AP Biology
Heredity (Meiosis and Gametogenesis) (Chapter 13)
Name: _________________________________
Big Idea 3: Living systems store, retrieve, transmit and respond to information essential to
life processes.
3.A.2 In eukaryotes, heritable
12.1, 12.2, 12.3
• Mitosis-promoting factor
information is passed to the next 13.1, 13.2, 13.3
(MPF)
generation via processes that
• Action of platelet-derived
include
growth factor (PDGF)
• Cancer results from disruptions
in cell cycle control
3.C.2 Biological systems have multiple processes that increase genetic variation. 13.4
1. How does asexual reproduction differ from sexual reproduction? (Campbell’s Activity
13A and Art Video on Hydra budding)
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
What are some examples of asexual reproduction?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
1
2.
Sexual Life Cycles
The human is an example of an organism that reproduces sexually.
We can observe human chromosomes by preparing a human karyotype:
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
Do the karyotyping activity - write up the answers to all the questions on the website activity.
2
What do we call the two chromosomes that make up a pair of chromosomes – one from each
parent? __________________________________________________________
3
What is the difference between autosomes and sex chromosomes?
_______________________________________________________________________________
_________________________________________________________________
What are gametes?
___________________________
___________________________
___________________________
___________________________
___________________________
__________________________
How many chromosomes are
carried by the human sperm?
_________ egg? _________
A cell such as the egg or sperm
that carries a single set of
chromosomes is referred to as a
_______________________ cell.
During sexual reproduction a
sperm and egg unite in a process called ___________________________ The resulting cell is
called a ____________________
How many chromosomes does the human zygote carry? _________________ Cells with two sets
4
of chromosomes are referred to as ____________________ cells. All the cells in your body, with
the exception of your eggs or sperm are _________________________.
What type of nuclear division produced all your body cells (somatic cells) from the original
zygote? __________________________________
Why is it necessary for the gametes (egg and sperm) to be produced by a different type of
division? _____________________________________________________________
What do we call the type of division that produces haploid cells from diploid cells?
___________________________________
5
3.
Describe some other examples of sexual life cycles: (*U3. relate meiosis to gametogenesis)
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
*U4. describe similarities and differences between gametogenesis in animals and in plants
____________________________________________________________________________________
____________________________________________________________________________________
6
*U9. Compare and contrast the results of meiosis and mitosis in plant cells (look at plant life cycles)
Meiosis results in spores (haploid) and mitosis results in new body cells.
The haploid spore grows into the haploid gametophyte.
The haploid gametophyte produces haploid gametes which fuse to form a
diploid zygote. The diploid zygote grows into a diploid sporophyte. Mitosis
continues for the sporophyte to increase in size.
*U10. Compare and contrast the results of meiosis and mitosis in animal cells (look at animal life cycles)
In animals meiosis results in gametes (haploid).
Mitosis results in new body (somatic) cells,
and the formation of the adult body from the fertilized egg,
repair of damaged cells,
asexual reproduction,
regeneration,
Mitosis is 2n to 2n.
Student self-study: Go to the following website, view the animation and/or the step through activity and
then do the quiz that follows http://www.sumanasinc.com/webcontent/animations/content/meiosis.html
Explain how meiosis reduces the number of
chromosomes in a cell from diploid to haploid
_____________________________________________
Chromosomes replicate in interphase.
In meiosis 1 homologous chromosomes
separate to form two haploid cells. One
replicated chromosome from each pair goes
to each of the new cells.
In meiosis II the sister chromatids separate
and result in 4 cells with one set of unpaired
chromosomes each.
7
3.
Outline the steps in meiosis: (See BioFlix on Meiosis and the Meiosis Animation in
Campbell’s 13B)
8
4. *U5. discuss the key mechanical and genetic differences between meiosis and mitosis
Page 256 and 257
9
*U6. describe how independent assortment and crossing over can generate genetic variation among the products
of meiosis
Student self-study: Go the following website, view the animation and do the quiz.
http://www.sumanasinc.com/webcontent/animations/content/independentassortment.html
(Act 13C)
Independent assortment
This is as result of the random orientation of homologous pairs of chromosomes on the metaphase plate
at metaphase of meiosis I. There is a 50% chance that a particular daughtrer cell will get the maternal or
the paternal chromosome of a homologous pair. Each maternal or paternal chromosome may orient
itself to face a given pole independently of every other pair. The number of possible combinations in
10
humans is 223 which equals about 8 million.
What happens during synapsis and crossing-over? (Campbell’s 13C)
4.
This occurs in early prophase when
homologous chromosomes pair loosely
along their lengths. Each gene is
aligned precisely with the
corresponding gene on the other
homologue. The DNA molecules of one
maternal and one paternal chromatid of
a homologous pair are broken at the
same place and then joined to the
other’s DNA.
How does crossing-over lead to
increased variation in offspring?
Since crossing over produces
recombinant chromosomes variation is
increased in offspring. Recombinant
means that the DNA is derived from 2
different individuals.
•
•
In crossing over, homologous portions of two nonsister chromatids trade places
Crossing over contributes to genetic variation by combining DNA from two parents into
a single chromosome
11
Mistakes made in meiosis
Student self-study: Go the following website, view the animation and answer the questions that
follow.
http://www.sumanasinc.com/webcontent/animations/content/mistakesmeiosis/mistakesmeiosis.html
What is non disjunction?
What may the consequences of non-disjunction be?
How does aneuploidy differ from polyploidy?
7.
Compare spermatogenesis and oogenesis
In spermatogenesis the embryonic cells of the testes differentiate into spermatogonia, the stem cells that
give rise to sperm. Spermatagonia divide by mitosis to produce primary spermatocytes which divide by
meiosis to produce haploid secondary spermatocytes. See next page
12
Spermatogenesis takes place in the testes:
Page 1008
In spermatogenesis, each diploid cell produces ___four__ haploid sperm cells.
13
Oogenesis takes place in the ovaries: Page1009
14
In oogenesis, each diploid parent cell produces ___________ haploid ovum (egg) and two nonfunctional _____________________ bodies.
15
*U1. describe features of meiosis which are important in sexual reproduction
1. Independent assortment of chromosomes increases variation by allowoing for missing of the maternal and
paternal genes that the gametes will carry.
2. Crossing over rearrages the genes that will be passed to the next generation.
3. Random fertilization adds to the genetic variation leading from meiosis as the fusion of a single male
gamete among millions will produce a zygote with 8 x 8 = 64 trillion variations.
*U2. explain how meiosis is important in heredity
•
•
•
•
Heredity is the transmission of traits from one generation to the next
Meiosis allows for a variation of traits to be passed to the next generation. There
will not only be a mixture of homologues but the chromosomes will also have
experienced changes.
The Evolutionary Significance of Genetic Variation within Populations
Natural selection results in the accumulation of genetic variations favored by the
environment
Sexual reproduction contributes to the genetic variation in a population, which
originates from mutations
16
Some links with animations:
Independent assortment
http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/independentassortment.html
Cell cycle
http://www.wisc-online.com/objects/index.asp?objID=AP13604
Mitosis and cytokinesis
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter11/animations.html#
Mitosis and Meiosis
http://www.lewport.wnyric.org/jwanamaker/animations.htm
Meiosis
http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html
17