chapter 5 Section 3 Notes
17e - compare and contrast the outcome of meiosis and mitosis
17f - recognize that selective breeding can produce plants or animals with desired traits
(GPS)
What are the main events that take place in Meiosis?
What is the end result and purpose of Meiosis?
What is the difference in cell division in Mitosis and Meiosis?
What methods are used to produce animals or plants with desired traits?
What is the difference between inbreeding and hybridization?
How are these artificial selection instead of natural selection?
Recall from 26-1
Asexual ________________________ has only ______parent and produces
offspring _______________ to the parent
– Processes of….
• Mitosis (in body or somatic cells)
• ____________fission
• Budding
• ___________________
Sexual Reproduction=The reproductive process that involves ______ parents who
______________________ their genetic material to produce a new organism,
which________________ from both parents.
• Meiosis creates the sex cells (_________________) that are used in sexual
reproduction.
– Gamete examples: ___________, egg, pollen, _________
Sutton: a scientist who ________________ that the number of
______________________ in sex cells (gametes) was __________that of the
number of chromosomes in ____________ (somatic) cells.
• so during __________________ - each sex cell will contribute half (called
haploid) of the________________ number of chromosomes so when the
sex _______ combine to produce offspring, the resulting cell will have the
_____________ normal number of chromosomes (called diploid)
• Sutton __________________ that chromosomes carried Mendel’s
hereditary ____________ (genes).
Chromosome ____________ of inheritance: genes are ____________ from
parents to their __________________on chromosomes.
Chromosomes are made up of a large number of ________ joined together
• Each chromosome has a ___________________ chromosome that codes
for the _________ genes (called homologous chromosomes)
• Offspring _______________one chromosome in a ______ from each
parent.
Homologous= similar in structure
Homologous chromosomes= chromosomes which _______ for the same genes
-________ match up to form ______ for a ___________
•
•
•
In a pair, ___________________ are made up of the same genes, lined up
in the same ___________ (see pg 76 in wkbk)
And the different ______ of the genes in the pair are called alleles.
Recall-the pair of alleles can be the same (__________________) or they
may be _________________ on one of the pair than on the other
(________________________)
*Sex cells have ______________ the number of chromosomes so that when
___________________ occurs it restores the ______________ number of
chromosomes.
Sex cells
 in humans and other animals…
-sperm (define)
-egg (define)
 Plants
• _______sex cell is pollen, on the anther
• Female sex cell is the _____, in the ovary
• Fertilized ova becomes the _______.
•
Sex cells are _____________ with only half (haploid) the normal number
of chromosomes through the ______________of meiosis.
Meiosis= the process by which the ____________ of chromosomes is reduced
by _______to form _______ sex cells.
-Each sex cell gets only ________ chromosome from each
homologous ____________
• Two _______________ (I and II)
-each division includes a ________________, metaphase,
anaphase and ____________________
• Interphase 1
-chromosomes are ______________(forms sister chromatids,
connected by ________________) called double stranded
chromosomes (X shape)
• Prophase 1
- Chromosomes ______________ and centrioles form
• Metaphase 1
-_____________________ chromosome _________line up in
center of cell
• Anaphase 1-the homologous pairs ____________ and are distributed to
two different ___________.
-Each chromosome is still ______________ stranded
-two new cells are formed each with half the ___________ of
chromosome (Telophase 1)
• Metaphase 2-double ____________chromosomes line up in _____
• Anaphase 2 then the ________________ split at the centromeres and go to
_______________ ends (forming ___________stranded chromosomes)
• Telophase 2 = new ____________form
•
•
Cytokinesis = each cell ___________ into two
End Result: produces ________sex cells, each with _______the normal
(_______ cell) number of chromosomes.
• Males produce ________sperm cells
• Females produce ______egg and 3 polar _________ (the egg gets
all the _______________ and cell organelles, polar bodies are
mostly _________)
So, during _________________reproduction only _______allele for each trait is
passed onto the _________________ from each parent.
