chapter 11: genetics. 1. asexual reproduction a. a single celled organism undergoes ______________...
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Chapter 11: Genetics
1. Asexual Reproduction
a. a single celled organism undergoes ______________ to create 2 identical offspring
b. prokaryotes undergo ______________ to create 2 identical offspring
2. Sexual Reproduction
a. ______________ must occur between 2 specialized
reproductive cells (gametes).
b. ______________ - the division of a cell to create gametes with __ the genetic information of a normal cell
______________ – the passing of characteristics or traits from one generation to the next.
binary fission
Heredity
fertilization
mitosis
Meiosis
1/2
identical
Genetically Different
11-4 Meiosis A Purpose of Meiosis
a ________ gametes – ____________ divisionb genetic ______________
1 crossing over2 independent assortment
Chromosome # Somatic Cell Gamete
DiploidHomologous Pairs
Diploid HaploidNo Homologous Pairs
Homo sapianHumans
DrosophilaFruit Fly
Pisum sativumCommon Pea
reduction
variation
2n 2n n
46 46 23
8 8 4
12 12 6
B. Phases of Meiosis – Interphase Meiosis 1Meoisis II
1. Interphase – a. G phases (G1 & G2) - cell growth, protein
synthesis organelle productionb. S phase - DNA replication
2. Meiosis I – segregation of __________
PROPHASE I•homologous pairs form _________
•nucleus and nucleolus _________•_______________ occurs•2n, duplicated
Prophase I
tetrads
disappearcrossing over
Homologous pairs
Interphase I
Metaphase I
METAPHASE I•spindle fibers attach•tetrads____________
*Independent Assortment
ANAPHASE I•homologous pairs (alleles) _____________ (segregate)
*Principle of Segregation
Anaphase IProphase I
line up
separate
Interphase I
TELOPHASE I (with cytokinesis)•nuclear membrane reforms•2 ______________ daughter cells
•______________ •1n, duplicated
Prophase I Metaphase I Anaphase I
Telophase I
(with cytokinesis)
haploidnot identical
Interphase I
Prophase II Metaphase II Anaphase II Telophase II (and Cytokinesis)
o nucleus and nucleolus disappear
o 1n, duplicated
o sister __________line up
o spindle fibers attach
o sister chromatids ____________
o nucleus reforms o ______________ daughter cells (__________) o 1n, unduplicated o genetically unique
3. Meiosis II – separation of _________________ sister chromatids
chromatidsseparate
4 haploidgametes
C. Formation of Gametes
1. Female – ______________
a.____ haploid cells are produced
1 1 viable cell (gamete) = ___________
2 3 __________ due to unequal distribution of cytoplasm and organelles
2. Male – Spermatogenesis
a. 4 viable cells (gametes) = ______________
oogenesis4
eggpolar bodies
sperm
http://wps.prenhall.com/esm_freeman_biosci_1/7/1957/501052.cw/index.html
The human life cycle
Room for sketch in notes
Com
parison of Mitosis
and Meiosis
*Handout
http://biologyinmotion.com/cell_division/
Mitosis Meiosis
Number of daughter cells
Type of cells produced
Number of divisions
Number of DNA replications
Purpose of division
2 diploid cells
1
1
Growth, repair, asexual reproduction
gametes
2
1
4 haploid cells
Sexual reproduction, genetic variation
Somatic Cells/Body cells
11-1 The Work of Gregor Mendel
A. Gregor Mendel’s Peas1. Mendel (1822-1884)
a. a priest, mathematician, scientist and teacher
b.experiments with ________laid the foundation for the science of genetics
pea plants
2. The Common Pea (Pisum Sativum)
a. Monoecious – a plant have both male and female sexual parts (________________)b. Self Pollinating – The sperm cells pollinate the eggs cells of the ______________ c. True- breeding – the plants produced offspring ______________ to themselvesd. Mendel ___________ these flowers to see what would happen
stamen/pistil
same plant
identicalcross pollinated
B. Mendel’s Discoveries
1. Mendel crossed plants with contrasting traits to study the outcome (yellow seed x green seed)
2. P – parental (true breeding) yellow seed x green seed
F1 – filial (hybrid) the result of a P cross
all offspring came out yellow
Mendel’s Traits
Seed Shape
Flower Position
Seed CoatColor
Seed Color
Pod Color
Plant Height
PodShape
Round
Wrinkled
Round
Yellow
Green
Gray
White
Smooth
Constricted
Green
Yellow
Axial
Terminal
Tall
Short
Yellow Gray Smooth Green Axial Tall
2 CONCLUSIONS:
1. Factors (genes) have different forms (alleles)
ex. seed color – gene; green and yellow - alleles
2. ________________________: a. Some alleles are dominant and others are
recessive
b. Dominant, Y (capital letter), Recessive, y
(lower case)
Principle of Dominance
3. Were the recessive alleles gone forever?
a. Mendel crossed the hybrid plants of all 7 crosses F1 x F1 to produce the F2 generation.a. F1 Yellow x F1 Yellow = F2 about ¼ of the
plants were ____________ and the rest were yellow
b. The trait reappears. c. ____________________________:
a. At some point the allele for yellow seeds and the allele for green seeds are segregated
b. ______________: This occurs during the formation of gametes, every gamete carries only ______________ of the gene
Principle of Segregation
green
Meiosis I
one copy
(one allele)
11-2 Probability and Punnett Squares
A. Genetics and Probability
1. Probability can be used to predict genetic crosses.2. When alleles segregate, it is random much like
the toss of a coin. 3. Past outcomes cannot predict future outcomes.
