source of _____ _______, and create different versions of genes called _______ However, the behavior of chromosomes during _______ and fertilization is responsible for most of the variation that arises in each generation Three mechanisms contribute to genetic variation: -Independent _______ of chromosomes -_________ over -Random _________

genetic diversity; alleles; meiosis assortment; crossing; fertilization

In genetics, the _____ number is designated as "n"

haploid

in a cell that has no homologous pairs, the cell would be... haploid or diploid?

haploid

A gamete (sperm or egg) contains a single set of chromosomes, and is haploid or diploid? Gametes are created by ___________.

haploid ; meiosis

one thing that's special about metaphase 1 of meiosis is that ____ ____ occurs!

independent assortment

Females are born with all of their egg germ cells. These germ cells will eventually go through _____ to become eggs (aka ovum)

meiosis

name the stage: Like Mitosis: 1.Chromosomes line up at the _______ plate by their association with spindle fibers at their kinetochore Unlike Mitosis: 1.Instead of single chromosomes, ______ line up at the metaphase plate 2.The chromosomes line up ______ of the other chromosomes. This is known as the Law of Independent Assortment- _________ in which side the chromosomes line up like for example whether moms chrom line up all on left side and dads all on right side ; gen recombination.

metaphase metaphase tetrads independently randomness

-In meiosis II, the chromosomes line up at the _____ ____ -During anaphase, the _____ ________ separate (break at the centromere)

metaphase plate sister chromatids

Meiosis can be thought of as cells undergoing _____ twice, but with a few key changes

mitosis

lacking chromosomes =?

monosomy

errors in mitosis: what disease is this? 45 chromosomes (X) 1:3000 live births. The only known survivable monosomy disorder. Only 1% of monosomy X babies survive until birth.

monosomy X : Turner syndrome

Sometimes meiotic division does not occur correctly. _________ occurs when chromosomes or chromatids do not separate during cell division in either half of meiosis - they create cells that add or lack ______

nondisjunction chromosomes

_______ is the creation of the egg, aka oocyte. A mature oocyte is known as an _______

oogenesis ovum

-In animal cells, a cleavage furrow forms; in plant cells, a cell ____ forms -No chromosome _______ occurs between the end of meiosis I and the beginning of meiosis II because the chromosomes are already replicated -So there isn't any real ______ between meiosis I and II

plate; replication interphase

for eggs, Meiosis I begins during embryonic development, but is halted at _______ I. After reaching puberty, during each ovulation cycle, meiosis continues until __________ II (in meiosis II). Meiosis II is only completed after _____________.

prophase metaphase fertilization

name this stage: Like Mitosis: 1.Chromosomes _____ and the nuclear envelope breaks down Unlike Mitosis: 1._____________ chromosomes are paired together as tetrads through a process called synapsis 2. ________ over occurs between Prophase I and Metaphase I

prophase 1 condense homologous crossing

Uneven division during meiosis is important for embryonic development. The larger ovum must be able to: 1.Have all the nutrients/_________in order to form a baby 2.Contain enough __________ to produce energy for the baby to form 3.Be large enough that it can -______ multiple times without limiting nutrients to each cell in the newly forming embryo (more on this later)

protein mitochondria divide

Sertoli cells secrete ______ that trigger sperm cells to get really long ________. Sperm cells contributes chromosomes and then ________.

protein; tails dies

oogenesis summary : Before birth: 1.Germ cells ________ to make lots of germ cells. 2.These germ cells begin _______ I, but stop after prophase. ● After birth, during ovulation: 1. One of the germ cells finishes ________ I, producing 1 oocyte and 1 polar body. The polar body can divide, but usually __________. 2.The oocyte beings meiosis II, but stops during/after ________. After the egg is fertilized: 1. The fertilized oocyte finishes meiosis II and begins ________

replicate meiosis meiosis degenerates metaphase embryogenesis

the 23rd chromosome determines your ______. does mom's or dad's chromosome dictate your sex ?

sex; dad's

In ____ _____, two parents give rise to offspring that have unique combinations of genes inherited from the two parents

sexual reproduction

rules for sexual reproduction : The alternation of meiosis and fertilization is common to all organisms that reproduce ________ The three main types of sexual life cycles differ in the ______ of meiosis and fertilization: Gametes are the only _______ cells in animals They are produced by _______ and undergo no further cell division before fertilization Gametes _____ to form a diploid ________ that divides by ______ to develop into a multicellular organism

sexually ; timing ; haploid ; meiosis , fuse, zygote; mitosis

Mitosis is great for cells that require a lot of cells for cell function, like _____ cells

skin

In a _____ cell, the sex chromosome may be either X or Y

sperm

Spermatogenesis is the creation of _________, and begins at puberty. In human males, this process is __________ (unless there are changes to hormone levels) After _______ II, the 4 ______ daughter cells are known as spermatids.

sperm continuous meiosis haploid

name this phase : Like Mitosis: 1.(For many organisms) Nuclear envelope reforms and chromosomes condense 2.Cytokinesis occurs due to formation of cleavage furrow/_____ contractile ring

telophase and cytokinesis 1 actin

During prophase, homologous pairs find each other and link together to form a ___

tetrad

So, in humans, at prophase I, there are 23 _______ in the cell.

tetrads

having an extra chromosome= ?

trisomy

Natural selection results in the accumulation of genetic ______________ favored by the environment Sexual reproduction contributes to the genetic variation in a population, which originates from _____

variation; mutations

In most fungi and some protists, the only diploid stage is the single-celled _______ there is no multicellular diploid stage The zygote produces _________ cells by meiosis Each haploid cell grows by _____ into a haploid multicellular organism The haploid adult produces ____ by mitosis

zygote; haploid; mitosis ; gametes

how much is in a tetrad

4

Meiosis is great for creating _______ in the gene pool (ex: sperm and egg)

variation

For humans, the diploid number is ___ (2n = 46)

46