• Gametes are ______________ (half the chromosomes)
• After _______________ the cell is again _____________(normal number)
(46 for us)
• Each offspring inherits a total of _______ alleles for each gene, one from
each _____________.
How is Gender determined?
• _______________ of an offspring is determined by a specific _______ of
chromosomes (called sex ___________________)
• humans can have ______ X chromosomes (female)
• or one X & one Y chromosome (__________)
•
Sex chromosomes are the _________ of chromosomes that determine the sex
(gender) of an ________________.
• Females receive two X _______________ chromosomes for the 23rd pair
(therefore females can only ___________________ an X to the egg)
• Males ___________one X shaped and one Y shaped chromosome.
• Eggs ___________________ with an X will be a female
• Eggs fertilized with a Y will be a _____________
Gender linked ____________:
Sex-linked genes- {define}
• -traits controlled by these ___________are called sex-linked traits
• The X and Y chromosome are _______________shapes
• the Y ________________is ‘missing’ part of the alleles, so male
_______________ may only have one ____________for a trait
• a _______________________ allele on the X chromosome will produce
the trait in a male since there is _____ dominant allele to _________ it.
• therefore males are more likely to ____________ a sex-linked trait than a
________________.
• females must have two _________________ alleles (one from each
parent) for it to be expressed/visible (so very ________).
• EX: colorblindness, hemophilia
Carrier = {define}
• carrier does not ________ the trait but can _________ the trait to
offspring.
How can we determine if a trait runs in a family?
• Pedigree = {define}
•
-sex-linked traits often ________ generations in a pedigree, because a man
_____________ the gene to his daughters, who are _____________, and
they may pass it on to their _________ who show the trait.
Fertilization and Development
After fertilization (define) the zygote (define) begins to divide by
__________________ to grow into a ____________ organism.
• First it divides into ______ cells, than _____, than eight and so on.
• All by mitosis.
• After there are ________ cells, each cell differentiates and becomes a new
kind of ________ cell (skin, nerve etc)
• Each cell type divides to make ___________.
• Different tissues ___________ to create _________.
Once the growing mass of _________________ of cells forms a ________ ball,
It is than called an embryo for about the next ten _________.
• Embryo= {define}
-implantation to 10 wks in humans.
Fetus = {define}
• From the _________ week on until birth, the ____________ is called a
fetus.
Gestation period= the ________ from fertilization to __________
• -different for all _______________
• -about _______months in humans
Identical __________ occur when the zygote cell ____________ all the way to
produce two ________________ each with ____________ chromosomes and
genes. also called ____________ or ‘from one zygote’.
• ________________can change their appearance so they don’t ______
exactly alike. DNA is identical.
•
Fraternal twins occur when there are ______ eggs released and fertilized by two
______________sperm. They are no more ________ than regular siblings.
• Also called Dizygotic twins (two Zygotes)
Selective Breeding= Artificial Selection = organisms with ___________
characteristics are _________ to produce desired ________________ in the
offspring.
• focus on increasing the __________ of the plant or ___________ to
people.
• Ex: cows ______ to produce more milk;
-fruits and vegetables bred to resist ______________
ex: corn
-pets bred for desired traits
2 types of selective breeding: Inbreeding and Hybridization
Inbreeding = _______________ individuals with the same traits to produce
offspring with those same traits.
•
•
•
•
•
Produces homozygous/purebred individuals
_________is to produce species with _____________ traits
EX: disease resistance, more milk, specific color flowers, coat color,
height, fruit color.
increases the ____________________ that organisms may inherit alleles
that ________ to genetic ________________
_________________ an offspring’s chances of inheriting _______ allele
combinations (therefore ________________adaptability,
_______________ and genetic diversity)
Hybridization = crossing individuals to get _______ or more desired
characteristics/traits in ______ animal
• -result is an offspring that has the _______ traits from both parents.
• -problem is the ____________cannot control whether the desired
___________will be passed from parent to offspring.
• Most often used in ____________________ to make better _____ crops
and livestock.
Breeders Use hybridization ______to gain desired traits
•
And then inbreeding of __________________ with the desired traits to
produce more offspring with those _________ (purebreds).