Biology
1
Chapter
10
Mendel and Meiosis
Inheritance the
passing of traits by heredity
Heredity the
transmission of traits from _____________offspring
Gregor Mendel --
Austrian Monk who studied pea plants; the father
of ___________
Seven Traits of pea plants studied:
1.
seed
texture round, wrinkled
2.
seed
color yellow, green
3.
seed
coat color colored white
4.
pod
appearance inflated, constricted
5.
pod
color green, yellow
6.
flower
position on stem axial, terminal
7.
stem
length tall, short
q Mendel wanted to know if there was a _________________
pattern of inheritance
q He used mathematical statistics to analyze data
(___________________ data
counted results)
Dominant = the trait seen
Recessive = the trait masked
hidden
Genotype = the genes you have
Phenotype = what you look like
Complete dominance
homozygous dominant and heterozygous have same phenotype
B black BB-black
b white Bb
black
bb - white
q Therefore no middle or new color
Incomplete dominance
phenotype of heterozygous offspring somewhere halfway
between
parents
(red parent X white parent = pink
offspring) -Therefore a new trait or color is made
Codominance
phenotype of heterozygous offspring have both
parent phenotypes
equally
(black chicken X white chicken =
black and white checkered chicken)
Pure organisms that
__________ produce offspring with a certain allele (homozygous)
P1 parent generation = original
pure plants
F1 first filial generation =
kids
F2 second filial generation =
grandkids etc
Strain all plants ___________
for a specific trait
__________________ trait the trait
that is expressed
_________________ trait the trait that does not show up, that is masked
Gene a piece of DNA on a chromosome that _______________ a
particular trait
Allele contrasting
form of a _____________
Represented by letters:
T= tall
t= short
v
Dominant trait =
capital letter (T)
v
Recessive trait =
lower case letter (t)
Multiple alleles-
having 3 or _______ alleles for a trait (i.e. blood type, A, B, O, - alleles
Autosomes in humans
there are 22 pairs of autosome chromosomes
(all
chromosomes except ________
chromosomes)
Sex chromosomes the
23rd pair of chromosomes
q the last 2 chromosomes may be different ___________
q they control the sex of the offspring
Female
(___ ___)
Male (___ ___)
Sex-linked traits
traits controlled by genes found on ______ chromosomes (X or Y)
q color blindness > X-linked
q hemophilia -> X-linked
Polygenic inheritance
a trait controlled by 2 ____ ________
genes
q the genes may be on the same or different chromosome
(Humans skin color, height, hair color)
If you have an unknown organism, how do you
know its genetic make up?
_______________ a
cross of individual of unknown genotype, to an individual of
known homozygous recessive genotype
Carrier _______________
individual > looks like dominant trait but __________
recessive
gene
Pedigree a family
tree
Male-
Female -
Affected -
Mating -
Offspring -
Selective breeding / Artificial Breeding:
_______________ breed only individuals with ___________ trait to increase
probability of offspring having the trait desired.
Inbreeding mating between ___________ related individuals
can bring out harmful recessive
trait
(English Royal family
hemophilia; retriever dogs hip
disorder)
___________
the offspring of 2 closely related ___________
if both parents are pure bred often hybrid is larger and
stronger
v
(hybrid vigor = done in plants that give us food supply = bigger, hardier, more quantity of fruit per
parent plant)
The Sexual Cell Cycle
Meiosis-
v
Cell cycle that
produces ____________ via sexual reproduction
v
The process of cellular division that reduces the number of
chromosomes to half (gametes are 1n haploid)
v
Offspring are genetically _____________
v
_____ nuclear divisions occur in meiosis
v
Contains 4 phases
(occasionally 5)
§
Interphase
§
Meiosis I
§
(Sometimes Cytokinesis)
§
Meiosis II
§
Cytokinesis
A. Interphase- ___________ part of the cell cycle
1. G1 Cell doubles in size; organelles double in #
2. S (Synthesis) DNA Replication
3. G2 Rapid growth; Enzymes made for division
Draw this stage
B. Meiosis I (______ Nuclear
Division)
Four steps:
1.
Prophase I
a. DNA coils and becomes
chromosomes
b. Spindle apparatus forms
C. ____________ fibers
D. __________________ fibers
c. Nuclear envelope and nucleolus
disappear
d. 
Centrioles move apart
e. _______________ pairs line upsynapse
f. Form a tetrad where crossing over occurs
Crossing
over is responsible for genetic variety
Draw this stage
Crossing Over
2. Metaphase I The tetrads (homologous pairs) line up at the
___________________ _____________
Draw this stage
3. Anaphase I The homologous pairs __________(one to each pole) by
the pulling apart of the
kinetochore fibers
Draw this stage
4.
Telophase I
a. Cytoplasm divides
b. Organelles separate
c. Cleavage furrow forms
Draw this stage
C. Cytokinesis Optional here
2 complete intermediate daughter cells still 2N
You may wish to draw this stage
D. Meiosis II (_____ Nuclear division)
No gene replication in these stages
Structures form perpendicular
to previous structures
1.
Prophase II
a. New spindle fibers form
b. Nuclear envelope not apparent
Draw this stage
2.
Metaphase II
a. Chromosomes move to metaphase
plate
b.
The centromere of the sister chromatids splits
Draw this stage
3.
Anaphase II
a.
Kinetochore fibers
pull _________ ____________ to opposite
sides of cell
b.
Organelles separate
Draw this stage
4.
Telophase II
a.
Spindle fibers
dissolve
b.
Nucleus and nucleolus reform
c.
Cleavage furrow forms
Draw this stage
E.
Cytokinesis
a.
Cleavage furrow deepens with continued invagination
b. Complete separation of ___ genetically __________ daughter cells (all, ____)
Draw this stage