Download 1/4 RR

Chapter 10
Figure 10.1a
Self-pollination
SELF-POLLINATION
Stigma (receives pollen)
Anthers
(produce pollen
grains, which
contain male
gametes)
Ovules (produce female gametes)
Figure 10.1b
CROSS-POLLINATION
1. Remove anthers
from one plant.
2. Collect pollen
from a different plant.
3. Transfer pollen
to a stigma of the
individual whose
anthers have been
removed.
Figure 10.2 upper
Phenotypes
Trait
Seed shape
Round
Wrinkled
Yellow
Green
Seed color
Pod shape
Inflated
Constructed
Pod color
Green
Yellow
Figure 10.2 lower
Phenotypes
Trait
Flower color
Purple
White
Axial (on stem)
Terminal (at tip)
Flower and
pod position
Stem length
Tall
Dwarf
Figure 10.3a
First half of reciprocal cross
…to stigma of
wrinkled-seeded
parent
Pollen from roundseeded parent…
All progeny have round seeds
Figure 10.3b
Second half of reciprocal cross
Round-seeded parent
receives pollen...
All progeny have round seeds
…from wrinkledseeded parent
Results of second generation
crosses



Mendel found that the recessive traits
reappeared in some individuals
He found 14,949 plants in his second
generation with the dominant trait and
5,010 with the recessive trait
This ratio of 2.98 to 1 suggests a threeto-one ratio
Figure 10.7
R = Dominant allele for seed shape (round)
r = Recessive allele for seed shape (wrinkled)
= Round-seeded phenotype
= Wrinkled-seeded phenotype
Mother
Rr
Female gametes
Father
Rr
Male gametes
R
r
R
RR
Rr
Rr
rr
r
Resulting genotypes: 1/4 RR : 1/2 Rr : 1/4 rr
Resulting phenotypes:
3/4
: 1/4
Chapter 9
Meiosis is a Special Type of Cell
Division that Occurs in Sexually
Reproducing Organisms

Meiosis reduces the chromosome
number by half, enabling sexual
recombination to occur.

Meiosis of diploid cells produces haploid
daughter cells, which may function as
gametes.
Figure 9.2a
Each chromosome replicates prior to undergoing meiosis.
Paternal
chromosome
Maternal
chromosome
Duplication
Sister chromatids
Centromere
Homologous pair of
premeiotic chromosomes
Figure 9.2b
Parent cell
contains
homologous
pair of
chromosomes
Homologs
separate
Sister
chromatids
separate
Four daughter cells contain one chromosome each.
These cells become gametes.
Daughter
cells
contain
just one
homolog
MEIOSIS II
MEIOSIS I
During meiosis, chromosome number in each cell is reduced.
Figure 9.2c
A full complement of chromosomes is restored during fertilization.
Female
gamete
Male
gamete
Fertilization
Diploid offspring
contains homologous
pair of chromosomes
Figure 10.7
R = Dominant allele for seed shape (round)
r = Recessive allele for seed shape (wrinkled)
= Round-seeded phenotype
= Wrinkled-seeded phenotype
Mother
Rr
Female gametes
Father
Rr
Male gametes
R
r
R
RR
Rr
Rr
rr
r
Resulting genotypes: 1/4 RR : 1/2 Rr : 1/4 rr
Resulting phenotypes:
3/4
: 1/4