How many total chromosomes are found in human cells?
46
How many of human chromosomes are autosomal?
44
How many sex chromosomes do humans have?
2
How many pairs of chromomes do humans have?
23
How many autosomal pairs do humans have?
22
What two chromosomes will cause a person to be female?
XX
What two chromosomes will cause a person to be male?
XY
How many pairs of sex chromosomes do humans have?
one
Why is it important for the total number of chromosomes to be reduced by half in gametes?
Because each parent will donate 23 chromosomes for a total of 46.
A single set of chromosomes that code for the same traits are known as:
homologous pairs
What is a karyotype?
an ordered display of chromosomes by size
Why would you utilize a karyotype?
to examine or assess issues in chromosome distribution or construction
True or False: As the number associated with the homologous pair increases, size of the chromosome, as well as the amount of data it encodes, decreases.
True
Is the amount of genetic information the same on all of our chromosomes?
no
Define a homologous pair.
Two chromosomes, one from each parent, that code for the same traits
Describe a replicated homologous pair.
A homologous pair after DNA replication where each chromosome has 2 sister chromatids.
A replicated homologous pair has a total of _____ sister chromatids.
four
Of the four chromatids that make up a replicated homologous pair, the two newly replicated chromatids are:
non-sister chromatids
Of the four chromatids in a homologous pair, the two that are identical in genetic data are:
sister chromatids
True or False: After replication the number of chromosomes is doubled.
False - the amount of DNA is double but the number of chromosomes is still 2n.
True or False: Of the four chromatids that make up a replicated homologous pair (2 sets of sister chromatids), all four code for the same traits.
True
Meiosis one results in two haploid cells each with how many chromatids?
46, two for each of the 23 chromosomes
Meiosis II results in four haploid gametes with how many chromatids?
23
How much genetic variation is possible in a gamete?
8.4 million (223) possible combinations
How many genetic combinations are possible in a zygote?
70 trillion (223 x223)
How does independent assortment create genetic variation?
chromosomes line up differently during metaphase
Describe "crossing over" in regards to genetic variation.
replicated homologous pairs form a synapse and information is exchanged between non-sister chromatids
When genetic information from "dad's" chromosome is exchanged with genetic information from "mom's" chromosome you have a process known as:
crossing over
What is a chiasma?
the site of genetic "crossing over"
Chromosomes that have swapped genetic data are then known as:
recombinant chromosomes
What is a major difference of interphase in meiosis from interphase in mitosis?
lack of a G2 subphase
When does DNA replication occur in a cell performing meiosis?
during the S subphase of interphase
What are the phases of Meiosis I?
prophase I
metaphase I
anaphase I
telophase I
What are the phases of Meiosis II?
prophase II
metaphase II
anaphase II
telophase II
List the six discussed characterstics of prophase I.
chromosomes begin to condense and become visible
homologous pairs begin to line up together
crossing over occurs
nuclear envelope fragments
early spindle formation
microtubules begin to attach
List the two events of metaphase I.
homologous pairs line up at the metaphase plate
microtubules attach to each of the homologous pairs
List the two major events of anaphase I.
contraction of microtubules pulls sisters pairs apart and towards the poles
cell elongates
True or False: During metaphase I, the non-sister chromatids move together as a unit.
False - the sister chromatids move together as a unit
True or False: In telophase I, each half of the cell contains a haploid set of replicated (sister) chromosomes.
True
Following Meiosis I, you have two cells with an n=23 but each chromosome has a:
sister chromatid
In which phase of Meiosis I are both sister chromatids attached to microtubules?
metaphase I
In which phase of Meiosis I are chiasmatas visible?
prophase I
In which phase of Meiosis I do chromosomes condense and become visible?
prophase I
In which phase of Meiosis I do the homologous pairs line up at the metaphase plate?
metaphase I
In which phase of Meiosis I does crossing over occur?
prophase I
True or False: Crossing over occurs during Meiosis I and Meiosis II.
False - only during Meiosis I
In which phase of Meiosis I do the homologous chromosomes separate and move towards the poles?
anaphase I
In which phase of Meiosis I do microtubules begin to attach?
prophase I
In which phase of Meiosis I does a single cell contain 2 haploid sets of chromosomes, one at each end?
telophase I
List the two major events of prophase II.
new mitotic spindle forms
any nuclear envelope that has formed fragments
List the two major events of metaphase II.
sister chromatids line up at the metaphase plate
microtubules attach to each sister chromatid
True or False: Independent assortment occurs during metaphase I and metaphase II.
True
List the two major events that occur during anaphase II.
cohesion proteins that bind sister chromatids are severed
individual chromatids are pulled towards the poles
List the two major events of telophase II.
mitotic spindle disappears
nuclear envelope forms
At the end of Meiosis II you are left with ______ gametes, each with 23 single chromosomes.
four
In which phase of Meiosis II do the chromosomes line up at the metaphase plate?
metaphase II
In which phase of Meiosis II do microtubules attach to sister chromatids?
metaphase II
In which phase of Meiosis II does the mitotic spindle begin to form?
prophase II
In which phase of Meiosis II does the nuclear envelope reform?
telophase II
In which phase of Meiosis II do we see the separation of sister chromatids?
anaphase II
In which phase of Meiosis II are sister chromatids pulled towards the poles of the cell?
anaphase II
True or False: Following telophase II you are left with four gametes each with an n=23.
False - after cytokinesis you have four gametes each with n=23
How many chromosomes will the cells contain after DNA replication.
46 - DNA is doubled by number of chromosomes stays the same
At the end of Meiosis I are the cells that result haploid or diploid?
haploid
How many chromosomes does a cell have at the end of Meiosis I?
23 - but each one has two sister chromatids
At the end of Meiosis II are the resulting cells haploid or diploid? How many chromosomes do they contain?
haploid. 23 - one of each
Compare nuclear division between mitosis and meiosis.
mitosis - 1 nuclear division
meiosis - 2 nuclear divisions
Which process, mitosis or meiosis, results in more daughter cells?
meiosis
True or False: Mitosis results in 2 daughter cells while meiosis results in 4 daughter cells.
True
Are the daughter cells produced during mitosis diploid or haploid?
diploid
True or False - Daughter cells resulting from meiosis are diploid.
False - they are haploid
Which process, mitosis or meiosis, yields genetically identical cells?
mitosis
What is the main similarity between mitosis and meiosis?
