Campbell Biology Chapter 13

reproductive cells that transmit genes from one generation to the next; sperm and eggs; haploid
gametes
the generation of offspring from a single parent without the fusion of gametes; DNA is copied and the offspring are exact copies of the parents; creates clones
asexual reproduction
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the generation of offspring from two parents that have unique combos of genes inherited from the two parents;
sexual reproduction
a pair of chromosomes that have the same length, centromere position, and staining pattern; control the same inherited characters; one chromosome from father and one from mother
homologous chromosomes
chromosomes not involved in determining sex; 22 pairs
autosomes
all cells of the body except the gametes; have homologous chromosomes
somatic cells
any cell with two chromosome sets (2n)

for humans, diploid number is 46

diploid cell
2 sets of 23 chromosomes for a total of 46
humans have how many chromosomes
a cell with one set of chromosomes

for humans, n=23 (22 autosomes and 1 sex chromosome)

haploid cell
a type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication; results in cells with half the number of chromosome sets as the original cell (haploid cells), counterbalancing the doubling that happens at fertilization
meiosis
homologs pair and segregate away from each other; cell division in meiosis that separates homologous chromosomes; after this, cells are haploid; reductional division
meiosis I
cell division in meiosis that separates sister chromatids; the chromosome number remains the same; equational division
meiosis II
recombination
What is important for the pairing of homologs?
shuffles genetic variants and holds homologs together until anaphase of meiosis
recombination
locations where crossing over occurs and two homologous chromosomes exchange genetic material
chiasma
synaptonemal complex and chiasmata
What holds homologs together?
chromosomes condense, homologous chromosomes pair (tetrads), crossing over, centrosomes move to opposite poles, spindle formation, nuclear envelope breaks down, recombination occurs
prophase I
the exchange of genetic material between homologous chromosomes’s nonsister chromatids;
crossing over
where nonsister chromosomes join and crossover
chiasmata
Paired homologs attached to a spindle line up at the metaphase plate
metaphase I
homologous pairs separate and move towards opposite poles of the cell
anaphase I
Homologous chromosomes are pulled to opposite poles and partitioned to daughter cells
cell splits (cytokinesis) and is now haploid; chromosomes disappear, nuclear envelope forms
telophase I
chromosomes condense, centrosomes move to opposite poles, spindle forms, nuclear envelope breaks down; no crossing over is done
prophase II
chromosomes align at equatorial plate (the two sister chromatids of a chromosome are not genetically identical)
metaphase II
cell elongates, sister chromosomes separate and move towards opposite poles as individual chromosomes
anaphase II
chromosomes disappear, nuclear envelope forms; cytokinesis; produces four daughter cells, each haploid
telophase II
one duplication of chromosomes
how are mitosis and meiosis alike?
1. crossing over/ genetic material exchange
2. pairing of homologous chromosomes at the metaphase plate (as tetrads in metaphase I)
3. Separation of homologs, two chromosome divisions (homologous pairs, then sister chromatids)
How is meiosis unique?
How do Mitosis and meiosis differ?
Meiosis goes through mitosis twice, results in 4 haploid gametes, one round of DNA replication and two rounds of division, and recombination and a paring of homologs. Mitosis results in only two diploid cells, one round of DNA replication and one round of division, and no recombination or paring of homologs.
How do Mitosis and meiosis differ?
no they don’t have the same DNA sequence, but they do have the same genes in the same order, but have different genetic variants
Do homologous chromosomes have the same DNA?
yes
Do sister chromatids have the same DNA?
23
Meiosis takes a cell and produces a cell with how many chromosomes?
Meiosis II
Is Meiosis I or Meiosis II like mitosis?
Meiosis II
In which Meiosis do sister chromatids separate?
Meiosis II
A mistake seen in two cells can occur during
Meiosis I
A mistake seen in 4 cells can occur during
Meiosis and recombination
What contributes to genetic diversity?
sexual reproduction through independent assortment, recombination, and random fertilization
What increases genetic diversity and how?
increases genetic diversity in metaphase I and shuffles chromosomes and creates gametes with unique combinations of genetic variants
independent assortment
individual chromosomes that carry genes derived from two different parents
recombinant chromosomes
meiosis I
homologous chromosomes move towards opposite poles of a dividing cell during
sister chromatids separate during anaphase
meiosis II is similar to mitosis in that
2x, x
if DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be…
What about the DNA content of a single cell at metaphase of Meiosis II?
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