Topic: Genetics
Aim: Explain the basic principles of genetics.
Do Now: Take out your metamorphosis ISA.
HW: Genetics Reading notes due tomorrow.
1. Identify structure X. Support
your answer. Pollen tube
2. Describe the function of the
structure X.
•Enables POLLEN (sperm
nuclei) to travel into the ovary.
3. Why do the sperm nuclei travel
into the ovules?•For fertilization.
4. Describe what occurs to the
flower once all eggs in the ovary
are fertilized.
•Ovules turn into seeds.
•Ovaries turn into fruit.
1.Identify all structures labeled in the diagram.
2.Describe the function of structure C.
seed coat B
embryoA
C
cotyledon
Stores food for
embryo
An adaptation for reproduction in
most terrestrial organisms is
(1) regeneration
(2) internal fertilization
(3) mitosis
(4) external fertilization
External fertilization occurs
most often in
1. mammals and birds
2. reptiles and birds
3. amphibians and reptiles
4. fish and amphibians
Which represents binary fission?
Support your answer.
1. Identify • Gregor Mendel
the
founder of
genetics.
2. Identify
the organism
Mendel
investigated.
• Pea plants
3. Identify
• Genetic inheritance
what Mendel
investigated?
Identify the traits Mendel observed when working with
pea plants.
A
B
F
C
D
G
E
4. Explain • To predict the probability and
what a
outcome of genetic inheritance
Punnett
Square is
used for.
5. Identify
what genes
consist of.
• Alleles or alternate forms of
the same gene
Gene
B
A
Replicated chromosome
C
DNA
1. Identify the two alleles for eye color in fruit flies.
2. How many alleles are necessary for this trait?
6. How are
alleles
expressed?
• As dominant OR
recessive
7. Describe • The genetic makeup of an
genotype.
organism.
8. Describe • The observed
phenotype.
characteristics of an
organism.
9. Identify • Color
some
• Shape
examples of
phenotype. • Size
• Behavior
10. Describe • Phenotype depends on
the
genotype.
relationship
between
phenotype
and genotype.
(What does
phenotype
depend on?)
Bb
Brown
Explain the meaning of this statement.
11. How
many alleles
represent
the genes
for a trait?
• TWO
Gene
from
dad
Gene
from
mom
12. Identify
the letter
representing
a dominant
gene.
• Capital letter
•B
13. Identify
the letter
representing
a recessive
gene.
• Lower case letter
•b
14. Describe • 2 alleles or genes that are
what a
the same
homozygous
•
Ex:
BB
or
bb
pair of alleles
consists of.
15. Identify
the pair of
alleles that
consist of
two dominant
genes.
• Homozygous dominant
• Ex: BB
16. Identify
the pair of
alleles that
consist of
two
recessive
genes.
• Homozygous recessive
• Ex: bb
17. Identify • One dominant and one
what a
recessive gene
heterozygous
•
Ex:
Bb
pair of alleles
consists of.
18. Identify
another term
with the same
meaning as
heterozygous.
• Hybrid
19. When will • It is always expressed
a dominant
unless there are two
gene be
recessive genes.
expressed?
• Ex:
– BB
– Bb
20. When will • When there are two
a recessive
recessive genes.
gene be
•
Ex:
bb
expressed?
The allele for
brown eyes is
dominant. The
allele for blue
eyes is
recessive.
Why does Bb
combination
result in brown
eyes and not
blue?
1. The trait for height in pea plants can be
represented by using the letter “T.” T represents the
allele for tall and t represents the allele for short.
a. What do we call the genotype for TT?
Homozygous dominant
b. What is the phenotype for TT? Tall
c. What do we call the genotype for tt?
Homozygous recessive
d. What is the phenotype for tt ?short
e. What do we call the genotype for Tt ?
Heterozygous
f. What is the phenotype for Tt ? tall
2. The trait for seed color in pea plants can be
represented by using the letter “G.” G represents the
allele for green seeds and g represents the allele for
yellow seeds.
a. What do we call the genotype for gg?
Homozygous recessive
b. What is the phenotype for gg? yellow
c. What do we call the genotype for Gg?
Heterozygous
d. What is the phenotype for Gg? green
e. What do we call the genotype for GG?
Homozygous dominant
f. What is the phenotype for GG? green
3. The trait for seed shape in pea plants can be
represented by using the letter “R.” R represents the
allele for round seeds and r represents the allele for
wrinkled seeds.
a. What do we call the genotype for rr?
Homozygous recessive
b. What is the phenotype for rr? wrinkled
c. What do we call the genotype for Rr?
Heterozygous
d. What is the phenotype for Rr? Round
e. What do we call the genotype for RR?
Homozygous dominant
f. What is the phenotype for RR? Round
4. The trait for flower color in pea plants can be
represented by using the letter “P.” P represents the
allele for purple flowers and p represents the allele
for white flowers.
a. What do we call the genotype for pp?
Homozygous recessive
b. What is the phenotype for pp? White flowers
c. What do we call the genotype for Pp?
Heterozygous
d. What is the phenotype for Pp? Purple
e. What do we call the genotype for PP?
Homozygous dominant
f. What is the phenotype for PP? Purple
Conclusion Questions:
1. Contrast genotype and phenotype.
Genotype is the genetic makeup of an organism,
phenotype is the observed characteristics.
2. Contrast a homozygous pair of alleles and
heterozygous pair of alleles.
Homoszygous is two of the SAME alleles.
Heterozygous are two different alleles.
3. Identify the 3 possible genotype combinations
(NAMES, NOT LETTERS)
Homozygous recessive
Homozygous dominant
Heterozygous
DOMINANT
F
RECESSIVE
f
DOMINANT
H
RECESSIVE
h
W = widow’s peak
w = straight hairline
P = bent pinkie
p = straight pinkie (cannot bend
inwards)
E = attached earlobes
e = unattached earlobes
R = Rolling of the tongue
r = cannot roll tongue
C = Cleft chin
c = smooth chin
D = Dimples
d = Without dimples
Let’s summarize…
1. Explain what is studied in genetics.
2. Who is the father of genetics? What did
he use in his experiments?
3. How many alleles are needed for every
trait?
4. Explain the difference between a dominant
and recessive gene.
5. Explain the difference between genotype
and phenotype.
6. Explain the difference between
homozygous and heterozygous.
Sometimes tens, or even
hundreds of genes can play a
role in just one trait!
Melanin, a brown pigment, is
controlled by the following
genes:
• brown-blue gene on
chromosome 15
• green-blue gene on
chromosome 19
Another brown-type gene was
also discovered on
chromosome 15.
Recently, a gene for a brownish
yellow pigment, lipofuscin,
that appears in amber, green
and violet irises was
discovered.
And there's likely at least one
other gene, not yet located,
that plays a role in iris color.
Goldfish have 96 chromosomes in each cell
while humans only have 46. Dogs have 78
chromosomes. And here’s the real shocker, a
fern has 512 chromosomes.
You can easily see that the
skin on your fingertips is
folded into patterns called
dermal ridges. They form
whorls, arches and loops. The
# of dermal ridges in a
fingerprint pattern is
determined by genetics, but
the pattern can also be
changed early in pregnancy.
During weeks 6-13, the fetus
touches the finger and toe
pads to the wall of the
amniotic sac which sometimes
can alter the ridge pattern.
This is why the fingerprints of
identical twins are not exactly
alike, even though they have
identical genes.