1. Every time you flip a coin you have a ½ chance of getting heads.
2. What is the probability of flipping heads twice in a row? three times?
½ x ½ = ____ ½ x ½ x ½ = ______
4. The larger the number of tries (offspring), the more likely the predicted numbers are accurate
1/4 1/8
B. Punnett Squares1. A way to determine the probable outcomes of genetic crosses.2. Punnett Square Vocabulary:
(using attached and free earlobes) Homozygous (true breeding) – both alleles are the
same ex. ______________ Heterozygous – having 2 different alleles ex. ______________ Genotype – the actual genes, alleles carried ex. ______________ Phenotype – the physical characteristic ex. __________________________
FF, ff
Ff
FF, Ff, ff
free or attached
True Breeding Cross:
Two true breeding plants are crossed (P), a yellow seed (YY)with a green seed (yy). Show the probable offspring (F1)using a Punnett square. Parents:_________ Possible Gametes: _______ x ________
F1:
YY x yyY, Y y, y
Y
Yy
Yy
Yy
Yy
yy
Y
Genotype:
100% Yy
Phenotype:
Yellow Seeds
Gamete
s
Hybrid Cross: Two F1 hybrid yellow seed plants are
crossed. Show the probable offspring (F2) using a Punnett square.
F1: ___________ Possilble Gametes:______x _______
F2:
Yy x YyY, y Y, y
Y
y
Y y
YY Yy
Yy yy
G 1:2:1
YY - 25% - yellowYy - 50% - yellowyy - 25% - green
P 3:1
11-3 Exploring Mendelian Genetics
A. Independent Assortment1. Mendel wondered if one gene or pair
of alleles had an affect on another pair. ex. Does seed shape affect the color
of the plant?
2. To illustrate what Mendel was attempting a ______________is used.Dihybrid Cross
True Breeding Dihybrid Cross (2 Factor Cross)
A homozygous round, yellow seed plant is crossed with a homozygous wrinkled, green seed plant.
P: ______________1. Make possible gametes FOIL method2. ______________ x ______________
1. Place gametes on the axis of the Punnett Square1. Cross the gametes
F1: _________
genotype: _____________ phenotype: _____________
RRYY x rryy
RY, RY, RY, RY ry, ry, ry, ry
RY
RY
RY
RY
ry ry ry ry
RrYy100% RrYy
RrYy
Round, yellow
RrYy RrYy RrYy
F1 Dihybrid Cross (2 Factor Cross)
Cross the F1 generation from the true breeding dihybrid cross.
F1: ______________1. Make possible gametes FOIL method2. ___________x________3. Place gametes on the axis of the Punnett Square4. Cross the gametes
RrYy x RrYy
RY, Ry, rY, ry RY, Ry, rY, ry
RY
Ry
rY
ry
RY Ry rY ry
F1 Dihybrid Cross (2 Factor Cross)
RRYY RRYy RrYY RrYy
RRYy RRyy RrYy Rryy
RrYY RrYy rrYY rrYy
RrYy Rryy rrYy rryy
RY
Ry
rY
ry
RY Ry rY ry
genotype phenotype1RRYY, 2RrYY, 4RrYy, 2RRYy = ____ round yellow1RRyy, 2Rryy = ____ round green2rrYy, 1rrYY = ____ wrinkled yellow1rryy = ____wrinkled green
F2: 9:3:3:1_______________Phenotypic ratio
9
331
Mendel’s actual F2 generation had a ____________________.
Did they sort independently? _____. Seed color and texture were not
connected to each other. All of the traits that Mendel worked with
were on different _______________. They illustrate the idea of
______________________________. What happens if two genes are on the
same chromosome? They can be _______________. the _______________ out the gene is on the
chromosome, the higher chance it can be switched ______________________.
the _______________ genes are to each other, the more likely they are to be linked
similar ratio
YES
chromosomes
Independent Assortment
linkedfarther
during crossing overcloser 2
OVERVIEW: Principle of Dominance
One allele will be _______________ over another allele
FF, ff, Ff Law of Segregation
The different traits/alleles from each parent are _______________ from each other (homologous pairs)*
_______________ Independent Assortment
Different genes located on different chromosomes sort independently from one another.
_______________ Ex. _________________________
________________
expressed
separated
Anaphase I
Metaphase IYellow seeds are not always smooth
B. Beyond Dominant and Recessive
1. Incomplete Dominance – the phenotype of heterozygous individuals are a _______________ of the 2 alleles
ex. 4 o’clock flowers
blending
Incomplete Dominance in Four O’clock Flowers
Incomplete Dominance in Four O’clock Flowers
2. Codominance – both alleles are_______________but not blended
ex. chicken feathers, human blood types and cholesterol
expressed
3. Multiple Alleles – there are more than _______________for 1 gene
ex. rabbit coat color, human blood type
2 alleles
4. Polygenic Traits – ________________________ gene contributes to a characteristic
ex. skin color, eye color, weight and hair color in humans
More than 1
**Usually associated with a characteristic that has a range of phenotypes
Karyotype
http://www.genomenewsnetwork.org/resources/whats_a_genome/Chp1_2_1.shtml
Crossing Over
Section 11-4
Crossing-Over
Go to Section:
Crossing Over: exchange of genetic material between homologous pairs of chromosomes
Section 11-4
Crossing-Over
Go to Section:
Crossing Over
Section 11-4
Crossing-Over
Go to Section:
Crossing Over
Free and Attached Earlobes